收获时期对四川春玉米机械粒收质量的影响

Effects of harvesting date on mechanical grain-harvesting quality of spring maize in Sichuan Province

开展收获时期对玉米机械粒收质量影响的研究,对确定玉米适宜机械粒收时期和粒收技术的推广应用具有重要意义。本文以四川4个主栽玉米品种为材料,研究不同收获时期(7月31日、8月7日、8月13日、8月19日、8月25日、8月31日)对四川春玉米机械粒收质量的影响,并分析籽粒含水率与机械粒收质量之间的关系。结果表明:随收获日期推迟,玉米籽粒含水率逐渐降低,破碎率先快速降低后略有升高,杂质率快速降低并趋于稳定,而落穗损失率显著增加,落粒损失率变化规律不明显。机械粒收损失主要为落穗损失,占总损失率的比例平均为76.34%。随收获日期推迟籽粒破碎率和杂质率在品种间的差异逐渐减小,而落穗损失和总损失率在品种间的差异逐渐增大。籽粒含水率是影响机械粒收质量的关键因素,破碎率与籽粒含水率拟合方程为y=0.0329x2-1.3328x+15.529(R2=0.55**),含水率为10.76%~29.76%,破碎率低于5%;杂质率与籽粒含水率拟合方程为y=0.0318e0.1185x(R2=0.71**),含水率低于38.37%,杂质率低于3%;落穗损失率与籽粒含水率拟合方程为y=2083.3/x2.135(R2=0.68**);籽粒总损失率与籽粒含水率拟合方程为y=911.02/x1.769(R2=0.68**),含水率高于18.96%,籽粒总损失率低于5%。推迟收获有利于降低籽粒破碎率和杂质率,但增加落穗风险和籽粒总损失率。本试验播期条件下,玉米适宜机械粒收的籽粒含水率范围为18.96%~29.76%,适宜机械粒收时间在8月7-19日,较传统收获日期推迟10~15 d。

Studying the impact of harvesting date on mechanical grain-harvesting quality is of great importance to determine a suitable harvesting date and promote the mechanical grain harvest technology.This paper describes an experimental study of the effects of harvesting date(31st July,and 7th,13th,19th,25th,and 31st August)on mechanical grain-harvesting quality and the relationship between grain moisture content and mechanical grain-harvesting quality in Sichuan spring maize.The results showed that,with a delay in harvest date,grain moisture content decreased gradually,and the broken-grain rate decreased rapidly at first and then increased slightly.The impurity rate decreased rapidly and tended to be stable,while the ear-loss rate increased significantly and the variation in grain loss rate was not notable.The total grain loss rate was primarily associated with ear loss,which accounted for 76.34%of the total average grain loss.With a delay in harvest date,the differences in b roken-grain and impurity rates between varieties decreased gradually while they increased for ear-loss and total grain-loss rates.Grain moisture content was the key factor affecting the quality of mechanical grain harvest,the relationship between the br oken-grain rate and grain moisture content could be described by the equation y=0.0329 x2-1.3328 x+15.529(R2=0.55**,n=72).The broken-grain rate was lower than 5%when the moisture content was between 10.76%and 29.76%.The relatio nship between the impurity rate and moisture content could be described by the equation y=0.0318 e0.1185 x(R2=0.71**,n=72),and the grain impurity rate was lower than 3%when grain moisture content was lower than 38.37%.The relationship between the ear-loss rate and moisture content could be described by the equation y=2083.3/x2.135(R2=0.68**).The relationship between the total grain-loss rate and moisture content could be described by the equation y=911.02/x1.769(R2=0.68**),and the total grain-loss rate could be lower than 5%when grain moisture content was higher than 18.96%.A delayed harvest was associated with a decrease in the broken-grain and impurity rates and an increase in the risk of ear-loss and the total grain-loss rate.The optimal grain moisture content for mechanical harvesting in Sichuan spring maize was 18.96%–29.76%and the optimal mechanical-grain harvesting date was between August 7 and August 19 in this study,which was approximately 10–15 days later than the traditional harvest date.