Effects of Glutamic Acid and TDZ (Thidiazuron) on the Fruit Coloration and Quality of Litchi chinensis Sonn.

Abstract:

In order to accelerate or delay fruit ripening and improve fruit quality, two early mature litchi cultivars, Litchi chinensis Sonn. ‘Sanyuehong’ and ‘Shuidong’, were treated with L-glutamic acid (Glu) and Thidiazuron (TDZ) at 50 days after blossom, the coloration and quality of fruits were determined. The results showed that Glu could promote fruits turning red. As the concentration of Glu (500-1500 mg L^-1) increased, the red area and anthocyanin content in fruit pericarp increased. Treated with 1500 mg L^-1 Glu, the anthocyanin contents in ‘Sanyuehong’ and ‘Shuidong’ pericarp were 8.62 U g^-1 and 11.53 U g^-1, respectively, which were 1.33 and 1.25 folds to control. Glu promoted total sugar accumulation in ‘Sanyuehong’ fruits, but had little effects on fruit size and weight of two cultivars. Fruit coloration was retarded with TDZ treatment, and anthocyan content was decreased at harvest stage. After treated with 5.0 mg L^-1 TDZ, anthocyanin contents in the ‘Sanyuehong’ and ‘Shuidong’ pericarp were 1.23 and 3.4 U g^-1, respectively, which significantly lower than those in control. After treated with TDZ, the total soluble solid and sugar contents in fruits decreased, but the fruit size and weight increased. Therfore, litchi fruits sprayed with L-glutamic acid on the 50^th day after blossom could accelerate maturation, but TDZ delayed.