Difference in grain phosphorus content of high-yielding wheat cultivars and its relation to NPK uptake and utilization in dryland

Objectives The grain phosphorus content and its relationship to major agronomic and nutritional traits of the high-yielding wheat cultivars were studied in drylands, aiming to provide reference for optimizing fertilizer management and breeding new cultivars of both high yield and high nutritional quality.

Methods A field experiment was conducted in Weibei dryland during 2013 to 2016, there were 123 wheat cultivars grown under fertilization (N 150 kg/hm² and P₂O₅ 100 kg/hm²) and no fertilization conditions. The biomass accumulation, yield components and NPK uptake were analyzed. The relationship between grain P contents and the main agronomic traits of the cultivars were discussed.

Results The average yield of the high-yielding wheat cultivars was 6.9 t/hm² and the grain P contents varied from 2.5 to 3.7 g/kg with a variation of 51.1%. The grain yields were significantly and negatively correlated with the P content, every increase of 1000 kg/hm² in yield would lead to a decrease of 0.28 g/kg in P content. The grain yields and yield components of the high- and low-grain P cultivar groups were similar, while the high-P group had higher grain N contents and similar grain K contents, compared with those of low-P group. The high-P group accumulated higher N and P in grain and straw, but the N and P translocation from straw to grain were not significantly different between the two groups. The high-P group exhibited lower K translocation than the low-P group. Fertilization increased N, P and K uptake in grain and vegetative parts of both groups, with greater increase for the high-P group, but reduced the translocation of N, P and K from straw to grain, especially for the high-P group.

Conclusions The high-yielding and high-grain P content wheat cultivars have higher N content and uptake, and their response to fertilization is more significant. Fertilization will increase the biomass and N, P and K uptake, and consequently decrease the harvest index of the high-P cultivars. Therefore, cultivars with medium P contents and high P harvest indexes are encouraged in breeding high-yielding wheat. Fertilization regime should be adjusted according to the cultivar’s grain P content for increasing grain N contents and acquiring high-yield and high-quality wheat products in dryland.