青贮玉米抽雄期后生物量积累和饲用品质的动态变化规律

Dynamic changes in biomass accumulation and forage quality of silage corn after tasseling stage

为揭示青贮玉米(Zea mays)抽雄后期生物产量和饲用品质的动态变化规律,选用‘郑单958’(粮用型)、‘北农青贮368’(青贮专用型)和‘冀青贮1号’(粮饲兼用型)3个代表性青贮玉米品种为试验材料,于2018-2020年连续3年动态取样分析了青贮玉米抽雄期后干物质积累及饲用品质的动态变化。结果显示:青贮玉米生物产量呈逐渐增加趋势,从抽雄期的8559.2 kg·hm^(−2)增加到完熟期的24380.7 kg·hm^(−2),不同生育期之间差异显著(P<0.05)。全株粗蛋白(CP)含量、酸性洗涤纤维(ADF)含量和中性洗涤纤维(NDF)含量逐渐下降,淀粉含量逐渐增加,可溶性碳水化合物(WSC)含量和吨干物质产奶量呈先增加后降低趋势,吨干物质产奶量1/2乳线期最高(1446.5 kg·t^(−1))。进一步分析茎、叶、穗干物质积累和饲用品质变化规律显示,茎、叶比重随着生育期进程显著降低,而穗比重及穗干物质积累量显著增加(P<0.05);茎和叶中CP含量逐渐下降,ADF和NDF含量逐渐增加;穗中CP含量差异不显著(P>0.05),ADF和NDF含量逐渐降低,淀粉含量显著增加(P<0.05)。综合分析公顷产奶量变化趋势显示,1/2乳线期青贮玉米公顷产奶量最高(32027.5 kg·hm^(−2)),为青贮玉米生物产量和饲用品质综合评价最佳生育期。建议1/2乳线期收获青贮用玉米。

In order to reveal the dynamic changes in biological accumulation and forage quality of silage corn(Zea mays)after tasseling stage,three silage corn varieties‘Zhengdan958’(grain type),‘Beinongqingzhu 368’(silage type)and‘Jiqingzhu 1’(grain and silage type)which were used as experimental materials were tested and analyzed the dynamic changes in dry matter accumulation and forage quality of silage corn after tasseling stage from 2018 to 2020.The result showed that the biological yield of silage corn increased gradually from 8559.2 kg·ha^(−1) in tasseling stage to 24380.7 kg·ha^(−1) in ripe stage,and there was significant difference between different growth stages(P<0.05).The content of CP,ADF and NDF with whole plant had a trend of gradual decline,while starch content showed a trend of gradual increase from tasseling stage to ripe stage.WSC and milk yield per ton of dry matter increased first and then decreased,and the highest of milk yield per ton of dry matter was in 1/2 milk line stage(1446.5 kg·t^(−1)).The dynamic changes in biological accumulation and forage quality of stem,leaf and ear showed that the proportion of stem and leaf were significantly decreased,while the proportion of ear and the biological accumulation were significantly increased as the silage corn developed and matured(P<0.05).The content of CP in stem and leaf decreased gradually,while the content of ADF and NDF increased gradually.The content of CP in ear was no significant,ADF and NDF content in ear decreased gradually,while the content of starch in ear increased significantly(P<0.05).Comprehensive analysis of the change trend of milk yield per hectare showed that silage corn had the highest milk yield per hectare(32027.5 kg·ha^(−1))in the 1/2 milk line stage.1/2 milk line stage was the best growth stage for the comprehensive evaluation of biological yield and forage quality of silage corn.It is recommended to harvest silage corn at the 1/2 milk line stage.