Phosphorus efficiency comparison among cotton varieties cultivated at different times over 63 years

Improving the phosphorus (P) fertilizer utilization rate is a major challenge when attempting to supply sufficient P nutrients in agriculture. Modifying the crop variety can effectively address this problem. The differences in P utilization efficiency among various cotton varieties cultivated at different times in Xinjiang, China, were clarified by setting up a single-factor random block design field experiment that investigated 22 different cotton varieties cultivated between 1950 and 2013. The P absorption and utilization efficiency characteristics of different cotton varieties during their seedling, budding, flowering, and wadding stages were monitored. Correlation and cluster analyses were used to evaluate the P efficiencies of cotton varieties. The results showed that P absorption efficiency, P utilization efficiency, and P transfer efficiency (from shoot to seed) differed among the 22 cotton varieties. At the wadding stage, the P absorption efficiency was 164.26-395.75 mg·plant^-1 with a coefficient of variation of 3.3%; the P utilization efficiency was 0.25-0.40 g·mg^-1 with a coefficient of variation of 67.7%; and the P re-transfer efficiency was 16.0-58.1% with a coefficient of variation of 11.1%. The P utilization efficiency, which always stayed between 0.30-0.32 g·mg^-1, did not significantly change over the three time periods (every 20 years was one period). Furthermore, P transfer efficiency did not significantly change and was around 93.9%-94.9%. In contrast, P absorption efficiency increased from 225.5 mg·plant^-1 to 286.3 mg·plant^-1, which was a 27.0% increase; and P re-transfer efficiency increased from 26.8% to 38.3%, which was an 11.5% increase. The P economic utilization efficiency rose from 20.6 mg·mg^-1 to 30.4 mg·mg^-1, which was a 47.6% increase. The correlation analysis showed that biomass was positively correlated with P absorption efficiency, but there was no significant relationship with P utilization efficiency. The lint cotton yield was positively correlated with P absorption, transfer, re-transfer efficiency, and economic utilization efficiency, but had no relationship with P utilization efficiency. The cluster analysis divided 22 cotton varieties into four types: P high-efficient type, P medium-efficient, P inefficient type, and extremely inefficient type. 'Xinluzao 50' 'Xinluzao 57', and 'Junmian 1' were P high-efficient varieties. The P high-efficient varieties had higher biomasses and yields than the other three types. In conclusion, these results highlighted that the use of high yielding cotton varieties in Xinjiang had prominently contributed to improvements in the absorption, transfer, and economic utilization of P.