Estimate The Nutrient Requirements Of Grapevine And Evaluate The Effectiveness Of Foliar Potassium Application Using Gene Expression Information

Grapevine is one of the world’s most widely cultivated fruit crops,which is also one of the heaviest feeders of fertilizers.Fertilizer application plays an important role in the production of grape,which is crucial for the yield and quality of grape.The traditional fertilization techanques are mainly based on the phenological period of cropes and the experiences of agricultural producers which lack scientific foundation and can hardly meet the development of precision agrichlture.With the development of moleculat biology and the large-scale DNA secquencing is carried out,the characterization of functional genes is exploding.Based on this,researchers start to explore the approaches how to apply the gene information into the practical production.For this porpuse,this paper studied the feasibility of using gene expression information to depict the nutrient requiment of grapevine and to evaluate the effectiveness of fertilizers applied to grapevine.The results were as follows.1.in order to verify the feasibility of using gene expression information to depict the nutrient requirement of grapevine,grapevine cv.’Summer Black’(hybrid of V.vinifera and V.labrusca)was used as experiment material,the expression changes of thirteen N,P and Kuptake,transportatation and metabolic related genes during different developmental stages were analyzed by using qPCR.The fertilization-induced expression changes of these genes were evaluated by fertilization assay,and the effectiveness of the fertilizers applied at different developmental stages was evaluated by grape fruit quality investigation.The results showed that at flowering stage,P uptake related genes showed higher expression levels;at the first berry expansion stage,N metabolic related genes showed higher expression levels;at seed stone hardening stage,all these genes showe low expression levels;at the second berry expansion stage and the veraison stage,P and K uptake related genes showed higher expression levels.The fertilization assay results showed that applying fertilizers at the stages where the NPK uptake,transportatation and metabolic related genes peaked can better induce the expression of these genes,which indicates that grapevine has higher nutrient uptake efficiency at these stages than that at other stages.The investigation of fruit quality also verified this finding,which showed that applying fertilizers at the stages where the NPK uptake,transportatation and metabolic related genes highly expressed can better promote the development of grape berry,and result in heavier grain weight and higher sugar content of the grape than that applying fertilizer at other stages.All above findings showed that depicting the nutrient requirement of grapevine using the expression information of NPK uptake,transportatation and metabolic related genes was feasible.2.Fertilizer type is one of the most important limitation factors,as the specific nutrient requirement of grapevine has been clarified,in order to evaluate the effectiveness of foliar application of different kinds and different concentration of K fertilizers on grapevine in terms of physiology and gene levels,Grapevine cv.’Summer Black’ vines were used as experimental material,and different kinds and concentration of K fertilizers were sprayed at two key developmental stages,full-bloom stage and berry expansion stage,and then the physiological indexes including the growth rate of leaves and shoots,fruit setting rate,leaf chlorophyll content,single berry weight and total soluble solid were measured,and the expression changes of the four K uptake genes VvHAK13,VvKEA2,VvSIRK and VvSORK were analyzed by real-time quantitative PCR.The results showed that after foliar application of K fertilizers,various physiological indexes of grapevine were improved to different extents,and the expression of VvKEA2,VvSIRK and VvSORK were upregulated,but the expression of VvHAK13 was downregulated.Integrated the results of the physiological indexes and gene expression levels,the effectiveness of the four types of K fertilizers were evaluated as:K2SO4·2MgSO4>K2SO4>K2CO3>KCl.In full-bloom period,the optimum spraying concentration of K2SO4 and K2CO3 were 0.5%and the most appropriate spraying concentration of K2SO4·2MgSO4 and KC1 were 0.2%.In the berry expansion stage,the optimum spraying concentrations of K2SO4,K2SO4·2MgSO4 and KCl were 0.5%,and the optimum spraying concentration of K2CO3 was 0.8%.