Effects of phosphorus and potassium fertilizer on grain yield, nutrient uptake and utilization in low-gluten wheat

  Objectives  The experiment studied the effects of different phosphorus and potassium fertilizer application rates and methods on grain yield, protein content, NPK uptake, and utilization of wheat following rice, to provide a reference for optimizing yield and efficiency of rice-wheat rotation system.

  Methods   Field experiments with split plot design were carried out in Yizheng City, Jiangsu Province under rice and wheat rotation system from 2020 to 2021, and the teat wheat variety was low-gluten type, Ningmai 33, and all rice and wheat straw were returned to the field after harvest. The main factor was P fertilizer, including three primary base application 0, 72, and 144 kg/hm² (P0, P1, P2) treatment, and a basal plus topdressing at jointing stage at the rate of respective 72 kg/hm² (P3). K fertilizer was the secondary factor, with three primary base application treatments of 0, 72, and 144 kg/hm² (K0, K1, K2), and one treatment of base plus topdressing at jointing stage at the rate of 72 kg/hm² each time (K3). Wheat biomass and grain yield were investigated, NPK and protein contents in plants and grains were analyzed at harvest.

  Results  P and K fertilization had significant main effects and interaction on plant NPK accumulation, fertilizer use efficiency, grain yield and protein content. Appropriate P and K fertilization rate (72 kg/hm²) improved their synergy effect, while excessive rate (144 kg/hm²) offset or even led to negative impact, such as reducing fertilize efficiency and grain quality. Compared with P1, P2 did not significantly affect grain yield, protein content, N and K agronomic efficiency, but reduced P agronomic efficiency and the partial productivity of P fertilizer. Under the P0 condition, K2 had higher grain yield, PK accumulation than K1. Compared with P2, P3 did not affect grain yield, protein content and fertilizer use efficiency, and K3 did not affect grain yield and protein content compared with K2, but significantly increased the physiological use efficiency and agronomic efficiency of nitrogen and phosphorus. Among the combination treatments, P3K2, P1K2 and P1K3 performed better in terms of grain yield and fertilizer utilization than those containing P0, P2, and K1 rates.

  Conclusions  Applying P fertilizer twice did not show superiority over single basal application, while two-time application of K fertilizer had a significantly higher effect than one basal application. In general, the combination of P 72 kg/hm² and K 144 kg /hm², regardless of frequency of application is recommended for low-gluten wheat variety, Ningmai 33 in less fertile sandy loam soil.