烯效唑对遮阴下重穗型水稻渝香203茎秆形态结构和抗倒伏性的影响

Effects of Uniconazole on Stem Morphological Traits of Heavy-Panicle Type Rice Yuxiang 203 and Its Relationship with Lodging Resistance under Shading Condition

【目的】明确弱光下烯效唑对重穗型水稻植株倒伏风险的缓解效应及途径。【方法】以重穗型水稻渝香203为材料,设置裂区试验,主区为正常光照(CK)和遮阴处理(U),副区为0(U0)、40 mg/L(U40)、80 mg/L(U80)烯效唑处理,比较茎秆力学,物质积累分配及形态性状方面差异,并分析其与植株抗倒伏性的关系。【结果】较正常光照,遮阴处理显著降低渝香203产量,归因于有效穗、穗粒数和千粒重的降低。施用烯效唑显著增加了有效穗(P<0.05),产量略微增加;遮阴处理显著降低了基部节间茎鞘干重、基部节间茎粗、茎壁厚及单茎鞘干重,使得茎秆折断弯矩显著降低,倒伏指数增加,尽管弯曲力矩也显著降低。相关分析表明,断面模数,茎粗、茎壁厚、单茎鞘干重及茎鞘充实度与折断弯矩显著正相关,与倒伏指数显著正相关。随烯效唑用量增加,基部节间长度显著缩短,株高和重心高度降低,从而降低了弯曲力矩;同时,基部节间茎粗、茎壁厚及茎鞘充实度呈显著增加趋势从而提高了茎秆强度和抗倒伏性。【结论】弱光下重穗型水稻基部节间茎秆强度降低是植株倒伏风险增加的主要原因,烯效唑缩短基部节间长度,从而降低株高和重心高度,增加茎粗、茎壁厚及茎秆充实质量,增强了茎秆机械强度,提高了弱光下重穗型水稻抗倒伏性。

【Objective】The objectives of this study were to determine the alleviation effect and mechanism of uniconazole on the lodging risk of heavy panicle rice plants under shading condition.【Method】Field experiments were conducted by using three uniconazole application levels,namely 0 mg/L(U0),40 mg/L(U40),80 mg/L(U80) with heavy-panicle type rice Yuxiang 203 under normal light(CK) and shading(S) conditions. Stem physical parameters,dry matter accumulation and distribution and stem morphological traits were investigated,and their relationship with lodging resistance was also analyzed.【Result】Compared with CK,shading significantly decreased grain yield of Yuxiang 203,mainly due to reduction of panicles,spikelets per panicles and 1 000-grain weight. Spraying of uniconazole significantly increased panicles,and slightly improved grain yield with no significant difference. Also,shading treatments reduced stem diameter,stem wall thickness,culm and leaf sheath weight per cm of lower internodes,dry weight per stem and thereby,decreased breaking resistance(M) and increased lodging index(LI)with significant difference,in spite of significant reduction of bending moment by whole plant(WP). The correlation analysis showed that section modulus(Z),stem diameter,stem wall thickness,culm and leaf sheath dry weight per cm were positively and significantly correlated with M,but negatively and significantly correlated LI. With increasing levels of uniconazole,the length of basal internodes,plant height and gravity center height were significantly lowered,and thus reduced bending moment by whole plant(WP),but stem diameter,stem wall thickness,culm and leaf sheath dry weight per cm were significantly increased and thereby,improved stem physical strength and lodging resistance with significant difference.【Conclusion】The higher lodging risks of heavy-panicle type rice under low light condition were mainly due to significant reduction of M. Uniconazole lowered length of basal internodes,decreased plant height,also increased stem diameter,stem wall thickness and stem dry weight,thereby improved stem physical strength,enhanced lodging resistance of heavy-panicle type rice under low light condition.