Effects Of Elevated Temperature And Drought Stress On Sugar Accumulation And Coloring In Jujube Cultivar ’Lingwuchangzao’

Atmosphere temperature and drought stress is becoming more and more serious in Ningxia province in China under global climate change situation.Take 6-years old jujube cultivar’Lingwuchangzao’ saplings as experimental subjects,We studied the response of sugar accumulation and coloring of ’Lingwuchangzao’ to elevated air temperature and soil drought stress.Using open-top chamber simulated elevated air temperature environment.Solar powered soil moisture controller,sensor,electromagnetic valve and drip device,we assembled an automated soil moisture and fertilizer control system to control soil water levels.Setting two air temperature levels(natural environment temperature T1,elevated temperature T2,T2=T1+(2.0℃±0.5℃)).Three soil water levels,Normal water content in the soil(approximately 70～75%maximum soil water content,D1).Moderate level of soil drought stress(approximately 50～55%maximum soil water content,D2).High level of soil drought stress(approximately 30～35%maximum soil water content,D3).The effects of elevated air temperature and drought stress on the growth,fruit quality,sugar accumulation and fruit coloring of’Lingwuchangzao’ were studied.The main results are as follows:1.Elevated air temperature and drought stress has significant effects on the growth of’Lingwuchangzao,.The growth were promoted under elevated 2.0℃ air temperature environment,but with the intensified drought stress,it was not conducive to growth.2.The fruit size increased dynamically.At the beginning of the fruit enlargement(8/8)to coloring(8/28),single fruit weight,fruit vertical and horizontal diameter increased rapidly.The fruit vertical and horizontal diameter were reduced under the elevated 2.0℃ air temperature and drought stress,fresh weight and soluble solids content decreased,so the fruit shape became smaller and fruit weight loss.Elevated temperatures has intensified the reduction of drought stress.3.Under the elevated 2.0℃ air temperature and drought stress,the glycometabolism of’Lingwuchangzao’ still in the mode of direct accumulation of sugar and sucrose accumulation.The fruit of glucose,fructose and sucrose accumulation were promoted under moderate drought stress,the accumulation of glucose were inhibited and the starch were increased under high drought stress.Therefore,moderate drought stress is beneficial to the accumulation of sugar in fruit.The glucose,fructose,sucrose and starch content in fruit were increased under elevated air temperature,but moderate drought stress not conducive to the accumulation of soluble sugar in fruit.4.Drought stress increased NI enzyme in the early stage of fruit,then decreased in the later,AI,SPS,SS-s and net activity of sucrose metabolizing enzyme in fruit were increased under moderate drought stress,but high drought stress performed opposite effect just increased SS-c enzyme activity,elevated 2.0℃ air temperature slows down the effect of moderate drought stress,exacerbating the effects of high drought stress,sucrose metabolism enzyme activity have more sensitive response to drought stress,SPS and SS-s were key enzyme for sugar,glucose,total sugar accumulation in fruit,NI for fructose accumulation.5.ZjNI gene expression increased at the early stage of the fruit development under elevated 2.0℃ air temperature and under soil water level treatment.ZjNI 1 and ZjNl 2 were up-regulated to 14.25 and 14.52 times respectively as the main expression genes.ZjAI,ZjSPS and ZjSS genes were mainly up-regulated in later stage,while ZjSPS 1 and ZjSPS 4 were the main expression genes of ZjSPS genes,which were up-regulated most significantly under high drought stress with elevated temperature to 24.36 and 93.70 times respectively.ZjSS 1 and ZjSS 3 were the main expression genes of ZjSS gene,which were up-regulated under high drought stress with elevated temperature to 131.29 and 81.38 times respectively.The gene expression of sucrose metabolization enzymes was up-regulated with the increase of temperature,and the up-regulation became more obvious with the increase of drought stress.6.With the intensified drought stress,the fruit coloring rate decreased to 18.35%and 30.28%respectively,and the content of anthocyanin,flavonoids and chlorophyll were decreased.The fruit coloring rate were increased to 37.61%under elevated 2.0 ℃ temperature,and the content of anthocyanin and carotenoids were increased in fruit,the content of flavonoids and chlorophyll decreased.Stress had a negative effect on fruit coloring,sucrose had a greater effect on promoting anthocyanin accumulation in peel,which was beneficial to fruit coloring.Drought stress also have detrimental side effects on fruit coloring that were alleviated by elevated temperature.Sucrose had a significant effect on the accumulation of anthocyanin in fruit peel,which was beneficial to fruit coloring.