关键词: 免耕, 地膜覆盖, 玉米, 光合生理, 光合关键酶活性, 基因相对表达量, 籽粒产量

Abstract:

【Objective】Aiming at the problems of low photosynthetic performance and yield decline of maize leaves caused by large amount of plastic input and extreme high temperature in traditional maize planting in oasis irrigation area, the photosynthetic physiological mechanism of maize during grain filling period under two years of plastic mulching was studied, so as to provide the theoretical basis for the construction of high grain yield technology of plastic reduction in oasis irrigation area. 【Method】In 2013, a randomized block experiment was conducted in the oasis irrigation area of the Hexi Corridor. According to the duration of plastic mulching, three treatments were formed: no-tillage with plastic re-mulching and using (NTP), no-tillage in autumn and plastic mulching in spring (RTP), and conventional tillage with annual new plastic mulching (CTP, as the control). The response of chlorophyll content, gas exchange parameters, key enzyme activities of photosynthetic physiology, relative gene expression and key protein content of maize leaves to different plastic utilization methods was explored. 【Result】Different plastic utilization methods promoted the increase and stability of maize yield by regulating the photosynthetic physiological characteristics of maize filling stage. Compared with CTP, chlorophyll a and b in NTP filling stage increased by 15.1% and 8.3% on average, respectively, indicating that NTP treatment was beneficial to maintain the chlorophyll content of maize, thus effectively delaying the degradation of chlorophyll and promoting the photosynthesis of maize. Compared with CTP treatment, the net photosynthetic rate and transpiration rate under NTP increased by 25.2% and 11.5%, 20.0% and 12.2%, respectively, in the middle and late stages of grain filling, indicating that NTP treatment was beneficial to regulate the gas exchange parameters of maize during grain filling stage and enhanced the photosynthesis of maize during grain filling stage. At the same time, NTP maintained higher photosynthetic physiological key enzyme activity, relative gene expression and key protein content during the filling stage, which provided a guarantee for the improvement of photosynthesis. Compared with CTP, the activities of PPDK, PEPC, and Rubisco in maize leaves treated with NTP increased by 18.9%, 20.0%, and 30.6% on average, respectively, the gene expression of pepc, ppdk, and rub in maize leaves increased by 22.1%, 75.8%, and 70.6%, respectively, and the protein content of D1 and D2 in photosynthetic reaction center increased by 12.6% and 13.2%, respectively. Compared with CTP treatment, the activities of PPDK, PEPC and Rubisco in maize leaves under RTP increased by 15.6%, 16.4%, and 19.2%, respectively. The expression levels of pepc, ppdk, and rub genes in maize leaves increased by 13.6%, 53.9%, and 57.7%, respectively. The content of D1 protein in photosynthetic reaction center increased by 10.1%. In addition, the grain yield of NTP was 5.2%, 6.0%, and 5.3% higher than that under CTP in 2021, 2022, and 2023, respectively. The grain yield of RTP was only 5.2% higher than that under CTP in 2022. 【Conclusion】No-tillage with plastic re-mulching and using was an effective cultivation and management measure to maintain high photosynthetic performance, reduce plastic input, and increase maize yield in the northwest oasis irrigation areas.

Key words: no-tillage, plastic mulching, maize, photosynthetic physiology, photosynthetic key enzyme activity, relative gene expression, grain yield