The Relationship between Ca Uptake and Firmness in Cucumber Fruit

During nutrient solution culture of cucumber, paclobutrazol (PBZ) promoted the Ca uptake and accumulation of cucumber fruit, but significantly inhibited the shoot growth. In the medium and stem parts of the smaller cucumber fruits treated by PBZ, Ca uptake and accumulation were vigorous but in the blossom part did not do so. PBZ was effective in the maintenance of firmness in the smaller fruits. PBZ was an effective growth regulating chemical for Ca uptake of cucumber plant and storability of cucumber fruit. This Ca accumulated in cucumber fruit reduced loss of firmness during postharvest ripening, but led to the decrease of marketable fruit per plant, as well as productivity. To solve this problem, the direct application of Ca was conducted after anthesis. Foliar treatment of Ca on leaf area around fruit was ineffective in Ca uptake, but its direct application on fruit itself increased the concentration of Ca in fruit. The cucumber fruit that Ca was accumulated by direct application maintained the firmness longer after harvest.