How application times of 2,4-DP influence the ripening capacity of 'La France' pears

Abstract

The effective applications of synthetic auxin 2,4-DP on fruit ripening of 'La France' pears (Pyrus communis L.) were examined. A solution of 90 μL·L-1 2,4-DP was applied to fruit and leaves around the fruit as follows: Early 1 = 140 days after full bloom (DAFB); Early 2 = 140 and 150 DAFB; Late 1 = 150 DAFB; and Late 2 = 150 and 160 DAFB. The effects were compared with nontreated fruit Internal ethylene concentrations increased earliest and rapidly in Early 2 followed by Early 1. Fruit firmness decreased earliest in Early 2 and Early 1. Water-soluble polyuronide (WSP) concentrations in Early 2 were higher than other treatments, but hexametaphosphate-soluble polyuronide (HMP) and cellulose concentrations were lower. At 200 DAFB, 40% of fruit in Early 2 reached edible condition on the tree. In addition, the fruit in Early 2 required shorter periods of time to reach edible condition in a controlled room at 20°C after harvest of 170, 180, 190, and 200 DAFB. These results show that two 2,4-DP applications at 140 and 150 DAFB may be effective in inducing the ripening capacity of 'La France' pears on the tree. Chemical name used: 2-(2,4-dichlorophenoxy)-propionic acid (2,4-DP).