小麦秸秆还田方式对轮作玉米干物质累积分配及产量的影响

研究茬口对轮作作物的产量贡献及干物质积累与分配规律的影响,对于优化作物高产高效栽培理论和技术具有重要意义。本研究在甘肃河西绿洲灌区,通过田间试验,研究了前茬小麦不同秸秆还田方式(25 cm高茬收割免耕,NTSS;25 cm高茬等量秸秆覆盖免耕,NTS;25 cm高茬等量秸秆翻压,TIS;低茬收割翻耕,CT)对轮作玉米干物质积累和分配及产量的影响,以期为该区前茬小麦轮作玉米生产模式提供优化依据。结果表明,与CT相比,NTSS、NTS、TIS提高了玉米抽穗后干物质的积累量,两年平均高4.8%~12.7%,NTS较NTSS、TIS具有更高的干物质累积作用;NTSS、NTS、TIS可提高玉米叶、茎、鞘对籽粒的贡献率,提高幅度平均为12.8%~25.0%、6.3%~11.3%、18.3%~78.4%,其中NTS较NTSS、TIS提高作用更突出。NTSS、NTS、TIS提高了玉米的籽粒产量,增幅为11.3%~17.5%,其中NTS两年籽粒产量最高,分别达到13 470 kg hm–2和13 274 kg hm–2,较TIS高5.6%~9.0%;穗粒数增加是小麦秸秆还田提高轮作玉米产量的主要原因。同时NTS获得较高的收获指数,提高比例为6.4%~8.4%,说明NTS较其他处理增产的另一原因是提高了收获指数。本研究表明,其前茬小麦秸秆覆盖结合免耕(NTS)可作为绿洲灌区优化后茬玉米干物质累积规律及获得高产的理想耕作措施。

Effects of Wheat Straw Returning Patterns on Characteristics of Dry Matter Accumulation,Distribution and Yield of Rotation Maize

Research on the response of dry matter accumulation, distribution and yield of crops to previous straw returning usually plays an important role for optimizing cropping systems. In this investigation, a field experiment was carried out in typical oasis irrigation region, to determine the characteristics of dry matter distribution and yield of rotated maize with four previous wheat straw treatments, including 25 cm no tillage with straw standing (NTSS); 25 cm no tillage with straw covering (NTS); 25 cm tillage with straw incorporation (TIS); and conventional tillage (CT). The results showed that, compraed with CT,NTSS, NTS, TIS significantly increased dry matter accumulation by an average of 4.8% to 12.7% after maize heading stage in two years; and improved contribution rate to grain yield (i.e. GCR) of maize by an average of 12.8% to 25.0% from leaf, 6.3% to 11.3% from stem, and 18.3% to 78.4% from sheath, respectively. especially, NTS had more improvement than NTSS, TIS. The grain yield of maize was 11.3% to 17.5% higher in the three straw returning treatments than in CT check. NTS exhibited the most significant effect opf improving yield, reaching 13 470 and 13 274 kg ha^-1 in two study years, which was 5.6% to 9.0% higher than that of TIS due to the increase of kernel number per spike. Meanwhile, NTS had the best effect on increasing harvest index, which was increased by 6.4% to 8.4% during the two study years,and redulted in a high grain yield. Our results showed that NTS treatment is recommended as thebest feasible cultural method to optimize dry matter accumulation, distribution and obtain high yield for rotated maize in the oasis irrigation region.