| To coordinate relations of wheat varieties,water and nitrogen is of great significance for fully utilizing water and nitrogen resource using drought-resistant varieties and realizing high yield,saving cost and increasing efficiency to ensure the sustainable development of wheat production.Effects of different water and nitrogen on growth,photosynthetic characteristics,yield formation and expression patters of drought tolerance related genes were studied,the results are as follows:1.Under the same nitrogen level,reduced irrigation treatment decreased the plant height,LAI,total number of the stem per hectare and dry matter accumulation of Shimai 22 and Jimai 22.As the amount of nitrogen fertilizer be increased,the effects of water on the above parameters decreased.Under the normal irrigation conditions(W2),population and individual traits of Jimai 22 performed better,but under the condition of reduced irrigation(W1),the above parameters of Shimai 22 were better than those of Jimai 22.2.Normal irrigation increased SPAD,P_n,Tr and Gs of leaves,and reduced intercellular carbon dioxide concentration(Ci)under higher nitrogen level(N2),and Jimai 22 perform better than that of Shimai 22.While under one time irrigation in the Spring(W1),the SPAD,P_n,Tr and Gs of Shimai 22 were higher than that of Jimai 22 significantly,especially in the late growth stages of wheat.Under the condition of W1,the application of higher nitrogen fertilizer amount effectively increased the photosynthetic parameters such as the chlorophyll content and photosynthetic rate.3.Under the same nitrogen level,reduced irrigation(W1)increased the activity of cell cytoprotective enzymes(SOD,POD,CAT)and the content of malondialdehyde than that of normal irrigation.Of the two wheat varieties,the activity of SOD,POD and CAT of leaves of Shimai 22were significantly higher than that of Jimai 22,but the content of MDA was significantly lower than that of Jimai 22.This may be due to water deficiency resulting in cell membrane lipid peroxidation,accumulation of reactive oxygen species in the late growth stage.Induced by the increased substrate concentration,the activity of cytoprotective enzymes increased.4.Under the low nitrogen and one irrigation in the spring,the yield of Shimai 22 was significantly higher than that of Jimai 22.In terms of yield components,there was no significant difference in the number of spikes per hectare of tested wheat varieties,but the number of grains per spike and 1000-grain weight decreased significantly,especially,Jimai 22 decreased largely than that of Shimai 22.Under the condition of reducing irrigation and increased nitrogen fertilizer amount,the reduction of Shimai 22(5.19%)was less than that of Jimai 22(10.94%).It indicated that water and nitrogen fertilizers coordinate with each other and affect the formation of wheat yield.To use wheat varieties resistance to drought and reduce the irrigation times in the spring were lower cost and higher benefits combination.5.Under different nitrogen supply,10 NF-Y family genes,NFYA-A3,NFYB-A13,NF-Y subunit C,NF-YB3,NF-YA1,NF-YA3,NFYA-D3,NFYA-A2,NF-YB5 and NF-YB9 response to water deficiency differently.The expression patterns were variant in different varieties.The mechanism and expression pattern of the family genes response to water deficit have yet to be further studied.The analysis of the transcriptional characteristics of the leaves of Jimai 22 showed that there were1678 differentially expressed genes under the condition of reduced irrigation,among which 1241genes showed up-regulation trend and 437 genes showed down-regulation.Among those,766differentially expressed genes were enriched into 252 GO functional categories,and 121differentially expressed genes were enriched in 50 KEGG signaling pathways.In summary,nitrogen and water affected the chlorophyll synthesis and photosynthetic carbon assimilation ability of wheat,and improved the ability of osmotic adjustment and reactive oxygen species scavenging of wheat leaves,which in turn affected wheat yield and yield components.This study showed that Using drought-resistant varieties with normal nitrogen supply,and one time irrigation at jointing stage in spring is an efficient combination of varieties,water and nitrogen fertilizers,in which water and fertilizer use efficiency are both high.The differentially expressed genes in wheat leaves under water deficit conditions are mainly involved in biological processes such as redox,metabolism and protein phosphorylation,transmembrane transport,transcriptional regulation,etc.It indicated that the differently expressed genes played roles in the above biological process. |
