河西灌区不同耕作与秸秆还田方式对春小麦出苗及产量的影响

出苗率及出苗整齐度在很大程度上决定了作物生长状况和产量丰欠,针对不同耕作措施结合秸秆还田对绿洲灌区小麦出苗及群体动态影响研究薄弱问题,研究不同秸秆还田与耕作方式对小麦出苗与产量的影响,以及二者的相关关系,对于优化耕作措施具有重要指导意义。2014—2015年,在甘肃河西绿洲灌区,通过田间定位试验,研究了不同秸秆还田和耕作措施少耕25~30 cm高茬收割秸秆立茬还田(NTSS)、少耕25~30 cm高茬收割秸秆覆盖还田(NTS)、翻耕25~30 cm高茬收割秸秆还田(TS)和不留茬翻耕(CT)]对小麦出苗状况及产量、产量构成因素的影响,以期为优化试区小麦栽培技术提供依据。结果显示,与CT相比,NTSS、NTS降低了小麦出苗率以及出苗整齐度,TS则提高了小麦出苗率以及出苗整齐度。NTSS、NTS较CT的分蘖数分别高7.4%~10.5%、14.6%~19.1%,分蘖成穗率分别高13.5%~20.1%、33.0%~34.7%,有效穗数分别高7.5%~9.3%、10.3%~11.2%,穗粒数分别高15.7%~16.1%、18.5%~22.6%,千粒重分别高7.2%~8.9%、13.9%~14.2%,但TS与CT在以上指标间没有显著差异。NTSS、NTS与CT相比较,分别增产16.6%~17.4%、18.6%~21.4%,以NTS增产幅度较大,比TS高10.3%~11.0%。穗数和穗粒数的增加是少耕秸秆还田获得高产的主要原因,出苗率及整齐度对产量影响不显著。同时NTSS和NTS均获得较高的收获指数,提高比例分别为9.4%~10.7%与10.5%~11.1%,说明少耕秸秆还田提高籽粒产量的另一原因是提高了光合产物向籽粒中的转化。本研究表明,少耕秸秆还田是适用于试区小麦高产的理想耕作措施。

Effect of tillage and straw retention mode on seedling emergence and yield of spring wheat in the Hexi Irrigation Area*

Seedling emergence rate and uniformity of crops determine their growth and yield performance, while straw retention and tillage mode play an important role on seedling emergence and growth of corps. To explore the responses of seedling emergence and yield of crops to straw retention and tillage practices, a field experiment was carried out in a typical oasis irrigation region, Wuwei, Gansu Province, in 2014 and 2015, to determine the effects of treatments of straw retention combined with tillage patterns on seedling emergence, yield, and yield components of spring wheat. The treatments included reduced tillage with 25 to 30 cm high straw standing (NTSS), reduced tillage with 25 to 30 cm long straw covering (NTS), tillage with 25 to 30 cm long straw incorporation (TS), and conventional tillage without straw retention (CT, the control). The results showed that, compared with CT, reduced tillage combined with straw retention treatments (NTSS, NTS) significantly decreased seedling emergence evenness of wheat, while TS increased seedling emergence evenness. NTSS and NTS increased spring wheat tiller number by 7.4% to 10.5% and 14.6% to 19.1%, effective spike rate of tiller by 13.5% to 20.1% and 33.0% to 34.7%, spike number by 7.5% to 9.3% and 10.3% to 11.2%, kernel number per spike by 15.7% to 16.1% and 18.5% to 22.6%, and thousand-kernel weight by 7.2% to 8.9% and 13.9% to 14.2%, compared with CT, respectively. There was no significant difference between TS and CT treatments in the above parameters. NTSS and NTS treatments had 16.6% to 17.4% and 18.6% to 21.4% higher grain yield than CT. NTS had the highest increasing effect on wheat grain yield, which was 10.3% to 11.0% higher under NTS than under TS. The increase of spike number and kernel number per spike was the main reason for yield increase under reduced tillage with straw retention treatments. However, emergence rate and uniformity had no significant impact on wheat production. Meanwhile, NTSS, NTS treatments were 9.4% to 10.7% and 10.5% to 11.1% greater in harvest index than CT treatment, indicating higher conversion rate of photoassimilates in wheat under the two treatments. Therefore, our results showed that reduced tillage in combination with 25 to 30 cm high straw retention was the feasible technology of wheat production in the oasis irrigation region.