Grading of Soil Moisture Availability and Its Productivity on Goldspur Apple Orchard in Loess Hilly-Gully Region

With Li-Cor6200 photosynthesis determination system and Li-Cor1600 steady pore-meter,the quantitative relationship between soil water content (SWC) and net photosynthesis rate,transpiration rate (Tr),water use efficiency,stomatic conductance (gs),intercellular CO2 concentration (Ci) and stomatal limitation (Ls) in leaves of nine-year-old goldspur apple (Malus pumila cv. Goldspur) trees were studied,in semi-arid area on Loess hilly-gully region. Based on this, the soil water availability and its productivity of test apple orchard were graded and evaluated. The results showed that the soil relative content less than 21.5% belonged to "non-available water"; in the range of 21.5%～46.5%,"low productivity and low efficiency water";46.5%～65.0%,"middle productivity and high efficiency water";65.0%～75.0%,"high productivity and middle efficiency water";75.0%～79.0%,"middle productivity and low efficiency water";and more than 79.0%,"low productivity and low efficiency water".According to the essential aim of agriculture and forestry production to enhance water use efficiency in arid and semi-arid regions, the regulation criterion of soil relative content of apple orchard was ascertained as suitable range 46.5%～65.0% (in the range of "middle productivity and high efficiency water") and the optimum 65.0% that belonged to "high productivity and high efficiency water".