Effects of different selenium spraying scheme on the fruit quality, total selenium and organic selenium contents in ‘Red Fuji’ apple trees

The suitable spraying selenium(Se) concentration, spraying times and spraying periods in Red Fuji apple were studied, and the effect of spraying Se on the fruit quality, the Se content and the ratio of organic Se were analyzed in this experiment. The results show that Selenium stayed mostly in the above ground parts of apple trees after foliar application. The selenium content was in order of leaves branches fruits roots at the same Se spraying concentration. Spraying Se during the blooming and fruit setting period, the ratio of organic Se in the total Se content was increased in leaves and fruits. Spraying at close to fruit coloring period, the organic Se ratio was relatively low in spite of the increased total Se content in fruits. Spraying Se affects the quality of fruits. Spraying Se could increase the total soluble solid, total soluble sugar and Vc of the fruit, reduce the total titratable acid, and improve fruit flavor as a result under all the spraying concentrations and times. However, the flesh firmness is reduced to some extent, thus the storage and transport quality is influenced. Comparatively, spraying Se in 100 mg/L three times in May, June and July has the best effect on the Seenriching and yield among the designed treatments for Red Fuji apple trees. The total Se content in leaves and fruit is 2728.30 g/kg, FW and 10.10 g/kg, FW respectively, and the corresponding ratio of organic Se is 85.71% and 87.72%. The mean fruit weight reaches 256.8 g. Therefore, it is the safest and most effective Se foliage spraying scheme.