Effect Of Selenium Application On Selenium Content And Quality Of Pitaya (Hylocereus Polyrhizus Britt.& Rose) Fruit

This experiment firstly analyzed the selenium contents in the soil of different planting places,branch and fruit.Then,Pitaya（Hylocereus polyrhizus Britt.&Rose cv.‘soft branch dahong’）introduced from Taiwan planted in Langqi Rongsheng Leisure Farm in Mawei District of Fuzhou,Fujian province was used as experimental material.The absorption of selenium in branches and fruit,fruit quality and mineral element content in soil and pitaya fruit were surveyed after branch smear and soil application different concentration of Na₂SeO₃ solution in the field and analysise in the laboratory.The results showed as follows:1.The soil selenium,water-soluble selenium and pH of different pitaya producing areas in Guangxi,Guangdong,Hainan and Guizhou were analyzed.The results showed that soil pH was one of the important factors controlled soil water-soluble selenium.The same Pitaya varieties‘jindu no.1’planted three different orchards places such as Guangdong province,Hainan province and Guangxi provinces（municipality）were stueied by determing the selenium content in fruit and branches,the results showed that the total selenium content soil>total selenium content>total selenium content in branches,among them,the soil,branches and fruits in Guangxi was significantly higher than the total selenium content of Hainan province,Guangdong province.When different pitaya varieties were planted in the same orchard,the total selenium content of the branches and fruits of‘pearl’in the orchard of Guangdong province was significantly higher than that of‘jindu no.1’,‘soft branch bright red’and‘hongbaolong’.In orchards of guizhou province,the total selenium content of branches and fruits of purplish red dragon is significantly higher than that of red crystal.2.When soil application of 500 mg/L concentration,the total selenium content of branches and fruits increased first,then decreased,and finally leveled off.respectively,When applying 100 mg/L concentration on branches,the total selenium content of branches and fruits increased first and then decreased.At the same time,selenium application in soil changed the distribution of selenium in branches and fruits,which was manifested as the total selenium content in fruits>branches after selenium application.3.Within the test selenium concentration,the two methods of applying selenium in soil and branch application are as follows:With the increase of selenium fertilizer concentration,increased the total selenium,organic selenium and organic selenium conversion rate of fruits and The selenium absorption rate of fruits decreased.The absorption rate of selenium by branch selenium treatment is higher than that by soil application.One application of selenium in the bud stage（T1）and one application of selenium in the early fruit stage（T2）had no significant effect on the total selenium content of the fruit.With the increase of selenium application concentration,the fruits total selenium content of T1and T2 selenium treated increased less,the fruits total selenium content of the budding period and the early fruiting period selenium treated showed a greater increase.Among them,the application of T3 with 50 mg/L selenium had the best effect on selenium-enriched fruits.The total selenium content of the fruit was 59.11μg/kg,and the conversion rate of organic selenium was 89.92%.4.There was no significant effect on the average single fruit weight,fruit shape index,edible rate and other external qualities of the fruit after soil and branch application of Na₂SeO₃ solution.Soil selenium application increased the content of total phenols and pectin,but decreased the content of betaine and Vitamin C.Applying selenium on branches increased the content of Vitamin C,soluble total sugar,soluble protein,betagin,total phenol and pectin in the fruit.5.Application of selenium in Soil increased soil and fruit calcium content and reduced iron content,With the increase of soil selenium application concentration,the content of lead and cadmium in soil and fruits decreased first and then increased.Application of selenium on branches increased potassium and calcium content in fruits and reduced phosphorus and iron content in fruits.With the increase of the selenium concentration in the branches,the lead and cadmium contents of the fruits increased first and then decreased.6.It was recommended to apply or spray 50 mg/L sodium selenite solution in the two stages of the bud period and the initial fruit stage of the dragon fruit,no selenium residue on the tree and supplement the phosphorus and iron fertilizer appropriately.