Study On The Technology Of RDI Applied To Irrigation With Mulching And High-efficient Use Of Soil Water And Temperature In The Inland Irrigation District Of Hexi

The field experiment was conducted from March to August in 2005 growing seasons to evaluate the effects of Regulated deficit irrigation(RDI) applied to irrigation with mulching of spring wheat in an arid area of Northwestern China(Zhang ye). The experiment have two tillage: film mulching and bare field, designed three soil water content gradients: free from water deficit, low water deficit and severe water deficit. The purpose of this paper was to deal with the impacts of different growth stages and last time of water stress on irrigation parameters, soil water content, soil temperature, biomass characteristic, allocation of apparatus in dry matter accumulation, grain yield and water use efficency.by comparing and research on the optimized irrigation model of RDI applied to irrigation with mulching, the main results as follows:1. Water consumption of check in the whole growth period of spring wheat.significance difference occurred in check among all the treatments. The peak value of water consumption variation with the water stress degree. The water consumption and its ratio of the phasic crop water consumption in total water use was the highest in one stage suffered severe water deficit. There were no difference between treatments of two stage alternate and continuum suffered different water gradients. Increased and decreased with water deficit in the same corresponding period.2. As to soil temperature, film mulching temperature was higher than bare field in different time and deepth.The highest soil temperature of bare field delayed one hour than film mulching in the same free from water deficit. treatments Diurnal temperature range decreased with soil depth increased respectivily 21.2℃,19.3℃,13.0℃,8.5℃,4.0℃,2.5℃.The soil temperature of different seasons changed in different treatments, as a trend of increased-decreased-increased -decreased. the average soil temperature among medium water deficit of bare field , low water deficit and severe deficit film mulching treatments increased 0.9℃,1.5℃,1.4℃,2.6℃..The effect of irrigation on bare field treatment was most significant, with the surface soil temperature differenced from 3.68℃..to6.34℃..before and after irrigation decreased with depth .3. Plastic film mulching improved the growth stages of spring wheat under different treatments,Especially in seeding stage. The effect of water stress on growth stage delayed in early period and accelerate in the later period, made the filling and dough stages shorten. Plant height was significantly (P<0.01) correlated with film mulching and bare field treatment. The degree of effect of different period on plant height was sowing to tiller stage suffered severe water deficit. The film mulching treatment was most significant 88.29cm. The later was free from water deficit in the whole growth stage.Alternation stressed treatment was higher than continuum stressed .4. The leaf area index increased 12.34～40.11% than bare field treatment . peak value occurred 5～7 days earlier than bare field treatment. The variation range of LAI of bare field border than film mulching. And the maximum of LAI was the treatment of jointing stage suffered severe water deficit increased notability after re-watered significantly (P<0.05)...