RESUMEN
Film mulching has been extensively used to improve agricultural production in arid regions of China. However, without sufficient mulch film recovery, large amounts of residual film accumulated in the farmland, which would affect crop yield and water use efficiency (WUE). In order to comprehensively analyze the effects of residual film on crop yield and WUE, and clarify its influencing mechanism, present study adopted a meta-analysis to systematically evaluate the impacts of residual film on soil physicochemical properties, crop root growth, yield, and WUE. The results showed that residual film significantly increased soil bulk density and the soil moisture content in 0-20 cm soil layer, but decreased soil porosity, soil organic matter, soil total nitrogen content, and soil moisture content in >20 cm soil layer, especially when residual film amount was >400 kg ha-1. Residual film significantly reduced crop root dry weight, root length, root diameter, root volume and root surface area. Generally, crop yield and WUE decreased with the increase of residual film amount; and crop yield was reduced by about 14.00 % when the residual film amount increased by 1000 kg ha-1. In average, crop yield and WUE under film residual condition were significantly decreased by 13.46 % and 9.21 %, respectively. The negative effects of residual film on root growth, yield and WUE were greater for cash crops (cotton, tomato and potato) than for cereal crops (wheat, maize). The structural equation model indicated that residual film generated indirect negative effects on crop yield and WUE by directly affecting soil physicochemical properties and crop root growth, with the standard path coefficients of -0.302 and - 0.217, respectively. The results would provide a theoretical basis for reducing residual film pollution on farmland and promoting the green and sustainable development of agriculture.
Asunto(s)
Agricultura , Productos Agrícolas , Raíces de Plantas , Plásticos , Suelo , Suelo/química , Productos Agrícolas/crecimiento & desarrollo , Raíces de Plantas/crecimiento & desarrollo , China , Agricultura/métodos , Agua , Producción de Cultivos/métodosRESUMEN
Pot experiments were carried out to explore the approach of optimizing crop group performance through restriction of individual growth redundancy and increasing crop yield potential. Two winter wheat varieties of 'Xiaoyan-22' (with moderate tillering ability) and 'Zhengmai-7698' (with strong tillering ability) were chosen to investigate the effects of two irrigation schedules (full irrigation and regulated deficit irrigation) and three kinds of tillering interference (only retaining the main stem and the biggest tiller at jointing stage; removing all nonbearing tillers at heading stage; and without any interference as the control treatment). Thus, we simulated the compensation effects of different water supplies and unpredictable disturbances on the physiology, growth, yield, and water use efficiency of winter wheat. The results showed that there existed growth redundancy for both varieties. Compared with 'Xiaoyan-22', 'Zhengmai-7698' had relatively higher tillering number but weak panicle traits. Regulated deficit irrigation and removing all nonbearing tillers at heading stage could reduce growth redundancy, weaken competitive ability, change source-sink relations, and optimize resources allocation. However, excessive elimination of redundancy (e.g. only retaining the main stem and the biggest tiller at jointing stage) could destroy the inherent root-shoot balance and functional structure of plant and lead to inadequate compensation. In contrast to the control treatment (full irrigation and without any disturbance), the combination of regulated deficit irrigation and removing all nonbearing tillers at heading stage could help crops sufficiently exploit and utilize their own regulation potentials at spatial and temporal scales and finally realize compensation growth. The combination above could increase the water use efficiency by 20.4% - 25.4% without remarkable impact on grain yield, and hence, could be suitable for wheat growth redundancy reduction.