Overcoming the Failure of Fruit-set and Fruit Drop of Siam Orange on Off-season Period through Application of Mycorrhizal Inoculants and ZnSO4 Micro Fertilizer Dosage

This research was carried out at Kintamani District, Bangli Regency, Bali-Indonesia, from February to October 2019 with aimed to overcome the failure of fruit-set and fruit drop of Siam orange on off-season period through application of mycorrhizal inoculants and ZnSO4 micro fertilizer dosage. This experiment was arranged as a randomized block design consisted of 2 factors. The first factor was mycorrhizal inoculant (0, 50, 100 and 150 g/tree), while the second factor was the dosage of ZnSO4 micro fertilizer (0, 5, 10 g/tree). All treatments were repeated 3 times. The results showed that the interaction between mycorrhizal inoculant treatment and ZnSO4 micro fertilizer dosage did not significantly affect all of the variables observed. Mycorrhizal inoculant dose 150 g/tree could overcome the failure of fruit-set and fruit drop and improved the quantity and quality of fruit of Siam oranges on off-season, which was reflected by increased number of fruits harvest per tree (249,00 fruits), weight per fruit (106,10 g), weight of fruit harvested per tree (26,34 kg) and total dissolved solids (13.52% Brix), or increase 31,44%; 18,15%; 54,58%; and 35,74%, respectively, compared to without mycorrhizal inoculant i.e 189,44 fruit; 17,04 kg; 89,80 g and 9,96% Brix. Treatment of ZnSO4 micro fertilizer dosage of 10 g/tree could also overcome the failure of fruit-set and improved the quantity and quality of fruits of Siam oranges on off-season, which was reflected by the higher number of fruit harvested per tree (233,50 fruit), weight per fruit (100,90 g), weight of fruit harvested per tree (23.68 kg) and total dissolved solids 12,83% Brix) or increase 18,88%; 23,18%; 23,91% dan 33,50% compared to without micronutrient of 196,42 fruits; 19,11 kg; 81,91 g; and 9,61% Brix.