关键词: 稻麦轮作, 磷肥减量, 蛋白质组分, 微量元素含量, 生物有效性

Abstract:

【Objective】 The aim of this study was to explore the effects of reduced phosphorus (P) application on crop yield and nutritional quality, so as to provide a theoretical basis for increasing the P use efficiency and producing high grain quality of crops under the rice-wheat crop rotation system in the Chaohu Lake Basin. 【Method】 A field trial of reduced P application rates was conducted from 2017 to 2019 with five treatments in the Chaohu Lake Basin, which were contrast (CK, No phosphorus), farmers’ application rate (P1, 90 kg P₂O₅·hm^-2), 10% P reduction (P2, 81 kg P₂O₅·hm^-2), 20% P reduction (P3, 72 kg P₂O₅·hm^-2), and 30% P reduction (P4, 63 kg P₂O₅·hm^-2). The effects of reduced P application rates on rice and wheat grain yield and its components, grain protein and fraction content, micronutrients and their bioavailability were analyzed. 【Result】 Compared with no P application, the P application significantly increased the grain yield of rice and wheat by 9.8% to 28.3% and 56.6% to 89.7%, respectively. The 10% and 20% P reduction treatments for rice and wheat grain yield were not significantly different from the farmers’ P fertilizer application (P>0.05). However, the rice yields under the 30% P reduction treatment were significantly decreased by 14.4%. Compared with the farmers’ P application rate, the P reduction treatments significantly affected the crop protein, gliadin and glutenin content, while which had no significant effect on structural protein (albumin and globulin); the P reduction of 20% reduced rice grain protein and glutenin content by 2.7% and 32.3%, respectively. Compared with farmers’ P application rate, the grain protein and glutenin content of rice and wheat under the 30% phosphorus reduction treatment reduced by 6.8% and 21.9%, 48.4% and 31.6%, respectively. Phosphorus application also significantly affected the micronutrients content and bioavailability in rice and wheat grains. Compared with the farmers’ P application rate, P reduction treatments increased iron (Fe), copper (Cu) and zinc (Zn) concentration in rice and wheat grains by 21.2% and 19.3%, 11.9% and 15.8%, 14.5% and 19.9%, respectively; meanwhile, P/Fe, P/Cu and P/Zn molar ratios also reduced by 21.6% and 26.3%, 20.6% and 27%, 17.7% and 21.3%, respectively. The grain zinc concentration of rice and wheat increased linearly with decreasing P application, while the iron, manganese (Mn) and Cu concentrations were no significant differences among the P reduction treatments. P/Zn molar ratio of rice reduced with lower P application, but the P/Fe, P/Mn and P/Cu molar ratios had no significant differences among P reduction treatments. The P/Fe, P/Mn, P/Cu and P/Zn molar ratios in wheat grains reduced with lower P application, and then increasing the bioavailability of Fe, Cu and Zn in wheat grains. 【Conclusion】 In the rice-wheat crop rotation area of the Chaohu Lake Basin, reduced P application by 20% (from 90 kg P₂O₅·hm^-2 reduction to 72 kg P₂O₅·hm^-2) could still ensure stable crop yields. The reduced application of P fertilizer significantly increased the micronutrients concentration and its bioavailability in rice and wheat grains, although the grain protein and glutenin content lower than the farmers’ P application rate. In conclusion, the P3 (20% reduction in P fertilizer application based on the farmers’ P application rate) was the recommended P fertilizer rate to achieve P use efficiency and double high (yield and quality) of crop production in the rice-wheat rotation areas of the Chaohu Lake Basin.

Key words: rice-wheat rotation, phosphate fertilizer reduction, protein components, micronutrient concentration, bioavailability