Effects Of The Artificial Alternate Bearing Technology On The Growth Of Shoot,Tree Nutrition And Fruit Quality Of ’Guiwei’ Litchi

Litchi（Litchi chinensis Sonn.）is an important fruit crop that is widely cultivated in the southern subtropical of China.However,on and off-year of litchi has seriously affected the enthusiasm of farmers.The alternate bearing technology is a new labor-saving cultivation model of litchi,in which the tree can be divided into fruit bearing tree and fruit non-bearing tree.The fruit non-bearing tree completely don’t carry fruit this year,and will have a large number of fruit in the next year;But the fruit bearing tree have a completely different situation with the fruit non-bearing tree.In order to provide evidence on theory and practice for the alternate bearing model,‘Guiwei’litchi was used as the material in this study,which has a typical on and off-year.The differences in growth of shoot,tree nutrition,fruit quality,economic benefit and other aspects were compared between alternate bearing model and conventional bearing model.They were intended to provide theoretical and empirical evidence for the promotion of alternate bearing models.The main results are as follows:1.The main differences between the alternate bearing model and the conventional bearing mode were the winter pruning and pulling of the non-bearing tree in the next year.The fruit non-bearing tree was obviously dwarfed after pruning.The height and crown diameter were 2.9m and 6.0m,with a decrease of 9%and 16%,respectively.And the branches were reduced remarkably.The top three grade of main tree trunk in the alternate bearing model were three trunks,six trunks,and twelve branches.There was not change after pruning.The 80%branches of the fifth-grade side branches were pruned and the branches of seventh-grade side were pruned completely.Besides,in order to increase the angle with the vertical direction significantly,the lateral branches were pulled from the third-grade.2.The fruit bearing branches of alternate bearing treehad a length of 20 cm and a diameter of 4 mm at least.However,the conventional fruit bearing branches hada length of20 cm and a diameter of 4mm or less.3.The picking cost and the production cost were reduced by 0.58 yuan per kilogram and by 25.4%,respectively,in alternate bearing orchard,comparing with conventional bearing orchard.However,the average unit price of the fruits was higher by 1.952 yuan per kilogram.And the profit increased by 1.22 times.4.The content of soluble sugar in leaf and shoot of alternate bearing tree was higher from March to July,which indicated that alternate bearing tree will have a plenty nutritional in the next year.From September to March of the following year,non-bearing tree has a higher content of soluble sugar in leaf and 2cm shoot and a plenty carbon and nutrients,which could increase the ratio of C/N of the tree and provide convenience for flowering in the next year.After a large number of fruiting,the content of starch in non-bearing tree was significantly lower than conventional bearing tree in March.After a year off,the content of starch in the leaf and shoot and the rate of starch consumption in each part have a higher level in alternate bearing tree.This model will accumulate sufficient carbon nutrition and provide a guarantee for a large number of flowering,fruiting and the quality of fruit in the next year.5.The changes in content of N,P and K in leaf were similar between alternate bearing tree and conventional bearing tree.From March to June,the development period of flower and fruit,the content has a downward trend and then it showed an upward trend from July to September.There had a sharp decline from September to October,and a rise again from October to December.6.In 2019,the rate of flowering of‘Guiwei’was generally less than 20%.However,the rate can reach to 82.3%in alternate bearing tree,which was significantly higher than the rate of 17.4%in conventional bearing tree.In 2018,the yield per plant in alternate bearing tree increased by 17.5%.For conventional bearing tree,which has a significantly fruit abscission from 19^thApril to 4^thMay,and has a lower fruit set rate by 7.5%than alternate bearing tree from19^thApril to the fruit ripening.Overall,the alternate bearing model could remarkable improve the rate of flowering,fruit set and the yield per plant.7.The fruit coloration and internal quality of alternate bearing tree have a certain improvement.The fruit coloristic angle H°of alternate bearing tree has a significantly lower level.The content of TSS and Vc in fruit of alternate bearing tree was 18.9%and29.86 mg/100m L,which was significantly higher than conventional bearing tree of 16.6%and 26.34 mg/100m L,respectively.There had not significant difference in terms of single fruit weight,rate of edible,content of TA,and rate of coke nuclear.8.The main component of sugar in litchi is sucrose.The rate of receding sugar of sucrose,glucose,fructose and total sugar in alternate bearing tree were 1.41,0.72,0.23,and2.31 mg/（m L·d）,which significantly lower than the conventional bearing tree of 1.72,1.34,0.82,3.67 mg/（m L·d）,respectively.These results indicated that the alternate bearing tree has a longer harvesting period.Above these results indicated that the alternate bearing tree has significant advantages in yield,fruit quality and cost of labor.After taking one year off,the tree is beneficial to the restoration and provide plenty carbon nutrient for the large-scale flowering in the next year.In conclusion,the alternate bearing model has a wide application prospect in litchi.