SOIL WATER CONTENT AND PHOTOSYNTHETIC GAS EXCHANGE OF SPRING WHEAT UNDER CONSERVATION TILLAGE SYSTEMS IN THE DRYLAND WESTERN LOESS PLATEAU AREA IN CHINA

Abstract

The adoption of improved cultivation practices in field crops may mitigate increasing water shortages in many rainfed semi-arid areas. It is not clear whether improved conservation tillage practices can alleviate this issue while increasing crop productivity. Spring wheat (Triticum aestivum L.) was grown using four long-term tillage (CT) systems: conventional tillage with straw removed (T), no-till with straw removed (NT), no-till with straw retention (NTS) and conventional tillage with straw incorporated (TS). These tillage systems were compared for soil water content, crop photosynthesis and grain yield production in semi-arid Loess Plateau of China. Treatments were arranged in a Complete Randomized Block Design with three replications. Results showed that NTS increased soil water content in the 0 – 30 cm depth range by approximately 35% and 27% at anthesis and milking stages, respectively, compared with T (P < 0:05). The contribution to increased soil water content was higher on straw treated plots. Stomata conductance and net photosynthesis rate in the NTS treatment increased by approximately 24% to 38% compared to T. The straw treatments also improved leaf water potential and leaf area index (P < 0:05), which supported the above results. Water use efficiency in the NTS and TS treatments was approximately 45% higher than T and NT (P < 0:05), which translated into increased grain yield. Our results clearly support the long-term advantages of adopting NT practices with residue retention, in rainfed semi-arid regions for better rainwater utilization, enhancing crop photosynthesis and increasing yields.