Screening And Research On Nutrition Difference Of Sweet Maize With Phosphorus Efficiency

Plants have different tolerance to the lack of phosphate and studies showed that the efficiency of phosphorus varied with genotypes. First, main biological traits of sweet maize and their relationships were investigated in the pot experiments under both low phosphorus and high phosphorus conditions, with 18 varieties in the seedling stage. Relative dry matter weight, P accumulation and P content could be used as screening indexes of sweet maize on tolerance to low- phosphorus and the tested 18 varieties were divided into three categories, namely P efficient varieties, P inefficient varieties and the middle P efficient varieties. Then the biological traits, yield and quality of P efficient sweet maize varieties (Dingjian and Taiwanhuazhen) and low-P efficient sweet maize varieties (Jinmao NO.3 and Jinshengwang) screened in the seedling stage were researched in 4 phosphorus conditions(no applying phosphate P0, low phosphorus P1, moderate phosphorus P2, high phosphorus P3)in the field experiments.The main results were as follows:(1) The results showed that in the pot experiments the root volume, side root number, root dry weight, shoot dry weight, P content and P accumulation decreased while ratio of root to shoot and Apase activity secreted by the leaves raised in low phosphorus conditions. Different sweet maize had evident differences in the tolerance to low-phosphorus stress, and the relative biological traits of P efficient sweet maize were higher than P inefficient ones.(2) P content and P accumulation were influenced by low phosphorus and they were different because of the different varieties and periods. The effect of low phosphorus to the P inefficient varieties was obviously higher than the P efficient varieties in the jointing stage and the heading stage. The P content and P accumulation of different sweet maize were biggest in P1 condition in the seedling stage and that were biggest in P2 condition in the jointing stage. But in the heading stage, the P content and P accumulation of P efficient sweet maize varieties were biggest in P2 condition while that of P inefficient sweet maize varieties were biggest in P3 condition.(3) The N content, K content, N accumulation and K accumulation of sweet maize in no applying P condition were significantly lower than that in applying P conditions and the difference in N, K content and accumulation among different varieties were very obvious. The effect of low phosphorus to the P inefficient varieties was significantly higher than the P efficient varieties.(4) The low phosphorus influenced P content, N content and K content of different organs in the mature stage and the difference among P inefficient varieties and P efficient ones was evident. The P content of different organs reached the maximum in P2 condition and the N and K content of leaves and grain also reached the maximum in P2 condition while the N and K content of stems reached the maximum in P1 condition. The order of P and N content of various organs was stem