Abstract:

In this study, the effects of coordinately application of nitrogen (N), phosphorus (P), and potassium (K) on nutrient contents in plants and soils as well as yield in wheat were investigated under field conditions. Results indicated that among the treatments covering three N levels (i.e., low N with 135kg N/hm ², medium N with 225kg N/hm ², and high N with 315kg N/hm ²) and two levels of P and K amounts (i.e., P₂O₅-K₂O 90-120kg/hm ² and P₂O₅-K₂O 135-180kg/hm ²),the plant biomass, concentrations and accumulative amounts of N and K were increased along with the elevated N levels. Under the equal N condition, the treatments with more P and K exhibited lowered N concentrations in plants whereas the accumulative amounts of N, P, and K were elevated with the increase of P and K amounts. The N available contents in soils at various growth stages across the nutrient treatments exhibited a fluctuating pattern, showing decreases at erection stage relative to before winter, gradually elevation from erection stage to flowering stage, decline from flowering to filling stage, and re-rising from filling to the maturity stage. Along with growth progression, the available P contents in soils gradually reduced whereas the soil available K contents changed in a "V" style pattern that was the lowest at flowering stage. Meanwhile, the available contents of P and K at various growth stages under high N level condition were lower than those under lower N level condition. Under the equal N condition, the available contents of P and K in soils were increased in treatments supplemented with more P and K amounts. The spike numbers per unit was elevated with the increased N whereas the kernel numbers per spike and 1000-grain weight reached the peaks at medium N condition. The yields were similar to spike numbers, but relatively little variation observed between the treatments of medium N and high N. At equal N condition, the treatments with increased P and K drastically improved the yield components and yields. Along with increase of the N levels, the grain production capacity per N unit whereas the grain production capacity per unit of P and K exhibited a low-high-low pattern. These results indicate that the medium N treatment (225kg N/hm ²) together with coordinately application of P and K (P₂O₅-K₂O 90-120kg/hm ²and P₂O₅-K₂O 135-180kg/hm ²) can positively regulate the nutrient supply in soils by which to improve the plant nutrient uptake, biomass production, and yield formation.

Key words: Wheat, Coordinately application of N, P, and K, Plant nutrient acquisition, Available nutrient contents in soils, Yield