Spatio-Temporal Windows Of Photosynthetically Active Radiation On The Winter Wheat Canopy In Jujube Intercropping Alley

Aiming at competition for land and light between forestry and agriculture in southern Xinjiang basin recent years, to improve the land utilization, ensure the safe and stable production of fruit and crops in the road of sustainable development of agriculture in Xinjiang. The jujube and wheat strip intercropping systems were set as the object. Based on the photosynthetic physiological parameters and canopy PAR of winter wheat, combined the method of field sampling with indoor analysis. The PAR spatio-temporal windows and its influencing factors on winter wheat canopy in jujube intercropping alley were studied. The influence of shading by jujube to the canopy light distribution and yield of winter wheat were explored. The main results were as follows:In different growth periods of winter wheat, it has obvious difference in the demand and utilization of light. The light saturation point(LSP) of winter wheat was filling period > flowering period > heading period > jointing period > tillering period > mature period. The light compensation point(LCP) was mature period > tillering period > jointing period > heading period > filling period > flowering period. The LSP of winter wheat at filling period reached to a maximum of 1428.16 μmol·m-2·s-1, and the minimum was 1171.33 μmol·m-2·s-1 at mature period. The highest LCP of winter wheat was 86.07 μmol·m-2·s-1 during mature period, and the lowest was 59.32 μmol·m-2·s-1 at flowering period.With jujube plant and row spacing increases, the lighting conditions in intercropping alley better, saturated and unsaturated PAR spatio-temporal window bigger and invalid PAR spatio-temporal window smaller. In the whole growth period, the saturated PAR spatio-temporal window of winter wheat canopy in roadway was 3 m×4m>2 m×4 m>2 m×3 m>1 m×2.5 m>1 m×3 m, the unsaturated PAR spatio-temporal window was 2 m×4 m>3 m×4 m>1 m×3 m>2 m×3 m>1 m×2.5 m, the invalid PAR spatio-temporal window was 2 m×4 m>3 m×4 m>1 m×2.5 m>1 m×3 m>2 m×3 m.The canopy PAR and yield of winter wheat showing a “high middle, both sides low” and “west side high, the east side low” trend. The interception amount of photosynthetically active radiation determined the effective panicle number, grain number per spike and 1000-grain weight of winter wheat per unit area, thereby determined the yield of winter wheat. The reduction degree of winter wheat in different plant and row spacing intercropping system was 1 m×2.5 m>1 m×3 m>2 m×3 m>2 m×4 m>3 m×4 m, the average reduction rate were 35.68%, 31.23%, 23.44%, 19.62% and 11.46%.The spatio-temporal windows of PAR on winter wheat canopy was influenced by sun elevation angle, plant and row spacing, height, crown width, LAI, Tr besides the physiological activity of winter wheat and the density of jujube branches. Among them, the sun elevation angle, plant and row spacing, Tr was the major factor influencing spatio-temporal windows of PAR on intercrop canopy.