四川玉米生理成熟后抗倒性能变化及其影响因素

Changes of maize lodging resistance after physiological maturity and its influencing factors in Sichuan

玉米茎秆强度下降是造成生理成熟后玉米倒伏的重要因素。为明确玉米生理成熟后茎秆强度变化及影响因素,本试验以玉米品种‘正红6号’为材料,设置不同密度处理,通过研究其生理成熟后茎秆强度、单位长度干重、含水率等变化规律,分析影响生理成熟后茎秆强度的关键因素,为机械粒收技术推广提供科学指导。结果表明,玉米生理成熟后节间茎秆强度逐渐下降,随着时间推移,降低幅度逐渐减小;生理成熟后玉米茎秆单位长度干重、含水率逐渐降低,节间长粗比略有增加。不同密度间茎秆强度差异显著,生理成熟后茎秆强度下降幅度不同,在4.5万~10.5万株∙hm^(-2)密度范围内,随着密度增加,茎秆强度下降幅度呈降低趋势,低密度茎秆强度下降幅度大于高密度处理。种植密度增加导致玉米茎秆单位长度干重显著降低,节间长粗比显著增加。本研究发现玉米生理成熟后茎秆单位长度干重降低是茎秆强度降低的主要原因;种植密度增加显著降低了茎秆强度,同时随着站秆时间的延长,茎秆强度进一步降低,增加了玉米倒伏风险。因此,合理密植、适期收获能降低因生理成熟后站秆能力下降而导致倒伏的风险。

Densification planting and delayed harvesting are important measures for the promotion and development of mechanized grain harvesting technology of maize,but they also reduce the lodging resistance of stalks and increase the risk of lodging.The appearance of maize lodging not only increases the difficulty of mechanical harvesting and reduces the speed of mechanical harvesting,but also increases the loss of ear caused by lodging and reduces the yield of mechanical grain harvest.Therefore,the purpose of this experiment was to explore the changing law of the lodging resistance ability of maize stalks after physiological maturity under different densities and to provide a scientific basis for the development of maize dense planting and high-yielding mechanical grain harvest technology.This experiment used‘Zhenghong 6’as the material and set 6 density treatments:3.0×104 plants∙hm^(-2)(B1),4.5×104 plants∙hm^(-2)(B2),6.0×104 plants∙hm^(-2)(B3),7.5×104 plants∙hm^(-2)(B4),9.0×104 plants∙hm^(-2)(B5),and 10.5×104 plants∙hm^(-2)(B6).In the physiological maturity period(August 6,A1),11 d after physiological maturity(August 17,A2),22 d after physiological maturity(August 28,A3),and 35 d after physiological maturity(September 10,A4),5 plants in each plot were sampled and the changing laws of stalk strength,internode morphology,internode dry matter,moisture content,etc.were determined.The results showed that the internode stalk strength of maize decreased after physiological maturity,but the decreasing range gradually reduced with time.After physiological maturity,the dry weight per unit length and water content of stalk decreased,while the internode length-to-diameter ratio increased slightly.Stalk strength and it’s change with time were significantly different among different densities after physiological maturation.In the density range of 4.5×104 plants∙hm^(-2) to 10.5×104 plants∙hm^(-2),the decreased amplitude of stalk strength showed a decreasing trend with the increase of density,and that of stalk strength of low density was greater than that of high density.The increase in planting density resulted in a significant decrease in stalk dry weight per unit length and a significant increase in the internode length-to-diameter ratio.The results showed that the decrease of stalk dry weight per unit length after physiological maturity was the main reason for the decrease of stalk strength.The increase of planting density significantly reduced the stalk strength,and with the extension of standing time,the stalk strength further decreased.The stalk strength of different densities decreased differently,and the decrease rate of low density was greater,but the stalk strength of high density was still lower than that of low density treatment all the time.Therefore,properly dense planting and harvest at the right time can reduce the risk of lodging caused by the decline of the standing capacity of culms after physiological maturity of maize.