The role of seed viability in the development of corky tissue in sapota (Manilkara achras) fruit in India.

摘要

Corky tissue (CT) is a major disorder affecting the fruit of sapota (Manilkara achras) 'Cricket Ball' in India. Affected fruit have a hard lump in the pulp and dry acidic flesh, but have no external symptoms. The main objective of the present study was to investigate the role of seed in the disorder. Treating fruit with 1.0 g l-1 gibberellic acid (GA₃) at 50% maturity increased fruit fresh weight and presumably seed growth, and reduced the incidence of CT compared with that in untreated control fruit. In contrast, fruit treated with 3.0 g l-1 paclobutrazol (PBZ) showed the opposite response. Fruit treated at 70% or 90% maturity gave no response, suggesting that poor seed viability during the early stage of fruit development was associated with CT. Seed stored for 30 d under ambient conditions lost water and had lower viability. There were decreases in the moisture content and calcium concentration in seed and pulp as the severity of CT increased in fruit harvested in the field, indicating a "reverse flow" of water and nutrients from the fruit. It is proposed that the incidence of CT is related to reduced seed viability and the consequent losses of water and calcium from fruit due to competition for resources with the rest of the tree. Further studies are required to assess the potential of the application of GA₃ to reduce the incidence of CT in commercial orchards.