Soya Bean (Glycine max L. Merr.) Genotype Response to Early-season Flooding: II. Aboveground Growth and Biomass

Soya bean is often grown in regions prone to periodic flooding, thus selecting cultivars that maintain production under waterlogged conditions is desirable. An experiment involving flooded soya beans was planted in southern Florida to examine (1) stem and leaf growth; (2) morphological adaptations; and (3) the relationship between early‐season and late‐season flood tolerance in flooded soya beans. Eleven soya bean genotypes previously defined as tolerant or sensitive to flooding were subjected to three treatments at 21 days after sowing (DAS): (1) no flood, (2) 2‐week flood and (3) 4‐week flood. All plants were harvested 49 DAS. Flooded plants exhibited lower stem dry weights but greater partitioning to the stem. Non‐flood treatments had greater leaf dry weight, leaf area and partitioning to leaves than flooded plants. There were positive correlations of genotype stem dry weight and leaf dry weight to early‐season flood tolerance but stem partitioning was negatively correlated with early‐season flood tolerance. Genotypic rankings of early‐season flood tolerance in this study were not correlated with earlier studies basing flood tolerance on seed yield. Our study highlights the range of soya bean morphological adaptations in response to flood. However, our results indicate that early‐season screening may not be an accurate predictor of soya bean genotypic response to late‐season flood.     

Physiological Responses and Dry Matter Partitioning of Summer Mungbean (Vigna radiata L.) Genotypes Subjected to Drought Conditions

Drought is the most important limitation to summer mungbean production in the tropics and subtropics dependent on usually insufficient summer rainfall. As increased irrigation is not a viable answer to the problem, an economically and environmentally desirable solution is new varieties with drought tolerance. However, there is little genotypic information on drought tolerance in summer mungbean. The objectives of this study were to assess the genotypic differences in physiological traits and dry matter partitioning in mungbean and to measure the association of these traits with crop performance under drought conditions. Six mungbean genotypes were tested in drought micro plots at CCS Haryana Agricultural University, Hisar, India. A split plot design was used; two irrigation treatments (watered and droughted) in the main plots and six mungbean genotypes in the subplots with three replicate micro plots. Drought decreased leaf water status, rates of photosynthesis (P_n) and altered dry matter partitioning in different plant parts. Our results showed that P_n did not limit yield, but it was partitioning of dry matter governed by leaf water content (RWC) which influenced the final yield. RWC was positively correlated to the number of pods per plant and seed yield, genotypes maintaining high RWC produced higher seed yield. Therefore, the drought tolerance of summer mungbean was related to the maintenance of high RWC, which can be used as a physiological marker to identify and develop superior genotypes suited to drought-prone environments.     

Soya Bean (Glycine max L. Merr.) Genotype Response to Early-season Flooding: I. Root and Nodule Development

Soya bean is often grown in regions subject to periodic flooding, with the rooting zone most affected by flooding due to its proximity to the source of stress. Our objectives were to examine the effects of flooding soya bean on its primary roots, adventitious roots and root nodules, and to determine relationships between root morphological changes and early‐season flood tolerance. The experiment was conducted in Belle Glade, FL with 11 soya bean genotypes subjected to (i) no flood, (ii) 2‐week flood 21–35 days after sowing (DAS) or (iii) 4‐week flood 21–49 DAS. All plants were harvested 49 DAS. Flooding reduced soya bean primary root weight, length and volume across genotypes. Adventitious root length and volume were greater in the 4‐week than the 2‐week flood. Soya bean nodule dry weight was threefold higher in the non‐flooded treatments. Genotypic differences in root development and tolerance to flooding were noted, with early‐season flood tolerance correlated with primary root dry weight, length and surface area, and adventitious root dry weight. However, there was no correlation between this study's early‐season root development and late‐season flood tolerance based on seed yield from previous studies. Our results indicate that full season trials may be necessary to identify flood‐tolerant soya bean germplasm.     

Water Relations, Abscisic Acid and Yield of Wheat Plants in Relation to the Interactive Effect of Seawater and Growth Bioregulators

Irrigation of wheat plants with seawater (10 and 25 %) led to significant increases in free and bound abscisic acid (ABA) in leaves, especially at 25 %. The relative water content (RWC) and water use efficiency (calculated from grain yield, WUE_G, or from biomass yield, WUE_B) of the seawater-irrigated plants were lower than those of the control. Grain pre-soaking in gibberellic acid (GA₃), indole-3-acetic acid (IAA) or ABA reduced the levels of accumulated ABA (free and bound) produced by seawater irrigation. The stress imposed by seawater generally reduced yield and yield components of wheat plants and the effect was more pronounced at the higher level of seawater irrigation (25 %). Furthermore, seawater treatments decreased the carbohydrate content and increased the protein content of the developing grains. The effect of seawater treatments on ion concentrations in the developing grains was not consistent. The application of growth bioregulators appeared to mitigate the effect of seawater salinity stress on wheat productivity. GA₃ was the most effective hormone in this regard. The economic yield (grain yield) had a strong positive correlation with RWC, WUE_G, WUE_B, plant height, shoot fresh and dry weight, grain number/main spike, kernel weight and harvest index.     

Interactive Effect of Seawater and Growth Bioregulators on Water Relations, Abscisic Acid Concentration and Yield of Wheat Plants

Irrigation of wheat plants with seawater (10 and 25 %) led to a significant increase in free and bound ABA in leaves, especially at 25 %. The relative water content (RWC), particularly at 25 %, and water use efficiency of the seawater-irrigated plants were lower than those of the control. Grain pre-soaking in GA₃, IAA or ABA reduced the levels of accumulated ABA (free and bound) resulting from seawater irrigation. The stress imposed by seawater generally reduced yield and yield components of wheat plants, and the effect was more pronounced at the higher level of seawater (25 %). Furthermore, seawater treatments decreased the carbohydrate content and increased the protein content of the developing grains. The effect of seawater treatments on ion concentration in the developing grains was not consistent. The application of growth bioregulators appeared to mitigate the effect of seawater salinity stress on wheat productivity. Gibberellic acid gave the best effect. The economic yield (grain yield) had a strong positive correlation with RWC, water use efficiency for grain yield, water use efficiency for biomass, plant height, shoot fresh and dry weights, grain number/main spike, kernel weight and harvest index.     

Effects of Salt Stress on Some Physiological and Photosynthetic Parameters at Three Different Temperatures in Six Soya Bean (Glycine max L. Merr.) Cultivars

The effect of NaCl (?0.1, ?0.4 and ?0.7 MPa) on some physiological parameters in six 23‐day‐old soya bean cultivars (Glycine max L. Merr. namely A 3935, CX‐415, Mitchell, Nazl?can, SA 88 and Türksoy) at 25, 30 and 35 °C was investigated. Salt stress treatments caused a decline in the K⁺/Na⁺ ratio, plant height, fresh and dry biomass of the shoot and an increase in the relative leakage ratio and the contents of proline and Na⁺ at all temperatures. Effects of salt stress and temperature on Chl content, Chl a/b ratio (antenna size) and qN (heat dissipation in the antenna) varied greatly between cultivars and treatments; however, in all cases approximately the same qP value was observed. It indicates that the plants were able to maintain the balance between excitation pressure and electron transport activity. Pigment content and the quantum efficiency of photosystem II exhibited significant differences that depended on the cultivar, the salt concentration and temperature. The cultivars were relatively insensitive to salt stress at 30 °C however they were very sensitive both at 25 and 35 °C. Of the cultivars tested CX‐415 and SA 88 were the best performers at 25 °C compared with SA 88 and Türksoy at 35 °C.     

Physiological and Molecular Characterization of Faba bean (Vicia faba L.) Genotypes for Adaptation to Drought Stress

Faba bean (Vicia faba L.) is one of the most important and drought sensitive grain legumes. Drought stress is thus one of major constraints in global faba bean production. In this study, twenty local and exotic faba bean genotypes were characterized on physiological and molecular basis. Seeds of faba bean genotypes (six per pot) were sown in poly venyl chloride pots. After seedling emergence, soil moisture was maintained at 100%, 50% and 25% of field capacity designated as well watered, moderate drought and severe drought, respectively. Drought stress significantly influenced the leaf area, leaf temperature, stomatal conductance, relative leaf water contents, grain yield and water‐use efficiency. Faba bean genotypes also differed for the leaf area, leaf temperature, relative leaf water contents, grain yield and water‐use efficiency. Faba bean genotypes Kamline and L.4 were better equipped to curtail water loss, maintain tissue water status, produce stable grain yield and had better water‐use efficiency under mild and severe drought stress, and may be used in breeding programmes. Amplified fragment length polymorphism markers showed high potential in detecting polymorphism and estimating genetic diversity among faba bean genotypes. Unweighted pair group method with arithmetic mean cluster analysis of the genotypes illustrated considerable association between molecular diversity, genetic background and geographic origin. In crux, high polymorphic rate and polymorphism information content values, together with the low genetic similarity observed among tested genotypes suggests a high level of heterogeneity, which may be used in breeding programmes to assemble different drought tolerance mechanisms in one genotype.     

滨海盐渍土抗虫棉养分吸收和干物质积累特点

以转Bt基因抗虫棉(Gossypium hirsutum L.)中早熟品种鲁棉研18和早熟品种鲁棉研19为材料,对黄河三角洲滨海盐渍土高、中、低产田抗虫棉的主要养分吸收、光合速率和干物质积累特点进行了研究。结果表明,中、低产田抗虫棉的主要养分吸收量显著低于高产田,而养分生理利用效率显著高于高产田。高、中、低产田抗虫棉的氮素生理利用效率分别为4.81、6.33和8.05 kg皮棉 kg^-1 N,磷素生理利用效率分别为28.57、40.06和50.48 kg皮棉 kg^-1 P,钾素生理利用效率分别为9.16、11.58和12.76 kg皮棉 kg^-1 K。养分吸收比例总体上N高于K,更明显高于P。中、低产田抗虫棉的净光合速率和生物产量明显低于高产田,皮棉产量也显著低于高产田,分别低12.44%和36.93%,但棉柴比显著高于高产田。表明滨海盐渍土中、低产田的盐分高而养分有效性和供应能力差,影响抗虫棉的养分吸收和光合作用,进而阻碍棉花生长发育和干物质积累。滨海盐渍土棉田经济施肥的原则是保证中、低产田的肥料供应,高产田重施P、K肥,低产田重施N、P肥。     

玉米根、茎、叶中脱落酸含量和产量形成对土壤干旱的响应

对不同程度土壤干旱胁迫下玉米根、茎、叶中脱落酸含量与产量形成进行了试验研究。充足底墒播种后采用5个土壤水分处理（分别占土壤田间持水量>80%、70%～80%、60%～70%、50%～60%、40%～50%,代号为WT1～WT5）,并遮去自然降水。试验结果表明,拔节期从中等干旱胁迫开始,玉米根、茎、叶中ABA含量大幅度增加,干旱加剧会使根     

Effect of Irrigation Patterns on Accumulation and Distribution of Dry Matter,Yield and Water Use Efficiency of Cotton in Southern Hebei

[Objective] This study examines how irrigation patterns affect soil moisture, growth and yield of cotton in southern Hebei, China. The results are used to inform irrigation patterns and improve the water use efficiency of cotton. [Method] Using the Nongda 601 cotton variety, a field split plot experiment was conducted in 2016 and 2017. The main treatments were no film (NF) and mulching film (MF), with side treatments of border irrigation (W1, 600 m³·hm^-2), limited amount every-other furrow irrigation I (W2, 450 m³·hm^-2) and limited amount every-other furrow irrigation II (W3, 300 m³·hm^-2). Six treatments NFW1, NFW2, NFW3, MFW1, MFW2, and MFW3 were applied. The film-covered border irrigation represents the conventional cultivation mode of local cotton. Impacts were measured as dry matter mass, yield and water use efficiency. [Result] (1) Dry matter mass of MF was significantly higher than that of NF in 2016 and 2017. However, there was no significant difference in different irrigation treatments under MF. When compared with the dry matter mass of NFW1 in 2016, that of NFW2 and NFW3 were significantly lower: by 14.28% and 13.44%, respectively. In 2017, the dry matter quality of NFW2 significantly increased by 11.29% compared with that of NFW1, but NFW3 showed no significant difference. (2) Cotton yield and water use efficiency showed similar trends in both years. There was no significant difference in yield and water use efficiency for the different irrigation treatments under MF. Compared with NFW1, NFW2 and NFW3 significantly decreased by 10.21%–16.00% and 13.63%–18.84% in yield, respectively, whereas water use efficiency significantly decreased by 8.33%–13.80% and 9.72%–14.61%, respectively. Compared with MFW1, yield and water use efficiency of NFW1 decreased slightly, but not significantly. Compared with MFW2, yield and water use efficiency of NFW2 significantly decreased 12.96%–16.62% and 13.73%–16.51%, respectively. Compared with MFW3, yield and water use efficiency of NFW3 significantly decreased 15.04%–16.29% and 15.03%–16.31%, respectively. [Conclusion] In wet and normal precipitation years, the NFW1 treatment resulted in high cotton yield while preventing residual film pollution; MFW2 and MFW3 treatments also achieved high yields and improved water use efficiency when irrigation quantity was reduced.     

测墒补灌条件下高产小麦品种水分利用特性及干物质积累和分配

2007-2009年连续2个小麦生长季,利用测墒补灌技术,设置0~140 cm土壤相对含水量低(拔节期65%, 开花期55%~60%)、中(拔节期75%, 开花期65%~70%)、高(拔节期75%, 开花期75%) 3个处理,比较了14个小麦生产品种的水分利用特性及干物质积累和分配的差异。以小麦籽粒产量和水分利用率为指标的聚类分析,将14个小麦品种分为3组,分别是超高产高水分利用率组(I组)、超高产中水分利用率组(II组)和高产低水分利用率组(III组)。比较各组代表品种的耗水量、耗水模系数及日耗水量,播种至拔节期山农15 (I组)显著低于济麦22 (II组)和烟农21 (III组),拔节至开花期山农15显著高于济麦22和烟农21,开花至成熟期品种间无显著差异。在中水分条件下,山农15的土壤贮水消耗量及其占总耗水量的比例显著高于济麦22和烟农21,而在低和高水分条件下,3个品种无显著差异。在中、高水分条件下,山农15开花期的干物质积累量显著高于济麦22和烟农21,成熟期与济麦22无显著差异,但显著高于烟农21;营养器官开花前贮藏同化物向籽粒的转运量和转运率及对籽粒的贡献率均显著高于济麦22和烟农21;3品种的经济系数以山农15最大,济麦22次之,烟农21最小。     

Soil Type Influences Relative Yield of Barley and Wheat in a Mediterranean-type Environment

In the eastern wheatbelt of Western Australia the yield of barley relative to wheat is influenced by soil type. Field trials studied detailed aspects of growth, development, yield and water use of a range of barley and wheat cultivars on 2 soil types at 2 locations to identify those factors that lead to the differential relative yields.
Barley had greater grain yields than wheat on both fine and coarse textured soils. On both soil types barley had a greater number of mainstem leaves which appeared faster than those of wheat and this was associated with greater tillering (6.5 v. 3.5 shoots/plant), higher GAI and greater dry matter production (845 v. 804 g/ m). The difference in yield between the two species was greater on the fine textured soil (15 v. 7 %). Barley also had greater harvest index than wheat (6—15%), and this combined with greater dry matter production on the fine textured soil led to a larger yield advantage over wheat than occurred on the coarse textured soil. Water use efficiency was greater for barley than for wheat on both soils.
The greater yield advantage of barley over wheat on the fine textured soil was the result of greater biomass production by barley and greater harvest index. Differences in pattern of water use, and water use efficiency of grain production were associated with greater barley yields but are not themselves considered to be the cause of relative yield differences across soil types. The possible implications of factors such as intrinsic nutrient supply on the 2 soil types in relation to observed yield differences are discussed.     

Photosynthesis is Reduced,and Seeds Fail to Set and Fill at Similar Soil Water Contents in Grass Pea (Lathyrus sativus L.) Subjected to Terminal Drought

Grass pea (Lathyrus sativus L.) is an indeterminate grain legume considered adapted to dry environments, but the mechanisms of its adaptation are not well understood. Grass pea plants were exposed to terminal drought from podding, and the development of water deficit was measured together with its effects on leaf photosynthesis, stomatal conductance, carbon remobilisation to the seeds, flower production and abortion, pod production and abortion, seed set, seed growth and the neurotoxin β‐N‐oxalyl‐L‐a, β‐diaminopropionic acid (β‐ODAP) concentration. Predawn leaf water potential (Ψ_leaf), stomatal conductance (gs), rate of leaf photosynthesis (Pn), flower production, pod production, filled pod number, seed number, seed size and yield decreased, while flower abortion, pod abortion and seed abortion increased, and the concentration of β‐ODAP was unchanged under terminal drought conditions. gs and Pn began to decrease at a higher plant‐available soil water content (PAWC) (67.2 ± 2.3 % and 62.9 ± 2.3 %) than Ψ_leaf (43.7 ± 1.1 %). Flowers and pods ceased being produced only when the PAWC decreased below 40.1 ± 4.6 % and 35.3 ± 3.0 %, respectively, but seed set and seed growth ceased when PAWC decreased below 55.5 ± 1.6 % and 58.0 ± 3.7 %, respectively. The mobilization of ¹³C labelled assimilates from the stems was greater under terminal drought than under well‐watered conditions, but the transfer to the seed was small. We conclude that seed set and seed growth decreased as the soil dried due to a reduction in current photosynthesis as a result of stomatal closure.     

The Interaction of Sowing Date and Water Availability in Determining Plant Architecture, Fruiting Pattern and Yield Components of Soybean (Glycine max L. Merr.)

A 2-year trial has been carried out in northern Italy on soybean (cv. Hodgson) grown in lysimeters, comparing three soil water regimes (well-watered conditions and water stress during vegetative and reproductive stages) at two sowing dates. Plant evapotranspiration and water uptake depth were calculated from volumes of water independently supplied to eight lysimeter layers; at harvest, plant architecture, yield components and fruit distribution along the main stem and lateral branches were evaluated.
Although water stress intensity was not severe, crop evapotranspiration and water uptake depth were severely restricted by water shortage. Both low water-availability and late sowing significantly modified the architecture of plants, decreasing total height, number and length of internodes and lateral branches. Seed allocation along the stem was shifted downwards both by delaying the sowing date and by reducing the water supply; the component most responsible for yield decrease was the number of pods per plant, while unit seed weight was only slightly affected by water stress. Grain yield reduction was higher when water availability was inadequate during the reproductive phase in the early-sown crop and during the vegetative stage in the late-sown crop. This suggests that the intensity of the water shortage, plant phenological stage of stress application, as well as the date of stress application within the growing season determine the yield response of soybean.     

Physiological and Yield Responses of Faba bean (Vicia faba L.) to Drought Stress in Managed and Open Field Environments

Water scarcity is threatening the sustainability of global food grain production systems. Devising management strategies and identification of crop species and genotypes are direly required to meet the global food demands with limited supply. This study, consisted of two independent experiments, was conducted to compare faba bean (Vicia faba L.) genotypes Giza Blanka, Goff‐1, Hassawi‐1, Hassawi‐2 and Gazira‐2 in terms of physiological attributes and yield under water‐limited environments. In first experiment, conducted in a growth chamber, osmotic stress of ?0.78, ?0.96, ?1.19 and ?1.65 MPa was induced using polyethylene glycol for 4 weeks. In second experiment, conducted in open field for two consecutive growing seasons, water deficit treatments were applied 3 weeks after sowing. In this experiment, irrigation was applied when an amount of evaporated water from the ‘class A pan’ evaporation reached 50 mm (well watered), 100 mm (moderate drought) and 150 mm (severe drought). Water deficit, applied in terms of osmotic stress or drought, reduced the root and shoot length, related leaf water contents, total chlorophyll contents and efficiency of photosystem‐II, plant height, grain yield and related attributes in faba bean; increased the leaf free proline, leaf soluble proteins and malondialdehyde contents, and triggered the maturity in tested faba bean genotypes. However, substantial genetic variation was observed in the tested genotypes in this regard. For instance, root length of genotypes Giza Blanka and Hassawi‐2 decreased gradually, whereas it was increased in genotypes Goff‐1, Hassawi‐1 and Gazira‐2 with increase in the level of osmotic stress. Genotypes Gazira‐2 and Hassawi‐2 had better relative leaf water contents, leaf free proline and soluble proteins under water deficit conditions; however, these were minimum in genotype Giza Blanka. Better accumulation of leaf free proline, soluble proteins, and maintenance of chlorophyll contents, tissue water, efficiency of photosystem‐II and grain weight in water‐limited conditions helped some genotypes like Hassawi‐2 to yield better. Future breeding programs for developing new faba bean genotypes for water‐limited environments may consider these traits.     

Legume Production and Irrigation Strategies in the Aral Sea Basin: Yield,Yield Components,Water Relations and Crop Development of Common Bean (Phaseolus vulgaris L.) and Mungbean (Vigna radiata (L.) Wilczek)

With world population expected to reach 9.2 billion people by 2050, improved irrigation methods will be needed to increase the productivity of agricultural land and improve food supply worldwide. The objective of this work was to examine the effect of regulated deficit irrigation (RDI) and alternate furrow irrigation (AFI) on the yield and yield components of two legume species (common bean and mungbean) produced as a second crop following winter wheat in Uzbekistan, Central Asia. Water relations and crop development were also examined. The research was conducted during two successive growing seasons in the Fergana valley. Production of mungbean using the severe stress RDI treatment in combination with AFI resulted in the highest yields with the lowest quantity of applied water in 2004. In addition, yields of common bean in the moderate stress treatment were not different from the recommended schedule, although irrigation events were decreased from 4 to 2. AFI did not reduce yields, and it did not interact with RDI to reduce yields further. In general, mungbean yields were higher than those of common bean. The combination of AFI and RDI can allow legume production with reduced water inputs.     

Interaction Amongst Soybean [Glycine max (L.) Merrill] Genotype, Soil Type and Inoculant Strain with Regard to N2 Fixation

The nitrogen (N₂)‐fixing bacterial inoculant strain for soybean [Glycine max (L.) Merrill] is not indigenous to South African soils. The interaction between soybean genotype, soil type and inoculant strain, however, has a definite influence on soybean production and compatibility should be optimized. This paper reports a growth chamber study using three different soybean genotypes (Barc‐9, Avuturda and Talana), three Bradyrhizobium japonicum inoculant strains (WB108, WB112 and WB1) and three soil types (Avalon, Arcadia and sand) to evaluate the effectiveness of N₂ fixation by different genotype × soil type × inoculant strain combinations, using different measuring parameters. These parameters included nodule fresh mass (NFM), amount of N₂ fixed (P_fix), as determined by the ureide method, seed protein content (SPC), average seed mass per plant (SMP) and average foliar N content (FNC). The comparison amongst the three‐way interactions, genotype × soil type × inoculant strain, did not differ significantly for the parameters used. Significant two‐way interactions were soil × inoculant for FNC, P_fix and SMP; soil × genotype for FNC and SMP, and inoculant × genotype for FNC (P < 0.05). The soil × inoculant strain interaction was significant for P_fix (P < 0.05). NFM, P_fix, FNC, SMP and SPC correlated positively with soil pH and negatively with soil clay content and soil NO₃^– and NH₄⁺ content (P < 0.05). SPC was significantly different (P < 0.05) for soil type, genotype and inoculant strain. P_fix and NFM did not reflect the protein content of the seeds, indicating that nodule evaluation should be used with caution as a N₂ fixation parameter. Low soil pH and high mineral N content inhibited N₂ fixation. NFM correlated negatively with the clay content of the soil. This finding confirms that soybean production in South Africa can be improved by appropriate selection of genotypes and inoculant strains for their compatibility in different soils.