Effects Of SprayingFoliar Selenium On Photosynthetic Characteristics And Fruit Quality Of Walnut And Grape

Selenium is a beneficial element in plants,adding appropriate selenium concentration is beneficial to plant growth and development,it has a positive effect on the improvement of fruit quality.The cultivation area and yield of walnut and grape in China are developing rapidly at present Improving the quality and increasing the efficiency of walnut and grape production is of great significance to improve their market competitiveness.Walnut(Juglansregia L.)cv.Yuxiang and grape(Vitis vinifera L.×V.labrusca L.)cv.Summer Black,Jumeigui and Shine Muscat were used as test materials,spraying different concentrations of sodium selenite by foliar application during fruit development,to study the effects of selenium on photosynthetic characteristics and fruit quality of walnut and grape.The main results are as follows:1.The diurnal variation of net photosynthetic rate of walnut leaves showed a single peak curve,and peak at 12:00.Compared with the control check(CK),Selenium treatment increased net photosynthetic rate and transpiration rate of walnut leaves from from 8:00 to 12:00,and the net photosynthetic rate of 250 mg·L-1 selenium treatment was significantly higher than that of 500 mg·L-1 selenium treatment,but there is no difference in transpiration rate between the two selenium treatments.250 mg·L-1 and 500 mg·L-1 selenium treatment reduced intercellular CO2 concentration(8:00—10:00)and increased stomatal eonductance(8:00-12:00)in walnut leaves.However,there was no difference in intercellular CO2 concentration and stomatal conductance between the two selenium treatnents except that the stomatal conductance of leaves treated with 250 mg·L-1 selenium was higher than that treated with 500mg·L-1 selenium at 8:00.The light use efficiency and water use efficiency of walnut leaves were improved by 250 mg·L-1 and 500 mg·L-1 selenium treatment from 8:00 to 10:00,the two parameters of 250mg·L-1 Selenium treatment were higher than 500 mg·L-1 selenium treatment2.Compared with the CK,250 mg·L-1 and 500 mg·L-1 selenium treatment increased green fruit weight,kernel weight,vertical and transverse diameter of'Yuxiang' walnut,the green fruit weight increased by 11.09%and 8.13%,respectively,the kernel weight increased by 10.39%and 2.03%,the vertical diameter of nuts increased by 14.25%and 17.46%,the transverse diameter of nuts increased by 7.44%and 10.66%,under two selenium treatments,but there was no difference between the two treatments,except the kernel weight of250 mg·L-1 selenium treatment was higher than 500 mg·L-1 selenium treatment In addition,selenium treatment had no effect on the nut weight,kernel percent and lateral diameter of 'Yuxiang' walnut3.The single berry weiglt,vertical diareter and transverse diameter of three grape berries increased first and then decreased with the increase of selenium concentration.and reached the maximuum value under 50 mg·L-1 selenium treatment Conroared with the CK,25 mg·L-1 selenium treatment increased the fruit shape index of 'Jumeigui'grape,but other treatments had no effect on the frult shape index of grape.Moreover,anthocyanin content in skin of 'Summer Black' and 'Jumeugui' grapes,and decreased chromatic aberration L*and b*value of berries.The anthocyanin content in skin increased by 106.32%and 74.86%under 50 mg·L-1 selenium treatment compared with the CK.Selenium treatment reduced chronatic aberration L*a*,and b*values of'Shine Muscat' grape and increased chlorophyll content in skin,the chlorophyll content increased by 80.65%cselenium treatment significantly increased chromatic aberration L*value of berries and ompared with the CK.4.The soluble solid content,soluble solid:titratable acid ratio and vitamin C content of three grape berries increased first and then decreased with the increase of selenium concentration,and reached the maximum under 50 mg·L-1 selenium treatment.Compared with the CK,The soluble solids content of 'Sumler Black','Jumeigui' and'Shine Muscat' grapes increased by 4.39%,11.99%and 8.06%,respectively,the soluble solid:titratable acid ratio increased by 23.43%,37.70%and 27.96%,and the vitamin C content increased by 63.74%,53.31%and 42.7%.On the contrary,the titratable acid content of grape berries was lowest under 50 mg·L-1 selenium treatment,at this concentration,it was 16.1%,22.86%and 21.05%lower than the CK.In addition,comared with its treatment,the firmness of berries was significantly increased by 50 mg·L-1 selenium treatment,and 'Summer Black','Jumeigui'and'Shine Muscat' grapes increased by 17.32%,8.72%and 13.00%respectively conpared with the CK.5.In this study,the optimum concentration of spraying foliar application sodium selenite of walnut and grape were 250 mg·L-1 and 50 mg·L-1,respectively.