Effect of foliar application of fulvic acid on plant growth and fruit quality of tomato ( Lycopersicon esculentum L.)

This study was conducted to investigate the effects of foliar application of fulvic acid on plant growth, fruit quality, and yield of tomato. Fulvic acid (20 mL) was sprayed on the leaves of tomato plants at 10, 20 and 30 days after transplant (DAT) at rates of 0 (control), 0.8, 1.1, or 1.6 g·L -1 in water. The 0.8 g·L -1 treatment led to a significant increase in plant height and fresh and dry weight, while the 1.6 g·L -1 treatment led to a significant reduction. The contents of P and Ca were increased, but those of most of the other elements were unchanged in response to the 0.8 and 1.1 g·L -1 treatments. Fruit number and yield of medium- and large-sized fruits were significantly increased in the 0.8 and 1.1 g·L -1 treatments, which subsequently resulted in an increase of marketable yield. The incidence of cracking was generally high in all treatments, except for the 1.6 g·L -1 treatment, which showed a significant reduction in cracking and much smaller fruit size. Blossom-end rot was greatly reduced in all fulvic acid treated plants, and no incidence was observed in the 1.6 g·L -1 treatment. Our study demonstrated that foliar application of fulvic acid at about 0.8 g·L -1 could be used to promote plant growth and increase marketable yield in tomato production.