Evaluation of common bean genotypes for drought tolerance

ABSTRACT The aim of this study was to evaluate twelve genotypes of common bean for intermittent drought stress and for root growth angle. The water deficit experiments were conducted in 2015 and 2016in a randomized block experimental design with split plots and three replications. Two treatments were applied: an irrigated treatment and a water deficit treatment, in which irrigation was suspended in pre-flowering and remained suspended up to the time at which the matrix potential of the soil was measured to be near –199 kPa. Atthe maximum point of water deficit, physiological and morphological traits were evaluated, and at physiological maturity, the yield compounds and grain yield. To evaluate root growth angle in 2016, a growth pouch system was used in a randomized block design, with five replications. Water deficit reduced genotype performance for all the traits except leaf temperature and first pod height. In relation to grain yield, the genotypes SEA 5 and Carioca Precoce performed better under water restriction conditions in both evaluations. The genotype Gen TS 4-7 performed better in the 2015 evaluation, and Gen TS 3-1 andGen TS 3-3 in 2016. SEA 5, Gen TS 3-1, and Carioca Precoce had the highest harvest indexes in 2015; and Gen TS 3-1, Gen TS 3-2,Gen TS 3-3, Gen P5-4-3-1, IAPAR 81, Carioca Precoce, and SEA 5 in 2016. SEA 5 and Carioca Precoce had the best root growth angle and were considered sources of tolerance to water deficit.

摘要 本研究旨在评估12个普通菜豆（common bean）基因型的间歇干旱胁迫响应及根系生长角度。2015年与2016年开展水分亏缺试验，采用裂区随机区组设计，设置3次重复。试验设置2个处理：常规灌溉处理与水分亏缺处理，后者于开花前暂停灌溉，并维持该状态直至土壤基质势测得接近-199 kPa。在水分亏缺的峰值时点，测定供试材料的生理与形态性状；在生理成熟期，测定产量构成因素与籽粒产量。2016年为评估根系生长角度，采用生长袋系统（growth pouch system）开展随机区组试验，设置5次重复。结果表明，水分亏缺会降低所有性状的基因型表现，仅叶温与第一结荚高度除外。就籽粒产量而言，基因型SEA 5与Carioca Precoce在两次评估的水分限制条件下均表现最优。基因型Gen TS 4-7在2015年评估中表现更佳，而Gen TS 3-1与Gen TS 3-3则在2016年评估中表现更优。2015年，SEA 5、Gen TS 3-1及Carioca Precoce的收获指数最高；2016年该指标表现优异的基因型为Gen TS 3-1、Gen TS 3-2、Gen TS 3-3、Gen P5-4-3-1、IAPAR 81、Carioca Precoce与SEA 5。SEA 5与Carioca Precoce拥有最优的根系生长角度，可被视为干旱胁迫耐受种质资源。