Abstract: To clarify the appropriate rate of phosphorus application and physiological mechanism for promoting wheat tillering and efficient utilization of phosphorus fertilizer with supplementary irrigation, we used ‘Jimai 22' wheat variety as the test material, to set up three phosphorus application treatments, including low (90 kg P₂O₅·hm^-2, P₁), medium (135 kg P₂O₅·hm^-2, P₂), and high (180 kg P₂O₅·hm^-2, P₃) application rates, with no phosphorus application as the control (P₀). We increased the relative soil water content of each treatment at join-ting stage and anthesis stage to 70%, and measured the area of tiller node, the content of endogenous hormones, the number of tillers in each tiller position, photosynthetic parameters, the distribution of ¹³C assimilates in each stem and tiller, as well as the grain yield and partial productivity of phosphate fertilizer. The results showed that compared with P₀ and P₁ treatments, P₂ significantly increased the area of tiller node and the trans-zeatin (tZ), the photosynthetic parameters of the uppermost expanded leaves of the main stem, the total tillers per plant, and the distribution of ¹³C assimilates in each tiller. The number of ears per plant was increased by 0.51 and 0.36, and grain yield was increased by 40.3% and 13.2%, respectively. In P₃ treatment, the number of tillers increased, but the panicles per plant, and the grain yield and phosphate fertilizer partial productivity decreased. Our results suggested that the moderate phosphorus treatment (135 kg·hm^-2) under supplementary irrigation was suitable for high yield and high efficiency of wheat.

Key words: wheat, phosphorus application rate, tillering and spike formation, grain yield, phosphate fertilizer partial productivity