Study Of Wheat Responding To Water And Nitrogen Under Different Cultivation Patterns In Irrigation Region Of Northern Henan Province

In order to investigate the response of winter wheat to water and nitrogen under different cultivation patterns,the study was carried from two aspects,assimilation process and morphological structure.Based on the precious studies,field experiment and rhizo-box experiment were designed in this study.In the filed experiment,five cultivation patterns including control cultivation pattern(CK),local cultivation pattern used by farmers(FP),super high-yield cultivation pattern(SH),high efficiency cultivation pattern(HE)and high-yielding and high efficiency cultivation pattern(HH)were designed to study assimilation and the using types of assimilates.Fifteen sampling points were set in the whole wheat growth period,and the time interval between sampling points was about two weeks.In the rhizo-box experiment,three cultivation patterns including SH,HE and HH were designed to study the growth of winter wheat root system.Eight sampling points were set from returning green stage to maturity stage,and sampling was carried out every two weeks.For the filed experiment,The chlorophyll content and chlorophyll fluorescence values were measured to verify physiological status of wheat firstly.The dry matter weight,the water content and the total nitrogen content of individual wheat were measured at every sampling point.The data sets of the three indices in time domain were fitted using high degree polynomial equation.The dry matter weight of individual wheat was taken as input,while the water content and the total nitrogen content of individual wheat were taken as output.Based on the polynomial equation of input and output,the transfer functions were set up using Laplace transform.Through high-order system analysis,the response rate of dry matter weight to water and nitrogen were investigated and compared under different cultivation patterns.the leaf position of wheat from jointing to anthesis and tillering were recorded and fitted through distribution fitting to study the using types of assimilates.At mature period,the yield and yield components of winter wheat were measured under different patterns.For the rhizo-box experiment,using soil coring method,the root diameter frequency distributions were decided in 0-20 cm and 20-40 cm soil layers under different cultivation patterns.These diameter frequency distributions were fitted using lognormal distribution to get the corresponding parameters,? and ?,variation of which suggest topological structure of root system.The main results were as follows:1.While the dry matter weight of individual wheat responded faster to water under HH pattern,it was closely followed by SH,CK,FP and HE,the dry matter weight of individual wheat responded faster to nitrogen under HH,closely following by SH,HE and FP.the optimization of cultivation pattern can improve the response rate of individual wheat to water and nitrogen.The HH pattern,which was based on SH and HE pattern,would be a promising cultivation pattern.2.Compared with CK and FP,there was high probability for wheat with more tillers under SH,HE,and HH,which reduced the losses of assimilate before jointing stage.Under HH pattern,the time to maximum tiller number was earlier than under HE and SH,which enabled the tillers to be allocated more assimilate,and reduced tiller mortality.3.Effected by cultivation pattern,different strategies to utilize solar energy were adopted.Under CK and HE,the uniform canopy architecture were maintained at middle growth stage,while under FP and HH,the uniform canopy architecture couldn't be maintained at late growth stage,which contributed to assimilation process.Under SH,the uniform canopy architecture couldn't be maintained at middle growth stage,which could damage the redistribution at filling stage,but contributed to utilizing solar energy at filling stage.4.The results indicated that the topological structure of root system was herringbone at specific periods in two soil layers under different cultivation patterns.The herringbone root system exploit nutrients more efficiently,which would provide material support for growth of winter wheat.The occurring period and location of herringbone root system was different under different cultivation patterns.Under HE pattern,the herringbone root system occurred in two soil layers before jointing stage and grain filling stage.Under HH pattern,the herringbone root system occurred in two soil layers before jointing stage,in 0-20 cm soil layer before grain filling stage,and in 20-40 cm soil layer during the middle and late stage of grain filling.Under SH pattern,the herringbone root system occurred in 0-20 cm soil layer before jointing stage,in two soil layers during jointing stage,and in 20-40 cm soil layer during the middle and late stage of grain filling.Under HH pattern,the vegetative growth of winter wheat would be restricted indirectly,and root system could exploit nutrients in deep soil layer at filling stage.5.Yield and yield traits.Compared with CK and FP patterns,under optimized cultivation patterns,SH,HE,and HH patterns,the higher yields can be achieved with less water or nitrogen input,and the winterwheat have advantages in yield traits,which means longer ear,more spikelets and kemels per spike,and more thousand seed weight.In conclusion,under SH,HE,and HH patterns,the optimized cultivation patterns,the nutrient substance from environment could be utilized by winter wheat in time,and methods to utilized assimilation substance,morphological structure,could be in favour of exploring environment and utilized resource.Among the three optimized cultivation patterns,under HH pattern,winter wheet had outstanding performance in responding to substance and morphological structure,which was relate to delayed sowing,reasonable seeding rate,and dressing ratio 3:7.Therefore,HH pattern was a promising cultivation pattern for cultivation pattern design.