绿洲灌区小麦免耕秸秆还田对后作玉米产量性能指标的影响

Effect of wheat straw return to soil with zero-tillage on maize yield in irrigated oases

产量性能是决定作物生长发育和产量形成的关键因素,研究前茬秸秆处理方式对后茬作物产量性能指标的影响,对于建立高效种植制度、优化栽培措施具有重要指导意义。2009—2012年,在甘肃河西绿洲灌区,通过田间定位试验,研究了前茬小麦不同秸秆还田和耕作措施(NTSS:25 cm高茬收割立茬免耕;NTS:25 cm高茬等量秸秆覆盖免耕;TIS:25 cm高茬等量秸秆翻耕;CT:不留茬翻耕对照)对后作玉米产量性能指标的影响,以期为优化试区玉米种植模式提供依据。结果表明,与CT相比,前茬小麦秸秆还田降低了后作玉米大喇叭口期之前的叶面积指数(LAI)与光合势(LAD),但增大了吐丝期之后的LAI与LAD,延缓了衰老,以NTSS、NTS延缓衰老作用突出;NTSS、NTS和TIS处理玉米全生育期的平均叶面积指数(MLAI)比CT分别提高12.8%、19.1%和7.0%,总光合势分别提高12.9%、18.6%和6.8%,免耕秸秆还田(NTSS和NTS)提高MLAI和LAD的效果最好。免耕秸秆还田提高了玉米全生育期的平均净同化率(MNAR),以NTSS提高作用明显,较CT高10.7%;但净同化率(NAR)表现为吐丝期之前增大,吐丝期之后降低。NTSS、NTS提高了后作玉米的籽粒产量,比CT分别高13.0%、15.6%,TIS比CT提高7.9%,NTS增产效应最大。不同秸秆还田及耕作方式下,玉米籽粒产量与MLAI、穗数(EN)、穗粒数(KNE)呈极显著正相关性,与收获指数(HI)呈显著正相关性,但与MNAR无显著相关性。MLAI、EN、KNE增加、HI提高是前茬小麦免耕秸秆还田提高后作玉米产量的主要原因。前茬秸秆免耕还田优化后茬玉米主要产量性能指标的效果最好。因此,前茬小麦25 cm秸秆覆盖免耕还田是绿洲灌区优化后作玉米产量性能指标及获得高产的可行栽培措施。

Yield capability is a key factor for crop growth and yield formation. The response of yield capability of crops to straw return to soils usually has been important in establishing highly efficient cropping systems and optimizing cultivation practices. A field experiment was carried out in a typically irrigated oasis region in 2009-2012 to determine the effects of yield capability of maize with different treatments of wheat straw return to soil and different tillage operations. The tillage operations included （i） no tillage with straw standing （NTSS）, where no tillage was combined with 25 cm length wheat straw standing in the field after wheat harvesting in the previous fall; （ii） no tillage with straw covering （NTS）, where no tillage was combined with 25 cm length wheat straw chopped and evenly spread on the soil surface at wheat harvest in the previous fall; （iii） tillage with straw incorporation （TIS）, where 25 cm length wheat straw was incorporated into the soil through conventional deep tillage （30 cm） at wheat harvest in the previous fall; and （iv） conventional tillage （as control）, where conventional deep （30 cm） plow was done with wheat straw removed from the field. The results showed that compared with the control, wheat straw return treatments reduced leaf area index （LAI） and leaf area duration （LAD） of maize before the large bell mouth stage. However, it increased LAI and LAD of maize after silking, which effectively delayed senescence. No tillage with straw standing and straw covering （NTSS and NTS） had the best effects on senescence delay among all treatments. Mean leaf area index （MLAI） increased by 12.8% under NTSS, 19.1% under NTS and 7.0% under TIS. Similarly, total LAD increased by 12.9% under NTSS, 18.6% under NTS and 6.8% under TIS. Specifically, the increase in MLAI and LAD under NTSS and NTS treatments was the highest. No tillage with straw retention improved mean net assimilation rate （MNAR） of maize growth season, which was 10.7% greater under NTSS treatment than under the control. But NAR of maize increased before silking, and decreased after silking under treatments of no tillage with straw retention, compared with the control. Straw return treatments had higher grain yield than the control, which increased by 13.0% under NTSS, 15.6% under NTS and 7.9% under TIS, with NTS had the best effect on grain yield increase. There was a high significant positive correlation between grain yield and MLAI, ear number （EN） and kernel number per ear （KNE）, a significant positive correlation between grain yield and harvest index （HI）, but no correlation between grain yield and MNAR. Increased MLAI, EN, KNE and HI were the main reasons for high grain yield of maize under wheat straw return conditions. No tillage with 25 cm length straw mulching over the soil surface （NTS） was the most suitable straw return strategy for optimal yield capability. Based on the results therefore, no-tillage with 25 cm length straw return to soil was recommended as the most feasible cultural method to optimize yield capability of maize ration with wheat in irrigated oasis regions.