收获期对玉米籽粒产量和秸秆青贮品质的影响

Effect of different harvesting periods on grain yield and stalk silage quality of maize

本研究旨在探究不同收获期(CK:蜡熟中期;S1:蜡熟后期,推迟1周;S2:完熟前期,推迟2周;S3:完熟中期,推迟3周;S4完熟后期,推迟4周)对"玉米(Zea mays)-大豆(Glycine max)"套作模式中玉米籽实产量、秸秆营养成分及青贮品质的影响,以确定西南地区玉米综合利用的适宜收获期。结果表明:随着收获时期的推迟,玉米籽粒的产量呈先增加后持平的趋势,其中,S2处理玉米籽粒产量最高,较CK高9.47%(P<0.05);秸秆干物质(DM)含量、酸性洗涤性纤维(ADF)和中性洗涤性纤维(NDF)含量随收获时期延长而升高,其中CK、S1和S2处理的ADF和NDF含量无显著差异(P>0.05),但均显著低于S3和S4处理;可溶性碳水化合物(WSC)含量则随收获期的推迟呈下降趋势(P<0.05),但均在干物质含量的8%以上。秸秆青贮饲料pH随收获期的延迟显著上升,但均低于4.2,乳酸(LA)含量则呈显著降低的趋势(P<0.05),所有处理青贮料中均未检测出丙酸(PA)和丁酸(BA)。各处理氨态氮∶总氮(NH3-N∶TN)随收获时期延长呈上升趋势,但均低于5%。综上,在保证籽粒产量的基础上,同时兼顾秸秆的营养品质,西南地区玉米的适宜收获时期为玉米籽粒的蜡熟后期至完熟前期。

The influence of the harvesting date of maize（CK：mid dough stage,harvesting on traditional date;S1：Late dough stage,harvesting delayed one week;S2：Early full ripening stage,harvesting delayed two weeks;S3：Mid full ripening stage,harvesting delayed three weeks;and S4：Late full ripening stage,harvesting delayed four weeks）on grain yield,and the nutritional value of straw and silage was investigated to determine the optimum harvesting date with a＂Maize-Soybean＂relay intercropping system in southwestern China.The results showed that the grain yield first increased together with increasing harvesting date until it reached a plateau.Grain yield was the highest at S2 being 9.47% higher than that of CK.The dry matter content（DM）,acid detergent fiber（ADF）,and neutral detergent fiber（NDF）of straw gradually increased together with the harvesting date.The ADF and NDF of CK,S1,and S2 were not statistically different;however,they were significantly lower than those of S3 and S4.The soluble carbohydrate content significantly decreased with the increasing harvesting date,but it was greater than 8% of that of DM.The pH values of silage significantly increased with the increasing harvesting date but were lower than 4.2,whereas the lactic acid content decreased（P〈0.05）.Propionic acid and butyric acid were not detected in all treatments.Ammonia nitrogen/total nitrogen in each treatment increased but was less than 5%of that of DM as harvesting date increased.In conclusion,the optimum harvesting date of corn was at the late dough stage to early full ripening stage in the southwest region,which guaranteed the highest grain yield and nutritional value.