倒伏是制约玉米产量的重要因素，喷施化学调节物质可有效提升玉米茎秆机械强度，预防倒伏现象的发生。为明确不同时期化控对玉米茎秆发育及产量的影响，以MC670、登海618 2个玉米品种为供试材料，分别于不同的生育期(5展叶、6展叶、8展叶、10展叶、12展叶、15展叶、抽雄期)进行化控处理，通过调查植株节间形态及机械强度、节间碳水化合物含量、产量及其构成因素的变化特征，研究化控时期对玉米茎秆发育及产量形成的影响。结果显示，MC670在6展叶化控处理下平均节间穿刺强度较对照不使用化控剂提高10.8%，基部节间(1~6)节直径增加6.1%，上、中、下部节间干重分别增加5.4%、18.9%、19.0%；纤维素、半纤维素、木质素含量分别增加12.5%、14.8%、5.4%。登海618在8展叶化控处理下基部(1~5节)平均节间穿刺强度较对照不使用化控剂提高16.6%，中部节间直径增加14.6%，下、中部节间长度分别缩短11.9%、2.0%，中、上部节间干重分别增加33.1%、45.0%。15展叶化控处理下2品种产量较对照不使用化控剂提高5.5%~11.2%，有效穗数与对照不使用化控剂无显著差异，但穗粒数及百粒重均较高。

Lodging is a major limiting factor for maize yield, and the application of chemical regulators can effectively enhance stalk mechanical strength and prevent lodging. To clarify the effects of chemical regulation at different growth stages on stalk development and yield, this study used two maize varieties, MC670 and Denghai 618, as materials, chemical regulation was applied at different growth stages(5-leaf stage, 6-leaf, 8-leaf, 10-leaf, 12-leaf, 15-leaf, and tasseling). Parameters such as internode morphology, mechanical strength, internode carbohydrate content, yield and its components were determined to investigate the effect of chemical regulation timing on stalk development and yield formation. Results showed that for MC670, the average internode puncture strength under the 6-leaf stage treatment increased by 10.8% over the control with no chemical regulation, the diameter of the basal 1 to 6 internodes increased by 6.1%, and internode dry matter at top, medium and bottom increased by 5.4%, 18.9% and 19.0%, respectively. The contents of cellulose, hemicellulose, and lignin increased by 12.5%, 14.8% and 5.4%. For Denghai 618, the average internode puncture strength of the basal 1 to 5 internodes under the 8-leaf treatment increased by 16.6% over the control with no chemical regulation, the diameter of medium internodes increased by 14.6%, internode length at bottom and medium were shortened by 11.9% and 2.0%, respectively, and internode dry matter at medium and top increased by 33.1% and 5.0%, respectively. Under 15-leaf treatment, yields of both varieties increased by 5.5%~11.2% compared to the control with no chemical regulation. The number of ears harvested did not significantly differ from the control, but the number of kernels per ear and 100-kernel weight were higher.

S513

新疆维吾尔自治区重点研发计划项目(2023B02040-2)。