| There is relatively low production of wheat in South Henan Province.The unsuitable sowing date and multi mixed species were main limited factors affacting local wheat production by means of a field survey at the five counties in Xinyang,Henan.Related field experiments were carried out at Gushi county Agricultural Bureau and Luoshan County Agricultural Science Institute in Henan Province in 2014-2015 year.(1)Experiment in screening of sowing date.Five sowing dates and six wheat varieties were selected to study effects of sowing date on grain yield,dry matter accumulation,nitrogen transportion and absorption of wheat following rice.(2)Experiment in screening of wheat varieties on abiotic stresses.Nitrogen utilization,disease resistance,moisture resistance,maturity performance of eleven wheat varieties were investigated under three nitrogen levels.(3)Experiment in screening of wheat varieties on nitrogen fertilizer.Grain yield of 22 wheat varieties were investigated under four nitrogen levels.The main results are as follows:(1)The influence of sowing date on wheat productionThe results showed that wheat grain yield increased firstly and then decreased with delay of sowing date,and there were a significant difference between different sowing dates(P < 0.05).Through analysis of yield components,sowing date had a significant effect on number of effective tillers,but no significant difference between the kernel number per spike and thousand grain weight.In addition,there were also significant differences in grain yield,effective ear,grain number per spike and thousand grain weight of six varieties.The results indicated that selecting suitable wheat varieties can have an important role to improve wheat production in southern Henan Province.Sowing date has significant effects on the growth and development of wheat.The number of basic seedling decreased quickly with delay of sowing date.The tiller number and plant height in early sowing and late sowing treatments were significantly less than suitable sowing treatment.The number of secondary roots in early sowing was significantly higher than that of late sowing in jointing stage,and suitable sowing date was higher than early sowing and late sowing in flowering stage.Late sowing date treatment had relatively low LAI and leaf age,but with the advance of growth and development the gap was short in different sowing dates.The SPAD value of suitable sowing treatment was significantly higher than that in early sowing and late sowing at jointing stage,but there was no significant difference between the different sowing date treatments at flowering stage.Among varieties,the value of the basic seedling number and tiller number was not significantly different,but the secondary root number,leaf age,LAI and SPAD value were related with the characteristics of the variety.Sowing date affects on accumulation and migration of dry matter and nitrogen in wheat.With delay of sowing date,the translocation amount,the translocation efficiency and the contribution rate to grain of dry matter after anthesis were all presented as the first increased and then decreased.Late sowing significantly increased the translocation amount,translocation efficiency and contribution rate to grain of nitrogen.The study identified that dry matter translocation amount,contribution rate to grain of dry matter and the translocation efficiency of nitrogen also had the obvious difference between six varieties after anthesis,but there was no significant difference in the translocation efficiency of dry matter,the translocation amount and contribution rate of nitrogen.The economic coefficient and grain nitrogen content of late sowing wheat was significantly higher than that of early sowing wheat,but the suitable sowing wheat had the highest nitrogen harvest index.Sowing date could also affect the absorption ability of wheat on soil nutrients,leading to the obvious differences in soil nutrient content of topsoil.During jointing stage,the content of nitrate nitrogen and ammonium nitrogen was the lowest in early sowing treatment,and the highest in late sowing treatment.By blooming stage and mature stage,the content of available nitrogen was the lowest in suitable sowing treatment.Before jointing stage,the nitrogen uptake of wheat decreased gradually with delay of sowing date,after flowering stage,the suitable sowing wheat had a strong ability to absorb nitrogen,while the absorption capacities of nitrogen in the early sowing and late sowing wheat were poor.According to the relationship between soil nutrient condition and grain yield at different stages of wheat growth,the contribution rate of available nitrogen in blooming period was largest,reaching 39.0%,while the next was up to 21.7% in jointing stage.The total contribution rate of N,P and K from flowering to maturity was 16.5%,and the contribution rate of soil ammonium nitrogen reached 9.1% in jointing stage.In this experiment conditions,sowing date affected the yield by influcing the number of effective spike,and the yield in suitable sowing date treatment was the highest.Under different sowing date,some indexes were higher in the early sowing treatment including the plant height,number of secondary roots per,Leaf age,LAI;some indexes were higher in the suitable sowing treatment including the translocation amount,translocation efficiency and contribution rate of dry matter.But others were higher for late sowing treatment including plant and grain nitrogen content,the translocation amount,translocation efficiency and contribution rate of Nitrogen.Nitrogen harvest index was higher for suitable sowing date,meanwhile,the main soil nutrient uptake of wheat was higher.Comprehensive analysis,the suitable sowing period was from October 27 to November 3 at wheat following rice region in southern Henan.(2)Screening and utilization of wheat varieties on abiotic stresses.In the local production condition,11 wheat varieties were divided into three categories according to the response to nitrogen,wet resistance,drought resistance,scab resistance,anti dry green,kernel plumpness and wheat mature appearance by clustering analysis method,it was found that the Haomai 1 and Yangmai 13 were more suitable for planting in the area in terms of yield,resistance and mature appearance.(3)Screening and utilization of wheat varieties on nitrogen fertilizerConsistent with previous studies,the results of this study also showed that the response of different wheat cultivars to nitrogen was different.Nitrogen application rate affected wheat tiller number,and wheat plants was stunted under no nitrogen treatment.High nitrogen treatment significantly increased plant height,ear length and other indicators,and significantly increased the grain yield of wheat.Through analysis of yield components of wheat,nitrogen significantly increased the number of effective ear and kernels number per ear finually resulting in increase of wheat grain yield.Moreover,through the cluster analysis of nitrogen use efficiency of different wheat varieties,these eight wheat varieties(Luo 3429?Zhengyumai 518?Luomai24……)are relatively suitable for planting in this area. |
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