Effects of water-nitrogen management patterns and phosphorus and potassium fertilizer combined application on grain yield and quality of hybrid rice Gangyou 725 in rapeseed (wheat)-rice planting area of Chengdu plain
Abstract: Hybrid rice Gangyou 725 was used to investigate the effects of three waternitrogen management patterns [submerged irrigation and optimized nitrogen (N) application, W1N1; controlled alternate irrigation and optimized N application, W2N1 and dry cultivation and optimized N application, W3N2] and different phosphorus (P)-potassium (K) combined application on grain yield, quality and nutrient distribution of rice in rapeseed (wheat)-rice planting area of Chengdu plain. The results show that different water-nitrogen management patterns and P-K fertilizer combined application significantly affect rice quality, nutrient absorption and distribution and grain yield. The yields, head rice rates, amylose contents, protein contents and RVA profile values under different waternitrogen management patterns are higher than those of different P-K fertilizer combined applications, while the chalkiness degrees, percentages of chalky kernel and gel consistencies are opposite. The average of grain yield is decreased under the W1N1 and W3N2 treatments (3.02% under the W1N1 treatment, 28.21% under the W3N2 treatment) compared with the W2N1 treatment. Furthermore, the W2N1 and suitable P90K90-180 combined application (P applied amount 90 kg/ha, K applied amount 90 kg/ha-180 kg/ha) would be useful to regulate seed setting rate and 1000-grain weight, enhance nutrient absorption, head rice, gel consistency, protein content, peak viscosity and breakdown, decrease chalkiness degree, percentage of chalky kernel, amylase and setback, and improve yield and rice quality. The suitable P90K90 combined application is considered to be optimum under the W2N1 Compared with the W1N1, the W3N2 results in yield reduction and bad rice quality, while the W3N2 and suitable P90K180 has compensation for yield outputs and rice quality.