Study On The Occurrence Mechanism Of Southern Fresh Jujube Cracking

Jujube(Zizjphus jujuba Mill.)has over 7,000 years of cultivation history.The mature period of the southern China's jujube is mainly concentrated in the middle of August to mid-September,while the precipitation in the south is mainly concentrated in the period from June to September,which led to the emergence of a large amount of fruit crackeg in the southern jujube,which seriously affected the quality of the jujube fruit.Production to bring huge economic losses.In this study,the experiment was carried out in purple planting base of Xinfeng Fruit Industry Co.,Ltd.in Qidong County of Hunan Province.'Mid-Autumn crisp jujube'as experimental material.The contents of soluble sugar,starch,soluble protein and other contents in jujube fruit were determined by anthrone colorimetry and Coomassie brilliant blue method.Field experiments were used to study the formation process of jujube fruit cracked.Spraying different concentrations of amino acids,calcium nitrate,hydrogen peroxide,sodium chloride and mercuric chloride reagents,carry out the study of indoor soaking fruit,the effects of stomatal characteristics,epidermal thickness,epidermal relative conductivity and dietary water channel protein expression on jujube fruit were also analyzed.The following conclusions are drawn from the study:(1)Precipitation and temperature are important factors that cause jujube fruit cracking.High temperature,precipitation to damage the epidermis of jujube fruit,the formation of small cracks,heavy rainfall or continuous precipitation eventually jujube fruit skin swell caused jujube crack.At the same time,it was found that there was no correlation between cracked fruit and fruit form;There is a difference between normal fruit and fruit content.The contents of soluble sugar,reducing sugar and Vc in the ripe fruit were lower than cracked fruit for 3.75%,2.93%and 0.15mg/g,respectively.The contents of starch and soluble protein were higher than cracked fruit 1.14%and 1.62mg/g,respectively.The contents of Ca,Na The contents of K and Mg were higher than cracked fruit 9.18mg/100g and 0.33mg/100g,respectively,while that of K and Mg were lower than cracked fruit 920.83mg/100g and 7.71mg/100g,respectively;Spraying a certain concentration of amino acids,calcium nitrate,mercuric chloride reagent can effectively reduce the fruit cracking rate.7000 times,8000 times the amino acid,60mg/L of calcium nitrate and 100umol/l of mercuric chloride have good crack resistance,the fruit cracking rate was 45.90%,42.67%,48.21%,46.5%.The best anti-cracking effect is 8000 times the amino acid reagent,40.73%lower than the control group.The results showed that the fruit cracking rate was negatively correlated with the time required to start the fruit cracking,and had no significant correlation with the initial water absorption rate.(2)From white ripening to maturity,the thickness of the tissues of the jujube skin was increased first and then decreased,the fruit cracking rate was negatively correlated with the thickness of the epidermis and the thickness of the subcutaneous layer.Spraying 7,000 times the amino acid reagent can significantly improve the thickness of jujube skin.7000 times amino acid reagent processing jujube fruit skin thicker up to 90.96um,21.12 um higher than the control group in ripening period;There was a significant positive correlation between the rate of stalk and the stomatal density and stomatal opening.The higher the stomatal density and the number of stomatal cracking,the greater the fruit cracking rate,and had no significant correlation with stomatal size and stomatal opening.7000 times the amino acid treatment of stomatal cracking at least 3.67p/mm2,control group,the maximum number of stomata cracking 6.83p/mm2;There was a significant positive correlation between relative electrical conductivity and fruit cracking rate.Spraying 8000 times the amino acid can effectively reduce the relative conductivity of jujube skin,reduce the damage of jujube skin.The maximum relative conductivity was 60.31%for the blank control,the smallest was A5(8000 times amino acid):22.21%.Fruit shoulder(35.26%)>fruit surface(31.70%)>fruit top(28.41%),indicating that the damaged parts of jujube peel are mostly fruit shoulders and fruit surface.(3)Calcium nitrate,sodium chloride,hydrogen peroxide and mercuric chloride reagent have a certain inhibitory effect on the expression of aquaporin mRNA.The inhibitory effect of 60mg/L calcium nitrate on aquaporin expression in jujube fruit was higher than that in other stress treatments,while 0.01%hydrogen peroxide was more effective than other stress treatments in jujube pulp.There was a significant positive correlation between the fruit turnover rate and the relative expression of water channel protein.