种植密度对四川丘陵区玉米抗倒粒收的影响

Effect of Planting Density on Anti-lodging Mechanical Grain Harvesting of Maize in Sichuan Hilly Areas

为明确不同密度下玉米茎秆抗倒特性和机收质量的变化及其相互关系,以‘先玉1171’和‘仲玉3号’为试验材料,设置6个密度开展大田试验:3.0万、4.5万、6.0万、7.5万、9.0万、10.5万株/hm^(2),研究不同密度对玉米茎秆形态、力学强度、倒伏率及机械粒收质量的影响。结果表明,随种植密度增加,玉米株高和穗位增加、基部节间变长变细,节间穿刺强度和压折强度降低,植株倒伏风险大大增加,相关分析发现压折强度可作为机械抗倒粒收的判定指标。玉米倒伏率、籽粒含水率、杂质率、破碎率和产量总损失率同样随着种植密度的增加而增加,适宜机械粒收的籽粒含水率范围为17.83%~25.76%。玉米产量随密度增加而先增后降,二者呈二次函数关系。本试验条件下,‘先玉1171’的适宜种植密度为7.08万株/hm^(2),而‘仲玉3号’的适宜种植密度为7.99万株/hm^(2),生产中可根据气候条件和作物衔接情况适时晚收,来提高四川丘陵区玉米机械粒收质量。

In order to clarify the changes of stalk lodging resistance and mechanical grain harvesting quality of maize under different planting densities and the correlations between them,‘Xianyu 1171’and‘Zhongyu 3’were used as experimental materials,and six planting densities,including 3.0×104,4.5×104,6.0×104,7.5×104,9.0×104,and 10.5×104 plants/hm^(2),were set to carry out field experiments to study the effects of different planting densities on maize stalk morphology,mechanical strength,lodging rate and mechanical grain harvesting quality.The results showed that with the increase of planting density,the plant height and ear position of maize increased,the basal internodes became longer and thinner,the rind penetration strength and stalk breaking strength decreased,and the lodging risk increased greatly.Correlation analysis found that the stalk breaking strength could be used as a judgment index of anti-lodging mechanical grain harvesting.The lodging rate,grain moisture content,impurity rate,breakage rate and total yield loss rate of maize also increased with the increase of planting density,and the suitable range of grain moisture content for mechanical harvesting was 17.83%-25.76%.As the planting density increased,the maize yield first increased then decreased,and the relationship between planting density and maize yield was quadratic function.Under this experimental condition,the suitable planting density of‘Xianyu 1171’was 70800 plants/hm^(2),while the suitable planting density of‘Zhongyu 3’was 79900 plants/hm^(2).According to climatic conditions and cropping scheme,the harvest can be delayed properly to improve the mechanical grain harvesting quality of maize in hilly areas of Sichuan.