Tolerance To Low Phosphorus Characteristics Of Corn Inbred Lines Of Phosphorus Nutrition

Phosphate (P) deficiency in soil is among the major nutrient factors that limit the yield of crops. Although, application of inorganic phosphate fertilizers can improve the phosphorus nutrition of crops, it can increase the cost of farmers and also cause environment problem. Furthermore, the utilization efficiency of P fertilizers applied in fields is very low; the rock P resource is non-reproductive and would be exhausted in future. Under these situations, it is urgent to breed low P tolerance crop germplasms by bio-techniques. In these studies, the P nutrition characteristics of the several maize inbred lines with low P tolerance coming from cell engineering and the skeleton maize inbred line,Qi319 (the control inbred line), were investigated under field, sand and solution culture conditions. The primary purpose of these studies is to elucidate the possible mechanisms of the low P tolerance maize lines and cultivate P high efficiency germplasm. The results were shown as follows:(1) Four low P tolerance maize inbred lines (SD-A, SD-B, SD- C and SD-D) coming from cell engineering and inbred lines Qi319 (as control) were planted in the field and supplied with low P and high P. The P efficiency of these materials was graded at seedling, drawing knurl and maturity stage. The results showed that at seedling stage, P uptake efficiency was the main resource of different P efficiency among these lines. Compared with Qi319, low P tolerance inbred lines had stronger ability in P absorption which led to more biomass. At drawing knurl stage, the difference of P efficiency among these lines was originated from both uptake and utilization efficiency. At maturity stage, there was significant variation in grain yield among these inbred lines. The yield of Line SD-B was the highest, and was 1.40 times higher than Qi319. Basing on grain yield at the two P levels, these lines could be graded into four groups in phosphorus efficiency: double P efficient varieties (SD-B, SD-C), P efficient one at high P(SD-D), and double P inefficient ones (Qi319, SD-A). These datas indicated that the significant variation in uptake and utilization efficiency existed among these lines at the same P supply during maturity. At both P levels, P uptake efficiency was correlated positively with P efficiency while utilization efficiency was not. Uptake efficiency was the main contributor to P efficiency during maturity; the inbred lines coming from cell engineering had stronger uptake ability than Qi319.