| In this study,the wheat varieties i.e.Yannong 19 and Xinmai 26 were used.The effects of different nitrogen applications on basal second and third internode morphological structure,the production and transportation of dry matter and yield were investigated.This study revealed growth and development response to different nitrogen application and stem lodging resistance and grain yield,as well as the associated mechanism,which contributes high and stable yield,resistance of Huaibei plain wheat quality to provide theoretical basis.The following research results were obtained:1.Number of stem and tillers per unit increased at early stage but decreased at jointing stage following an uni-modal pattern,however,the number of stem and tillers declined slowly after jointing stage.Significant increase of grain number(P<0.01)was observed proportionally to the increase of nitrogen application,but after jointing stage,stem tillers was significantly reduced under high nitrogen treatment compared to low nitrogen treatment,and following the trend of N4>N3>N2>N1.Under the condition of same nitrogen application rate,the highest stem tillers number was obtained in N3R3 treatment;the increase of fertilizer proportion can reduce the death rate of wheat stem tillers,increase the number of effective panicles and increase the rate of tillering(R4>R3>R2>R1).It can be seen that increasing basal fertilizer at the early stage can increase the tiller number of wheat population at tillering stage and ensure the nutrition supply of wheat before winter,but too much basal fertilizer can significantly increase the ineffective tiller number of wheat at jointing stage,resulting in too much tiller number of wheat population,which is not conducive to the growth of wheat and reduces the lodging resistance of wheat.Top dressing at jointing stage was beneficial to ensure adequate nutrient supply to wheat plants and increase the number of effective panicles.Rational nitrogen fertilization could increase the effective spike number,decrease the ineffective tillers and increase the yield of wheat.2.The plant height,barycenter height,lodging degree and lodging rate of wheat plants,all increased significantly with the increase of nitrogen application and basal fertilizer.Among them,the plant height and barycenter height of the two studied wheat varieties were the highest at N4 level and increased by 8.73%and 12.9%respectively,compared with the lowest level N1.The lodging rate and degree were the highest in N4R1 treatment,reaching 56%.Under N3 conditions,the thickness of the second and third internode of the base,thickness of the stem wall,stem strength and the lodging resistance index were all higher in comparison to other nitrogen fertilizer levels.Compared with N1 conditions,these traits increased by 18.89%,15.16%,33.03%,48.42%and 48.95%,respectively.Under the same nitrogen application condition,the stem thickness and thickness of R3 were significantly greater over other treatments,and the morphological characteristics of the second and third internode of the base treated with N3R3 were significantly better than those of other treatments.Comparison between the different varieties showed that in Yannong 19,plant height,height of center of gravity,internode length were significantly greater than in Xinmai 26(P<0.01).Xinmai 26 basal internode stem,stem thickness,mechanical strength and resistance index were significantly greater than Yannong 19,and in Xinmai 26,lodging rate and degree was significantly less than in Yannong 19.Thus,in a condition of reasonable nitrogen management to ensure wheat lodging resistance,variety genetic characteristics is the precondition of wheat lodging resistance.The lodging resistance of different tillers of wheat exhibited the first and second tillering of main stem.3.According to the increase of nitrogen application,the panicle length,single panicle weight,grain number per spike and differentiated spikelet number were significantly increased(P<0.01),but the differences in different basal ratio were not significant.The postponing nitrogen significantly reduced the number of degenerated spikelets,increased grain weight,and increased the panicle seed setting rate.The number of second tillering degenerated spikelets between main stem and second tillers was significantly greater than that between main stem and first tillers(P<0.01),and the number of differentiated spikelets of the main stem was greater than that of its two large tillers.Under the application of rational nitrogen fertilizer condition,the number of differentiated spikelets was increased,number of degenerated spikelets was decreased,and then,the grain yield of wheat was increased.4.The grain yield of wheat at 135?225 kg·hm-2 increased proportionally to the increase of nitrogen application rate,but decreased when the nitrogen application rate exceeded 225 kg hm-2(N3>N4>N2>N1).Under the conditions of the same nitrogen application amount,different base ratio showed R3>R2>R1>R4.The two tested wheat varieties attained the maximum grain yield in the combination of N3R3,respectively 8279.14 kg·hm-2 and 8062.36 kg·hm-2.Compared with the N1R1 treatment with the lowest yield,the two varieties increased their yield by 21.75%and 15.82%,respectively.Under the conditions of this experiment,the nitrogen application amount of 180?225 kg·hm-2,and the ratio of basal and top-dressing fertilizer was 5:5 could be used as the effective and recommended nitrogen fertilizer application mode for ensuring high and stable yield of wheat plant in Huaibei plain. |
PDF Full Text Request