Comparison of non-hydraulic root-sourced signaling and grain yield satiability under drought stress in two soybean [glycine max (L.)Merr. ] cultivars | 干旱条件下两个大豆品种非水力根信号特征及稳产性比较

中国人. 【目的】非水力根信号（non-hydraulic root signal,nHRS）特征在判别植物的干旱适应能力上具有重要意义,研究其与作物生长和产量性状的关系可为抗旱节水农业提供理论支持。【方法】采用盆栽试验,分别于大豆分枝期、始花期和鼓粒期,在土壤渐旱过程中跟踪测定两个大豆供试品种（晋大74和晋豆24）的nHRS特征;测量其在高土壤水分[2007年的高水处理（H）和2008年的充分供水（WW）,对照]及干旱胁迫[2007年的低水处理（L）,及2008年的轻度干旱（LD）和严重干旱（SD）]处理下收获时的根冠生物量及籽粒产量。【结果】在分枝期,晋大74出现nHRS时的土壤含水量阈值低于晋豆24,在始花期和鼓粒期,则高于晋豆24;在上述3个生育期内nHRS结束时的土壤含水量阈值均以晋大74为高;晋豆24 nHRS的平均阈值宽度为田间持水量的9.3%,较晋大74（田间持水量的8.1%）要宽。干旱胁迫可显著降低（P＜0.05）两品种地上部、地下部干物质重和籽粒产量,且晋大74的降幅大于晋豆24;晋豆24的稳产性高于晋大74;两品种根冠比在较严重的干旱（L和SD）条件下显著提高（P＜0.05）,且晋豆24增幅较大;干旱胁迫条件下,晋豆24的水分利用效率（WUE）显著高于晋大74。【结论】在轻度干旱条件下,产量和WUE较高的晋豆24有较低的根冠比和较好的稳产性可能与非水力根信号土壤含水量阈值范围较宽有关。

英语. 【Objective】 To clarify the correlations of drought-induced non-hydraulic root signals (nHRS) with plant growth and grain yield formation could provide a mechanism basis for water-saving agriculture. 【Method】 Pot experiments were conducted with two soybean cultivars, i.e, Jinda 74 and Jin 24. nHRS were traced during manipulative progressive soil drying period at branching, early flowering and grain-filling stages. The effect of water deficit on plant biomass and grain yields of the cultivars were investigated under good soil conditions, high water (H) treatment in 2007 and well-watered (WW) in 2008 experiment, and drought conditions, low water (L) treatment in 2007 as well as light drought (LD) and severe drought (SD) in 2008. 【Result】 In response to soil drying, nHRS appeared earlier in Jinda 74 at branching stage, and later at early flowering and grain-filling stages than in Jin 24, while it disappeared earlier for Jinda 74 than Jin 24 at all the three growth stages. Jin 24 exhibited a wider average soil water content threshold range of nHRS (TR). Drought stress (both LD and SD treatments) significantly decreased the above-ground dry mass, root dry mass and grain yield (P＜0.05), more dramatically for Jinda 74 than Jin 24 which showed a higher maintenance rate of grain yield than the former. The root/shoot ratio was significantly promoted (P＜0.05) under severe drought conditions, i.e., L and SD treatment, more extensively for Jin 24 than Jinda 74. Water use efficiency (WUE) was notably higher (P＜0.05) in Jin 24 than Jinda 74 under drought conditions in both experiments in 2007 and 2008. 【Conclusion】 Soybean cultivar of wider soil water content threshold range for nHRS yielded more, and exhibited lower root/shoot ratio but higher WUE and maintenance rate of grain yield under mild water deficit in pot-cultured condition.