Tolerance indices for P deficiency and Al toxicity and their interactions in soybean

Some tolerance indices for P deficiency and Al toxicity in five soybean genotypes collected from South China were studied in nutrient solution culture The results indicated that genetic variation existed within the tested soybeans in P efficiency and Al tolerance Soybean varieties No 62, Le Chang and Guangzhou had relatively high P efficiency and Al tolerance Under low P and Al toxicity conditions, they were relatively higher in biomass, P content, leaf area, chlorophyll content, total acid exudation and tap root length Low P and Al toxicity affected shoot P uptake, and increased concentration P in nutrient solution could significantly ameliorate Al toxicity in soybean There was no significant variation in Al concentration in the shoot, but under Al toxicity stress, the Al concentration in the root was five or six times as that in the shoot, with significant differences among genotypes Our results indicate a possible relationship between P efficiency and Al tolerance in soybean, but this relationship should be further verified by linkage analysis with the molecular marker technique