Effect of Time of Humic Acid, Zinc Sulphate and Boric Acid Application and Its Concentration on Improving Quantitative Characteristics of Strawberry Fruit

Strawberry (Fragaria × ananassa) has high nutritional value that can be used freshable and processed. Nowadays¡ fertilizers play an important role in increasing the yield and quality of fruits and vegetables. In this study¡ effect of different levels of humic acid (0¡ 20 and 40 mg l1)¡ zinc sulphate (0¡ 50 and 100 mg l-1)¡ and boric acid (0¡ 50 and 100 mg l-1) on quantitative characteristics of fruit and increase of yield of „Camarosa‟ strawberry were investigated. Strawberry plants were sprayed by chemicals in two stages of 30 days after planting and beginning of blooming stage. The experimented layout was 7x2 factorial in a completely randomized design with four replications. The results showed that application of chemical at both stages¡ increased weight of primary and secondary fruit¡ number of their achenes¡ diameter¡ and length of fruit but beginning blooming stage was very effective compared with 30 days after planting stage.Total yield was significantly increased by all treatments compared to control treatment at both stages of application¡ specially at beginning blooming stage. Also¡ the highest average of fruit weight and yield observed at beginning blooming stage. In general¡ 40 mg l-1humic acid¡ had the highest effect on improving of fruit quantitative characteristics.