Interaction Between Seeding Rate And Nitrogen Rate On The Relationship Of Winter Wheat Individual Plant-population,WUE And NUE In A Plastic Film-mulched Ridge And Unmulched Furrow System

The combined use of mulching with ridge-furrow cultivation can improve themicro-environment of the farmland, harmonize the supplement of water and fertilizer,increase the tiller as well as the spike density et.al, and increase yields ultimately byharvesting rain water, reducing soil evaporation, increasing soil moisture retention, preservingsoil nutrients, enhancing soil surface temperatures, and controlling weeds et.al. Bandapplication of fertilizer under film-mulched ridges could increase the nutrient supply duringthe latter part of the growing season, which can overcome the problem of top dress owing tono rainfall in dry season. In the plastic film-mulched ridge and unmulched furrow system(PFRUFS), wheat is only sown in the unmulched furrows. This means that the wheat growingarea is less than that under conventional practices. The individual plants grow well; however,there are fewer plants. It results in lower spike density and potentially, lower yields. Hence,aim to balance the relationship between individual plants and crop population, establish anappropriate group structure, maximizing the advantage of plastic film-mulched ridge andunmulched furrow system (PFRUFS) in rainfed land area; and provide theoretical support andpractice guidance for dryland farming. A central composite rotatable design with two factors(i.e., seeding rate and N fertilizer rate) was used during three years to study the relationshipbetween individual plants and crop population, WUE and UNE of winter wheat in a PlasticFilm-mulched Ridge and Unmulched Furrow System (PFRUFS). The wheat cultivar was'Xiaoyan22'. The results indicated that:1. Appropriate seeding and N fertilizer rates can regulate winter wheat populationdynamics, establish an appropriate community structure, optimize the relationships betweenindividual plants and the plant community, balance the relationships among the three yieldcomponents, and achieve a high yields.The seeding rate controlled the initial seedling number.Increasing seeding rates can increased tiller formation before winter, but reduced tillerformation in the spring. Higher seeding rates also increased spike density, but grain yieldsdecreased when seedling density was too high. The application of N fertilizer increased tiller number, spike density, and grain yield in the three cropping seasons. Through tillering, winterwheat plants had the ability to regulate their population dynamic in some extent. Under highN fertilizer rates (201.08～214.00kg N/ha), moderate seeding rates (88.7～119.4kg/ha) wasbenefit to the grain yield, but the seeding rate should be increased to balance the relationshipsbetween individual plants and the plant community when the tiller were stressed by droughtor low temperature.2. Appropriate seeding and N fertilizer rates can regulate the physiological traits ofwinter wheat after anthesis in some extent. In the early milking stages, leaf area indexincreased as the seeding density increased, but it was dropped as seeding density increased inlater milking stage, chlorophyll content and net photosynthesis rate of flag leaf and the grainyield per plant decreased with seeding rate increasing. Leaf area index after anthesis,chlorophyll content and net photosynthesis rate of flag leaf increased with the increase of Nfertilizer rate. Appropriate seeding density was beneficial to optimize relationships ofindividual plants and crop population, proper nitrogen input was favorable to improvephysiological traits post anthesis and enhance yield of winter wheat. Under experimentcondition, medium seeding rate plus higher nitrogen input were a beneficial scheme tooptimize relationships of individual plants and crop population, establish a good communitystructure with a reasonable leaf area index after anthesis, higher chlorophyll content and netphotosynthesis rate of flag leaf, and higher grain yield per plant, and high yield per unit area.3. Seeding rate and N fertilizer rate have no significant influences on water consumptionduring the cropping season (2011), but can significantly influence the water use efficiency(WUE). In a Plastic Film-mulched Ridge and Unmulched Furrow System, as the seeding rateincreased, WUE increased initially, peaking at appropriate seeding rate and then decreasedgradually; as the N input increased, WUE increased, peaking at222kg N/ha, and thenremained stable. Under high N fertilizer rates (204～227kg N/ha), moderate seeding rates(119～134kg/ha) was benefit to the water use efficient (WUE) of winter wheat.4. Both seeding rate and nitrogen rate had significant influences on N accumulationamount, apparent nitrogen recovery, agronomic nitrogen efficiency and physiological nitrogenefficiency. As seeding rate increased, N accumulation amount, apparent nitrogen recovery,agronomic nitrogen efficiency and physiological nitrogen efficiency increased initially,peaking at moderate seeding rate, and then decreased gradually. N accumulation amount,apparent nitrogen recovery and agronomic nitrogen efficiency gained maximum in a higherseeding rate, while physiological nitrogen efficiency was higher at lower seeding rate. Naccumulation amount increased significantly with the increase of N fertilizer, but apparentnitrogen efficiency, agronomic nitrogen efficiency and physiological nitrogen efficiency decreased as the N fertilizer increased at medium or low seeding rate.5. Soil profile beneath the furrows was similar to that of conventional practices withoutfertilizer, neither had obvious nitrogen accumulation. Under the ridges, nitrate nitrogenaccumulated mainly in the0～80cm soil profile, and there was no obvious nitrate nitrogenaccumulation in the soil layer below80cm, and no significant difference among differenttreatments. The larger the seeding rate was,the more N residues existed in the top soil(0～20cm), but the difference became unobvious with the soil depth increasing. In the0～80cmsoil layer, residual nitrogen decreased with the seeding rate increasing. Under plasticfilm-mulched ridge and unmulched furrow system (PFRUFS), residual nitrogen after winterharvested had obvious effect on the corn yield, which demonstrate that the residual nitrogenwas a nonnegligible available N bank and can be absorbed by the crops.