Abstract
The effects of covering fruits with polyethylene bags and spraying with Ethephon and calcium carbonate (Clefnon : 95% pure calcium carbonate) on the transpiration rate and the occurrence of watercore in the Japanese pear 'Housui' were studied. 1. Pears which were covered with polyethylene bags or sprayed with Ethephon had more symptoms of watercore than did the non-treated, control fruits. 2. Fruits sprayed with 3% Clefnon produced less watercore symptoms than did the non-treated fruits, especially after eight treatments at 2-week intervals after flowering. A 1% Clefnon solution was less effective than the 3% one. However, eight applications of 3% Clefnon at 2-week intervals after flowering to reduce watercore and surface residue of calcium carbonate at harvest. No differences in fruit quality were detected between treated and non-treated fruits. 3. The temperature of the fruit surface treated with Clefnon was cooler than that of the non-treated fruit ; whereas it was warmer on fruits sprayed with Ethephon than the control fruit. We believe that Clefnon promoted the transpiration rate of the fruit but Ethephon did not. We attribute the inhibition of watercore by Clefnon to this acceleration of the transpiration rates.
