春小麦秸秆还田对后茬玉米干物质积累及产量形成的调控效应

干物质是作物光合作用产物的最高形式,其积累动态特性与籽粒产量有密切关系,研究前茬作物不同秸秆还田方式对后茬地膜覆盖作物地上干物质积累特性与产量形成的影响,对优化作物高产高效栽培理论和技术具有重要意义。本研究通过田间试验,在干旱内陆灌区研究了前茬春小麦不同秸秆还田方式(免耕秸秆覆盖还田,NTM;免耕秸秆立茬还田,NTS;传统翻耕秸秆还田,CTS;传统翻耕无秸秆还田,CT,对照)对后茬玉米地上干物质积累规律及产量形成的调控效应。结果表明:前茬春小麦免耕秸秆还田(NTM,NTS)提高了后茬玉米地上干物质最大增长速率和干物质平均增长速率,延迟了干物质最大增长速率出现的时间,以NTM处理作用效果最明显,较CT玉米地上干物质最大增长速率和干物质平均增长速率分别提高5.7%、11.2%,玉米地上干物质最大增长速率出现时间延迟3.4d,差异达显著水平(P0.05)。NTM、NTS处理可长时间保持后茬玉米相对较高的地上干物质积累速率,有效延缓吐丝至灌浆期后茬玉米地上干物质积累速率的降低,维持较长的地上干物质积累期,提高完熟期地上干物质积累量,NTM和NTS较CT处理玉米收获期地上干物质积累量分别提高11.3%和9.9%(P0.05)。NTM、NTS和CTS比CT处理分别增产15.6%、13.0%和7.8%,以NTM处理增产幅度较大,较CTS增产7.3%(P0.05),增产的主要原因为穗数、穗粒数及粒重的协同提高。通过关联矩阵分析表明,通过优化前茬春小麦秸秆还田方式影响后茬玉米穗数来调控群体大小,进而协调穗粒数与粒重,通过三者相互协调发展可实现增产。因此,前茬春小麦免耕25～30cm覆盖秸秆还田(NTM)是典型干旱内陆灌区优化后茬玉米干物质积累特性及获得高产的理想耕作措施。

Responses of dry matter accumulation and yield in a following maize crop to spring wheat straw returning

Dry matter accumulation is the highest form of photosynthetic products in crops, and its accumulation dynamic characteristics are closely related to grain yield. Therefore, it is important to identify the effects of different straw retention methods on dry matter accumulation and crop yield with plastic film mulching. In this study, a field experiment was carried out in a typical irrigated inland region with an arid climate, to determine the characteristics of the above-ground dry matter accumulation and the yield of maize under different retention methods of straws of the preceding spring wheat. The treatments were: no-tillage with long spring wheat straw mulched in the field (NTM), no-tillage with spring wheat straw standing in the field (NTS), conventional tillage with long spring wheat straw incorporated into the soil (CTS), and conventional tillage without straw retention (CT). The results showed that the NTM and NTS treatments increased the maximum and the mean dry matter accumulation rate and delayed the emergence time of the maximum dry matter accumulation rate of maize. The NTM treatment had the most obvious effect. Compared to CT, the NTM treatment significantly increased the maximum and mean dry matter accumulation rate of maize by 5.7% and 11.2%, respectively. The emergence time of the maximum dry matter accumulation rate underh NTM was delayed by 3.4 days (P<0.05). The NTM and NTS treatments maintained a high dry matter accumulation rate, effectively delaying the decline of dry matter accumulation rate for maize from the silking to filling stage. This prolonged the duration of dry matter accumulation and increased the amount of dry matter accumulation at the maturing stage. Compared to CT, NTM and NTS treatments significantly increased the dry matter accumulation of maize at the harvest stage by 11.3% and 9.9% (P<0.05), respectively. The grain yield of maize was 15.6%, 13.0%, and 7.8% higher in NTM, NTS, and CTS treatments than in CT treatment (P<0.05). The most significant effect on improved yield was from NTM treatment, which was 7.3% higher than that of CTS (P<0.05). The main reason for the increased yield was the combined increase in spike numbers, grain numbers per spike, and 1000-grain weight. Correlation matrix analysis showed that the population size of following maize could be regulated by optimizing the previous spring wheat straw returning methods, which affected the growth and yield characteristics. Our results showed that the NTM (no-tillage with spring wheat straw mulch) is the most appropriate cultivation method to optimize dry matter accumulation and obtain high yields of maize in an arid inland irrigation region.