Water use efficiency of winter wheat in ridge cultured wheat||spinach-tomato cropping system

Ridge planting and intercropping of winter wheat (Triticum aestivum L.) are important cropping systems in the North China Plain (NCP), in which there exists an acute shortage of water resources especially for crop production. This study analyzed water use efficiency (WUE) of winter wheat in wheat||spinach-tomato cropping system using both traditional and ridge cultivation as the control practices. Traditional cultivated spinach (Spinacia oleracea L.) and tomato (Lycopersicon esculentum Miller) system was the control cropping practice for the spinach||tomato intercropping system. The results showed that wheat grain yield under ridge planting and intercropping was 11% less than under traditional cultivation (401 kg·667m^-2). The reduction in grain yield was attributed to low tiller number as ridge-edge effect was not fully exploited. Tiller numbers of ridge-planted ridge-intercropped wheat were 13.2% and 8.2% less than traditional cultivated wheat system. Row tiller number was much less in either ridge-planted or ridge-intercropped systems than in traditional cultivation system. Comparisons among the three cropping systems suggested that traditional wheat cropping had the highest WUE (1.039 kg·667m^-2·mm^-1), and that intercropping had the lowest WUE (0.868 kg 667m^-2·mm^-1). Ridge cultivation had a smaller WUE (0.944 kg·666.7m^-2·mm^-1) than traditional cultivation system because between- ridge water was not fully utilized. Yield of spinach was, however, not affected by wheat. Yields of intercropped and traditional cultivation spinach systems were 826 kg·667m^-2 and 851 kg·667m^-2, respectively, with a difference not statistically significant. However, tomato growth was greatly hampered under the intercropping system. Stem diameter and biomass per plant under intercropped tomato was respectively 27% and 37% less than that under traditional cultivation system. This suggested that after spinach harvest, tomato transplanting should be postponed as long as possible so as to shorten crop symbiosis and make the cropping system more manageable. It was therefore concluded that wheat||spinach-tomato cropping system facilitated di-season vegetable and food production, provided that the wheat and vegetable cultivars were properly selected and cultivated.