Abstract:

To explore the traits and mechanical characteristics of lodging-resistant stems of high-quality late-season rice under water-nitrogen interaction conditions, this study used the high-quality late-season rice variety Nongxiang 42 as the test material and designed a split-plot experiment. Water management served as the main-plot factor, with two treatments: alternate wetting and drying (W1) and continuous flooding(W2). Nitrogen fertilizer management acted as the sub-plot factor, with three nitrogen application levels set at 120 kg/hm² (N1), 180 kg/hm² (N2), and 240 kg/hm² (N3). The results indicated that nitrogen fertilizer management significantly influenced rice plant height, center-of-gravity height, center-of-gravity ratio, internode wall thickness, bending moment, and lodging index. Specifically, compared with the N1 treatment, the center-of-gravity height under the N2 and N3 treatments significantly increased by 11.08% and 15.32%, respectively, while the center-of-gravity ratio significantly increased by 9.36% and 12.93%, respectively. The internode wall thickness of the 3rd internodes under the N3 treatment significantly increased by 16.85%, while that of 4th internode significantly decreased by 12.00%. For the internode wall thickness of the 4th and 5th internodes under the N2 treatment significantly decreased by 24.67% and 8.70%, respectively. While the water-nitrogen interaction had a particularly notable impact on internode wall thickness, bending resistance, and lodging index. Under the same water management level, bending resistance showed a trend of first decreasing and then increasing with the increase in nitrogen application levels. Compared with the N1 treatment, the lodging indices of the 1st to 3rd internodes under the N2 treatment increased by 27.06%, 37.84%, and 25.51%, respectively. The lodging indices of the 4th and 5th internodes under the N2 and N3 treatments significantly increased by 74.38%, 65.01% and 60.37%, 64.19%, respectively. Correlation analysis revealed that the bending resistance of the 2nd to 4th internodes was significantly positively correlated with internode wall thickness, internode fullness, and bending modulus, and significantly negatively correlated with the maximum stress on the cross-section. The lodging indices of the 2nd to 4th internodes were significantly positively correlated with the center-of-gravity height and the maximum stress on the cross-section, and significantly negatively correlated with internode wall thickness and internode fullness. In conclusion, under a certain nitrogen fertilizer level (<180 kg/hm²), the use of alternate wetting and drying irrigation can effectively enhance the lodging resistance of the high-quality late-season rice variety Nongxiang 42 by improving its center-of-gravity height, center-of-gravity ratio, and internode wall thickness.

Key words: high-quality late rice, water and nitrogen interaction, stem trait, mechanical characteristic, lodging resistance

摘要：

为探究水氮互作条件下优质晚稻抗倒伏茎秆的性状与力学特征，本研究以优质晚稻品种农香 42 作为供试材料，设计裂区试验，以水分管理为主区因素，设置干湿交替（W1）和常淹水（W2）2种处理；氮肥管理为副区因素，设置 120 kg/hm²（N1）、180 kg/hm²（N2）、240 kg/hm²（N3）3个氮肥施用水平。结果表明，氮肥管理对水稻株高、重心高度、重心比例、节间壁厚、弯曲力矩和倒伏指数影响显著。具体而言，与N1处理相比，N2、N3处理下的重心高度分别显著增加了11.08%、15.32%，重心比例分别显著增加了9.36%、12.93%；N3处理下第3节和第4节的节间壁厚分别显著增加16.85%和显著降低12.00%；N2处理下第4节和第5节节间壁厚分别显著降低24.67%和8.70%。而水氮互作对节间壁厚、抗折力、倒伏指数影响尤为显著。在同一水分管理水平下，抗折力随施氮水平的增加呈现出先降低后增加的趋势。与N1处理相比，N2处理下第1节至第3节的倒伏指数分别增加了27.06%、37.84%、25.51%；N2、N3处理下第4节和第5节倒伏指数分别显著增加了74.38%、65.01%和60.37%、64.19%。相关性分析表明，第2节至第4节的抗折力与节间壁厚、节间充实度、抗弯曲模量呈显著正相关，与断面所受最大应力呈显著负相关；第2节至第4节的倒伏指数与重心高度、断面所受最大应力呈显著正相关，与节间壁厚、节间充实度呈显著负相关。综上所述，在一定氮肥水平（<180 kg/hm²）下，采用干湿交替灌溉方式，能够改善水稻的重心高度、重心比例和节间壁厚，有效提升优质晚稻农香42的抗倒伏能力。

关键词: 优质晚稻, 水氮互作, 茎秆性状, 力学特征, 抗倒伏