| Taking 32 cotton varieties as the research object, P efficiencies of these genotypes of cotton varieties are studied at seeding and bud stage through water culture experiment by setting 2 phosphorous consistency condition (KH2PO4 1×10-3 mol·L-1, KH2PO4 0.01×10-3 mol·L-1) culture experiments. Three cotton varieties of P efficiency and three cotton varieties of P inefficiency are screened, and selected respectively. Mechanism of phosphorus efficiency of cotton is studied by water culture experiments and growth period dynamic monitoring. The study provides theoretical basis for breeding and selecting phosphorus efficient use of varieties of cotton. The results are as follows:1. Coefficients of variation of relative dry matter, relative P uptake and relative P rates present higher traits than others. In seeding, coefficients of variation are 27.30%, 46.60%, 50.30%, and 51.70%, 57.10%, 45.10% in bud stage, which indicates that these three indexes can be selected as screening index. Cluster analysis shows that Xinhai18, Xinluzao19 and Zhongmian 42 are of high P efficiency, and Xinluzao 13, Xinluzao 17 and Xinluzao 26 are of low P efficiency.2. Under the low phosphorus condition, the root to shoot ratio of phosphorus efficient genotypes of cotton varieties is higher than P inefficiency of cotton varieties. Study indicates that phosphorus stress has minimum impact on Xinluzao19, and the greatest impact on Xinluzao17.3. With extended growth period, dry matter and phosphorus accumulation are growing, and phosphorus content of roots, stems and leaves decreasing. Under different phosphorus supply, phosphorus content of roots is higher than leaves, and leaves are higher than stems because roots contact nutrient solution fully under conditions in water culture, and promote the growth of leaves.4. Under conditions of high phosphorus, chlorophyll content of different genotypes of cotton varieties is higher than those under conditions of low phosphorus in the whole growth period. |
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