Effects of phosphorus concentration on adaptive mechanisms of high- and low-P efficiency soybean genotypes when grown in solution
Shujie, M.,Chinese Academy of Sciences, Harbin (China). Northeast Inst. of Geography and Agro-Ecology | Yunfa, Q.,Chinese Academy of Sciences, Harbin (China). Northeast Inst. of Geography and Agro-Ecology
Low availability of phosphorus in soil is a major constraint for crop production in agricultural ecosystems. Therefore, it is very important to explain the adaptive mechanism of crops under low P conditions. The response of high- and low-P efficient soybean genotypes to various external P level was carried out in nutrient solution culture. Results showed that Dongnong1031 (low P-efficient genotype) undergoes major changes in terms of dry mass, root length, root number and root surface, whereas the response of Hai 616 (high P-efficient genotype) was less pronounced after five weeks of growth. The higher P level in solution, the smaller difference between the two genotypes in these characteristics. The amount of H+ released by root of Dongnong1031 was lower than that of Hai 616, except when supplied with 50 micromol external P. There was a positive relationship between relative P absorption efficiency (RPAE) and P concentration in shoot and root material at all P levels, irrespective of soybean genotype. An exponential relationship was found between P utilization efficiency (PUE) and P concentrations in shoots and roots. These results suggested that an increase in measured root characteristics coupled with H+ release by roots were key mechanisms for soybean genotypes with high-P efficiency to cope with low P conditions when grown in solution. In order to best select high soybean genotype with high-P efficiency one should pay attention to PUE combined with high RPAE.
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