| The field experiment was carried out at the trial station of Dingxi county in semi-Arid Area of central Gansu in Match-November, 1999. Wheat and corn were selected to study as trial crop, and supplementary irrigation(S.I.) quantities and S.I. stages were selected as trial factor. Yield and water effect and physiological properties of wheat . corn and wheat/corn were studied making use of catchment rainfall installations what have existed and natural precipitation. The results of experiment showed that it has improved the level of yield and water use efficiency(WUE) of crop under S.I., and there were compensation or over-compensation effect for dry-land farming crop. 1. Yield of crops were increased under limited S.I. with catchment rainfall, arid the yield of S.I. treatments of several cropping patterns were higher than that of CK, and yield of them rise with increasing of S.I. quantities. Extents of increasing production were obvious different in different S.I. stages. Among sole-wheat treatments, there was highest grain production when irrigated by 81mm water in jointing + booting stage, it was rise 78.1% than that of WCK; Meanwhile, there was higher yield when irrigated by 40.5mm water in jointing + booting stage, and compared to CK, efficiency of increasing production was 70.2%; The sole-film corn has highest yield when irrigated once by 120mm water in big-horn stage , it increased production 40.24% than that of CCK. There was an over-compensation effect for yield (32.37%) when irrigated once by 60mm water in big-horn stage; Because of competitive using soil moisture of two kinds of crop, wheat/corn has more distinct increase production effect. Compared to the CK, S.I. treatments had increasing production extent of 35.0-80.9%. There has highest yield when irrigated by 42mm water in jointing + booting sage of wheat and 90mm water in before tassel +fihling stage of corn. Efficiency of S.I. of irrigation more times in different stages were superior to irrigation once at the same amount of water. 2. S.I. had improved WUE of crop, and WUE of S.I. treatments of three cropping patterns were higher than that of the CK. Among of sole-wheat and sole-corn treatments, WUE and IWUE were reduced with a increasing amount of S.I. quantities, especially IWUE more.The order of IWUE of the sole-wheat in different S.I. stages was jointing ooting>booting>jointing; and the onler of WUE was booting> joingting眀ooting> joingting; Compared to the CK, WUE was rise by 68.0%-b 58.0%and 40.0% , respectively; Both of the order at different 8.1. stage was the big-horn stage>joingting+big-hom stage>joingting. Compared to the CK,WUE increased by 11 .02% 8.47% and 4.24%, respectively; WUE of wheat/corn rise when irrigated within 0-105mm water, and reduced when irrigated within 105-180mm water, its maximum was 0.939kg/mu.mm(lOSmm); IWUE reduced continually with increasing S.I. quantities. The maximum of IWUE was 2.67kg/mu.mm(45mm), and its minimum was l.O6kg/mu.mm(l8Omm); The mean WLTE of S.f. treatment increased by 35.76% compared to WCCK when irrigated within 105-150mm water. 3. Wheat and corn were contented with demand of soil moisture for 8.1. enhanced diy matter(DM) accumulation. expanded canopy .. improved photosynthesis increased LAI and LAD of them; Mean photosynthesis . mean LAI and mean LAD of S.f. treatments of wheat were increased by l38.39%- 59.26% and 55.32% than that of the WCK. Among of them, LAD and yield were suited to next equation:y- 85.8873+1 8.6599SQR(x)(r=0.9503**). S.I. increased DM accumulation and partitioning... |
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