青海高原草地净初级生产力和降水利用效率时空特征

为了探究青海高原草地净初级生产力（Net primary productivity,NPP）和降水利用效率（Precipitation use efficiency,PUE）的时空特征,基于遥感估算的NPP数据和降水空间插值数据,采用地理空间统计法分析了2001—2017年青海高原草地NPP和PUE的时空特征。结果表明：2001—2017年青海高原草地NPP均值为42.81 gC·m^-2,其中高值区域主要分布在青海高原的东部和南部,低值区域主要分布在青海高原的西北部。2001—2017年青海高原草地NPP年际变化总体较为平稳,以年均速率0.09 gC·m^-2呈微弱的波动上升。2001—2017年青海高原草地PUE均值为0.089 gC·m^-2·mm^-1,其中高值区域主要分布在青海高原的东部和南部,低值区域主要分布在青海高原的西部和西北部。2001—2017年青海高原草地PUE年际变化呈微弱的波动下降趋势,下降速率为年均0.0023 gC·m^-2·mm^-1。2001—2017年青海高原草地PUE年际变化整体上与降水年际变化为负相关。本研究为青海高原草地可持续利用提供了重要理论参考和数据支撑。     

不同基因型春小麦对磷胁迫的适应性反应

采用缺磷的石灰性土壤，利用盆栽试验研究了不同供磷水平对4个不同基因型春小麦的根系特征、酸性磷酸酶活性及产量的影响，以探讨不同基因型春小麦对低磷胁迫的适应性反应。结果表明，在高磷水平下，甘春20号根干重和地上部干重的增加率均高于其它基因型，产量比其它基因型高8．7％～25．1％；在缺磷条件下，甘春20号体内酸性磷酸酶活性比适当供磷和高磷处理分别增加了41．6％和101．9％，高于其它基因型，说明此基因型主要通过向根际释放磷酸酶以适应缺磷环境。在三个供磷水平下，定西33号和会宁18号的根都最长，平均比甘春20号和眈春16号长26．4％～36．7％，说明这两个旱地品种主要是通过增加根长扩大磷素吸收范围来适应缺磷环境的。根系酸性磷酸酶和根系形态参数可分别作为小麦耐低磷品种筛选的指标。     

Evaluating decision rules for dryland rotation crop selection

No-till dryland winter wheat (Triticum aestivum L.)-fallow systems in the central Great Plains have more water available for crop production than the traditional conventionally tilled winter wheat-fallow systems because of greater precipitation storage efficiency. That additional water is used most efficiently when a crop is present to transpire the water, and crop yields respond positively to increases in available soil water. The objective of this study was to evaluate yield, water use efficiency (WUE), precipitation use efficiency (PUE), and net returns of cropping systems where crop choice was based on established crop responses to water use while incorporating a grass/broadleaf rotation. Available soil water at planting was measured at several decision points each year and combined with three levels of expected growing season precipitation (70, 100, 130% of average) to provide input data for water use/yield production functions for seven grain crops and three forage crops. The predicted yields from those production functions were compared against established yield thresholds for each crop, and crops were retained for further consideration if the threshold yield was exceeded. Crop choice was then narrowed by following a rule which rotated summer crops (crops planted in the spring with most of their growth occurring during summer months) with winter crops (crops planted in the fall with most of their growth occurring during the next spring) and also rotating grasses with broadleaf crops. Yields, WUE, PUE, value-basis precipitation use efficiency ($PUE), gross receipts, and net returns from the four opportunity cropping (OC) selection schemes were compared with the same quantities from four set rotations [wheat-fallow (conventional till), (WF (CT)); wheat-fallow (no-till), (WF (NT)); wheat–corn (Zea mays L.)-fallow (no-till), (WCF); wheat–millet (Panicum miliaceum L.) (no-till), (WM)]. Water use efficiency was greater for three of the OC selection schemes than for any of the four set rotations. Precipitation was used more efficiently using two of the OC selection schemes than using any of the four set rotations. Of the four OC cropping decision methods, net returns were greatest for the method that assumed average growing season precipitation and allowed selection from all possible crop choices. The net returns from this system were not different from net returns from WF (CT) and WF (NT). Cropping frequency can be effectively increased in dryland cropping systems by use of crop selection rules based on water use/yield production functions, measured available soil water, and expected precipitation.     

杉木无性系测定林磷素利用效率的比较

对福建漳平五一国有林场17年生不同杉木无性系测定林的生物量及磷含量进行测定,对不同无性系全树磷利用效率及干材磷利用效率进行比较研究,筛选出磷利用效率高的优良杉木无性系.结果表明:不同无性系各器官生物量排序为:干>根>枝>皮>叶>枯枝.M10号无性系干材分配比例最大,M41次之.M41林分总生物量最高,M17次之.从干材生物量看,M41最大,是最小无性系M45的2.01倍.不同杉木无性系中M34的林分磷积累量最大,是参试无性系平均值的1.39倍.M1号杉木无性系全树磷利用效率最高,M10和M17次之,M34最低.M1号杉木无性系干材磷利用效率最高,M10、M9、M17和M41依次递减,而M24、M34和M37较低.M1、M10和M17号无性系为磷利用效率较高的基因型.     

Maize in-Season Growth Response to Organic Acid-Bonded Phosphorus Fertilizer (Carbond P®)

Phosphorus is essential for agriculture, but soil interactions antagonize uptake. An organic acid P fertilizer, Carbond® P (CBP), increases P solubility. One maize (Zea mays L.) glasshouse study on three soils and two field studies were conducted comparing CBP and ammonium polyphosphate (APP) on early season growth. In comparison to maize fertilized with APP, CBP fertilization produced significantly more biomass (in two glasshouse soils and one field study), stem thickness (one glasshouse soil and both field studies), plant height (one field study), and P concentration/uptake (one glasshouse soil and one field study). Although not always resulting in significant increases, CBP never resulted in decreases compared to APP. Increases occurred more commonly in highly calcareous soil (6–12%) low in bicarbonate extractable P (7 mg kg^?1). Improvements in early and late season growth parameters using CBP compared to APP warrant its use and further investigation to understand its benefits and limitations.     

Path and Correlation Analyses of the Factors affecting Biomass Production of Brassica Cultivars under Phosphorus‐Deficiency Stress Environment

Abstract

Path analysis is a statistical technique that partitions correlations into direct and indirect effects and distinguishes between correlation and causation, whereas correlation in general measures the extent and direction (positive or negative) of a relationship occurring between two or more variables. The estimates of correlation and path coefficients can help us to understand the role and relative contribution of various plant traits in establishing growth behavior of crop cultivars under given environmental conditions. Dependence of shoot dry‐matter (SDM) production of six hydroponically grown Brassica cultivars on various growth parameters and characteristics of P metabolism was investigated using the modified Johnson's nutrient solution to maintain deficient (10 µM) and adequate (200 µM) P levels. Root dry‐matter (RDM), total dry‐matter, P content in shoot, and P‐utilization efficiency (PUE) had significant and positive effects on production of SDM in a P‐deficient environment. Root–shoot ratio (RSR), however, negatively affected SDM of cultivars exposed to P‐deficient conditions and did not show any impact on SDM production in either of the two treatments. In a pot study, six Brassica cultivars were grown in a sandy loam soil that was deficient in NaHCO₃‐extractable P (3.9 mg P kg^?1 soil) for 49 days. Significant positive correlations were observed between SDM and some other plant traits such as RDM, leaf area per plant, P uptake, and PUE, at both genotypic and phenotypic levels. The correlations of SDM with RSR, however, were not observed, implying that relative partitioning of biomass into roots or shoots had little role to play in SDM production by Brassica cultivars under P‐deficiency stress. Path analysis revealed that favorable impact of RDM and leaf area on SDM production was indirect through positive effect of these parameters on P uptake and PUE. Thus, under P‐deficiency stress, better P acquisition and efficient P utilization by the cultivars for biomass synthesis collectively formed the basis of higher SDM production by the cultivars, evidencing that P uptake and utilization efficiency are two important plant traits for selecting P‐deficiency‐stress‐tolerant Brassica cultivars.     

Growth Behavior,Nitrogen-Form Effects on Phosphorus Acquisition,and Phosphorus–Zinc Interactions in Brassica Cultivars under Phosphorus-Stress Environment

Phosphorus (P) and zinc (Zn) interact both in plants and soils and hence may affect the availability and utilization of each other. To investigate P and Zn nutritional status and P–Zn interactions, two genetically diverse Brassica cultivars classified as P tolerant (Brown Raya) and P sensitive (Sultan Raya) were grown in a sand-based pot culture. Jordan rock phosphate (RP) and monocalcium phosphate [Ca(H₂PO₄)₂] were used as P sources, and ammonium nitrate (NH₄NO₃) or nitrate (NO₃ ^--) only were used as nitrogen (N) sources. Two Zn levels [0.25 (low Zn) and 2.5 (high Zn) mg zinc sulfate (ZnSO₄·5H₂O) kg^?1 sand, respectively] were applied along with recommended doses of other essential nutrients in the culture media. Cultivars differed significantly for their response to added P for biomass accumulation, but Zn supply had little effect. Cultivar Brown Raya had greater P uptake and P-utilization efficiency (PUE) than Sultan Raya under a P-stress environment, irrespective of Zn and N supply. Zinc supply had little effect on tissue P concentration and P uptake per unit of root dry matter (RDM) in either cultivar, irrespective of N supply. An increase in P supply caused a significant reduction in specific Zn uptake (Zn uptake per unit of RDM; SZnU) and tissue Zn concentration of both cultivars. The reduction in tissue Zn concentration cannot be ascribed entirely to a dilution effect. Zinc concentrations and uptake by P-efficient cultivar Brown Raya were significantly lower and more sensitive to P uptake than those of P-sensitive Sultan Raya cultivar. It is suggested that high PUE may depress plant Zn uptake and therefore cause a reduction in Zn concentration of Brassica grown in low-P and possibly low-Zn soils. In NH₄NO₃ nutrition, plants had significantly lower cation concentrations compared to NO₃ ^-- nutrition only. Brown Raya consistently had lower cation concentrations than Sultan Raya under P stress. The differences in cation concentrations decreased with increased P availability, but Zn supply had no significant effect. In Brown Raya, the ratio of potassium in roots to shoots was always greater than in Sultan Raya. This suggested that lower cation concentrations in Brown Raya were due to root carboxylate exudations, which in turn were related to better P acquisition and PUE under insufficiently buffered P-stress environment.     

桐麦间作系统小麦光合生理适应性规律的研究

桐麦间作系统内外的对比研究表明,试验期间系统内小麦平均光能利用率是系统外的１３３．３％,光能利用率在１１时～１３时之间最低．整个时段平均光合速率为系统外对照点的８７．６％,其中,小麦抽穗开花期为９７．９％,灌浆期为８６．３％,成熟期为７８．６％．桐麦间作对小麦光合作用的影响主要在灌浆期与成熟期．光合速率在１１时～１３时之间是最大的,呈单峰曲线．桐麦间作系统对小麦叶面Ｂａｌ Ｂｅｒｙ指数的影响,表现在灌浆期末期和成熟期,在小麦抽穗开花期没有影响．从抽穗开花期到灌浆期和成熟期,小麦光合作用与光量的关系逐渐减小．     

Identification and selection of low-phosphate-tolerant germplasm in barley (Hordeum vulgare L.)

Phosphorus (P) deficiency is one of the major constraints to crop yield worldwide, and genotypes or cultivars with high phosphate use efficiency (PUE) sustain growth when exposed to phosphate stress. Therefore, it is imperative to develop the genotypes or cultivars with high PUE. A pot experiment was conducted to evaluate the PUE among 150 barley (Hordeum vulgare L.) genotypes. Two high-tolerant and -sensitive accessions were selected. These two candidate materials were used to investigate the differences among the root morphology characteristics, antioxidant enzyme activity, inorganic phosphate (Pi) content and gene expression of HvPT5 under P-deficiency and P-sufficiency conditions. The values of these parameters were higher in the low-P-tolerant genotype than in the sensitive one. In pot experiment 1, all genotypes showed a significant difference in low-P tolerance, with variety GN121 achieving the highest tolerance, and GN42 being most sensitive. The results of this study may provide elite genetic germplasms for future work on isolation of P-related genes, and the improvement of PUE in barley.

Abbreviations: PUE: phosphate use efficiency; CAT: catalase; POD: peroxidase; SOD: superoxide dismutase; DMSO: dimethyl sulphoxide; MDA: malondialdehyde; TOPSIS: technique for order preference by similarity to an ideal solution; MCDM/MADM: multi-criteria (or attribute) decision making