Effect Of Potassium On Photosynthesis,Fruit Quality And Sugar Metabolism Of Jujube

The Jujube planting area and output in Xinjiang both are ranking first in the country.Potassium fertilization is not only strengthen fruit tree,especially to promote sugar accumulation and improve fruit quality.The application of potassium are receiving more and more attention in xinjiang jujube industry production with the requirement of international and domestic market for jujube fruit quality is increasing day by day.But the fertilization ways,fertilization period and amount of potassium are unreasonable.Therefore the application effects of potassium with different methods,application period,fertilizing amount on the soluble sugar contents and sucrose metabolism of `Junzao'?Ziziphus jujuba Miller.?fruit during growth and development were studied.The expression of enzyme genes related to fruit sucrose-metabolism were analyzed by Real-time fluorescent quantitative PCR.The results are as follows:?1?The fruit present single "S" type growth curve.The main souble sugars in 'Junzao' fruit are glucose,fructose and sucrose.The fruit of 'Junzao' is belong to sucrose accumulation type.The experimental treatment of 0.6%KH₂P0₄ with foliage spray observably increased jujube fruit quality and yield.Total soluble sugar,sucrose,fructose,glucose,starch,Vc content in fruit were increased by 22.45%,21.95%,30.77%,37.27%,13.27%and 6.41%,and organic acid content dropped by 6.81%,sugar acid ratio increased by 14.12%.?2?Potassium fertilization in soil with the amount 450 kg/hm2 significantly improve jujube fruit quality.The fruit weight,soluble sugar,sucrose,fructose,glucose,starch,sugar to acid ratio and Vc content were higher than that of CK respectively by 14.87%,16.10%,6.35%,6.73%,10.96%,27.55%,24.92%and 16.94%,and the organic acid content reduced by 7.06%,the yield increased by 15.09%,and followed by fertilization in fruit hardcore period.There was no significant difference in fruit quality compared with CK applied fertilizer of potassium in fruit setting period.?3?The chlorophyll content of jujube leaf was significantly improved both by foliar spraying with KH₂P0₄ and potassium application in soil with K2SO4.The fertilization amount of 450 kg/hm2 significantly increased net photosynthetic rate?Pn?and water use efficiency?WUE?of jujube leaf.?4?Potassium fertilizer in soil significantly enhanced the enzyme activities of sucrose phosphate synthase?SPS??sucrose synthase?SS??acid invertase?AI?and neutral invertase?NI?,and that the response of enzyme activities for potassium were mainly reflected in the period of fruit enlargement and hardcore period.The activities of SS and SPS were significantly increased by experimental treatment of fruit setting combined fruit expansion period?Kse?and fruit expansion period?Ke?,the NI activity was increased by fruit setting period?Ks?and Kse,and AI activity by Ke and fruit hardcore period?Kh?.The fertilization amount of 450 kg/hm2 was best for activities of SPS,AI and NI.Spraying on the leaf with 0.6%KH₂P0₄ helped improve four kinds of enzyme activities in early period of the jujube fruit development.?5?Degenerate Primer were design by sucrose-metabolism enzyme homologous gene of apple,pear,peach fruit and obtained the four genes named as ZjVII?ZjCWIl?ZjSS1 and ZjSPS.The impact of potassium on ZjSS1,ZjCWII,ZjVI1 and ZjSPS1 gene expression of jujube fruit were measured by Real-time fluorescent quantitative PCR.The results showed that the expression of ZjSS1and ZjSPS1 were decreased significantly than that of CK in the process of fruit development under the condition of potash fertilizer treatment.The expression level of ZjCWI1and ZjVI1 in fruit white-ripe period was significantly inhibited by potassium,meanwhile promoted the gene expression level of ZjCWIl and ZjVI1 in 'Junzao' fruit crisp-ripe period.