玉米宽窄行交替休闲保护性耕作的根系和光分布特征研究

为探明宽窄行交替休闲种植玉米产量变化的原因,在2007—2008年设置大田试验,比较研究了宽窄行和均匀垄两种耕作方式下玉米光合有效辐射和根系分布等指标的变化动态。结果表明:深松后(6月25日—9月20日),宽窄行处理的土壤紧实度低于均匀垄处理,降低25.17%~52.04%,在0~45 cm不同土层间平均降低14.08%~53.16%,差异最大值出现在11~20 cm土层。在0~45 cm土层,均匀垄处理的根系干重在乳熟期和成熟期显著高于宽窄行处理,分别高13.47%和29.62%;但在根系垂直分布中,宽窄行比均匀垄处理显著增加了根系在深层土壤所占的比例,在15~30 cm土层,宽窄行和均匀垄处理在吐丝期、乳熟期和成熟期根系分布比例分别为6.59%、8.21%、9.00%和5.21%、7.48%、5.42%,在30~45 cm土层分别为2.30%、2.61%、3.24%和1.62%、2.53%、2.09%;不同品种和当年的降雨情况均会影响宽窄行模式下根系的生长。均匀垄处理中部透光率整体上低于宽窄行处理,6月18日、7月24日、8月29日宽窄行底部透光率分别比均匀垄处理高16.12%、5.15%、4.95%,差异达显著水平。因此,提高种植密度将有利于宽窄行处理截获更多的光合有效辐射,从而提高群体的光能利用率。

Effect of conservation tillage of wide/narrow row planting on maize root and transmittance distribution

A field experiment was conducted to explore maize yield variability in relation to canopy structure,root distribution and other factors under conventional tillage planting and wide/narrow row planting in 2007—2008.The results showed lower soil com-paction under wide/narrow row planting than conventional tillage planting by 25.17%～52.04% after sub-soiling during the period from June 25 to September 20.In the upper 45 cm soil layer,soil compaction decreased by 14.08%～53.16%.The least soil compac-tion was in the 11～20 cm soil layer.Root dry matter under conventional tillage planting was 13.47% and 29.62% higher than that of wide/narrow row planting at milking and maturity stages,respectively.However,percent root matter in the deep layer under wide/narrow row planting was higher than that of conventional tillage planting.At the 15～30 cm soil layer,percent root matter under wide/narrow row planting was 6.59%,8.21% and 9.00% at silking,milking,maturity stages,respectively.Similarly,percent root matter under conventional tillage planting was 5.21%,7.48%,5.42% for the 3 growth stages,respectively.While it was 2.30%,2.61% and 3.24% at the 30～45 cm soil layer at the 3 stages under wide/narrow row planting,percent root dry matter under conven-tional tillage planting was 1.62%,2.53% and 2.09%.Different varieties and rainfall distributions influenced root growth under wide/narrow row planting.Photosynthetical active radiation(PAR) at middle part of plants under conventional tillage planting was lower than that under wide/narrow row planting.However,PAR at bottom of plant on June 18,July 24 and August 29 under wide/narrow row planting was significantly higher than that of conventional tillage planting by 16.12%,5.15% and 4.95%,respec-tively.Increasing plant density therefore increased PAR under wide/narrow row planting,which eventually enhanced photosynthetic efficiency.