Correlations Between Plant Biomass and Soil Respiration in a Leymus chinensis Community in the Xilin River Basin of Inner Mongolia

This paper reports on two years of measurement of soil respiration and canopy-root biomass in a Leymus chinensis community in the Xilin River basin of Inner Mongolia. Correlations between components of plant biomass and soil respiration rates were examined. From respiration data based on CO2 uptake by NaOH and corresponding root biomass values for each run of 10 plots, a linear regression of CO2 evolution rates on root dry weights has been achieved for every ten days. By applying the approach of extrapolating the regressive line to zero root biomass, the proportion of the total soil respiration flux that is attributable to live root respiration was estimated to be about 27% on average, ranging from 14% to 39% in the growing season in 1998. There were no evident relations between the total canopy biomass or root biomass and CO2 evolution rates, but a significant exponential relation did exist between tire live-canopy biomass and CO2 evolution rates.

Relation of Wind-induced Sand Displacement to Plant Biomass and Plant Sand-binding Capacity

Desertification is a process in which vegetation cover degrades followed by increased wind and water erosion. Plants adapted to moving sand conditions are able to reverse this process. They can stabilize die substrate. Not much data is available on the soil stabilization capacity of plants. This study was conducted to investigate the wind-induced sand displacement around plants in relation to their biomass. Sand displacement is examined in relation to the biomass allocation pattern of three different plant species. A new method was developed to experimentally investigate plant sand-binding capacity. The relationship between sand displacement and plant biomass was not linear. Apart from the amount of biomass, species-specific plant characters like the biomass allocation pattern and plant structure may be very important in determining the sand-binding capacity.

Biodegradation and Sugar Release from Canola Plant Biomass by Selected White Rot Fungi

Canola crop is rich in plant biomass. It is considered a major cash crop in North America and a potential source for biofuel. We evaluated six strains of white rot basidiomycetes under solid state fermentation (SSF) for their potentials to secrete oxidative and hydrolytic enzymes to biodegrade canola plant biomass (CPB), and release sugars. Fuscoporia gilva and Pleurotus tuberregium produced high amount of laccase (440.86 U/L and 480.63 U/L at day 7), as well as carboxylmethylcellulase (CMCase) (4.78 U/mL at day 21 and 3.13 U/mL at day 14) and xylanase (4.48 U/mL and 7.8 U/mL at day 21), respectively. Bjerkandera adusta showed high amount of MnP (50.4 U/L) and peroxidase (64.5 U/L), relative to the other strains. Loss of organic matter peaked after 21 days of incubation in all the tested strains;however, the best result (34.0%) was shown in P. tuberregium. The highest lignin loss was observed in Coriolopsis caperata strains. Among the sugar polymers, hemicellulose was highly degraded by P. tuberregium and P. pulmonarius (4.1% - 4.6%), while cellulose (3.3% - 4.3%) was mainly degraded by F. gilva and B. adusta. Glucose was the dominant sugar released by all the fungi tested, with the highest concentration of 1.25 mg/mL produced by B. adusta at day 14 of incubation. Results indicate that selected white rot fungi can achieve significant delignification of CPB within 14 days of solid state fermentation. Their importance in low cost pretreatment of lignocellulosic biomass prior to conversion into biofuels and bio-products of economic importance is discussed.

Effects of Biochar Application on Soil Properties, Plant Biomass Production, and Soil Greenhouse Gas Emissions: A Mini-Review

Biochar has been applied extensively as a soil amendment over the past decades. This review summarizes the general findings of the impacts of biochar application on different aspects from soil physical, chemical, and microbial properties, to soil nutrient availabilities, plant growth, biomass production and yield, greenhouse gases (GHG) emissions, and soil carbon sequestration. Due to different biochar pyrolysis conditions, feedstock types, biochar application rates and methods, and potential interactions with other factors such as plant species and soil nutrient conditions, results from those studies are not inclusive. However, most studies reported positive effects of biochar application on soil physical and chemical properties, soil microbial activities, plant biomass and yield, and potential reductions of soil GHG emissions. A framework of biochar impacts is summarized, and possible mechanisms are discussed. Further research of biochar application in agriculture is called to verify the proposed mechanisms involved in biochar-soil-microbial-plant interactions for soil carbon sequestration and crop biomass and yield improvements.

Adsorption of α-Chymotrypsin on Plant Biomass Charcoal

The adsorption of α-chymotrypsin onto plant biomass charcoal (PBC), which was prepared from plant biomass wastes such as bagasse and dumped adzuki beans by pyrolysis, has been examined. The PBC was characterized by SEM, specific surface area, and pore size distribution. The adsorption isotherms were successfully correlated by the Freundlich equation. The amount of α-chymotrypsin adsorbed on PBC was dramatically dependent upon the solution pH and temperature. Maximum adsorptions of α-chymotrypsin on adzuki bean charcoal and bagasse charcoal were observed at weak acidic and near neutral pH, respectively. The amount of α-chymotrypsin adsorbed on PBC decreased with an increase in the concentration of salts. Plots of the amount of α-chymotrypsin adsorbed on PBC versus temperature exhibited an optimum temperature.

Plant Biomass, Primary Production and Mineral Cycling of a Mixed Oak Forest in Linnebjer, Sweden

Plant biomass, primary production and mineral cycling were studied in a mixed deciduous forest (Quercus robur L., Tilia cordata L. and Corylus avellana L.) in southern Sweden. Plant biomass amount above and below ground was 201 and 37 t&middotha-1, respectively. Primary production above and below ground was an estimated 13.3 and 2.3 t&middotha-1, respectively. Carbon was the dominant element in the forest ecosystem, comprising 133 t&middotha-1. Other major elements were: N > Ca > K > Si > Mg > S > Mn > P > Fe and Na (range 1123 to 18 kg&middotha-1), followed by some trace elements. Yearly litterfall restored 6.0 t&middotha-1 organic matter or 2.3 t&middotha-1 carbon. Approximately 45% decomposed and returned to the soil during the year. Monitoring of other elements revealed that the ecosystem received inputs through dry and wet deposition, in particular 34.4 kg&middotha-1 S and 9.4 kg&middotha-1 of N yearly as throughfall. Determination of yearly biomass increase showed that the oak forest ecosystem was still in an aggradation or accumulation phase.

Relationship between Plant Species Diversity and Plant Biomass of Orchard Grass and Lucerne Sown in Different Ratios in the Province of Salamanca, Spain

A field experiment was carried out at the CSIC Mu&#241ovela farm belonging to the Spanish National Research Council (CSIC) in order to evaluate the effect of sowing orchard grass (Dactylis glomerata var. Trerano) and lucerne (Medicago sativa var. Aragon) in monoculture and in combination. The experiment was based on a randomized block designed with a factorial arrangement (5 × 2). Experimental units were 40 plots distributed in four blocks. The phosphorus fertilization (P) factor included two types of conditions: basal fertilization without phosphorus (-P) and basal fertilization with phosphorus (+P), and the vegetation cover factor (T) included five conditions depending on the grass (G) and the legume (L). Above-ground biomass showed statistically significant differences among seasons and years (P Lolium perenne L. and Poa pratensis L. throughout the three years indicated that both species significantly increased their presence over time regardless of the treatments applied. The analysis performed for the other plant species (those other than grasses and legumes) allowed us to determine that the T1 and T5 treatments, which correspond to single species not treated with the application of phosphorus, influenced the presence of 70% of other species planted. Our specific aim was to explore how changing plant biotic diversity affects productivity under a given set of conditions. We manipulated plant species richness as an experimental factor to determine if productivity would be affected by changes in the ratios of plants sown.

Mechanism of the effect caused by highway construction on plant biomass in Longitudinal Range-Gorge Region

Taking Dabao （from Dali City to Baoshan City, Yunnan Province, China） and Sixiao （from Simao City to Xiaomengyang Town, Yunnan Province, China） highways in Longitudinal Range-Gorge Region as examples. Biomass, coverage and photosynthesis rate of different plant types on sampling points （at the distances from road of 5, 20, 40, 80, 120 and 200 m） and their control points were estimated on ground. The relations among biomass, coverage, photosynthesis rate were analyzed with an aim to explore the mechanism of the effect caused by highway construction on plant biomass. The results show, i） the impacts of highway construction on plant biomass are both positive and negative. Arbor is mainly negatively impacted, while shrub and herbage are mainly positively impacted. The effect of highway construction decrease with the increase of distance from the road; ii） highway construction exert obvious influence on plant biomass through altering the physiologic processes （reflected by the plant number） and photosynthesis, iii） highway construc- tion will result in the decrease of arbor number, photosynthesis rate and biomass, and increase of plant number, photosynthesis rate and biomass of shrub and herbage.

Sustainable land management interventions lead to carbon sequestration in plant biomass and soil in a mixed croplivestock system:the case of Geda watershed,central highlands of Ethiopia

Background:Sustainable land management interventions were introduced in Geda watershed in 2012 to reduce soil erosion,improve water infiltration,and increase plant-carbon inputs into the soil.This study explored the impact of the interventions on biomass production,carbon stock,and carbon sequestration.Stratified sampling was employed in the main and the dry seasons in the treated and untreated sub-watersheds that are found adjacent to each other.Above-and below-ground plant biomass,soil bulk density and organic carbon in 0-15-and 15-30-cm depths,and soil moisture content in 0-20-and 20-40-cm depths were collected from the crop,grazing,and tree lucerne plots.All analyses were performed based on standard procedures.Results:Plant biomass production,carbon stock,and carbon sequestration varied highly significantly(P≤0.001)among sub-watersheds,landscape positions,and land uses.Higher mean values were observed for treated subwatershed,lower landscape position,and tree lucerne plot.The higher mean values in the lower landscape position of the treated sub-watershed were due to tree lucerne plantation.Similarly,topsoil(0-15 cm)carbon stock was statistically higher(P≤0.001)in the treated sub-watershed and at tree lucerne plot(P≤0.05).In addition,carbon stock by sub-surface soil(15-30 cm)was significantly higher(P≤0.001)in the treated sub-watershed under crop and grazing lands but the higher value was in cropland and in the upper position.This could be due to the decomposition of organic materials from biomasses of crops and biological supporting measures(tree lucerne and Phalaris)facilitated by tillage.Six years of sustainable land management interventions led to the sequestration of 12.25,7.77,and 13.5 Mg C ha^(−1) under cropland,tree lucerne,and grazing plots,respectively.Conclusion:Sustainable land management interventions revealed auspicious ecological impacts in Geda watershed in terms of improving plant biomass production,carbon stock,and correspondingly capturing higher carbon dioxide equivalent taking untreated sub-watershed as a baseline.Prohibition of free grazing was the key element of the intervention to reduce biomass export and increase carbon sequestration in the treated sub-watershed.Thus,sustaining tree lucerne plants as a conservation measure and the prohibition of free grazing practices are principally essential.

Changes in plant biomass and species composition of alpine Kobresia meadows along altitudinal gradient on the Qinghai-Tibetan Plateau

Alpine Kobresia meadows are major vegetation types on the Qinghai-Tibetan Plateau. There is growing concern over their relationships among biodiversity, productivity and environments. Despite the im-portance of species composition, species richness, the type of different growth forms, and plant bio-mass structure for Kobresia meadow ecosystems, few studies have been focused on the relationship between biomass and environmental gradient in the Kobresia meadow plant communities, particularly in relation to soil moisture and edaphic gradients. We measured the plant species composition, her-baceous litter, aboveground and belowground biomass in three Kobresia meadow plant communities in Haibei Alpine Meadow Ecosystem Research Station from 2001 to 2004. Community differences in plant species composition were reflected in biomass distribution. The total biomass showed a de-crease from 13196.96±719.69 g/m2 in the sedge-dominated K. tibetica swamp to 2869.58±147.52 g/m2 in the forb and sedge dominated K. pygmaea meadow, and to 2153.08±141.95 g/m2 in the forbs and grasses dominated K. humilis along with the increase of altitude. The vertical distribution of below-ground biomass is distinct in the three meadow communities, and the belowground biomass at the depth of 0-10 cm in K. tibetica swamp meadow was significantly higher than that in K. humilis and K. pygmaea meadows (P<0.01). The herbaceous litter in K. tibetica swamp was significantly higher than those in K. pygnaeca and K. humilis meadows. The effects of plant litter are enhanced when ground water and soil moisture levels are raised. The relative importance of litter and vegetation may vary with soil water availability. In the K. tibetica swamp, total biomass was negatively correlated to species richness (P<0.05); aboveground biomass was positively correlated to soil organic matter, soil moisture, and plant cover (P<0.05); belowground biomass was positively correlated with soil moisture (P<0.05). However, in the K. pygnaeca and K. humilis meadow communities, aboveground biomass was posi-tively correlated to soil organic matter and soil total nitrogen (P<0.05). This suggests that the distribu-tion of biomass coincided with soil moisture and edaphic gradient in alpine meadows.

Planting density affected biomass and grain yield of maize for seed production in an arid region of Northwest China

Field experiments were conducted from 2012 to 2015 in an arid region of Northwest China to investigate the effects of planting density on plant growth, yield, and water use efficiency（WUE） of maize for seed production. Five planting densities of 6.75, 8.25, 9.75, 11.25 and 12.75 plants/m^2 were conducted in 2012, and a planting density of 14.25 plants/m^2 was added from 2013 to 2015. Through comparison with the Aqua Crop yield model, a modified model was developed to estimate the biomass accumulation and yield under different planting densities using adjustment coefficient for normalized biomass water productivity and harvest index. It was found that the modified yield model had a better performance and could generate results with higher determination coefficient and lower error. The results indicated that higher planting density increased the leaf area index and biomass accumulation, but decreased the biomass accumulation per plant. The total yield increased rapidly as planting density increased to 11.25 plants/m^2, but only a slight increase was observed when the density was greater than 11.25 plants/m^2. The WUE also reached the maximum when planting density was 11.25 plants/m^2, which was the recommended planting density of maize for seed production in Northwest China.

Ecological biomass allocation strategies in plant species with different life forms in a cold desert, China

Biomass allocation patterns among plant species are related to their adaptive ecological strategies. Ephemeral, ephemeroid and annual plant life forms represent three typical growth strategies of plants that grow in autumn and early spring in the cold deserts of China. These plants play an important role in reducing wind velocity in the desert areas. However, despite numerous studies, the strategies of biomass allocation among plant species with these three life forms remain contentious. In this study, we conducted a preliminary quadrat study during 2014–2016 in the southern part of the Gurbantunggut Desert, China, to investigate the allocation patterns of above-ground biomass(AGB) and below-ground biomass(BGB) at the individual level in 17 ephemeral, 3 ephemeroid and 4 annual plant species. Since ephemeral plants can germinate in autumn, we also compared biomass allocation patterns between plants that germinated in autumn 2015 and spring 2016 for 4 common ephemeral species. The healthy mature individual plants of each species were sampled and the AGB, BGB, total biomass(TB), leaf mass ratio(LMR) and root/shoot ratio(R/S) were calculated for 201 sample quadrats in the study area. We also studied the relationships between AGB and BGB of plants with the three different life forms(ephemeral, ephemeroid and annual). The mean AGB values of ephemeral, ephemeroid and annual plants were 0.806, 3.759 and 1.546 g/plant, respectively, and the mean BGB values were 0.106, 4.996 and 0.166 g/plant, respectively. The mean R/S value was significantly higher in ephemeroid plants(1.675) than in ephemeral(0.154) and annual(0.147) plants. The mean LMR was the highest in annual plants, followed by ephemeroid plants and ephemeral plants, reflecting the fact that annual plants allocate more biomass to leaves, associated with their longer life span. Biomass of ephemeral plants that germinated in autumn was significantly higher than those of corresponding plants that germinated in spring in terms of AGB, BGB and TB. However, the R/S value was similar in plants that germinated in autumn and spring. The slope of regression relationship between AGB and BGB differed significantly among the three plant life forms. These results support different biomass allocation hypotheses. Specifically, at the individual level, the AGB and BGB partitioning supports the allometric hypothesis for ephemeroid and annual plants and the isometric hypothesis for ephemeral plants.

Estimating above-ground biomass by fusion of LiDAR and multispectral data in subtropical woody plant communities in topographically complex terrain in North-eastern Australia

We investigated a strategy to improve predicting capacity of plot-scale above-ground biomass （AGB） by fusion of LiDAR and Land- sat5 TM derived biophysical variables for subtropical rainforest and eucalypts dominated forest in topographically complex landscapes in North-eastern Australia. Investigation was carried out in two study areas separately and in combination. From each plot of both study areas, LiDAR derived structural parameters of vegetation and reflectance of all Landsat bands, vegetation indices were employed. The regression analysis was carded out separately for LiDAR and Landsat derived variables indi- vidually and in combination. Strong relationships were found with LiDAR alone for eucalypts dominated forest and combined sites compared to the accuracy of AGB estimates by Landsat data. Fusing LiDAR with Landsat5 TM derived variables increased overall performance for the eucalypt forest and combined sites data by describing extra variation （3% for eucalypt forest and 2% combined sites） of field estimated plot-scale above-ground biomass. In contrast, separate LiDAR and imagery data, andfusion of LiDAR and Landsat data performed poorly across structurally complex closed canopy subtropical minforest. These findings reinforced that obtaining accurate estimates of above ground biomass using remotely sensed data is a function of the complexity of horizontal and vertical structural diversity of vegetation.

Periphyton Biomass Response to Phosphorus Additions in an Aquatic Ecosystem Dominated by Submersed Plants

An experiment was conducted to investigate the response of periphyton biomass to addition of phosphorus (P) in an aquatic ecosystem dominated by submersed plants. Aquatic ecosystems dominated by Hydrilla verticillata (L.f.) Royle and Vallisneria natans (Lour.) Hara were constructed in mesocosm aquaria. Mesocosms were dosed weekly with different P loads (0 μg/L/Week and 100 μg/L/Week) for 17 weeks. Total P (TP), total soluble P (TSP), and soluble reactive P (SRP) concentrations in the waters of mesocosms added with P were significantly higher as opposed to the unenriched control mesocosms. The biomass of the attached periphyton and the cover of floating periphyton remained abundant in P-unenriched control mesocosms throughout the test period with a TP, TSP, and SRP concentration ranging of 0.021 - 0.049 mg/L, 0.004 - 0.024 mg/L, and 0.003 - 0.018 mg/L, respectively. P addition caused the decline of attached periphyton biomass to a low level and loss of floating periphyton. Results indicate that P enrichment in an aquatic ecosystem dominated by submersed plants could reduce attached periphyton biomass and eliminate floating periphyton. The research would be useful to maintain periphyton by reducing excessive P in aquatic ecosystem dominated by submersed plants.

Can Stand Density and Stem Stratification Be Indicators of Aboveground Biomass in Woody Plant Recruitment in Savannah

Stem density and size stratification of woody species are informative of vegetation conditions and its physiognomy in savannah whereas their variation influence woody population functioning. Current study endeavoured to evaluate the stand density and size variability of woody species related to aboveground biomass in a Sudanian savannah. Total height, stem diameter at breast height (dbh) ≥ 5 cm were measured in 30 plots of 50 m × 20 m laid in respect to vegetation type as bowal, shrubland and woodland. Species diversity, stem density, height and basal area were calculated and compared across sites and variation in stem dbh classes evaluated. Total aboveground biomass was estimated and thereafter linear relationships were established between stand density and aboveground biomass, and basal area. Results revealed three different sites with an overall 58 species identified through vegetation type including liana species (4 stems in bowal) with 18 genera and 42 families. Fabaceae Combretaceae, Anacardiaceae and Rubiaceae were dominant families. Small sized trees represented 72% of total stem density considered in structure with significant higher basal area, while large sized trees as 28% were scarcely distributed. More than 70% variation in biomass was due to stem density and basal area with a dominance of small trees. In conclusion increase size in tree community indicated increase in accumulated aboveground biomass as positive regeneration features. But, change in vegetation structure strongly influence negatively species ability to grow from lower to upper size class and later on, disrupt ecosystem functioning. Plant stem density and stratification could be considered as indicators of aboveground biomass fluctuating in regeneration monitoring.

Cluster planting impact on cotton growth, yield and biomass accumulation in an arid region oasis

The cluster planting pattern （3 plants per hole） for cotton （Gossypium hirsutum L.） may increase economic yield over those of the traditional planting pattern （1 plant per hole） in arid regions of China. This increase in yield depends on either increased biomass production or greater partitioning to fruit. This study was conducted to determine whether differences in biomass accumulation or partitioning to reproductive growth contributed to higher yield in the cluster planting pattern compared with the traditional one. Growth parameters, biomass accumulation, crop growth rate and partitioning between cluster planting pattern and traditional planting pattern was compared in northwest of China. The biomass production and partitioning in cluster planting plot was higher than in traditional planting one. Biomass accumulation was faster early in the clustered treatment, and it was also higher at harvest time. Total dry matter production per unit area was significantly higher than in the traditional planting. On a per plant basis, dry matter accumulation was faster and total biomass production was significantly higher in the cluster planting pattern. Numbers of sympodia and boll sizes were also larger, indicating that facilitation among plants was promoting crop yield. The increase in yield in the cluster planting treatment occurred through increased partitioning of dry matter to fruits than in the traditional planting pattern, resulting in more bolls and increased lint yield in arid regions.

Post-fire recovery of Puya raimondii, vegetation and birds in the puna of Huascarán National Park, Perú

A large fire of 233 ha in Huascarán National Park in Peru provided an opportunity to compare plant and bird responses in burned and nearby unburned zones of the puna. Heights and live diameters of flagship Puya raimondii rosettes(assigned to four broad developmental phases), plant communities(66 species in 24 families and nine growth forms) and bird communities(77 species in six trophic guilds) were monitored after the fire. Although no mortality was observed, Puya raimondii plants were affected by the fire, losing approximately 60% of their photosynthetic area across all developmental phases, but recovered quickly during the first two years after fire. The comparison of Puya rosette recovery after fire was complicated by the changes in live rosette diameter for unburned plants, which showed plasticity of photosynthetic area linked to seasonal and annual fluctuations in precipitation in this relatively dry environment(decreased by 26% for mature adult plants over the study period). Fire caused an immediate change in the density, biomass and composition of vegetation. Although the species present remained similar, their abundances changed significantly immediately after the fire, with notable reductions in dominant tussock grasses. This provided opportunities for other plants, resulting in higher postfire diversity of plant species, genera, families and growth forms. In turn, the changes in vegetation after fire affected the composition of birds according to their trophic guild. Granivores largely disappeared,generalists were mostly unaffected, and other guilds showed a more complex response. As the vegetation recovered, most displaced birds returned within approximately one year.

磷矿粉在石灰性土壤中对紫花苜蓿的施用效果

磷矿粉是一种难溶性磷肥,一般认为其在石灰性土壤上施用效果不好。苜蓿(Medicago sativa)利用难溶性磷的能力较强,为探索磷矿粉在石灰性土壤对苜蓿的施用效果,本研究以3种不同品位磷矿粉PRⅠ、PRⅡ、PRⅢ为磷肥源,以水溶性磷肥过磷酸钙为对照(CK),对3个紫花苜蓿品种‘阿尔冈金’(M1)、‘陇东苜蓿’(M2)、‘金皇后’(M3)进行土培盆栽试验,研究了不同磷矿粉处理下紫花苜蓿两茬的生长、营养品质、磷素的吸收利用以及土壤磷素含量。结果表明,第2茬收获时PRⅠ处理下M1和M3的株高明显高于CK,PRⅢ处理下M2的株高明显高于CK。M1两茬干重均表现出PRⅠ磷矿粉处理最高,两茬总生物量干重达到8.61 g,比CK高46.9%,3个磷矿粉处理下M2第1茬、第2茬和总生物量干重均高于CK,磷矿粉处理对M3的生物量没有明显作用。PRⅠ和PRⅢ处理显著提高了第2茬M1的粗蛋白含量,PRⅢ处理M1和M2紫花苜蓿的粗脂肪含量均高于CK。第1茬磷矿粉处理中PRⅡM3处理的钙含量达到最高值,为2.18%,与CKM3处理差异不显著(P>0.05),第2茬PRⅠM1和PRⅢM2处理的钙含量最高,均为1.56%。PRⅠ和PRⅢ处理可显著提高第2茬M1和M2的磷吸收效率,PRⅠ能显著提高第1茬M1和M2的磷利用效率,而PRⅡ均显著提高了3个紫花苜蓿品种第2茬的磷利用效率。除PRⅡM1处理外,磷矿粉处理均显著提高了土壤全磷含量,且3个品种均表现出在PRⅠ和PRⅢ处理下的土壤全磷含量高于PRⅡ,相比施肥前,磷矿粉处理均显著提高了土壤有效磷含量,M3的土壤的有效磷含量低于M1和M2。因此,磷矿粉在石灰性土壤对紫花苜蓿的生长、营养品质和磷素吸收利用可超过或达到与过磷酸钙相当的水平,其效果因磷矿粉品位和苜蓿品种不同而有差异,本研究条件下,PRⅠ磷矿粉,M1和M2品种表现出较好的施用效果。

BIOMASS AND PHOTOSYNTHESIS OF VASCULAR PLANTS UNDER ICE

This paper reports a vascular plant study which showed that :1. Five species of vascular plants Potemogeton crispus L., Batrachium bungei L ., Myriophyllum spicatum L., Potemogeton maackianus A. Bennet and Ceratophyllum demersum L . lived under ice during winter in northern China . The freshweight biomass varied from 8 3087 g/m2 in the order P . crispus >P. maackianus>M. spicatum > C. demersum > B. burngei . 2. The oxygen produced by these plants through photosynthesis vaned from 0.11 t0 1.91 mg/(h·g)(plant) in the ordered P. crispus > B. bungei >M. spicatum >C. demersum . 3. The light compensation point of P. crispus at 2.5℃ was 99 lx, that of B. bungei was 168 lx;that of M. Spicatum was 207 lx; and that of C . demersum was 176 lx. The light saturation point of P . crispus was 13749 lx, that of B. bungei was 27697 lx. 4. Special biological characteristics enable certain vascular plants to survive and have high photosynthetic productivity in waterbodies covered with ice tens of centimeters thick .

带宽和株距对带状间作大豆物质积累分配及产量形成的影响

间套作系统中合理的田间配置能改善作物生长环境,增加系统产量。为进一步完善西南地区大豆-玉米带状间作系统高产高效的田间配置技术,本研究以大豆-玉米带状间作为研究对象,采用二因素裂区试验设计,综合分析2.0 m(B1)和2.4 m(B2)2个带宽与9 cm(P1)、11 cm(P2)、14 cm(P3)、18 cm(P4)4个株距对大豆物质积累分配、籽粒灌浆和产量的影响。结果表明,B2带宽下各株距处理的净光合速率均高于B1,其2年平均值在B2下较B1增加14.26%;相同带宽下净光合速率在B1P4和B2P4达到最大,开花期较B1P1和B2P1增加13.57%和25.21%。2个带宽下大豆群体物质积累均随株距增加呈先增后减的趋势且分别在B1P3和B2P2下达到最大,完熟期B2较B1增加9.82%~22.08%。同时,带宽与株距的增加促进了大豆花后物质的积累与向籽粒的转移,与B1相比,B2处理使大豆花后干物质积累量与干物质转移量分别增加13.82%~28.01%和13.38%~37.76%,籽粒物质积累占比增加到41.80%~44.26%。物质积累的增加改善籽粒灌浆过程,B2带宽下籽粒灌浆活跃期(D)较B1延长2~3 d;2种带宽下平均灌浆速率均在P4达到最大且分别较P1增加5.80%和6.58%。产量结果表明,大豆-玉米带状间作模式中,带宽和株距的增加降低了群体有效株数,增加了单株粒数和百粒重;B2带宽下的大豆产量较B1增加22.32%~36.87%,2个带宽下分别在B1P3和B2P2达到最大值,2年间较B1P1和B2P1增加17.83%~26.44%和10.71%~10.76%。综上所述,2.4m带宽下大豆株距为11 cm时能有效改善大豆花后干物质积累和分配,促进籽粒灌浆,增加单株粒数和百粒重,提高大豆群体产量,实现大豆-玉米带状间作系统的高产高效。