华北地区冬小麦生产中磷素利用特征研究

目前,中国农业集约化过程中普遍存在着化肥,特别是磷肥利用效率不高、土壤残留磷量较大的问题,这造成了磷肥资源的浪费以及由淋溶和径流造成的面源污染。笔者通过文献查阅,收集和筛选了自1980年以来中国公开发表的小麦田间试验论文,对华北平原及山西和陕西等地区小麦田间试验数据进行分析,对小麦生产和磷肥利用特征进行统计分析。本研究获得了冬小麦籽粒与秸秆产量的回归方程,以及施磷量与籽粒和秸秆含磷量的回归方程。在施磷为61 kg P₂O₅/hm ²时,冬小麦-土壤系统表现为磷素表观平衡;随着磷肥数量增加,磷素表观盈亏量呈线性增加。在当前华北地区常规磷肥(102 kg P₂O₅/hm ²)水平下,冬小麦一季在土壤中磷肥累积量约为25.7 kg P₂O₅/hm ²。华北地区冬小麦磷肥平均利用效率为(14.7±7.6)%,氮肥增加有利于提高磷肥利用效率。整体上,冬小麦对磷酸二铵的利用效率高于过磷酸钙,有机肥和化肥配施有利于提高磷肥利用效率,‘郑麦9023’的磷肥利用效率较高。所以选择合适的磷肥品种,通过合理的氮肥水平以及有机肥与化肥配施,能够提高华北地区的冬小麦磷肥利用效率。这对于该地区提高磷肥利用效率、降低磷肥损失和土壤污染风险,具有重要参考价值。     

磷肥用量对油菜籽产量及品质的影响

油菜是重要的油料作物,对缺磷敏感,我国油菜主产区土壤供磷状况较差,缺磷常导致油菜籽减产。于2019—2021年度2季在长江中游地区进行磷肥用量田间试验,设置0、45、90、135和180 kg P₂O₅ hm^–2 5个施磷水平,探究磷营养供应状况同时对油菜籽产量和品质的影响。结果表明,施磷显著增加油菜单株角果数、角粒数和千粒重,进而增加了油菜产量。不施磷处理的平均产量仅190 kg hm^–2,施磷增产8.5～12.5倍,根据产量效应得到的最高产量施磷量为51.8～65.0 kg P₂O₅ hm^–2。油菜籽磷含量、含水率、含油率、蛋白质、硫甙、油酸、亚麻酸和硬脂酸对磷肥用量的响应均达到极显著水平,芥酸、亚油酸和棕榈酸的响应较小。随着施磷量的增加,油菜籽含油率呈先增后降的趋势(施磷90 kg P₂O₅ hm^–2和135 kg P₂O₅     

氮肥基追比和调亏灌溉对小麦水分利用效率和产量的影响

优化水肥管理对提高小麦生产效率,改善农业生态环境具有重要意义。在防雨棚下,采用桶栽土培法研究氮肥基追比和调亏灌溉对小麦水分利用效率、叶片光合速率的影响,为优化小麦水氮运筹模式提供依据。设置4种氮肥基追比（播前和拔节期施氮比例）处理,分别为10:0、7:3、5:5和3:7,记为N_10:0、N_7:3、N_5:5和N_3:7。2种水分处理:水分调亏（返青-拔节期）—复水—调亏（灌浆-成熟期）,记为D;全生育期正常供水,记为N。结果表明,拔节期追施氮肥显著提高小麦灌浆期的单茎叶面积;相同水分条件下,N_7:3、N_5:5和N_3:7灌浆期单茎叶面积递增且显著高于N_10:0处理。水分调亏显著降低拔节期N_10:0处理小麦最上部展开叶的光合速率,对其他氮肥处理小麦光合速率的影响则未达显著水平;相同水分条件下,N_5:5处理拔节期和灌浆期均具有较高的光合速率。随追氮比例的增加,小麦叶片光合速率和水分利用效率呈先升后降的趋势。氮肥基追比和水分调亏显著影响小麦产量和水分利用效率,且两者对小麦产量存在显著的互作效应。综合考虑产量和水分利用效率等因素,水分调亏配合氮肥基追比处理比例为5:5是最合理的水氮运筹模式。     

水分胁迫下葡萄糖对小麦幼苗光合作用和相关生理特性的影响

以15%聚乙二醇(PEG-6000)模拟水分胁迫,以不同浓度外源葡萄糖(Glc)处理小麦幼苗,探讨外源Glc对水分胁迫下小麦幼苗生长发育和光合特性的影响。结果表明,水分胁迫显著降低了小麦叶片水势和光合作用,抑制植株的生长,而水分胁迫下外源Glc处理能明显增加叶片水势和光合色素含量,并使水分胁迫和水分胁迫后复水处理条件下,小麦幼苗叶片的净光合速率(P_n)、气孔导度(G_s)胞间CO₂浓度(C_i)和叶片水分利用效率(WUE)显著升高,而使蒸腾速率(T_r)下降。同时,外源Glc处理显著提高了水分胁迫下叶片中可溶性糖和脯氨酸的积累,促进不定根和侧根的生长,植株干重比单一干旱处理提高14.32%~40.39%。由此表明,水分胁迫下外源Glc通过促进小麦根系生长和提高叶组织的渗透调节能力,改善叶片的水分状况,提高了叶片的光合功能,促进小麦幼苗的生长,降低了水分胁迫对小麦幼苗生长的抑制作用。     

不同磷水平设施菜田上结球生菜的适宜施磷量推荐研究

以结球生菜为试材,采用小区试验对比的方法,研究了高中低3种磷水平设施菜田上,不同施磷量对产量、品质、土壤有效磷含量和磷素农学效率的影响。结果表明：高磷菜田上,施磷量(P₂O₅)为36.54 kg/hm²时结球生菜产量最高;中磷菜田上施磷量(P₂O₅) 54.91 kg/hm²时结球生菜产量最高,硝酸盐含量较低,维生素C含量增加,土壤有效磷含量显著提高;低磷菜田上施磷量(P₂O₅) 91.35 kg/hm²时结球生菜产量最高,硝酸盐含量降低。土壤磷含量和施磷量增加,均会造成磷肥农学效率降低。因此,高磷菜田上不施磷肥或少施磷肥,中磷菜田配施中水平磷肥,低磷菜田配施高水平磷肥是提高结球生菜产量、品质和磷肥农学效率的有效措施。     

减磷加炭对北疆春小麦磷素利用及产量的影响

本试验探讨不同施肥模式对小麦磷素积累与转运及产量的影响,为合理减磷加炭、提高磷肥利用率提供理论参考。本试验磷肥（P₂O₅）设4个水平,生物炭设3个水平。比较不同施肥模式下小麦磷素积累分配、磷素利用率、产量与磷肥利用率等指标的差异。结果表明：在减量施磷15%(102 kg/hm²)配施生物炭22.5 t/hm²(P3B2)处理下各指标综合效果最好,在该处理下春小麦干物质量最高,为4.07 g/株,较对照增加8.24%,该处理下植株磷含量增加,且主要分配在穗部,较对照增加6.21%;茎部磷素转移在磷肥配施低炭时增幅最高,磷肥配施高量生物炭时增幅最低;叶部磷素转移在磷肥与生物炭配施时对植株叶部磷素的影响大于单施磷肥。本试验条件下,施磷102 kg/hm²同时施加生物炭22.5 t/hm²对提高茎、叶对籽粒的贡献率有明显的促进作用,提升了磷素利用效率与磷素生理效率,并且达到最好的增产效果,为北疆灌区磷肥减施增效提供理论依据。     

小麦叶片水分利用效率及相关生理性状的关系研究

利用19个抗旱性不同的小麦品种,对干旱状态下叶片水分利用效率和光合速率、蒸腾速率等12个指标之间的关系进行了研究。结果表明,叶片水分利用效率与叶片光合速率、蒸腾速率、气孔导度、胞间二氧化碳浓度、水势和叶片离体失水速率之间的关系密切,说明这些生理性状是瞬间和短时期叶片水分利用效率的直接影响因素;而与叶片抗氧化酶活性、蜡质含量、叶片湿度和相对含水量相关性不大。因此认为,应该有针对性地研究与水分利用效率关系密切的生理性状,为小麦抗旱节水遗传育种研究提供理论依据。     

氮素对高大气CO2浓度下小麦叶片光合功能的影响

为探讨高大气CO₂浓度下植物光合作用适应现象的光合能量转化和分配的氮素响应及其对C₃植物光合功能的影响,本试验对盆栽小麦进行2个大气CO₂浓度和2个氮水平的组合处理,通过测定小麦光合气体交换参数、叶绿素荧光参数和叶绿素含量等指标,研究施氮对高大气CO₂浓度下小麦叶片光合功能的影响。结果表明,大气CO₂浓度升高后,低氮处理小麦叶片光合速率发生明显的适应性下调,光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)下降;但高氮叶片则无明显的光合作用适应现象发生。高大气CO₂浓度下低氮叶片光化学速率、PSII线性电子传递速率(J_F)、光合电子流的光化学传递速率(J_C)、Rubisco羧化速率(V_C)和TPU下降,并随生育时期推进其下降趋势更为明显,但高氮叶片的上述参数无显著变化;小麦叶片J_C/J_F、V_C/J_C和V₀ /V_C随氮素水平和大气CO₂浓度的变化无显著变化,表明施氮能提高光合机构对光合能量的传递速率,但对光合能量的分配方向无明显影响。施氮提高小麦叶片氮素和叶绿素含量,并且使高大气CO₂浓度下光合氮素利用效率(NUE)明显增加。大气CO₂浓度升高后,施氮增强光合机构的光合能量运转速率,同化力提高,无明显的光合作用适应现象;由于氮素水平与大气CO₂浓度对小麦叶片的光合能量利用存在明显的交互作用,而且高大气CO₂浓度下施氮使得小麦叶片NUE增加、正常大气CO₂浓度下降低,证明高大气CO₂浓度下施氮对光合作用具有直接的影响。     

不同灌溉方式对两个马铃薯品种生理特性和水分利用效率的影响

研究了两个抗旱性不同的马铃薯品种(荷兰15号和克新1号）在不同灌溉方式下的生长、生理特性和水分利用效率。结果表明, 不同灌溉方式对马铃薯生理指标有显著影响。隔沟交替灌溉区的植株株高和叶面积高于常规灌溉区和固定隔沟灌溉区。隔沟交替灌溉提高了干旱胁迫应答抗氧化酶过氧化物酶（POD）、超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的活性,而反映胁迫受害程度的丙二醛（MDA）浓度均低于常规灌溉和固定隔沟灌溉处理。在隔沟交替灌溉条件下,克新1号的产量比常规灌溉提高了3.84％,水分利用效率比对照提高了35%。荷兰15号的产量与常规灌溉没有显著差异,水分利用效率比对照提高了28%。由此得出,在马铃薯生产中应用隔沟交替灌溉技术具有较大的节水增产潜力,其中克新1号是水分利用效率高、抗旱性强的品种。     

磷酸二铵施用量及方式对甜菜光合性能和产量的影响

光合作用是产量形成的物质基础,为筛选出最适宜甜菜产量形成的施磷方式及施磷量,优化甜菜施肥管理,设置3种不同施磷方式（播种前全部基施;播种前基施2/3,叶丛快速生长期追施1/3;播种前基施2/3,块根糖分增长期追施1/3）,每种施磷方式下设置5个施磷量（60、90、120、150和180kg/hm²）,研究不同施磷方式及施磷量对甜菜光合生理性能及产量的影响。研究结果表明,相同施磷方式下,随施磷量递增,甜菜的叶面积指数（LAI）、相对叶绿素含量（SPAD值）、净光合速率（P_n）、单株干物质积累量及产量均呈先升高后稳定或降低的变化趋势,当施磷量为150kg/hm²时,各光合指标和产量均达到最大值。相同施磷量条件下,基施2/3、叶丛快速生长期追施1/3磷肥的施磷方式对促进甜菜光合性能和产量形成效果最好。故推荐高产甜菜施磷量为150kg/hm²,分2次施入,播前基施2/3,叶丛快速生长期追施1/3。     

Brassinolide Application Improves the Drought Tolerance in Maize Through Modulation of Enzymatic Antioxidants and Leaf Gas Exchange

Brassinolides (BRs) are naturally occurring substances, which modulate plant growth and development events and have been known to improve the crop tolerance to abiotic stresses. In this study, possible role of exogenously applied brassinolide (BR) in alleviating the detrimental effects of drought in maize was evaluated in a rain‐protected wire‐house. Maize was subjected to drought at the start of tasseling for 6 days by withholding water application followed by foliar spray of BR (0.1 mg l^?1) to assess the changes in growth, gas exchange, chlorophyll contents, protein, relative leaf water contents (RLWC), proline, malonialdehyde (MDA) and enzymatic antioxidants. Drought substantially reduced the maize growth in terms of plant height, leaf area and plant biomass. Moreover, substantial decrease in gas exchange attributes (net photosynthetic rate (A), transpiration rate (E), stomatal conductance (g_s), water use efficiency (WUE), instantaneous water use efficiency (WUEi) and intercellular CO₂ (C_i) was also recorded. However, exogenous application of BR remarkably improved the gas exchange attributes, plant height, leaf area, cobs per plant, seedling dry weight both under drought and well‐watered conditions. BR‐induced promotion in growth and physiological and metabolic activities were mediated through increased protein synthesis enabling maintenance of tissue water potential and activities of antioxidant enzymes lowering the lipid peroxidation under drought.     

Wheat Rht‐B1 Dwarfs Exhibit Better Photosynthetic Response to Water Deficit at Seedling Stage Compared to the Wild Type

Wheat reduced height (Rht) genes encode modified DELLA proteins, which are gibberellin insensitive, accumulate under stress, restrain growth and affect plant stress response. The seedling reaction to soil water deficit regarding leaf gas exchange and chlorophyll fluorescence was compared in near‐isogenic lines carrying the alleles Rht‐B1a (tall), Rht‐B1b (semi‐dwarfing) and Rht‐B1c (dwarfing) and was related to leaf water content and anatomy. Under drought, Rht‐B1c line was characterized by less decreased CO₂ assimilation, delayed non‐stomatal limitation of photosynthesis and higher instantaneous water use efficiency. The functional state of its photosynthetic apparatus was better preserved as evidenced by the less decreased actual quantum yield (Φ_PSII) and potential maximum quantum yield (F_v/F_m) of PSII, and the less increased quantum yield of non‐regulated energy dissipation (Φ_NO). Rht‐B1b line also tended to perform better than Rht‐B1a, but differences were less pronounced. Although the leaves of both dwarf lines were smaller, thicker and more pubescent, their water content was not higher in comparison with the tall line. Nevertheless, in Rht‐B1c, leaf thickness was less decreased and mesophyll cells were less shrunk under drought. The more effective performance of the photosynthetic machinery of dwarf lines under water deficit could be explained by a combination of morpho‐anatomical and metabolic characteristics.     

膜下滴灌水分亏缺下棉花开花后非叶绿色器官光合特性及其对产量的贡献

选用北疆棉区主栽品种新陆早33号和新陆早45号,设置常规滴灌量(CI)、轻度水分亏缺滴灌量(SDI)、中度水分亏缺滴灌量(MDI)3种处理,在田间条件下研究了不同滴灌量对棉花叶片和非叶绿色器官叶绿素(Chl)含量、净光合速率(Pn)、气孔导度(gs)和光合物质累积的影响,明确了水分亏缺下棉株非叶绿色器官光合作用对产量的贡献。结果表明,各滴灌量条件下棉花非叶绿色器官单位面积的Pn、Chl含量下降幅度较叶片小,且随棉花生育进程的变化较小。在棉铃生长发育后期,随滴灌量减少,棉花非叶绿色器官光合物质生产能力对产量起着更为重要的作用。中度水分亏缺条件下,棉铃(铃壳和苞叶)和茎秆光合作用对铃重的相对贡献率分别增加至16.8%~34.9%和7.6%~17.5%。因此,采用膜下滴灌植棉技术时适当控制滴水量,在保证叶片具有较高光合速率的同时,发挥棉花非叶绿色器官的光合抗逆能力,对挖掘滴灌棉花节水增产潜力具有重要意义。     

Genotypic Variation of Gas Exchange Parameters and Leaf Stable Carbon and Nitrogen Isotopes in Ten Quinoa Cultivars Grown under Drought

Genotypic variations in leaf gas exchange and grain yield were analysed in 10 highland‐adapted quinoa cultivars grown in the field under drought conditions. Trials took place in an arid mountain region of the Northwest of Argentina (Encalilla, Amaicha del Valle, 22°31′S, 65°59′W). Significant changes in leaf gas exchange and grain yield among cultivars were observed. Our data demonstrate that leaf stomatal conductance to water vapour (g_s) is a major determinant of net CO₂ assimilation (A_n) because quinoa cultivars with inherently higher g_s were capable of keeping higher photosynthesis rate. Aboveground dry mass and grain yield significantly varied among cultivars. Significant variations also occurred in chlorophyll, N and P content, photosynthetic nitrogen‐use efficiency (PNUE), specific leaf area (SLA), intrinsic water‐use efficiency (_iWUE) and carboxylation capacity (A_n/C_i). Many cultivars gave promissory grain yields with values higher than 2000 kg ha^?1, reaching for Sayaña cultivar 3855 kg ha^?1. Overall, these data indicate that cultivars, which showed higher photosynthesis and conductances, were also generally more productive. Carbon isotope discrimination (Δ) was positively correlated with the grain yield and negatively with _iWUE, but δ¹⁵N did not show significant correlations. This study provides a reliable measure of specific responses of quinoa cultivars to drought and it may be valuable in breeding programmes.     

不同栽培模式对旱地春玉米光合特性和水分利用率的影响

明确旱地春玉米高产与水分高效协调的栽培技术及其生理原因,对提高水分限制条件下玉米水分利用效率及玉米可持续生产具有重要意义。本文以郑单958为材料,于2010年和2011年在陕西长武进行大田试验,设置当地农户栽培(对照)、高产高效栽培、超高产栽培和再高产高效栽培等4种栽培模式,比较了其对春玉米光合特性和水分利用效率的影响。结果表明,当地农户栽培、高产高效栽培、超高产栽培和再高产高效栽培产量平均达7.7、9.2、11.7和10.6 t hm^-2,高产模式较对照产量分别提高20.1%、52.9%和37.7%,水分利用效率分别提高27.8%、60.9%和45.1%。与当地农户栽培相比,高产高效栽培、超高产栽培和再高产高效栽培提高了花后叶片净光合速率(P_n)、蒸腾速率(T_r)和单叶水分利用效率(WUE_L);相对电子传递速率(ETR)、PSII实际量子产额(Φ_PSII)和光化学猝灭(q_P);延缓了叶片衰老;花后干物质积累量分别增加29.0%、82.3%和56.1%。结果说明通过地膜覆盖、增加密度和氮肥运筹等关键栽培技术的集成与优化,可实现旱地春玉米高产与水分高效30%以上的目标;其增产增效的主要原因在于显著增强玉米花后叶片光捕获能力与光化学效率,延缓叶片早衰,促进花后干物质积累及其对籽粒的贡献率。     

控释尿素水氮耦合对夏玉米产量和光合特性的影响

采用旱棚盆栽试验,以郑单958为材料设置3个水分水平(正常水分W3、轻度水分胁迫W2、重度水分胁迫W1)和高氮N3(施纯氮315 kg hm–2)、中氮N2(施纯氮210 kg hm–2)、低氮N1(施纯氮105 kg hm–2)、不施氮N0四个控释尿素施氮水平,探讨控释尿素水氮耦合对夏玉米产量和光合特性的影响。结果表明,控释尿素水氮耦合对夏玉米产量和光合特性具有显著影响。相同水分条件下,夏玉米产量随施氮量增加而增加,W1条件下增产13.17%~20.96%,W2条件下增产13.93%~32.48%,W3条件下增产14.37%~21.83%。相同施氮水平下,产量也随水分增加而增加,W2N3、W3N2和W3N3的产量在所有处理中较高。水氮耦合对夏玉米穗位叶净光合速率的影响显著,W1条件下N3、N2和N1处理间差异不显著,均显著高于N0,W2、W3各施氮处理的净光合速率随施氮量增加而增加,W3各处理的平均净光合速率高于其他2个水分处理,W2N3比W3N3和W3N2前期略低,后期无显著差异。水氮耦合效应能有效减缓穗位叶的实际光化学效率ΦPSII、叶片光化学猝灭系数qP以及PSII反应中心的最大光能转换效率的下降速率,提高光能利用率。控释尿素水氮耦合能有效提高夏玉米花后穗位叶净光合速率,保证籽粒对营养物质的需求,提高穗位叶实际和最大光化学效率,从而提高夏玉米的产量,产量构成因素中增加千粒重和穗粒数的优势较大。综合产量与光合特性、荧光特性的表现,在田间持水量为75%±5%的土壤条件下,控释尿素施氮量以纯氮210 kg hm–2为最佳;在田间持水量为55%±5%的土壤条件下,控释尿素施氮量以纯氮315 kg hm–2为宜。     

玉米叶片气孔特征及气体交换过程对气候变暖的响应

气孔是植物叶片表面控制大气与植物间气体交换的孔状结构,对于生态系统碳、水循环过程的调节起着非常重要的作用。本文利用典型农田生态系统实验增温平台,研究了未来气候变暖对玉米叶片的气孔特征(包括气孔频度、气孔开口大小和形状以及气孔分布格局)和气体交换过程的影响。结果表明:(1)尽管增温并没有改变气孔密度(P0.05),但却由于表皮细胞数目的减少导致气孔指数显著增加12%(P0.05);(2)增温使气孔开口的长度显著减小18%(P0.01),宽度增加26%(P0.01),面积和周长分别增加31%(P0.01)和13%(P0.05);(3)实验增温还使单个气孔之间最近邻域的平均距离显著增加,表明气孔在玉米叶片上的分布变得更加均匀;(4)增温导致玉米叶片的净光合反应速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)分别增加52%(P0.05)、163%(P0.001)和81%(P0.05);与此相反,玉米叶片的暗呼吸速率(Rd)却显著降低24%(P0.01)。增温没有对细胞间CO2浓度(Ci)和水分利用效率(WUE)产生显著的影响(P0.05)。本研究结果表明,未来全球气候变暖可能通过改变玉米叶片的气孔频度、气孔开口大小和形状及其在叶片上的空间分布格局来改变其气体交换过程。     

水肥交互作用对黄土高原南瓜光合特性及其产量的影响

通过不同的灌水和施肥处理,研究水肥交互作用对南瓜光合特性日变化及产量的影响,结果表明：水分与施肥因子对南瓜叶片的光合特性和产量有重要影响,在水分胁迫的情况下,肥水交互作用不显著,在水分较低的情况下,二者表现互为限制条件的协同作用;在水分较高的情况下,肥水交互作用转变成顺序加和作用。其中单因素效应大小表现为：氮>水>磷,耦合效应大小表现为：氮与水耦合>氮与磷耦合>磷与水耦合。在水分适宜时,适宜的施肥量（施氮量50kg／hm2、施磷量35 kg／hm2）可以提高南瓜光合速率和产量,不施肥或施肥量过高都会影响南瓜光合速率和产量。     

Physiological aspects of domestication in diploid wheat

Summary A comparative study of photosynthetic response to water stress was conducted with one genotype of wild einkorn (Triticum boeoticum, W) and one of domesticated einkorn (T. monococcum, C).Per unit leaf area, W showed a better performance for photosynthetic and transpiration activities, even under dry air and dry soil conditions. Its leaf water potential was always higher than that of C at any level of soil water potential. The difference in photosynthetic recovery from severe drought between W and C was also obvious. The photosynthetic rate, transpiration rate and water status of the leaves observed at 20 h after rewatering was almost the same as non-stressed leaves in W, whereas in C the photosynthetic rate was about half that of the non-stressed leaves, which was accompanied with a low transpiration rate and a high gas diffusion resistance. The ability of W to maintain a proper water balance over a wide range of soil water potential and to recover rapidly from severe drought seems to be a result of adaptation to its hard habitats.However, under favourable water supply, the photosynthetic rate per unit leaf nitrogen was higher in C than in W. This may be advantageous to bring about a better plant growth than W on the arable land where the improved water supply is guaranteed.     

Old and New Cultivars of Soya Bean (Glycine max L.) Subjected to Soil Drying Differ in Abscisic Acid Accumulation,Water Relations Characteristics and Yield

Two old (Huangsedadou and Longxixiaohuangpi (LX)) and two new (Jindou 19 (JD) and Zhonghuang 30 (ZH)) soya bean (Glycine max (L.) Merr.) cultivars were used to investigate the influence of soil drying on the abscisic acid (ABA) accumulation in leaves, stomatal conductance (g_s), leaf water relations, osmotic adjustment (OA), leaf desiccation tolerance, yield and yield components. The greater ABA accumulation was induced by soil drying, which also inducing g_s decreased at higher soil water contents (SWC) and leaf relative water content (RWC) significantly decreased at lower SWC in the new soya bean cultivars than in the old soya bean cultivars. The soil water threshold between the value at which stomata began to close and the RWC began to decrease was significantly broader in the new cultivars than in the old cultivars. The new cultivars had significantly higher OA and lower lethal leaf water potential than old cultivars when the soil dried. The old cultivars had greater biomass, but lower grain yield than the new cultivars in well‐watered, moderate stress and severe stress conditions. Thus with soil drying, the new soya bean cultivars demonstrated greater adaptation to drought by inducing greater ABA accumulation, stomatal closure at higher SWC, enhanced OA and better water relations, associated with increased leaf desiccation tolerance, greater water use efficiency and higher yield.