关键词: 小粒型杂交稻, 施氮量, 氮磷钾配比, 产量, 源库特性

Abstract:

To elucidate the effects of nitrogen application rate and N-P-K ratio on the source-sink characteristics of small-seed hybrid rice, a field experiment was conducted using the small-seed hybrid rice variety Zhuoliangyou 0985 as material. The experiment involved four nitrogen application levels [120 (N1), 150 (N2), 180 (N3), and 210 kg/ha (N4)] and three NPK ratios [1.0:0.5:0.8 (F1), 1.0:0.5:1.0 (F2), and 1.0:1.0:1.0 (F3)]. The results showed that leaf area index (LAI), high-efficiency LAI, relative content of chlorophyll (SPAD values), and dry matter accumulation increased with increasing nitrogen application rate. There were no significant differences between N3 and N4 treatments, but both were significantly higher than the N1 treatment. Among different N-P-K ratios, the F3 treatment generally resulted in higher values, though the differences were not significant. Total spikelets and total sink capacity increased with the increase of nitrogen application rate, and the available filled ratio of sink capacity followed the order of N1 > N3 > N2 > N4. Under different N-P-K ratios, the effective filling degree of sink capacity was generally the highest in F2, though the difference was not significant. Effective panicles increased with the increase of nitrogen application rate, while the number of grains per panicle initially increased and then decreased. Both seed-setting rate and 1000-grain weight decreased with the increase of nitrogen application rate, but these differences did not reach a significant level. Yield showed a trend of first increasing and then decreasing with the increase of nitrogen application, with the N3 treatment producing the highest yield. Among the interaction treatments, N3F2 achieved the highest yield, followed by N3F1. Correlation analysis indicated that LAI, high-efficiency LAI, leaf SPAD value, dry matter accumulation, total spikelets, total sink capacity, and effective panicles were extremely significantly and positively correlated with yield. The available filled ratio of sink capacity and seed-setting rate were negatively correlated with yield, while the number of grains per panicle was significantly and positively correlated with yield. No significant correlations were found between 1000-grain weight, grain-leaf ratio, and yield. Under the conditions of this experiment, N3F1 was considered the optimal treatment for Zhuoliangyou 0985. It had a relatively large leaf area, a high number of grains per panicle, a large sink capacity, and a high available filled ratio of sink capacity, with a moderate grain-leaf ratio, which coordinated source-sink relationship and achieved the dual effects of fertilizer saving and yield increase.

Key words: Small-seed hybrid rice, Nitrogen application rate, N-P-K ratio, Yield, Source-sink characteristics