Straw mulching and phosphorus fertilization increase the proton motive force of wheat root tips after anthesis in dry land area

Objectives The hilly area in southwest China is drought in winter and spring, and the soil is deficient in phosphorus. Phosphorous application could effectively alleviate the water and nutrient limitation of wheat. We studied the effect of straw mulching combined with different rates of phosphorus fertilizers on increasing the nutrient uptake capacity.

Methods A two-year experiment with split design was conducted in Renshou, Sichuan Province from 2020 to 2022. The main factor was straw mulching and no-mulch, and the sub-factor was P application rate (0, 75 and 120 kg/hm², denoted as P0, P75 and P120). The proton motive force of wheat root tips at anthesis stage (PMF) was determined. The nutrient uptake, dry matter accumulation and grain yield of wheat were investigated.

Results After 20 days anthesis, the PMF of P75 and P120 increased by 37.7% and 32.4% compared to P0 under straw mulching (SM), and increased by 20.3% and 36.5% under no-mulch (NSM). The average PMF of root tips in SM treatment increased by 29.4% compared to NSM wheat treatment. Compared with no-mulch, the accumulation of N, P, and K in wheat under straw mulching increased by 23.2%, 32.7%, and 31.9%, respectively, and the dry matter accumulation in nutrient organs during flowering and maturity stages increased by 30.9% and 38.5%, respectively. Straw mulching significantly increased the effective spike, grain number per spike, and yield, with an increase range of P120>P75>P0. Regardless of straw mulching, P75 and P120 achieved significantly higher N and K uptake efficiency than P0, P75 was recorded similar but P120 led to significantly lower N and K grain production efficiency than P0. Among the whole six treatments, straw mulching +P75 achieved the highest P utilization efficiency.

Conclusions Both straw mulching and P application could increase the proton motive force of wheat root tip after anthesis, so promote the nutrient uptake and dry matter accumulation, and increase the yield through improved effective spike number and grain number per spike. Considering the nutrient use efficiency and grain production efficiency, straw mulching combined with 75 kg/hm² of P application rate is an environmental friendly and cost effective measurement for wheat production in drought and hilly area of southwest China.