Selenium–nitrogen-co-doped carbon dots increase rice seedling growth and salt resistance

Soil salinity seriously affects the utilization of farmland and threatens the crop production.Here,a selenium-nitrogen-co-doped carbon dots was developed,which increased rice seedling growth and alleviated its inhibition by salt stress by foliar spraying.The treatment activated Ca^(2+)and jasmonic acid signaling pathways and increased iron homeostasis,antioxidant defense,and cell wall development of rice seedlings.It could be used to increase crop resistance to environmental stress.

Growth,leaf anatomy,and photosynthesis of cotton(Gossypium hirsutum L.)seedlings in response to four light-emitting diodes and high pressure sodium lamp

Background Light is a critical factor in plant growth and development,particularly in controlled environments.Light-emitting diodes(LEDs)have become a reliable alternative to conventional high pressure sodium(HSP)lamps because they are more efficient and versatile in light sources.In contrast to well-known specialized LED light spectra for vegetables,the appropriate LED lights for crops such as cotton remain unknown.Results In this growth chamber study,we selected and compared four LED lights with varying percentages(26.44%–68.68%)of red light(R,600–700 nm),combined with other lights,for their effects on growth,leaf anatomy,and photosynthesis of cotton seedlings,using HSP lamp as a control.The total photosynthetic photon flux density(PPFD)was(215±2)μmol·m-2·s-1 for all LEDs and HSP lamp.The results showed significant differences in all tested parameters among lights,and the percentage of far red(FR,701–780 nm)within the range of 3.03%–11.86%was positively correlated with plant growth(characterized by leaf number and area,plant height,stem diameter,and total biomass),palisade layer thickness,photosynthesis rate(Pn),and stomatal conductance(Gs).The ratio of R/FR(4.445–11.497)negatively influenced the growth of cotton seedlings,and blue light(B)suppressed stem elongation but increased palisade cell length,chlorophyll content,and Pn.Conclusion The LED 2 was superior to other LED lights and HSP lamp.It had the highest ratio of FR within the total PPFD(11.86%)and the lowest ratio of R/FR(4.445).LED 2 may therefore be used to replace HPS lamp under controlled environments for the study of cotton at the seedling stage.

Effects of site preparation methods on soil physical properties and outplanting success of coniferous seedlings in boreal forests

This study assessed the effect of patch scarification and mounding on the physical properties of the root layer and the success of tree planting in various types of forests.This study was conducted on 12 forest sites in taiga forests of the European part of Russia.A total of 54 plots were set up to assess seedling survival;root collar diameter,height,and heigh increment were measured for 240 seedlings to assess growth.In the rooting layer,240 soil samples were taken to determine physical properties.The study showed that soil treatment methods had no effect on bulk density and total porosity in Cladina sites.However,reduced soil moisture was noted,particularly in mounds,resulting in increased aeration.In Myrtillus sites,there were increased bulk density,reduced soil moisture,and total porosity in the mounds.Mounding treatment in Polytrichum sites resulted in reduced soil moisture and increased aeration porosity.In the Myrtillus and Polytrichum sites,patch scarification had no effects on physical properties.In Polytrichum sites,survival rates,heights,and heigh increments of bareroot Norway spruce seedlings in mounds were higher than in patches;however,the same did not apply to diameter.In Cladina and Myrtillus sites,there was no difference in growth for bareroot and containerised seedlings with different soil treatments.Growing conditions and soil types should be considered when applying different soil treatment methods to ensure high survival rates and successful seedling growth.

Relationship between Seed Priming Mediated Seedling Vigor and Yield Performance of Spring Wheat

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.

Seedling dynamics differ between canopy species and understory species in a tropical seasonal rainforest,SW China

We used 11 years of census data from 450 seedling quadrats established in a 20-ha forest dynamics plot to study seedling dynamics in tree species of a tropical seasonal rainforest in Xishuangbanna,southwestern China.We found that overall seedling recruitment rate and relative growth rate were higher in the rainy season than in the dry season.Both the recruitment rate of seedlings from canopy tree species(two species)and the relative growth rate of seedlings from understory species(nine species)were higher in the rainy season than in the dry season.However,in the rainy season,the recruitment rate of seedlings was higher for canopy tree species than for understory tree species.In addition,relative growth rate of seedlings was higher in the canopy species than in understory seedlings in the dry season.We also observed that,in both rainy and dry seasons,mortality rate of seedlings was higher for canopy species than for understory species.Overall,canopy tree species appear to have evolved a flexible strategy to adapt to the seasonal changes of a monsoon climate.In contrast,understory tree species seem to have adopted a conservative strategy.Specifically,these species mainly release seedlings in the rainy season and maintain relatively stable populations with a lower mortality rate and recruitment rate in both dry and rainy seasons.Our study suggests that canopy and understory seedling populations growing in forest understory may respond to future climate change scenarios with distinct regeneration strategies.

Dormancy of Amaranthus retroflexus L. Seeds and Physiological Response Seedlings to Acifluorfen Sodium

Amaranthus retroflexus L. is a serious and widespread malignant weed in soybean fields in Heilongjiang Province. Exploring the dormancy characteristics of A. retroflexus L. seeds and the physiological response of its seedlings to acifluorfen sodium can provide a basis for further researches on its resistance mechanism. Using newly harvested and stored A. retroflexus L. seeds for one year as experimental materials, the effects of different concentrations of HCl, NaOH, water temperature, gibberellic acid(GA) and polyethylene glycol(PEG) on the dormancy and germination of A. retroflexus L. seeds were studied. The sensitivity of A. retroflexus L.to acifluorfen sodium was determined using bioassay. The effects on leaf chlorophyll content and target enzyme activity were studied at a normal dosage of 360 g a.i. hm^(-2) and a doubling dosage of 720 g a.i. hm^(-2) of acifluorfen sodium. Newly harvested seeds exhibiting dormancy were soaked in water of various temperatures and in different concentrations of NaOH and HCl, which were ineffective in breaking the seed dormancy. GA could break seed dormancy, and the highest seed germination rate reached 93.33% when they were soaked at 3 000 mg·L^(-1) for 72 h and 4 000 mg·L^(-1) for 48 h. The drought stress was simulated with a 15%-25% polyethylene glycol solution, which had no significant effect on the seed germination rate. The GR_(50) value of acifluorfen sodium for A. retroflexus L. was 705.7 g a.i. hm^(-2), which was 1.96 times the recommended dose in the field. After the application of different doses of acifluorfen sodium, the chlorophyll content of A. retroflexus L. reached its minimum value 3 days after treatment(DAT), and then gradually increased. The activity of the target enzyme protoporphyrinogen oxidase(PPO) reached the highest value at 7 DAT under different dosages, and gradually returned to normal levels thereafter. Soaking with gibberellin was an effective method to break seed dormancy. A. retroflexus L. seeds had certain drought resistance during the germination process. A. retroflexus L. was not sensitive to acifluorfen sodium and acifluorfen sodium ether, and could not effectively inhibit the PPO activity, indicating that A. retroflexus L. had target resistance to acifluorfen sodium.

Effects of drought on non-structural carbohydrates and C,N,and P stoichiometric characteristics of Pinus yunnanensis seedlings

To study non-structural carbohydrate character-istics and nutrient utilization strategies of Pinus yunnanen-sis under continuous drought conditions,2-year-old seed-lings were planted in pots with appropriate water,light and moderate and severe drought treatments[(80±5),(65±5),(50±5),and(35±5)%of field water-holding capacity].Non-structural carbohydrates,carbon(C),nitrogen(N),and phosphorus(P)concentrations were measured in each plant component.The results show that:(1)With increasing drought,non-structural carbohydrates gradually increased in leaves,stems,and coarse roots,while gradually decreased in fine roots;(2)C concentrations of all were relatively stable under different stress levels.Phosphorous utilization of each component increased under light and moderate drought conditions,while N and P utilization efficiency of each plant component decreased under severe drought.Growth was mainly restricted by N,first decreasing and then increasing with increased drought;(3)There was a correlation between the levels of non-structural carbohydrates and C,N,and P in each component.Changes in N concentration affected the interconversion between soluble sugar and starch,which play a regulatory role in the fluctuation of the concentration of non-structural carbohydrates;and,(4)Plasticity analysis showed that P.yunnanensis seedlings responded to drought mainly by altering starch concentration,the ratio of soluble sugar to starch in leaves and stems,and further by alter-ing N and P utilization efficiencies.Overall,these results suggest that the physiological activities of all organs of P.yunnanensis seedlings are restricted under drought and that trade-offs exist between different physiological indicators and organs.Our findings are helpful in understanding non-structural carbohydrate and nutrient adaptation mechanisms under drought in P.yunnanensis seedlings.

Effects of Biostimulant NEAU10 on Growth of Rice Seedlings and Soil Physicochemical Parameters

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.

Correlation Analysis between Well-cellar Early Transplanting of Robust Seedlings and Diseases in Shiyan Tobacco-growing Area

[Objectives]The paper was to investigate the relationship between the well-cellar early transplanting of robust seedlings and the prevalence of diseases in the Shiyan tobacco-growing area.[Methods]The relationship between disease occurrence and meteorological factors during the field growth period was examined by analyzing the prevalence of flue-cured tobacco virus diseases,brown spot,and total disease in the Shiyan tobacco-growing area before(2013-2017)and after(2018-2022)the well-cellar early transplanting of robust tobacco seedlings.[Results]The implementation of a well-cellar early transplanting technique of robust seedlings resulted in a reduction in the average incidence of tobacco virus disease,brown spot,and total disease by 0.83%,8.85%,and 7.91%,respectively,in comparison to the incidence observed prior to early transplanting.These findings suggest that early transplanting can significantly reduce the incidence of flue-cured tobacco diseases.Prior to the well-cellar early transplanting of robust tobacco seedlings,there was a significant(including highly significant)positive correlation between the incidence of brown spot and total disease and precipitation in August and September.The incidence of brown spot and total disease in tobacco plants was found to be significantly positively correlated with May precipitation and significantly negatively correlated with May sunshine hours following the well-cellar early transplanting of robust seedlings.The advancement of the transplanting period by 20 d resulted in a reduction in the growing period of tobacco plants in the field under autumn rains(late August to November)in western China.This effectively circumvented the suitable conditions for disease occurrence and can reduce the incidence of disease.[Conclusions]This study offers a framework for enhancing the quality and efficiency of flue-cured tobacco production in the northwest tobacco-growing area of Hubei.

Molecular Dissection of Relationship Between Seedling Characteristics and Seed Size in Rice

Seedling characteristics such as leaf emergency, chlorophyll content, and height are important for early growth and also associated with seed size. Quantitative trait loci (QTLs) for rice (Oryza sativa L.) seedling characteristics (leaf length, chlorophyll content, seedling height) and seed size were identified with an attempt to explore the relationship between seedling characteristics and seed size, using a recombinant inbred population derived from a cross between Zhenshan 97A and Minghui 63. Two, one, five, four, four, and nine QTLs were detected for chlorophyll a content, total chlorophyll, length of the second seedling leaf, length of the third seedling leaf, seedling height, and seed size, respectively. The results indicated that four QTLs for seed size and four QTLs for seedling characteristics shared several similar regions (G359-RG532, C567-RG236, RZ403-R19, C371-C405a), respectively, suggesting a close association between seedling characteristics and seed size. Several chromosomal regions influencing seed size, however, had no effects on seedling characteristics, suggesting that it was possible to improve seedling vigor without increasing grain size.

Effects of Nitrogen Application Rate, Density and Seedling Age on Dry Matter Accumulation of No-tillage Rape in Seedling Stage

[Objective] The aim of the research was to find the optimal nitrogen application rate, density and seedling age for no-tillage rape in seedling stage. [Method] With the D-optimal quadratic regression design for three factors, the 310 scheme was designed to study the effects of nitrogen application rate, density and seedling age on dry matter accumulation of no-tillage rape in seedling stage. [Result] With the increase of nitrogen application rate, density and seedling age, the dry matter content appeared like a parabola, increasing firstly and then declining. The change of nitrogen application rate caused greater influence than that of density and seedling age; the interaction effects between nitrogen application rate and density were greater than that between nitrogen application rate and seedling age as well as between density and seedling age. [Conclusion] Considered comprehensively, the dry matter content of no-tillage rape in seedling stage reached the highest level (4 768.2 kg/hm2) when the nitrogen application rate, the density and the seedling age were 195 kg/hm2, 93 000 plants/hm2 and 33 d, respectively.

Seed germination and seedling development of Prunus armeniaca under different burial depths in soil

A semi-greenhouse study was conducted to understand the effects of soil burial depth on seed germination and seedling development. The seeds of wild apricot （Prunus armeniaca） were buried at the soil depths of 0-cm, 4-cm, 8-cm, and 12-cm, respectively, to simulate the seed hoarding behavior of rodents in the field. The results revealed that the rates of seed germination and established seedlings from buried seeds were both the highest in 4-cm burial depth group, and then decreased with increasing soil depth. The number of rotten seeds increased in deeper burial depth. It is unfavourable for seed germination at 0-cm burial depth （i.e., seeds were laid on soil surface）. There was insignificant effect of burial depth on growth of established seedlings. The results from this study indicated that proper burial depth in soil would be helpful for the seed germination and seedling growth. The seedlings derived from buried seeds at shallower depth （4 cm） in this research have advantage in their early development.

Effects of Seed Rate on Root Twining Power and Seedling Quality of Machine-transplanted Super Rice

In order to investigate the effects of seed rate on root twining power and seedling quality of machine-transplanted super rice cultivars, Yongyou 12 and Zhongzheyou No.l, total 6 seed rates were arranged, and the growth characteris- tics, quality and root twining power of machine-transplanted rice seedlings were studied. The results showed that seed rate had great effects on root twining power and qualityof rice seedlings; with the increase of seed rate, the root twining power of rice seedlings was increased, but the quality of rice seedlings was significantly reduced; under the condition of high seed rate, rice seedlings were weak with less accumulate dry matter and nonuniform growth, and the proportion of weak seedlings was higher. When the seed rate of both rice cultivars was reduced by 10 g/tray, the average seedling height was increased by 0.5 cm, leaf age was increased by 0.1, stem base diameter was increased by 0.1 cm, and root number per plant was increased by 0.3. When the seed rate was increased by 10 g/tray, the accumulated dry matter per plant was reduced by 5.1 mg. With the increase of seed rate, the seedling quality of Zhongzheyou No.1 was decreased rapidly, and the proportion of weak seedlings was increased rapidly. However, Yongyou 12 has a larger elasticity in seed rate. When the seed rate reached to 50 g/tray, blanket seedlings of Yongy- ou 12 were nursed with uniform growth and higher quality, but the shoots were sparse with lower leaf area index. However, when the seed rate was up to 50 g/tray, blanket seedlings of Zhongzheyou No.1 were nursed with uniform growth and higher quality, as well as higher-density shoots. From a comprehensive point of view, the optimum seed rates of Yongyou 12 and Zhongzheyou No.1 were 65 and 50 g/tray, respectively.

Field Experiment for the Effects of Rice Straw Returning and Seeding Pattern on Wheat Seedling Emergence and Grain Yield

In order to study the effect of rice straw returning and seeding patterns on seedling emergence and grain yield, field experiment was conducted to investi- gate the effects of straw mechanized returning and different seeding patterns on e- mergence rate, emergence uniformity and yield traits of wheat after rice. The results were as follows： in rice straw removal treatments, the emergence rate of mechani- cal seeding in drill was lower than that of mechanical uniform planting and manual broadcast sowing, which were 51.84%, 90.89% and 88.87%, respectively; the emer- gence uniformity of manual broadcast sowing was inferior to mechanical seeding in drill and mechanical uniform planting, which were 0.49, 0.26 and 0.23, respectively. As for the treatments with rice straw returning to the field, the emergence rate and emergence uniformity all decreased in the three seeding patterns, of which mechan- ical seeding in drill dropped markedly with emergence rate decreased by 36.54%. The emergence rate and emergence uniformity affected grain yield by affecting pan- icle, grains per spike and 1 000-grain weight. The grain yield for the treatment with rice straw removal was 6 091.34 kg/hm2, while that with rice straw returning to field was 6 476.20 kg/hm2, and both were higher than the yields of the other two seed- ing patterns. Therefore, mechanical uniform planting was？recommended for its higher emergence rate, better emergence uniformity, which was conductive to increase grain yield in wheat after rice production with rice straw returning to field.

Effects of Seed Soaking with Uniconazole and Substrate Formula on Seedling Quality of Rapeseed

[Objective] To cultivate blanket rapeseed seedlings suitable for automatic mechanical transplanting, the effects of seed soaking with uniconazole and substrate formula on seed germination and seedling quality of rapeseed were investigated using HY4 as the material. [Method] The rapeseed seeds were soaked in different concentrations（0, 5, 10, 20, 30, 40 and 50 mg/L） of uniconazole for 0, 1, 2, 4 and8 h, respectively. Subsequently, they were dried naturally. After the preliminary screening carried out in petri dishes and in a laboratory, the optimum soaking concentration and time of uniconazole were obtained. On the other hand, the rapeseed seeds were soaked in different concentrations（0, 5, 10, 15 and 20 mg/L） of uniconazole for 0, 1 and 2 h, respectively for outdoor pot experiment. At the same time, the screening of optimum substrate formula for cultivating blanket rapeseed seedlings was carried out. The field test was carried out to verify the screened optimum substrate formula. [Result] The results of petri dish experiment showed that seed soaking with uniconazole could delay seed germination, reduce seed germination rate, inhibit hypocotyl elongation and promote root growth. When the soaking concentration exceeded 30 mg/L and soaking time exceeded 2 h, the effect of seed soaking with uniconazole on seed germination was greater, and the seed soaking inhibited root growth. The results of outdoor pot experiment showed that the soaking concentrations and times all significantly reduced seedling height, slowed shoot growth and promoted root growth, which all contributed to the cultivation of blanket rapeseed seedlings suitable for automatic mechanical transplanting. In the substrate formula, the lower the proportion of soil was, the better the seedling growth was. In the substrate with lower proportion of soil, the seed germination rate, plant height,root vigor and dry matter accumulation were all increased（P〈0.05）, which was verified by the field test. When the soaking concentration was less than 10 mg/L and soaking time was less than 1 h, the uniconazole showed weaker regulation effect on seedling growth, and the rapeseed seedlings were higher. In the substrate with soil proportion less than 50%, the adequate fertility relatively weakened the regulation effect of uniconazole on seedling growth, and the rapeseed seedlings were larger. [Conclusion] When the soaking concentration ranged within 15-20 mg/L and soaking time ranged within 1-2 h and the proportion of soil in substrate was 50%,the height of cultivated rapeseed seedlings was less than 18 cm, there were 5-6leaves remained on each plant and the nursing period was shortened to 30-40 d,which were all beneficial to industrial production.

Effects of Shading Degree on Storage Rate and Growth of Phoebe bournei Seedlings in Fields

In the research, four shading treatments were set, including the treatments with shading degrees at 0, 40%, 60% and 70%, in order to explore storage rate and seedling growth of annual Phoebe bournei. The results showed that the storage rate is growing upon shading degree. In the research, for example, storage rate reached the peak with the shading degree at 70%, and only 42.2% with shading degree at 0. In addition, seedling height and ground diameter showed extremely significant differences among treatments, and the treatment with shading degree at 60% was the best.

Branching and growth of plantings in fifth year of a seedling seed orchard of Masson pine (Pinus massoniana Lamb.)

The features of branching and growth studied included height, diameter at breast height (DBH), total number of branches, annual height growth, annual branch elongation in the year of elongating, annual branch number for four consecutive years, diameter of branches of different ages, and diameter of stem where branch-whorl originates. For features of total growth and overall branching, no significant differences were found between families, except for DBH. For annual features, no significant differences were found in annual stem height growth, annual branch elongation in the year of elongation and diameter of branches. In the last four years, differences in number of branches were not significant in the first two years but were significant in the last two year; differences in stem diameter where branch-whorls grow were significant for the four consecutive years. Trend of annual growth and branching features of families can be divided into three types as increasing type, stable type and fluctuating type. Most of families have an increasing type with respect of annual height growth and annual branch elongation, while most families belong to a fluctuating type with annual branch number. The results indicated that in the fifth year after planted in seedling seed orchard, differences between families were mostly insignificant. This result may have two main explanations: one is the growth rhyme in early ages of Masson pine, the other one is the complex paternal components to form the open-pollinated families. Family selection seemed to be not useful based on the result. It is suggested to select some of families in the nursery instead of to use all the families when establishing seedling seed orchards with open-pollinated families from plus-trees.

Effects of Uniconazole on Physiological and Biochemical Properties of Roots of Different Sweetpotato Cultivars at Seedling Stage

Objective] This study almed to investigate the effects of uniconazoIe on physioIogical and biochemical properties of roots of different sweetpotato cuItivars at seedIing stage. [Method] Under hydroponic conditions in a greenhouse, the effects of exogenous uniconazoIe on physioIogical and biochemical properties of roots of different sweetpotato cuItivars at seedIing stage were analyzed under continuous drought stress simuIated by PEG-6000. [Result] Compared with normal water suppIy treatment （N）, drought treatment （D） decreased significantIy root Iength, root surface area, average root diameter and root voIume of Jishu 21 and Jihei 1; to be specif-ic, compared with Jishu 21, root Iength, root surface area and average root diame-ter of Jihei 1 decreased greatIy, but root voIume of Jihei 1 decreased sIightIy. SOD, POD, APX activities and MDA content of Jishu 21 and Jihei 1 increased, and root vitality of two sweetpotato cuItivars was reduced; to be specific, compared with Jihei 1, Jishu 21 exhibited significantIy improved SOD, POD, APX activities, sIightIy im-proved MDA content and remarkabIy reduced root vitality. IAA, GAs and ZR con-tents of Jishu 21 and Jihei 1 decIined at seedIing stage; ABA content of two sweetpotato cuItivars was improved; to be specific, compared with Jihei 1, IAA, GAs and ZR contents of Jishu 21 were reduced sIightIy, whiIe ABA content of Jishu 21 was improved sIightIy. Under stress conditions, uniconazoIe treatment increased sig-nificantIy root Iength and root surface area of Jihei 1 and increased sIightIy root voIume of Jihei 1 compared with Jishu 21; uniconazoIe treatment increased signifi-cantIy SOD, POD and APX activities and root vitality of Jihei 1 and decIined re-markabIy MDA content of Jihei 1 compared with Jishu 21; uniconazoIe treatment in-creased significantIy IAA, ZR and ABA contents of Jihei 1 compared with Jishu 21. [Conclusion] Drought-toIerant sweetpotato cuItivar Jishu 21 exhibits high pIasma membrane integrity and root vitality by increasing activities of antioxidant enzymes under drought stress and malntalning high contents of IAA, ZR and ABA. Unicona-zoIe exerts greater reguIatory effects on physioIogical and biochemical properties of drought-sensitive sweetpotato cuItivar Jihei 1 under drought stress.

Chromosome Location of the Male-sterility and Yellow Seedling Gene in Line 1066A of Foxtail Millet

Using foxtail millet (Setaria italica (L.) Beauv.) male-sterile line 1066A as female parent and Yugu 1 primary trisomic series (1 - 7) and tetrasomics 8, 9 as male parents, chromosome location of gene for male-sterility and yellow seedling in line 1066A was studied by primary trisomic analysis. The plants of F-1 generation of trisomics 2 - 9 were obtained by crossing with a great many plants of 1066A. F-1 generation of trisomics was similar to their male parent in morphologic characters, the color of their seedling was green, and pollen was partially fertile. The segregation ratio of fertility to sterility is 3:1 in F-2 generation of trisomics 2, 3, 4, 5, 7, 8 and 9; and 14:1 only in F-2 generation of trisomic 6 (chi(0.05)(2) = 0.012). The segregation ratio of green seedling to yellow seedling is 12:1 only in F-2 generation of trisomic 7 (chi(0.05)(2) = 0.31), but in other cases, this ratio is 3:1. The results indicated that the male-sterility gene was located on chromosome 6, and the gene for yellow seedling was monogenic recessive and located on chromosome 7. The rate of trisomics transmission by pollen was tested, trisomics 8 and 9 were the highest in rates of trisomics transmission and followed by trisomics 6 and 4.

Effects of Pb Stress on Seed Germination and Seedling Growth of Two Weed Species Seeds

Objective] The aim was to investigate the effects of Pb stress on seed germination and seedling growth of Chenopodium glaucum and Chenopodium serot-inum L. [Method] With C. glaucum and C. serotinum as the study objects, the ef-fects of different concentrations of Pb on their seed germination and seedling growth, as wel as on the leaf SOD, POD and CAT activity were studied primarily. [Result] The germination potential of both the two kinds of weed seeds increased first and then decreased with the increase of Pb concentration. The germination po-tential of C. serotinum and C. glaucum seeds reached the peak at Pb concentration of 25 and 50 mg/L, respectively. With the increase of Pb treatment concentration, the germination rate, germination index and vigor index of C. serotinum and C. glaucum seeds decreased, and their bud length and root length also reduced gradu-al y. ln overal , the leaf SOD, POD and CAT activity of C. glaucum and C. serot-inum_ seedlings increased first and then decreased with the increased treatment concentration of Pb. The leaf SOD and POD activity of C. glaucum and C. serot-inum seedlings reached the maximum at Pb concentration of 200 and 100 mg/L, respectively, and the leaf CAT activity reached the maximum at Pb concentration of 100 mg/L. [Conclusion] The two Chenopodium species had strong tolerance to Pb stress, and they could be used as alternative accumulator plants of soil Pb contami-nation.