Effect of phosphorus fertilization on morphological and physiological characteristics of adzuki beans

【Objective】 The study on the root morphology, the physiological adaptation and accumulation of phosphorus of plants under different phosphorus nutrition levels will be able to explore the P use potential, and help the screening of cultivars with high phosphorus use ability. 【Methods】 Three adzuki beans cultivars, Jin NO.1, adzuki bean Baohong 8824/17 and the Dongbeidahongpao, were chosen as test materials, and a pot experiment was conducted. Four levels of P2O5, 0(P1), 50(P2), 100(P3) and 200 mg/kg(P4) were designed. The beans were sown on May 18, 2013. Each basin was sown 15 seeds and eight seedlings were kept in each plastic basin after the first main leaf came out. When the adzuki bean grew to 30 d, the indexes related to physiological characters and the growth of plants were measured. 【Results】 1) Until the day of measurement, the leaf areas of Jin NO.1 are increased, the plant height increases first and then decreases with the increase of P2O5 rates,while the leaf areas and the heights of the other two cultivars are increased first and declined later. The total lengths and areas of roots are keep increased, affecting the shoot biomass and the total dry weights of roots. 2) With the increase of P2O5, the root activities present increases at first and then decrease, and the activities of acid phosphatase of the roots are decreased, while the accumulation of P in all the three cultivars show an increasing trend. 3) With the increase of the P2O5, the activities of SOD and POD present a trend that increase at first and then decrease. The MDA contents are higher under the levels of low and high P2O5, levels the SOD and POD activities in Jin NO.1 are lower, and the MDA content is higher than those in the other two cultivars. 4) Under the levels of low and high phosphorus, the chlorophyll relative contents are low, but the difference is not significant, the maximum fluorescence(Fm) and the maximal photochemical efficiency(Fv/Fm) are increased, and the initial fluorescence(Fo) is decreased. 【Conclusions】 Adzuki beans response to different phosphorus nutrition levels by physiological characters and changes in root architecture.In this study, there are obvious differences in the index of the plant morphology and physiology in the adzuki beans under different P supply levels. The shoot to root ratios of the three cultivars are evidently increased by elongating root length and increasing root area. There are obvious differences among the three adzuki beans to the phosphorus nutrition. The ability of tolerance to low and high phosphorus stress is stronger in cultivar Jin NO.1 than in the other two.