Interactive effects of low phosphorus and drought stress on dry matter accumulation and phosphorus efficiency of soybean plants
Low soil phosphorus (P) availability and seasonal drought were the main limiting factors for soybean production in acid red soils of South China. Improving and screening P-efficient genotypes of soybean germplasm which could better adapt to low P soils and drought climate was one of the efficient approaches to increasing soybean yields. Pot experiment with P-efficient ( BX10) and P-inefficient ( BD2) soybean genotypes was conducted to investigate the effects of P application and water deficit on dry matter accumulation and phosphorus efficiency of soybean plants. Three rates of P application were P0: 0, P1: 15, P2: 30 mg/kg soil, respectively. The two soil moisture treatments were 70%-80% of field water capacity ( FWC) as control and 30% -40% of FWC as drought stress at flowering and pod-setting stages respectively. The results showed that plant biomass and leaf chlorophyll content were increased, while root/shoot ratio of the two soybean varieties were decreased when soil available P increased; Drought stress increased root/shoot ratio of BX10 and BD2 at flowing and pod-setting stages under the same P application rate, but no significant effects were found on leaf chlorophyll content. Drought stress resulted in significant decrease of yield for both two varieties. Soybean yields in low P soils are significantly affected by medium P application ( Pt treatment) , but much less and even negatively by high Papplication (P2 treatment). The yield of BX10 was increased when soil available P increased, but the yields for BD2 in different P application rates were in the order; P1>P2>P0. BX 10 had higher yield than BD2 under all phosphorus and water treatments. Whatever drought stress in flowering or pod-setting stage, root phosphorus efficiency ratio, P uptake efficiency and P transfer efficiency of plant were increased when available soil P increased, in contrast, P utilization efficiency was decreased with the increase of P application level. In total, BX10 had higher level in P absorption efficiency and utilization efficiency, while relatively lower level in root P efficiency ratio and P transfer efficiency than BD2.
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万方数据
维普
