Effects Of Spraying Gibberellin And Cytokinin On Fruit Preservation Of Seedless Orah Mandrain

In 2012,the seedless Orah mandarin was successfully planted in Guangxi Zhuang Autonomous Region of China.This new late-ripening citrus variety has bright fruit color,tender juicy flesh,dense sweet taste,high quality,high planting value.In the same period,the Wuming District government of Nanning city made the seedless Orah mandarin into regional characteristic agricultural products and the important content of poverty alleviation and rural revitalization projects.In recent years,the planting area of citrus has developed rapidly,but serious physiological fruit dropping phenomenon has been found in the growth process of seedless Orah mandarin,which will directly affect the yield of seedless Orah mandarin.To solve this problem,this study investigated the effects of exogenous gibberellin and cytokinin spraying on the yield and quality of seedless Orah mandarin by investigating and counting the number of fruit set and fruit retention rate.The reason of physiological fruit dropping was studied by analyzing the carbohydrate of fruit and combining with the sectioning of fruit at the fruiting stage.By analyzing the mineral nutrients of fruits and leaves in different periods,the effects of exogenous gibberellin and cytokinin on the mineral nutrients in different periods were studied,so as to clarify the physiological causes of fruit dropping of 091 seedless Orah mandarin and put forward the optimal hormonal fruiting scheme.The results are as follows:1.Spraying GA3 and 6-BA can significantly improve the yield and economic benefit of seedless Orah mandarin.The yield of seedless Orah mandarin was 1233 kg/hm~2 under single application of water treatment,the yield of seedless Orah mandarin was 18891kg/hm~2 under combined application,which was 14.32 times higher than that under single application of water treatment.The net profit under single application of water treatment was-66369 yuan/hm~2.Net profit was 57237 yuan/hm~2 under combined application treatment.The yield of seedless Orah mandarin was 9666 kg/hm~2 under GA3 treatment alone,which was significantly increased by 6.84 times compared with water treatment alone,and the net profit under GA3 treatment was-7338 yuan/hm~2.The yield of the seedless Orah mandarin was 1809 kg/hm~2 under 6-BA treatment alone,which was 0.47times higher than that under water treatment alone,and the net profit under this treatment was-62172 yuan/hm~2.2.Application of gibberellin and cytokinin could significantly improve the external quality and internal quality of seedless Orah mandarin,and the combined application had the best effects,but had no significant effects on the color and quality of fruits.Single fruit weight,horizontal diameter and longitudinal diameter were 133.58 g,52.87 mm,44.30 mm and fruit type index were 0.85 under water treatment alone,while single fruit weight,horizontal diameter and longitudinal diameter were 143.68 g,65.8 mm,47.43 mm and fruit type index were 0.72 under combined treatment.The soluble solids,titratable acid,solid acid,vitamin C,juice yield and water content were 12.06%,0.39%,30.41,28.41 mg/100g,54%and 79%,respectively.Under the combined application,the soluble solid,titratable acid,solid acid,vitamin C,juice yield and water content were 14.08%,0.45%,31.29,33.53 mg/100g,60%,and 81%,respectively.3.Spraying gibberellin and cytokinin in fruit preserving stage can inhibit the abscission formation of fruit,thus achieving fruit preserving effect.Among them,combined application has the best inhibition effects on abscission formation.4.Spraying gibberellin and cytokinin could significantly increase the content of reducing sugar,soluble sugar and starch at fruiting stage;The reducing sugar contents of normal fruit were 3.92%,4.11%,4.24%,and 4.60%,respectively,which were 6.93%,4.20%,10.28%,and 13.02%higher than those of detached fruit,respectively.Under the same treatment,the soluble sugar content in normal fruit increased by 25.69%,29.11%,31.39%,and 1.82%,respectively,compared with exfoliated fruit.Starch content in normal fruit reached 2.81%,2.82%and,2.84%,respectively,under the treatment of gibberellin alone,cytokinin alone and combined application.Compared with the same treatment,the starch content of exfoliated fruit was significantly increased by 28.49%,30.33%,and 14.04%.5.Application of gibberellin and cytokinin had significant effects on the mineral nutrients at fruiting preserving stage and expanding and turning stage;The contents of nitrogen,phosphorus,calcium,magnesium,manganese,copper and boron in normal fruit were higher than those in deciduous fruit.The contents of nitrogen,calcium,iron,manganese,copper and zinc in the peel were higher than those in the flesh.However,there was no significant difference between the contents of potassium in peel and flesh.6.Spraying gibberellin and cytokinin can increase the absorption of nitrogen and calcium in spring shoot leaves,but inhibit the absorption of phosphorus,potassium,magnesium,iron,copper,zinc and manganese.Spraying gibberellin and cytokinin could inhibit the uptake of mineral nutrients in summer shoot leaves.Spraying gibberellin and cytokinin could promote the absorption of nitrogen,phosphorus,calcium,iron,copper,zinc and boron in fruit leaves.Spraying gibberellin and cytokinin could increase the absorption of calcium,magnesium,iron,copper and zinc in fruitless leaves,but had no significant effects on nitrogen,phosphorus and potassium.In conclusion,spraying GA3,6-BA and combined application can improve the number of fruit set and yield,inhibit the abscission formation of fruit,improve the content of carbohydrate in fruit,promote the absorption of mineral nutrients in normal fruit leaves,and finally achieve effect of fruit preservation.