Fruit Development And Ripening Of Ziziphus Jujuba ‘Dongzao’

Ziziphus jujuba Mill.’Dongzao’is a fresh late jujube variety with excellent quality.The fruits are delicious,crisp and juicy,early fruit and high yield,and the economic benefits are remarkable.The facility cultivation of jujube trees not only solves the problems in production,promotes fruit ripening,reduces the loss of cracked fruit and increases the economic income of jujube farmers,but also improves the ecological environment and has good economic and ecological benefits.In recent years,more and more date farmers choose to build cold shed facilities.Facility cultivation requires high management technology,if the management is not proper,it is easy to cause the sugar content of the fruit,the coloring is inhibited,the fruit is small or deformed fruit and other problems.In this study,Dali cold shed winter jujube fruits were used as experimental materials to explore the growth and development law of winter jujube fruits under the facility cultivation mode and the effects of exogenous hormones sprayed on fruit growth and development during fruit coloring stage,so as to provide certain theoretical basis for the rational water and fertilizer management of winter jujube fruits during their development stage,the rational use of exogenous hormones to improve fruit quality,and the scientific cultivation and management of jujube trees.The main research results are as follows:（1）The fitting effect of logstic model is the best for the growth curve of winter jujube fruit.During the growth and development of winter jujube fruit,the weight of single fruit is consistent with the change trend of fruit longitudinal diameter and transverse diameter,showing a slow-fast-slow growth trend,the growth rate first slow and then fast and slow,showing an S-shaped growth curve of gradual increase period,rapid increase period and slow increase period.From the point of view of growth,10d-30d after anthesis,the fruit gradually increased,30d-80d after anthesis was rapid growth,80d-110d after anthesis,the fruit entered a slow growth.In the early growth stage（about 20d after flowering）,the fruit shape index is greater than 1（1.43）,and the fruit shape index gradually decreases to less than 1（0.96-0.98）between the white ripening stage and mature stage（90d-110d after flowering）,and the fruit becomes nearly round.The number of cell layers was about 50 at about 10 days of fruit growth,and increased to about 160 at the maturity stage.From about80 days after flowering,the number of cell layers remained basically stable.At about 10d of fruit growth,the percentage of intercellular space was about 9%;at 110d,more large cavities appeared,and the percentage of intercellular space was up to about 60%.The fruit tissue structure gradually became loose,the pulp tightness decreased,and the fruit hardness also became smaller.（2）The accumulation of sugar in winter jujube fruits at the rapid expansion stage was mainly glucose and fructose,and at the mature stage was sucrose.During the development process,sucrose content showed an increasing trend,and there was a great difference in the accumulation of fructose and glucose.Sucrose accounted for the highest proportion of soluble sugar,so winter jujube fruit was sucrose accumulation type.During the growth and development of winter jujube fruit,the total acid content increased first and then decreased.In winter jujube fruit,malic acid accounts for the highest proportion of organic acids,so it is malic acid type fruit,but the content of different acids varies greatly.During the ripening period,the content of organic acids decreased gradually,which was just opposite to the change of sugar.As a result,the sugar-acid ratio increased,and the fruit flavor changed from sour to sweet.During fruit growth and development,vitamin C content increased first and then decreased.In the hardening stage of fruit cores,vitamin C content decreased,and50d after fruit growth and development,vitamin C content decreased slowly.（3）Spraying treatment with ETH（300mg/L）,MeJA（50mg/L）,ABA（50mg/L）and CK（water）at the coloring stage of winter jujube fruit had no obvious effect on the fruit shape index and single fruit weight,but it could increase the content of soluble solid,the ratio of solid acid to sugar acid,so as to improve the fruit quality.Meanwhile,the treatment of ETH（300mg/L）and MeJA（50mg/L）could significantly promote the fruit coloring.（4）The contents of endogenous ETH,ABA,GA₃,IAA and CTK increased in fruits treated with 300mg/L exogenous ETH.Exogenous MeJA（50mg/L）increased the contents of endogenous auxin IAA,abscisate ABA,gibberellin GA and ethylene ETH,while decreased the contents of cytokinin CTK.The contents of endogenous ABA and GA₃increased,the contents of IAA and CTK decreased,and the contents of ETH and CTK changed little in fruits treated with ABA treatment（50mg/L）.