水氮耦合对地膜玉米免耕轮作小麦干物质积累及产量的影响

前茬地膜玉米免耕种植后茬小麦水氮高效利用生产技术是绿洲灌区作物高效生产的新型农田管理技术。为构建该区地膜减量和水氮高效生产技术, 2015—2017年通过3年田间试验, 研究两种耕作方式、2种灌水水平和3个施氮量组合对小麦干物质积累和产量及产量构成的协同效应, 其中耕作方式为覆膜玉米茬免耕直播(NT)和玉米茬传统耕作(CT), 灌水量为传统灌水(I2)和传统灌水减量20% (I1), 施氮量为纯N 225 kg hm ^-2 (N3)、180 kg hm ^-2 (N2)和135 kg hm ^-2 (N1)。结果表明, 耕作方式、灌水水平、施氮量对小麦群体生长速率、干物质积累量均有显著影响。与CT相比, NT显著增大全生育期生长速率, 提高22.0%~28.0%, NT促进小麦地上干物质积累, 提高6.4%~7.4%, 收获期生物产量提高5.4%~15.1%。免耕低灌(NTI1)较传统耕作高灌(CTI2)的生长速率增大7.7%~13.4%, 干物质积累量提高3.1%~5.9%, 收获期生物产量提高8.7%~10.5%。免耕低灌中施氮(NTI1N2)较传统耕作高灌中、高施氮(CTI2N2、CTI2N3) 生长速率分别增大6.9%~20.5%与4.1%~14.0%, 收获期生物产量分别提高7.8%~9.7%与4.8%~10.2%。NT比CT增产10.1%~10.4%, NTI1较CTI2、CTI1分别增产13.0%~14.8%与9.4%~10.1%, NTI1N2比CTI2N2、CTI2N3分别增产3.7%~9.8%与15.2%~22.0%。从产量构成因素分析, NTI1N2提高了单位面积成穗数、穗粒数和千粒重, NTI1N2处理组合更有利于穗数、千粒重的增加。通径分析进一步证明, NTI1N2增产的主要原因是增加了单位面积穗数和千粒重。因此, 在施氮量为180 kg hm ^-2的基础上, 玉米茬地膜再利用免耕技术组装减少20%灌溉量(1920 m ³ hm ^-2)轮作小麦模式是河西灌区小麦高效生产的可行措施。

Effects of Water-Nitrogen Coupling Patterns on Dry Matter Accumulation and Yield of Wheat under No-tillage with Previous Plastic Mulched Maize

The high-efficient utilization of water and nitrogen in wheat production under no tillage with previous plastic mulched maize is a new field management technology in oasis irrigation areas. In order to construct the efficient production technology of water and nitrogen in this area, a three-year field experiment was conducted in 2015 to 2017 to determine synergetic effect on dry matter accumulation, yield and its components under two kinds of tillage practices for previous plastic mulched maize (no tillage with plastic mulching, NT; conventional tillage with plastic mulching, CT), two irrigation levels (conventional irrigation, I2; reduced 20% irrigation, I1) and three nitrogen levels (225 kg ha ^-1, N3; 180 kg ha ^-1, N2; 135 kg ha ^-1, N1). The tillage practices, irrigation and nitrogen application had significant effect on crop growth rate and dry matter accumulation of wheat. Compared with CT practice, NT significantly increased crop growth rate and dry matter accumulation of wheat by 22.0% to 28.0% and 6.4% to 7.4%, respectively, during the entire growth period; and improved biomass yield at harvesting stage by 5.4% to 15.1%. Similarly, no tillage with low irrigation (NTI1) increased crop growth rate and dry matter accumulation of wheat by 7.7% to 13.4% and 3.1 to 5.9%, respectively, during the entire growth period, and improved biomass yield at harvesting stage by 8.7% to 10.5%, as compared with conventional tillage with high irrigation (CTI2). No tillage with low irrigation and moderate nitrogen application (NTI1N2) improved crop growth rate by 6.9% to 20.5% and 4.1% to 14.0%, and enhanced biomass yield at harvesting stage by 7.8% to 9.7% and 4.8% to 10.2%, respectively, in comparison to conventional tillage with high irrigation and moderate, high nitrogen (CTI2N2, CTI2N3). Thus, NT practice had greater grain yield of 10.1% to 10.4% more than CT, NTI1 boosted grain yield by 13.0% to 14.8% and 9.4% to 10.1% over CTI2 and CTI1 patterns, respectively. NTI1N2 enhanced grain yield by 3.7% to 9.8% and 15.2% to 22.0%, in comparison to CTI2N2 and CTI2N3 treatments, respectively. In addition, the NTI1N2 treatment significantly increased spike number (SN), kernel number per spike (KNS) and thousand-kernel weight (TKW), and especially SN and TKW of the NTI1N2 treatment were higher than these of other treatments. The path analysis further confirmed that the increase of SN and TKW was the main reason for boosting grain yield of wheat under NTI1N2 treatment. Therefore, the model under no-tillage and previous plastic mulched maize combined with low irrigation (1920 m ³ ha ^-1) and moderate nitrogen (180 kg ha ^-1) is feasible for high-efficient production of wheat in an arid oasis irrigation area.