Effect Of Localized Supply Of Water And Nitrogen On Spatial And Temporal Root Distribution For Maize

Water and nitrogen play vital role in maize root growth process. The spatial andtemporal distribution of the crop root was controlled through the combined effect ofwater and fertilizer,to unearth the potential of the crops themselves adapted onmoisture, nutrients and other environmental factors,achieve high yield and quality oncrop grain,improve WUE and NUE and maintaining the sustainable development ofagriculture,has widely attracted the attention of researchers.In this study,with the spring maize of “Jinsui4” as experimental crop, set threeirrigation methods of the every furrow irrigation, fixed furrow irrigation andalternate furrow irrigation.as well as three nitrogen application methods withconventional nitrogen supply,fixed nitrogen supply and alternate nitrogen supply,was carried in crops scientific observation test station of Minsitry of Agriculture foreffective use of water in fileld in Wuwei,during April2011to September2011. Tostudy the irrigation and nitrogen application methods on spatial distribution anddynamic change of root system of maize,soil NO₃-N and soil moisture,then revealthe relationship between the root growth and soil moisture and nutrient distributionand the change of yield,WUE and NUE of maize under localized supply of water andnitrogen,the root,soil water and NO₃-N content of each soil layer was measured ineach growth period at different position of the soil layer of0-100cm.Throughresearch, the following conclusions was obtained:（1）It is more obvious applying irrigation compared with nitrogen applicationmethods on root volume effect.Under alternate furrow irrigation and evenlynitrogen application treatment,root length density,length and dry weight of root andetc for maize is lager in the soil layer of0-60cm. Maize root with the growthperiod decreased （except for part of soil and location）, alternative furrow irrigationand uniform nitrogen application maintain a relatively high level of it.During the whole growth period,the root is relatively uniform distribution with uniform furrow irrigation,nitrogen fertilizer and alternate furrow irrigation,nitrogentreatments.With fixed furrow irrigation treatment,the distribution of root system inirrigation lateral is more in tasseling stage,less in filling stage,in the soil layer of0-60cm,while the distribution of root system in irrigation lateral is always larger in the soillayer of60-100cm.Under the fixed nitrogen application treatment, the distribution ofroot system in no nitrogen lateral is more in tasseling stage,in nitrogen lateral is morein maturity stage, in the soil layer of0-60cm,the distribution of root system innitrogen is more from beginning to end in the soil layer of60-100cm.（2）On the whole,irrigation methods have greater influence on the change of soilwater than nitrogen application methods. nitrogen methods have great effect on soilNO₃-N changes than irrigation.During the early growth period of maize,nitrogencontent of larger side contains more water with fixed furrow nitrogen treatment.butthis difference is decrease in later growth period of maize. With fixed furrowirrigation treatment,the soil NO₃-N content in irrigation lateral is smaller in tasselingand mature stage.（3）Soil water content and soil NO₃-N content stays in the peak stage on rootgrowth of grain tasseling stage,grain filling period followed while mature period,theminimum.The north and south of the plant root distribution plant are more easilyaffected by soil water content and soil NO₃-N content.South part of the plant,as theirrigation side of fixed furrow irrigation and nitrogen side of fixed nitrogenapplication,the relative abundant water and nutrition supply can not alwaysguarantee the root amount maintain at a high level,sometimes even resulting in theinhibition.North part of the plant,as the no irrigation side of fixed furrow irrigationand no nitrogen side of fixed nitrogen application,during a certain period of time,theshallow soil without nitrogen is conducive to the growth of roots while the deep soilwater deficit promote root growth.（4）Irrigation way play more role than nitrogen application methods onyield,WUE and NUE of maize.Compared with conventional furrow irrigation andfixed furrow irrigation,alternate furrow irrigation improve the yield and WUE, yieldincreased by4.8%and13.9%,WUE increased by4.0%and12.7%,respectively;Compared with alternate nitrogen supply and fixed nitrogen supply, every nitrogensupply increase the yield and NUE,yield increased by1.3%and5.8%,NUE increasedby3.4%and11.3%, respectively.In conclusion, fixed furrow irrigation and conventional nitrogen supply is a local irrigation optimal nitrogen application model.