The process of rice(Oryza sativa L.)seedling cultivation is often subjected to adverse environmental stress.Biostimulants regulate the robust growth of rice seedlings and play a crucial role in promoting the green and...The process of rice(Oryza sativa L.)seedling cultivation is often subjected to adverse environmental stress.Biostimulants regulate the robust growth of rice seedlings and play a crucial role in promoting the green and ecological development of agriculture.In this study,1.0 and 2.0 g•m^(-2) of the biostimulant were applied to soil in rice seedbeds.Growth indicators of rice,antioxidant enzyme activities and soil physicochemical characteristics were assessed at the 2.5-leaf and 4-leaf stages of rice.The results indicated that applying 2.0 g•m^(-2) of the biostimulant at both the 2.5-leaf and 4-leaf stages had the most significant promoting effect on rice growth.At the 2.5-leaf and 4-leaf stages,the number of fibrous roots increased by 23.43%and 22.25%,stem base width increased by 19.05%and 19.58%,above ground dry weight increased by 18.09%and 16.47%,root dry weight increased by 19.67%and 18.28%,leaf peroxidase(POD)activity increased by 34.44%and 42.94%,superoxide dismutase(SOD)activity increased by 37.24%and 56.79%,malondialdehyde(MDA)content decreased by 18.60%and 27.67%,and chlorophyll content increased significantly by 28.31%and 34.24%,respectively.At the 4-leaf stage of rice,urease,phosphatase and cellulase activities in the seedbed soil increased by 42.13%,25.96%and 33.59%,respectively,while soil alkaline nitrogen,available phosphorus and available potassium content decreased by 19.76%,19.02%and 17.88%,respectively.The application of biostimulants played a crucial role in promoting the growth of rice seedlings and enhancing soil nutrient absorption.展开更多
Hedysarum laeve Maxim. (Leguminosae) is one of the major species used frequently in revegetation of dune_field in the sandlands of the northern part of China by means of aerial sowing. Seedlings of the species after e...Hedysarum laeve Maxim. (Leguminosae) is one of the major species used frequently in revegetation of dune_field in the sandlands of the northern part of China by means of aerial sowing. Seedlings of the species after emergence above the sand surface may be buried in sand to various depths during its establishment in late spring and early summer. A study was made to examine the effects of sand burial at different levels of 0 (control), 33%, 67%, 100% and 133% of their shoot height, on the survivorship, growth, and biomass allocation pattern of H. laeve seedlings (one and two weeks old after emergence). When burial depth was up to 100% of their shoot height, about 70% seedlings died; and the burial at depth of 133% of their shoot height led to death of all seedlings. When seedlings was buried at depth of 33% and 67% of their shoot height, respectively, after six_week growth, their biomass of whole plant, blade, and root and relative growth rate were higher than the unburied counterparts. The seedlings in both 33% and 67% sand burial treatments did not significantly change their biomass allocation pattern comparing with the unburied ones. Furthermore, the number of leaves and shoot height of the seedlings in both 33% and 67% sand burial treatments were not significantly different from those of unburied individuals, respectively. The newly born leaves of the surviving seedlings, in 33%, 67%, and 100% burial treatments, during the period of experiment, were significantly more than those in control.展开更多
The experiment was conducted at the Ganqika Sandy Land Ecological Station in Ke抏rqinzuoyihouqi County, Inner Mongolia, in a growing season from April 28 to October 28, 2001. Peat and weathered coal were added to the ...The experiment was conducted at the Ganqika Sandy Land Ecological Station in Ke抏rqinzuoyihouqi County, Inner Mongolia, in a growing season from April 28 to October 28, 2001. Peat and weathered coal were added to the aeolian sandy soil in different ratios. Two-year-old Pinus sylvestris var. mongolica seedlings and plastic pots were used in the experiment. The experimental results indicated that: 1) the peat and weathered coal could significantly improve the physical and chemical prop-erties of aeolian sandy soil, and thus promoted the growth of seedlings; 2) the effect of peat on seedling growth, including height, base diameter, root length and biomass, presented an order of 8%>10%>5%>2%>0 in terms of peat contents, and the effect of weathered coal on seedling growth presented an order of 5%>8%>10%>2%>0 in terms of weathered coal contents for height and basal diameter, 5%>8%>2% >10%>0 for root length, and 5%>2%>8% >10%>0 for biomass; 3) the effects of peat were generally greater than that of weathered coal. Meanwhile, 8% peat was the best treatment to promote the growth of P. sylvestris var. mongolica seedlings.展开更多
We studied the effects of different culture media on the growth of India sandalwood (Santalum album L.) seedlings in Zhanjiang, Guangdong Province in southern China. Five different growth substrates, lateritic subso...We studied the effects of different culture media on the growth of India sandalwood (Santalum album L.) seedlings in Zhanjiang, Guangdong Province in southern China. Five different growth substrates, lateritic subsoil, burnt soil, agricultural soil, peaty soil and coconut dust, were used as the basic culture materials and seven different treatments of composition were used as potting media. Kuhnia rosmarinifolia Vent. was used as a primary host plant for all treatments. Statistically significant differences were found between treatments in respects of survival rate (p 〈 0.001), height (p 〈 0.001), ground diameter (p 〈 0.001) and biomass (p = 0.002), as well as for quality index (p 〈 0.001) of S. album seedlings after 6-month growth in containers with different culture media. Among all treatments, the treatment combining burnt soil, peat and coconut dust in a weight ratio of 1:1:1 plus 2% calcium super-phosphate as basal manure achieved the best performance for most of the seedling growth parameters, including survival rate (98%), height (35.81 cm), ground diameter (0.56 cm), biomass (4.46 g) and quality index (0.65), followed by the treatment using only burnt soil plus 2% calcium super-phosphate as the culture medium (survival rate 86%, height 29.23 cm, ground diameter 0.48 cm, biomass 3.36 g and quality index 0.52), while the treatment using only lateritic subsoil plus the basal manure as the medium obtained the poorest results in survival rate (38%), height (12.04 cm), ground diameter (0.19 cm), biomass (0.26 g) and quality index (0.043). Increasing the proportion of lateritic subsoil in the medium when mixed with peat and coconut dust did not show statistically significant differences in survival, height, ground diameter, biomass nor in quality index. In consideration of cost, using burnt soil plus 2% calcium super-phosphate as basal manure may be the optimum culture medium for large-scale production of Indian sandal- wood seedlings in Guangdong, southern China.展开更多
A study was carried out to determine the influence of different types of sludges (municipal, industrial and residential) on field germination, growth and nodulation of L. leucocephala seedlings in the nursery. Befor...A study was carried out to determine the influence of different types of sludges (municipal, industrial and residential) on field germination, growth and nodulation of L. leucocephala seedlings in the nursery. Before sowing of seeds, different combinations of sludges were incorporated with the nutrient deficient natural forest soils. Field germination, nodulation status and physical growth parameters of seedlings (shoot and root length, vigor index, collar diameter, leaf number, fresh and dry weight of shoot and root and total dry biomass increment) were recorded after three and six months of seed sowing. Field germination, nodulation status and growth parameters were varied significantly in the soil amended with sludges in comparison to control. The highest number of nodule was recorded from soil amended with residential sludge ( 1:1 ) and highest fresh and dry nodule weight was also found from the same combination in both three and six month old seedlings. In case of growth parameters, the highest growth was recorded from soil and residential sludge ( 1:1 ) combination compared to control. From the study, it can be recommended that soil amended with residential sludge ( 1:1 ) provide better field germination, growth and nodule formation of L. leucocephala in degraded soil.展开更多
Understanding the characteristics of rice productivity is of great importance for achieving high yield formation.However,such traits have not yet been studied for different ages of hydroponically grown long-mat rice s...Understanding the characteristics of rice productivity is of great importance for achieving high yield formation.However,such traits have not yet been studied for different ages of hydroponically grown long-mat rice seedlings(HLMS),which constitutes a new method of seedling cultivation.Field experiments were conducted to evaluate the effects of seedling age on the growth stage,photosynthesis characteristics,dry matter production,and yield of HLMS.A conventional japonica rice cultivar(Wuyunjing 24)and an indica hybrid rice cultivar(6 Liangyou 9368)were used as test materials.The results showed that the whole phase was shortened by 13-15 days for young seedlings(13-day-old)compared with old seedlings(27-day-old),which occurred because the growth process accelerated with the transplantation of young seedlings.As seedling age increased,the dry matter weight of stems of individual plants and of the population increased at the transplanting stage but decreased at the maturity stage(MS).Compared with that of 27-day-old seedlings,the average ratio of panicle weight to total plant dry weight of 13-day-old seedlings during a 2-year period increased by 3.71%for Wuyunjing 24 and by 3.78%for 6 Liangyou 9368 at the MS.Moreover,as seedling age increased,the leaf area index and photosynthetic potential decreased for both cultivars,and the photosynthetic rate markedly decreased at the heading stage(HS).With the exception of that of Wuyunjing 24 from the jointing stage to the HS in 2014,the crop growth rate was higher for young seedlings than for old seedlings.Grain yield significantly decreased with seedling age,but no significant difference was detected between the 13-and 20-day-old seedlings for either cultivar.Therefore,equilibrious and high biological yield formation,vigorous growth in the late stages,and high photosynthetic production capacity are important characteristics and causes of the efficient and sustainable output of photosynthetic systems and for achieving high yield formation in young transplanted seedlings(13-20-day-old).展开更多
[Objective] This study aimed to study the seedling nursery and afforesta- tion of Liriodendron chinense (Hemsl.).Sarg. in northern Guangxi Province, thereby providing theoretical basis for the extension of L. chinen...[Objective] This study aimed to study the seedling nursery and afforesta- tion of Liriodendron chinense (Hemsl.).Sarg. in northern Guangxi Province, thereby providing theoretical basis for the extension of L. chinense in this region. [Method] The growth situation of L. chinense seedlings and soil fertility in northern Guangxi Province were investigated. [Result] The L. chinense seedlings in northern Guangxi Province showed significant changes during the growth period. Among the three- year-old L. chinense plants, the average plant height reached as high as 331.11 cm, the average ground diameter was 5.05 cm, and the average crown diameter was 122.22 cm. After three years' afforestation with one-year-old seedlings, the av- erage plant height of L. chinense was 357.20 cm, the average ground diameter was 6.53 cm, and the average crown diameter was 170.43 cm. The detection results of soil fertility were as follows: the soil was strongly acidic; the organic matter and to- tal phosphorus contents were moderate; and the total potassium content was rela- tively abundant. [Conclusion] L. chinense grows rapidly in northern Guangxi Province of China, and is suitable for extension in this area.展开更多
The three methods of slash disposal in this experiment were no treatment, strip piling and burning. The results obtained from this study showed that the soil erosion, water and nutrient loss were higher in the logged ...The three methods of slash disposal in this experiment were no treatment, strip piling and burning. The results obtained from this study showed that the soil erosion, water and nutrient loss were higher in the logged areas by burning than in the logged areas by no treatment and strip piling. The soil and water loss was not serious when the slope degree of the logged area was less than 16o. The survival rate of planted seedlings was higher and the growth was better in the logged areas followed by burning than in the logged areas by no treatment and strip piling. Burning should not be used when the slope was more than 23o.展开更多
The effectiveness of three pre-germination treatments in breaking dormancy of the seeds of Dialum guineense and effects of three watering regimes on the growth performance of the seedlings were investigated. The pre-g...The effectiveness of three pre-germination treatments in breaking dormancy of the seeds of Dialum guineense and effects of three watering regimes on the growth performance of the seedlings were investigated. The pre-germination treatments were: soaking in hot water for 10 seconds and cooling down in cold water (T1), soaking in cold water for 24 hours (T2), soaking in running water for 48 hours (T3) and control (T4), while watering regimes include: watering once daily in the morning (W1), watering once every two days in the morning (W2) and watering once every three days in the morning (W3). The results showed that germination occurred first at 5 days after sowing (5 DAS) among the seeds soaked in cold water for 24 hours before sowing (T2), while the untreated seeds (control) took the longest period of 12 days before germination occurred. T1 had the highest germination value of 49.6% while T3 had the least of 31.2%. The effects of watering regimes were found to be significantly different on stem-collar diameter, leaf area and total dry weight (P < 0.05). The least significant difference (LSD) test showed that W2 and W3 supported the best growth performance. It is concluded from the results that T2 should be adopted for breaking the dormancy of Dialium guineense seeds and watering interval of three days would not dispose the seedlings to water-stress.展开更多
Jojoba is a desert shrub,introduced in the marginal areas of Kenya during 1980s.Jojoba domestication is being faced by browsing problems due to pastoralism in these areas.Massive browsing of leaves lowers photosynthes...Jojoba is a desert shrub,introduced in the marginal areas of Kenya during 1980s.Jojoba domestication is being faced by browsing problems due to pastoralism in these areas.Massive browsing of leaves lowers photosynthesis leading to decline in plant functions.An experiment was set up in Maungu,with the aim of determining the effect of browsing on jojoba seedlings.The experimental design was a randomized complete block design with three treatments replicated three times.The treatments consisted of varying levels of browsing as follows:non browsed,50%browsed and fully browsed.Seedlings were raised for six months before sampling.Variables assessed were:survival,height,root-collar diameter,leaf size,root length and number,internode length,sprout number,root/shoot ratio and total biomass.ANOVA was performed to determine differences among the treatments whilst significant differences among the means were separated using least significant difference(LSD)at p≤0.05.Results showed fully browsed seedlings were significantly lower in height(26.2 cm),internode length(9.7 mm),leaf length(18.3 mm)and width(10.4 mm)and total fresh plant biomass(11.0 g)compared to the non browsed ones which showed 31.1 cm,23.2,36.1 and 16.6 mm and 17.8 g,respectively.On the other hand,fully browsed seedlings showed significantly higher root/shoot ratio.Seedling growth was negatively affected by severity of browsing which resulted in stunted growth.The study recommended that browsing of seedlings should be prevented since it hinders plant growth.展开更多
With annual Bischofia javanica seedlings as experimental material, the plasticity and comprehensive evaluation methods were employed to investigate the effects of different shading degrees (100% NS (natural sunshine...With annual Bischofia javanica seedlings as experimental material, the plasticity and comprehensive evaluation methods were employed to investigate the effects of different shading degrees (100% NS (natural sunshine), 41.3% NS, 14.6% NS and 3.6% NS) on B. javanica seedlings growth, so as to obtain the shade toler- ance in B. javanica. The results showed that with the shading degree increasing, the seedling height increment, diameter increment, leaf area, fresh weights (above- ground part, underground part and whole plant) and dry weights (aboveground part, underground part and whole plant) of B. javanica seedlings all increased first and then decreased, and reached peak values under 41.3% NS, while the total root length, average root diameter, total surface area, total root volume and total root number all presented a decreasing trend. Also the comprehensive evaluation by subordinate function value method and plasticity analysis were carried out on these growth indexes. It was concluded that B. javanica seedlings have medium shade tol- erance from the comDrehensive analysis of growth indexes.展开更多
Seed priming is a pre-germinated technique that can enhance seed germination percentage,faster and synchro-nized germination,better seedling growth,and yield under stress conditions.To ascertain the most effective see...Seed priming is a pre-germinated technique that can enhance seed germination percentage,faster and synchro-nized germination,better seedling growth,and yield under stress conditions.To ascertain the most effective seed priming method that would ensure the potential yield of wheat in Bangladesh,two experiments were carried out from December 2021 to March 2022 at the Department of Agronomy,Bangladesh Agricultural University.Two wheat varieties namely BARI Gom-28 and BWMRI Gom-1 were subjected to a range of priming chemicals in both lab and pot tests.These compounds included the following:control(no priming),hydropriming(distilled water),10000 ppm KNO_(3),15000 ppm KNO_(3),40000 ppm Mannitol,60000 ppm Mannitol,10000 ppm NaCl,20000 ppm NaCl,100 ppm PEG,150 ppm PEG,500 ppm NaOCl,1000 ppm NaOCl,10000 ppm CaCl_(2),20000 ppm CaCl_(2),10000 ppm KCl and 20000 ppm KCl.A complete randomized design(CRD)with three repli-cations was used to set up the experiments.The results showed that BARI Gom-28 and BWMRI Gom-1 responded best to KCl priming in terms of rapid seed germination and strong seedling development.On the other hand,the best priming agents for plant growth and productivity turned out to be CaCl_(2) and KCL.The results of this study support the possibility of using seed priming as a technique to improve wheat plant development and output by raising seed emergence and survival rates.展开更多
The research used bioassay method to explore seed tolerance of Cd in terms of seed germination and seedling growth. Specifically, 12 rice varieties of three types were investigated under Cd stress, covering germinatio...The research used bioassay method to explore seed tolerance of Cd in terms of seed germination and seedling growth. Specifically, 12 rice varieties of three types were investigated under Cd stress, covering germination rate, shooting index, vigor index, seedling and shoot lengths, and fresh weights. The results showed that as Cd concentration grew, seed germination and seedling growth kept increasingly inhibited; germination index, vigor index, root length, shoot length and fresh weights went down; inhibition effects on seed germination and seedling growth were conventional rice〉two-line hybrid rice〉three-line hybrid ,rice. Shanyou 9588, Tianyou 998, Chuanxiang 8, and Y Liangyou 1 performed ~rongly in Cd tolerance; C Liangyou 651, Nei 5 You 263, Xiangwanxian 16, Huanghuazhan, Xiangwanxian 13, and Zhunliangyou 527 performed poorly in Cd tolerance, and Cd tolerance of rest treatments were moderate.展开更多
With Firmiana simplex (L.) W. F. Wight as an experiment material, the effects of different concentrations of GA3 (Gibberellin A3), SA (Salicylic acid) and NAA (1-Naphthalene acetic acid) and stratification on ...With Firmiana simplex (L.) W. F. Wight as an experiment material, the effects of different concentrations of GA3 (Gibberellin A3), SA (Salicylic acid) and NAA (1-Naphthalene acetic acid) and stratification on the germination rate of seeds were studied firstly, and then the effects of GA3 and NAA on seedling growth were analyzed. The results showed that the germination rate could be improved by 0.075 g/L SA and stratification markedly. It was indicated by the experiment that the growth of the main root and main stem could be promoted by 0.050 g/L and 0.077 g/L NAA, respectively. However, the leaf length and leaf width decreased significantly in the GA3 and NAA treatments.展开更多
Seedling stage is an important period for forestry.The aim of this study was to estimate the growth trend of six local precious species and consider their implications for silviculture on forestry.We assessed height,d...Seedling stage is an important period for forestry.The aim of this study was to estimate the growth trend of six local precious species and consider their implications for silviculture on forestry.We assessed height,diameter near ground and crown width at 1,4,6 and 8-month.The variance analysis indicated that there were significant differences between species on all traits except diameter near ground and crown width at 8-month.There were no significant differences on height and crown width at all ages among replicates whereas there were significant differences on diameter near ground at 1 and 4 months,differences on diameter near ground at 6 months and no difference on diameter near ground at 8-month.The significant differences among interaction of species and replicates on diameter near ground at 1-months,4-month,6-month and crown width at 8-month were also found.Dalbergia odorifera had a higher growth period after 6-month.Aquilaria sinensis(Lour.)Spreng,Swietenia mahagoni(L.)Jacq.,Hopea hainanensis Merr.et Chun,Homalium hainanense Gagnep.and Cassia siamea Lam.had the same growth trend on all traits at the whole time.展开更多
Increasing atmospheric CO2 concentration is generally expected to enhance photosynthesis and growth of agricultural C3 vegetable crops, and therefore results in an increase in crop yield. However, little is known abou...Increasing atmospheric CO2 concentration is generally expected to enhance photosynthesis and growth of agricultural C3 vegetable crops, and therefore results in an increase in crop yield. However, little is known about the combined effect of elevated CO2 and N species on plant growth and development. Two growth-chamber experiments were conducted to determine the effects of NH4^+/NO3^- ratio and elevated CO2 concentration on the physiological development and water use of tomato seedlings. Tomato was grown for 45 d in containers with nutrient solutions varying in NH4^+/NO3^- ratios and CO2 concentrations in growth chambers. Results showed that plant height, stem thickness, total dry weight, dry weight of the leaves, stems and roots, G value (total plant dry weight/seedling days), chlorophyll content, photosynthetic rate, leaf-level and whole plant-level water use efficiency and cumulative water consumption of tomato seedlings were increased with increasing proportion of NO3- in nutrient solutions in the elevated CO2 treatment. Plant biomass, plant height, stem thickness and photosynthetic rate were 67%, 22%, 24% and 55% higher at elevated CO2 concentration than at ambient CO2 concentration, depending on the values of NH4^+/NO3^- ratio. These results indicated that elevating CO2 concentration did not mitigate the adverse effects of 100% NH4^+-N (in nutrient solution) on the tomato seedlings. At both CO2 levels, NH4^+/NO3^- ratios of nutrient solutions strongly influenced almost every measure of plant performance, and nitrate-fed plants attained a greater biomass production, as compared to ammonium-fed plants. These phenomena seem to be related to the coordinated regulation of photosynthetic rate and cumulative water consumption of tomato seedlings.展开更多
Through a pot culture lanthanum nitrate was applied to maize seedlings grown in a red loamy soil to investigate the physiological and toxic effects of added La on the growth of crop seedlings and La bioaccumulation to...Through a pot culture lanthanum nitrate was applied to maize seedlings grown in a red loamy soil to investigate the physiological and toxic effects of added La on the growth of crop seedlings and La bioaccumulation to help understand the environmental chemistry behaviors of rare earth element as fertilizers in soils. Compared to the control, La concentrations in shoots and especially in roots of maize seedlings increased with an increase of La in the soil. Also, with added concentrations of La≥0.75 g La kg-1 soil and≥0.05 g La kg-1 soil, the dry weight of shoots and roots of maize seedlings was significantly reduced (P≤0.05), respectively, compared with the control. Additionally, La≥0.5 g kg-1 in the soil significantly inhibited (P≤0.05) primary root elongation. Roots were more sensitive to La stress than shoots and thus could be used as a biomarker to La stress. Overall, in the red loamy soil studied, La had no significant beneficial effects on the growth of maize at the added La levels above 0.1 g kg-1 soil.展开更多
A study was conducted to test the influence of different inorganic fertilizers (phosphorous and potassium) on the nodulation and growth of Dalbergia sissoo grown in the nursery. Before seeds sowing, different combin...A study was conducted to test the influence of different inorganic fertilizers (phosphorous and potassium) on the nodulation and growth of Dalbergia sissoo grown in the nursery. Before seeds sowing, different combinations of P, K fertilizers were incorporated with the nutrient-deficient natural forest soils, and then amended with cowdung (soil: cowdung = 3:1). Nodulation status (nodule number, shape, fresh weight, dry weight and color) in the roots and the plant growth parameters (length of shoot and root, collar diameter, fresh and dry weight of shoot and root) were recorded 60 days after seeds sowing. Nodulation status and growth of the plants varied significantly (P〈0.05) in the soils amended with fertilizers in comparison to the control. The highest nodule number (62), fresh (0.50 g) and dry (0.07 g) weights were recorded with the dose of PK at the rate of 160 kg/hm2. Nodule shape and color also varied widely in different treatments. In case of plant growth parameters, shoot and root length, collar diameter, fresh and dry weight of the plants took on a significant difference (P〈0.05) among various combination of fertilizers. From the study, it is revealed that PK at the rate of 160 kg/hm^2 fertilizer with soil and cowdung mixture (soil: eowdung = 3:1) is recommended for optimum growth and nodule formation of D. sissoo in degraded soils at a nursery level.展开更多
We studied seedling survival and growth ofAquilaria malaccensis in three different environmental conditions (homegardens, green house and in different canopy conditions) of northeast India. Results show that mean se...We studied seedling survival and growth ofAquilaria malaccensis in three different environmental conditions (homegardens, green house and in different canopy conditions) of northeast India. Results show that mean seasonal survival was highest in green house (95.53%±2.33), followed by homegardens (89.3%±1.89) and different canopy conditions (77.62%±6.73); the highest values were found during February to April for both the homegardens (96%±1.68) and green house (98% ± 0.88) and lowest during November to January (78%±2.99) in homegardens and May to July (90%:t:4.53) in green house. In case of transplanted seedlings in different canopy conditions, mean seasonal survival was highest during May to July (98%±1.92) and lowest during August to October (66%±12.81). However, mean seasonal growth of collar diameter was highest in different canopy conditions (23.99%±1.76) compared to green house (21.52%±2.70) and homegardens (12.44%±1.33) and it was highest during rainy season (May to July) and lowest during dry winter (November to January) in all the three experi- mental sites. These variations may be due to the different microclimatic conditions as well as nutrient status of the soil in all the three experimen- tal sites. Although, seedling quality plays a great role in their survival and growth, based on the result of green house experiment, it can be concluded that maintenance of seedlings in green house conditions during their early growth period may improve both the survival and growth for large scale plantation of the species. Thus, the species can be reintroduced in its natural forest range to compensate the loss of natural population of this precious species in northeast India.展开更多
An investigation of seed germination and early seedling growth of Eucalyptus microtheca was based onseed collection from 10 widely,separated provenanes in Australia. Genetic variation of seed germination and carly see...An investigation of seed germination and early seedling growth of Eucalyptus microtheca was based onseed collection from 10 widely,separated provenanes in Australia. Genetic variation of seed germination and carly seedling growth was observed among a series of provcnances whose natural habitats range from different climatic condition Inthe ten provenances, both the model of seed relative germination percentage and the model of seed total germination percentage fitted Logistic regression [y=a/(1+exp(-cx+b))]. In comparison with provenanccs from four high temperature (meanannual maximum temperature >30.0 ℃: mean annual minimum temperature > 17.0 ℃) areas, six low temperature (meanannual maximum temperature <30℃, mean annual minimum temperature <17.0 ℃) areas showed the thst genninationrate and the high total germination percentage, For each provenance we have 45 seedlings equally divided into three watering levels (100%, 50%. and 25% of field capacity), and studies on relationship between early seedling growth and climaticfactors of the natural habitat of provenance. In control treatment. height growth of the seedling has beeb associated with intrinsically the driest quarter precipitation in the seed collection areas of provenance. In all the treatments, length growth ofthe biggest Ieaf of the seedling was related to mean annual maximum temperature and mean annual minimum temperaturein origin of provenance. In contrast, basal diameter growth of the seedling was related to mean annual minimum temperature of the seed collection areas in water stress treatment. From an ecological viewpint, the fast germination rate and thehigh total germination perecntage of the seed and rapid early grouth of the seedling appear to bc favourable adaptations tothe climatic conditions prevailing in the natural habitat of provenance.展开更多
文摘The process of rice(Oryza sativa L.)seedling cultivation is often subjected to adverse environmental stress.Biostimulants regulate the robust growth of rice seedlings and play a crucial role in promoting the green and ecological development of agriculture.In this study,1.0 and 2.0 g•m^(-2) of the biostimulant were applied to soil in rice seedbeds.Growth indicators of rice,antioxidant enzyme activities and soil physicochemical characteristics were assessed at the 2.5-leaf and 4-leaf stages of rice.The results indicated that applying 2.0 g•m^(-2) of the biostimulant at both the 2.5-leaf and 4-leaf stages had the most significant promoting effect on rice growth.At the 2.5-leaf and 4-leaf stages,the number of fibrous roots increased by 23.43%and 22.25%,stem base width increased by 19.05%and 19.58%,above ground dry weight increased by 18.09%and 16.47%,root dry weight increased by 19.67%and 18.28%,leaf peroxidase(POD)activity increased by 34.44%and 42.94%,superoxide dismutase(SOD)activity increased by 37.24%and 56.79%,malondialdehyde(MDA)content decreased by 18.60%and 27.67%,and chlorophyll content increased significantly by 28.31%and 34.24%,respectively.At the 4-leaf stage of rice,urease,phosphatase and cellulase activities in the seedbed soil increased by 42.13%,25.96%and 33.59%,respectively,while soil alkaline nitrogen,available phosphorus and available potassium content decreased by 19.76%,19.02%and 17.88%,respectively.The application of biostimulants played a crucial role in promoting the growth of rice seedlings and enhancing soil nutrient absorption.
文摘Hedysarum laeve Maxim. (Leguminosae) is one of the major species used frequently in revegetation of dune_field in the sandlands of the northern part of China by means of aerial sowing. Seedlings of the species after emergence above the sand surface may be buried in sand to various depths during its establishment in late spring and early summer. A study was made to examine the effects of sand burial at different levels of 0 (control), 33%, 67%, 100% and 133% of their shoot height, on the survivorship, growth, and biomass allocation pattern of H. laeve seedlings (one and two weeks old after emergence). When burial depth was up to 100% of their shoot height, about 70% seedlings died; and the burial at depth of 133% of their shoot height led to death of all seedlings. When seedlings was buried at depth of 33% and 67% of their shoot height, respectively, after six_week growth, their biomass of whole plant, blade, and root and relative growth rate were higher than the unburied counterparts. The seedlings in both 33% and 67% sand burial treatments did not significantly change their biomass allocation pattern comparing with the unburied ones. Furthermore, the number of leaves and shoot height of the seedlings in both 33% and 67% sand burial treatments were not significantly different from those of unburied individuals, respectively. The newly born leaves of the surviving seedlings, in 33%, 67%, and 100% burial treatments, during the period of experiment, were significantly more than those in control.
基金This research was supported by Key Knowledge Innova-tion Project (SCXZD0102) of Institute of Applied Ecology Chinese Academy of Sciences and sponsored by the Science and Technology Department of Inner Mongolia Autonomic Region,P. R. China (2001010)
文摘The experiment was conducted at the Ganqika Sandy Land Ecological Station in Ke抏rqinzuoyihouqi County, Inner Mongolia, in a growing season from April 28 to October 28, 2001. Peat and weathered coal were added to the aeolian sandy soil in different ratios. Two-year-old Pinus sylvestris var. mongolica seedlings and plastic pots were used in the experiment. The experimental results indicated that: 1) the peat and weathered coal could significantly improve the physical and chemical prop-erties of aeolian sandy soil, and thus promoted the growth of seedlings; 2) the effect of peat on seedling growth, including height, base diameter, root length and biomass, presented an order of 8%>10%>5%>2%>0 in terms of peat contents, and the effect of weathered coal on seedling growth presented an order of 5%>8%>10%>2%>0 in terms of weathered coal contents for height and basal diameter, 5%>8%>2% >10%>0 for root length, and 5%>2%>8% >10%>0 for biomass; 3) the effects of peat were generally greater than that of weathered coal. Meanwhile, 8% peat was the best treatment to promote the growth of P. sylvestris var. mongolica seedlings.
基金sponsored by the National Science and Technology Support Project "High efficient cultivation techniques of sandalwood plantation in south China (2006BAD24B0903)" a "Special construction project for improved variety experiment orchard (4400-32990190)".
文摘We studied the effects of different culture media on the growth of India sandalwood (Santalum album L.) seedlings in Zhanjiang, Guangdong Province in southern China. Five different growth substrates, lateritic subsoil, burnt soil, agricultural soil, peaty soil and coconut dust, were used as the basic culture materials and seven different treatments of composition were used as potting media. Kuhnia rosmarinifolia Vent. was used as a primary host plant for all treatments. Statistically significant differences were found between treatments in respects of survival rate (p 〈 0.001), height (p 〈 0.001), ground diameter (p 〈 0.001) and biomass (p = 0.002), as well as for quality index (p 〈 0.001) of S. album seedlings after 6-month growth in containers with different culture media. Among all treatments, the treatment combining burnt soil, peat and coconut dust in a weight ratio of 1:1:1 plus 2% calcium super-phosphate as basal manure achieved the best performance for most of the seedling growth parameters, including survival rate (98%), height (35.81 cm), ground diameter (0.56 cm), biomass (4.46 g) and quality index (0.65), followed by the treatment using only burnt soil plus 2% calcium super-phosphate as the culture medium (survival rate 86%, height 29.23 cm, ground diameter 0.48 cm, biomass 3.36 g and quality index 0.52), while the treatment using only lateritic subsoil plus the basal manure as the medium obtained the poorest results in survival rate (38%), height (12.04 cm), ground diameter (0.19 cm), biomass (0.26 g) and quality index (0.043). Increasing the proportion of lateritic subsoil in the medium when mixed with peat and coconut dust did not show statistically significant differences in survival, height, ground diameter, biomass nor in quality index. In consideration of cost, using burnt soil plus 2% calcium super-phosphate as basal manure may be the optimum culture medium for large-scale production of Indian sandal- wood seedlings in Guangdong, southern China.
文摘A study was carried out to determine the influence of different types of sludges (municipal, industrial and residential) on field germination, growth and nodulation of L. leucocephala seedlings in the nursery. Before sowing of seeds, different combinations of sludges were incorporated with the nutrient deficient natural forest soils. Field germination, nodulation status and physical growth parameters of seedlings (shoot and root length, vigor index, collar diameter, leaf number, fresh and dry weight of shoot and root and total dry biomass increment) were recorded after three and six months of seed sowing. Field germination, nodulation status and growth parameters were varied significantly in the soil amended with sludges in comparison to control. The highest number of nodule was recorded from soil amended with residential sludge ( 1:1 ) and highest fresh and dry nodule weight was also found from the same combination in both three and six month old seedlings. In case of growth parameters, the highest growth was recorded from soil and residential sludge ( 1:1 ) combination compared to control. From the study, it can be recommended that soil amended with residential sludge ( 1:1 ) provide better field germination, growth and nodule formation of L. leucocephala in degraded soil.
基金Funding was provided by the National Key Research and Development Program of China(2017YFD0301200,2018YFD0300803,2015BAD01B03)the Jiangsu Key Research and Development Program,China(BE2017369)the Jiangsu Agricultural Science and Technology Innovation Fund,China(JASTIF,CX(18)1002).
文摘Understanding the characteristics of rice productivity is of great importance for achieving high yield formation.However,such traits have not yet been studied for different ages of hydroponically grown long-mat rice seedlings(HLMS),which constitutes a new method of seedling cultivation.Field experiments were conducted to evaluate the effects of seedling age on the growth stage,photosynthesis characteristics,dry matter production,and yield of HLMS.A conventional japonica rice cultivar(Wuyunjing 24)and an indica hybrid rice cultivar(6 Liangyou 9368)were used as test materials.The results showed that the whole phase was shortened by 13-15 days for young seedlings(13-day-old)compared with old seedlings(27-day-old),which occurred because the growth process accelerated with the transplantation of young seedlings.As seedling age increased,the dry matter weight of stems of individual plants and of the population increased at the transplanting stage but decreased at the maturity stage(MS).Compared with that of 27-day-old seedlings,the average ratio of panicle weight to total plant dry weight of 13-day-old seedlings during a 2-year period increased by 3.71%for Wuyunjing 24 and by 3.78%for 6 Liangyou 9368 at the MS.Moreover,as seedling age increased,the leaf area index and photosynthetic potential decreased for both cultivars,and the photosynthetic rate markedly decreased at the heading stage(HS).With the exception of that of Wuyunjing 24 from the jointing stage to the HS in 2014,the crop growth rate was higher for young seedlings than for old seedlings.Grain yield significantly decreased with seedling age,but no significant difference was detected between the 13-and 20-day-old seedlings for either cultivar.Therefore,equilibrious and high biological yield formation,vigorous growth in the late stages,and high photosynthetic production capacity are important characteristics and causes of the efficient and sustainable output of photosynthetic systems and for achieving high yield formation in young transplanted seedlings(13-20-day-old).
基金Supported by Forestry Science and Technology Program of Guangxi Province[GLK(2015)26]Science and Technology Achievement Transformation and Application Fund of Guilin City(20140124-2)
文摘[Objective] This study aimed to study the seedling nursery and afforesta- tion of Liriodendron chinense (Hemsl.).Sarg. in northern Guangxi Province, thereby providing theoretical basis for the extension of L. chinense in this region. [Method] The growth situation of L. chinense seedlings and soil fertility in northern Guangxi Province were investigated. [Result] The L. chinense seedlings in northern Guangxi Province showed significant changes during the growth period. Among the three- year-old L. chinense plants, the average plant height reached as high as 331.11 cm, the average ground diameter was 5.05 cm, and the average crown diameter was 122.22 cm. After three years' afforestation with one-year-old seedlings, the av- erage plant height of L. chinense was 357.20 cm, the average ground diameter was 6.53 cm, and the average crown diameter was 170.43 cm. The detection results of soil fertility were as follows: the soil was strongly acidic; the organic matter and to- tal phosphorus contents were moderate; and the total potassium content was rela- tively abundant. [Conclusion] L. chinense grows rapidly in northern Guangxi Province of China, and is suitable for extension in this area.
基金Chinese Academy of Science and National Natural Science Foundation of China!(No. 39770609).
文摘The three methods of slash disposal in this experiment were no treatment, strip piling and burning. The results obtained from this study showed that the soil erosion, water and nutrient loss were higher in the logged areas by burning than in the logged areas by no treatment and strip piling. The soil and water loss was not serious when the slope degree of the logged area was less than 16o. The survival rate of planted seedlings was higher and the growth was better in the logged areas followed by burning than in the logged areas by no treatment and strip piling. Burning should not be used when the slope was more than 23o.
文摘The effectiveness of three pre-germination treatments in breaking dormancy of the seeds of Dialum guineense and effects of three watering regimes on the growth performance of the seedlings were investigated. The pre-germination treatments were: soaking in hot water for 10 seconds and cooling down in cold water (T1), soaking in cold water for 24 hours (T2), soaking in running water for 48 hours (T3) and control (T4), while watering regimes include: watering once daily in the morning (W1), watering once every two days in the morning (W2) and watering once every three days in the morning (W3). The results showed that germination occurred first at 5 days after sowing (5 DAS) among the seeds soaked in cold water for 24 hours before sowing (T2), while the untreated seeds (control) took the longest period of 12 days before germination occurred. T1 had the highest germination value of 49.6% while T3 had the least of 31.2%. The effects of watering regimes were found to be significantly different on stem-collar diameter, leaf area and total dry weight (P < 0.05). The least significant difference (LSD) test showed that W2 and W3 supported the best growth performance. It is concluded from the results that T2 should be adopted for breaking the dormancy of Dialium guineense seeds and watering interval of three days would not dispose the seedlings to water-stress.
文摘Jojoba is a desert shrub,introduced in the marginal areas of Kenya during 1980s.Jojoba domestication is being faced by browsing problems due to pastoralism in these areas.Massive browsing of leaves lowers photosynthesis leading to decline in plant functions.An experiment was set up in Maungu,with the aim of determining the effect of browsing on jojoba seedlings.The experimental design was a randomized complete block design with three treatments replicated three times.The treatments consisted of varying levels of browsing as follows:non browsed,50%browsed and fully browsed.Seedlings were raised for six months before sampling.Variables assessed were:survival,height,root-collar diameter,leaf size,root length and number,internode length,sprout number,root/shoot ratio and total biomass.ANOVA was performed to determine differences among the treatments whilst significant differences among the means were separated using least significant difference(LSD)at p≤0.05.Results showed fully browsed seedlings were significantly lower in height(26.2 cm),internode length(9.7 mm),leaf length(18.3 mm)and width(10.4 mm)and total fresh plant biomass(11.0 g)compared to the non browsed ones which showed 31.1 cm,23.2,36.1 and 16.6 mm and 17.8 g,respectively.On the other hand,fully browsed seedlings showed significantly higher root/shoot ratio.Seedling growth was negatively affected by severity of browsing which resulted in stunted growth.The study recommended that browsing of seedlings should be prevented since it hinders plant growth.
文摘With annual Bischofia javanica seedlings as experimental material, the plasticity and comprehensive evaluation methods were employed to investigate the effects of different shading degrees (100% NS (natural sunshine), 41.3% NS, 14.6% NS and 3.6% NS) on B. javanica seedlings growth, so as to obtain the shade toler- ance in B. javanica. The results showed that with the shading degree increasing, the seedling height increment, diameter increment, leaf area, fresh weights (above- ground part, underground part and whole plant) and dry weights (aboveground part, underground part and whole plant) of B. javanica seedlings all increased first and then decreased, and reached peak values under 41.3% NS, while the total root length, average root diameter, total surface area, total root volume and total root number all presented a decreasing trend. Also the comprehensive evaluation by subordinate function value method and plasticity analysis were carried out on these growth indexes. It was concluded that B. javanica seedlings have medium shade tol- erance from the comDrehensive analysis of growth indexes.
基金The authors are very much grateful to Bangladesh Agricultural University Research System(BAURES)Bangladesh Agricultural University,Mymensingh-2202,Bangladesh for the financial support through the research project entitled“Induction of Heat and Drought Tolerance in Wheat through Seed Priming”(Project No.2021/35/BAU)to carry out the research work.
文摘Seed priming is a pre-germinated technique that can enhance seed germination percentage,faster and synchro-nized germination,better seedling growth,and yield under stress conditions.To ascertain the most effective seed priming method that would ensure the potential yield of wheat in Bangladesh,two experiments were carried out from December 2021 to March 2022 at the Department of Agronomy,Bangladesh Agricultural University.Two wheat varieties namely BARI Gom-28 and BWMRI Gom-1 were subjected to a range of priming chemicals in both lab and pot tests.These compounds included the following:control(no priming),hydropriming(distilled water),10000 ppm KNO_(3),15000 ppm KNO_(3),40000 ppm Mannitol,60000 ppm Mannitol,10000 ppm NaCl,20000 ppm NaCl,100 ppm PEG,150 ppm PEG,500 ppm NaOCl,1000 ppm NaOCl,10000 ppm CaCl_(2),20000 ppm CaCl_(2),10000 ppm KCl and 20000 ppm KCl.A complete randomized design(CRD)with three repli-cations was used to set up the experiments.The results showed that BARI Gom-28 and BWMRI Gom-1 responded best to KCl priming in terms of rapid seed germination and strong seedling development.On the other hand,the best priming agents for plant growth and productivity turned out to be CaCl_(2) and KCL.The results of this study support the possibility of using seed priming as a technique to improve wheat plant development and output by raising seed emergence and survival rates.
基金Supported by Loudi City Science and Technology Project(2014-1)State Key Laboratory of Hybrid RiceKey Laboratory of Pesticide Harmless Application of Hunan Province~~
文摘The research used bioassay method to explore seed tolerance of Cd in terms of seed germination and seedling growth. Specifically, 12 rice varieties of three types were investigated under Cd stress, covering germination rate, shooting index, vigor index, seedling and shoot lengths, and fresh weights. The results showed that as Cd concentration grew, seed germination and seedling growth kept increasingly inhibited; germination index, vigor index, root length, shoot length and fresh weights went down; inhibition effects on seed germination and seedling growth were conventional rice〉two-line hybrid rice〉three-line hybrid ,rice. Shanyou 9588, Tianyou 998, Chuanxiang 8, and Y Liangyou 1 performed ~rongly in Cd tolerance; C Liangyou 651, Nei 5 You 263, Xiangwanxian 16, Huanghuazhan, Xiangwanxian 13, and Zhunliangyou 527 performed poorly in Cd tolerance, and Cd tolerance of rest treatments were moderate.
基金Supported by the Regional Fund of Natural Science Foundation of China(31360065)Fund for the Construction of Provincial Superiority Characteristic Key Discipline Ecology~~
文摘With Firmiana simplex (L.) W. F. Wight as an experiment material, the effects of different concentrations of GA3 (Gibberellin A3), SA (Salicylic acid) and NAA (1-Naphthalene acetic acid) and stratification on the germination rate of seeds were studied firstly, and then the effects of GA3 and NAA on seedling growth were analyzed. The results showed that the germination rate could be improved by 0.075 g/L SA and stratification markedly. It was indicated by the experiment that the growth of the main root and main stem could be promoted by 0.050 g/L and 0.077 g/L NAA, respectively. However, the leaf length and leaf width decreased significantly in the GA3 and NAA treatments.
文摘Seedling stage is an important period for forestry.The aim of this study was to estimate the growth trend of six local precious species and consider their implications for silviculture on forestry.We assessed height,diameter near ground and crown width at 1,4,6 and 8-month.The variance analysis indicated that there were significant differences between species on all traits except diameter near ground and crown width at 8-month.There were no significant differences on height and crown width at all ages among replicates whereas there were significant differences on diameter near ground at 1 and 4 months,differences on diameter near ground at 6 months and no difference on diameter near ground at 8-month.The significant differences among interaction of species and replicates on diameter near ground at 1-months,4-month,6-month and crown width at 8-month were also found.Dalbergia odorifera had a higher growth period after 6-month.Aquilaria sinensis(Lour.)Spreng,Swietenia mahagoni(L.)Jacq.,Hopea hainanensis Merr.et Chun,Homalium hainanense Gagnep.and Cassia siamea Lam.had the same growth trend on all traits at the whole time.
基金Project supported by the National Natural Science Foundation of China(No.30230250).
文摘Increasing atmospheric CO2 concentration is generally expected to enhance photosynthesis and growth of agricultural C3 vegetable crops, and therefore results in an increase in crop yield. However, little is known about the combined effect of elevated CO2 and N species on plant growth and development. Two growth-chamber experiments were conducted to determine the effects of NH4^+/NO3^- ratio and elevated CO2 concentration on the physiological development and water use of tomato seedlings. Tomato was grown for 45 d in containers with nutrient solutions varying in NH4^+/NO3^- ratios and CO2 concentrations in growth chambers. Results showed that plant height, stem thickness, total dry weight, dry weight of the leaves, stems and roots, G value (total plant dry weight/seedling days), chlorophyll content, photosynthetic rate, leaf-level and whole plant-level water use efficiency and cumulative water consumption of tomato seedlings were increased with increasing proportion of NO3- in nutrient solutions in the elevated CO2 treatment. Plant biomass, plant height, stem thickness and photosynthetic rate were 67%, 22%, 24% and 55% higher at elevated CO2 concentration than at ambient CO2 concentration, depending on the values of NH4^+/NO3^- ratio. These results indicated that elevating CO2 concentration did not mitigate the adverse effects of 100% NH4^+-N (in nutrient solution) on the tomato seedlings. At both CO2 levels, NH4^+/NO3^- ratios of nutrient solutions strongly influenced almost every measure of plant performance, and nitrate-fed plants attained a greater biomass production, as compared to ammonium-fed plants. These phenomena seem to be related to the coordinated regulation of photosynthetic rate and cumulative water consumption of tomato seedlings.
基金Project supported by the Jiangsu Provincial Natural Science Foundation of China (No.BK99034) the National Natural Science Foundation of China (No. 29890280-1)
文摘Through a pot culture lanthanum nitrate was applied to maize seedlings grown in a red loamy soil to investigate the physiological and toxic effects of added La on the growth of crop seedlings and La bioaccumulation to help understand the environmental chemistry behaviors of rare earth element as fertilizers in soils. Compared to the control, La concentrations in shoots and especially in roots of maize seedlings increased with an increase of La in the soil. Also, with added concentrations of La≥0.75 g La kg-1 soil and≥0.05 g La kg-1 soil, the dry weight of shoots and roots of maize seedlings was significantly reduced (P≤0.05), respectively, compared with the control. Additionally, La≥0.5 g kg-1 in the soil significantly inhibited (P≤0.05) primary root elongation. Roots were more sensitive to La stress than shoots and thus could be used as a biomarker to La stress. Overall, in the red loamy soil studied, La had no significant beneficial effects on the growth of maize at the added La levels above 0.1 g kg-1 soil.
文摘A study was conducted to test the influence of different inorganic fertilizers (phosphorous and potassium) on the nodulation and growth of Dalbergia sissoo grown in the nursery. Before seeds sowing, different combinations of P, K fertilizers were incorporated with the nutrient-deficient natural forest soils, and then amended with cowdung (soil: cowdung = 3:1). Nodulation status (nodule number, shape, fresh weight, dry weight and color) in the roots and the plant growth parameters (length of shoot and root, collar diameter, fresh and dry weight of shoot and root) were recorded 60 days after seeds sowing. Nodulation status and growth of the plants varied significantly (P〈0.05) in the soils amended with fertilizers in comparison to the control. The highest nodule number (62), fresh (0.50 g) and dry (0.07 g) weights were recorded with the dose of PK at the rate of 160 kg/hm2. Nodule shape and color also varied widely in different treatments. In case of plant growth parameters, shoot and root length, collar diameter, fresh and dry weight of the plants took on a significant difference (P〈0.05) among various combination of fertilizers. From the study, it is revealed that PK at the rate of 160 kg/hm^2 fertilizer with soil and cowdung mixture (soil: eowdung = 3:1) is recommended for optimum growth and nodule formation of D. sissoo in degraded soils at a nursery level.
基金supported by DBT,Govt. of India through the project "Mapping and quantitative assessment of geographic distribution and population status of plant resources of Eastern Himalayan Region"
文摘We studied seedling survival and growth ofAquilaria malaccensis in three different environmental conditions (homegardens, green house and in different canopy conditions) of northeast India. Results show that mean seasonal survival was highest in green house (95.53%±2.33), followed by homegardens (89.3%±1.89) and different canopy conditions (77.62%±6.73); the highest values were found during February to April for both the homegardens (96%±1.68) and green house (98% ± 0.88) and lowest during November to January (78%±2.99) in homegardens and May to July (90%:t:4.53) in green house. In case of transplanted seedlings in different canopy conditions, mean seasonal survival was highest during May to July (98%±1.92) and lowest during August to October (66%±12.81). However, mean seasonal growth of collar diameter was highest in different canopy conditions (23.99%±1.76) compared to green house (21.52%±2.70) and homegardens (12.44%±1.33) and it was highest during rainy season (May to July) and lowest during dry winter (November to January) in all the three experi- mental sites. These variations may be due to the different microclimatic conditions as well as nutrient status of the soil in all the three experimen- tal sites. Although, seedling quality plays a great role in their survival and growth, based on the result of green house experiment, it can be concluded that maintenance of seedlings in green house conditions during their early growth period may improve both the survival and growth for large scale plantation of the species. Thus, the species can be reintroduced in its natural forest range to compensate the loss of natural population of this precious species in northeast India.
文摘An investigation of seed germination and early seedling growth of Eucalyptus microtheca was based onseed collection from 10 widely,separated provenanes in Australia. Genetic variation of seed germination and carly seedling growth was observed among a series of provcnances whose natural habitats range from different climatic condition Inthe ten provenances, both the model of seed relative germination percentage and the model of seed total germination percentage fitted Logistic regression [y=a/(1+exp(-cx+b))]. In comparison with provenanccs from four high temperature (meanannual maximum temperature >30.0 ℃: mean annual minimum temperature > 17.0 ℃) areas, six low temperature (meanannual maximum temperature <30℃, mean annual minimum temperature <17.0 ℃) areas showed the thst genninationrate and the high total germination percentage, For each provenance we have 45 seedlings equally divided into three watering levels (100%, 50%. and 25% of field capacity), and studies on relationship between early seedling growth and climaticfactors of the natural habitat of provenance. In control treatment. height growth of the seedling has beeb associated with intrinsically the driest quarter precipitation in the seed collection areas of provenance. In all the treatments, length growth ofthe biggest Ieaf of the seedling was related to mean annual maximum temperature and mean annual minimum temperaturein origin of provenance. In contrast, basal diameter growth of the seedling was related to mean annual minimum temperature of the seed collection areas in water stress treatment. From an ecological viewpint, the fast germination rate and thehigh total germination perecntage of the seed and rapid early grouth of the seedling appear to bc favourable adaptations tothe climatic conditions prevailing in the natural habitat of provenance.