| Water resources shortage,time-space distribution uneven in north China,is limit increase crop production is one of the main factors. High-efficiency utilization of water and fertilizer resource unsustainable development of agriculture is guaranteed. so Take water conservation cultivation measures combined with limited irrigation of semi-arid land of winter wheat cultivation pattern is the north for the direction of regional agriculture development. In Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas,Northwest A & F University during2009-2010,.The root and soil moisture characteristics,growth and physiologic changes and water utilization efficiency of wheat(Tritium astound L.)were studied in three irrigation treatments and three different mulch and plant patterns that included ridge covered with plastic,straw mulch and convention tillage. The principal results were as follows:(1) Under straw mulch Planting,the seedling time and the process of growth and development of winter wheat were made advance 1-2d and 10～14d.(2) .Leaf area of the film mulched wheat grew faster at earlier stage,and photosynthetic accumulation was earlier at later stage,net assimilation rate was higher the continued period of fast growth was longer .Compared with wheat with no-mulched, the largest leaf area of a single plant of film mulched wheat in crease17.16%,the peak value of the largest green leaf area appeared 6d earlier,dry matter accumulation rate was higher 8.97% before an thesis. Ease of leaf area at earlier stage laid a good foundation for dry matter accumulation at later stage.(3) The film mulched wheat had higher relative growth rate,in particular,it's relative growth rate was higher 8.2～13.92% than winter wheat with no-mulched film ino～7d after an thesis. Therefore,dry matter accumulation and daily production amount of the former were obviously higher than the later after an thesis . From the peak stage of accumulation to l5～2ld after thesis,amount of dry matter accumulation of single shoot and colony and daily Production amount of the former were higher1 8.19～22.01% and 46.04～48.27%than that of the later,respectively.(4) Effects of mulch on wheat planting in group and dry matter dynamic changeExperimental results show that ridging coated ditch sown wheat significantly higher than traditional culture,laminating make leaf senescence slow,greenery more,with larger area number,photosynthetic green longer relevant. Judging from the dynamic change of dry matter,bounded by heading stage,the material production process is divided into in early and late,before heading to the dry matter production mainly used to build the vegetative organs and spike organ,mostly with structure material form,a few fixed down to running late,grain production material after heading mostly used to build and full grains. So late with reasonable structure material production,keep source-sink balance. Overall,before the regrinding from coated ridging planting in dry matter accumulation is low,from integrating the jointing regrinding,accumulation of dry matter of rapidly rising,and ridging planting in greater。(5) Effects of mulch of winter wheat on chlorophyllChlorophyll content is depended on the size of the photosynthetic rate,but also the important physiological indexes leaf senescence . The lower chlorophyll content is the major indexes of the wheat leaf senescence and its content discretion and degradation speed,to a certain extent,reflected how leaf senescence. Different processing conditions of chlorophyll relative contents of winter wheat passed a rose at first,then decreased process. In jointing stage,mature and heading to the treatment period,grouting between the relative content of chlorophyll winter without obvious difference. Each processing about flowering 5d flag leaf chlorophyll content are high,at that time is the most obvious differences between various treatments. Subsequent period,ridging laminating of winter wheat planting in the flag leaf chlorophyll content also always higher than traditional cultivation and the furrows culture broadcast. This shows ridging coated planting in winter wheat can longer maintain higher flag leaf chlorophyll content,namely,the function of the blades extend period.(6) Effects of mulch and irrigation on soil moisture and root growthThe results showed that the surface soil moisture changed strongly because it easily affected by the potential evaporation,water application and mulch mode .Straw mulch improved soil water conservation efficiently below 30cm soil depth and ridge covered with plastic film made a maximum contribution to moisture content of 0-30cm soil depth. After jointing stage and along with the development progress,ridge covered with plastic film appeared a water deficit zone in 30-120cm soil depth,but the soil content of straw mulch is always high in this layer. Field water consumption increased with the increase of irrigation,but the utilization of soil moisture below 70cm was decreased. At last,the efficiency of pre-sowing irrigation utilization descended. Our data showed that straw mulch and ridge covered with plastic film were different in the soil water conservation . . meanwhile film mulch is favorable to earlier growth and faster development,and increased ry matter weight of roots of winter wheat. Daily growth rate of roots of winter wheat mulched with Plastic film was higher 0.02～0.05cm/Plant.d than that of winter wheat no-mulched with Plastic film during Pre-jointing Period which is the fast period of roots extension. Dry matter weight of roots of winter wheat with film mulched was higher than that of the contrast winter wheat from beginning to end. Furthermore,the peak period of daily growth of the former was earlier15d than that of the later .Effect of nitrogenous application on roots growth of the former was quick-acting and short-term. Nitrogen application was favorable to increase of dry roots weight at any Stage of winter wheat development. Supplement nitrogen application during the middle and posterior period of winter wheat can increase the whole roots length.(7) Effects of mulch and irrigation on photosynthetic characteristics and water utilization efficiency of wheatComparing with convention tillage treatment,the mulch treatments improved the photosynthetic rate and WUE_L in the later growing season but had no dominance on WUE at population level and yield level .improved 5.06% The yield was increased significantly in the ridge covered with plastic film treatment. |
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