The Journal of Horticultural Science & Biotechnology
Vol. 79 No: 3
Effect of calcium supply on the physiology of fruit tissue in 'Andesu' netted melon
T. NISHIZAWA, T. KOBAYASHI and T. AIKAWA
Fruit development and physiological traits were evaluated in ĎAndesuí netted melon plants grown with and without calcium.
Calcium exclusion accelerated softening, alcoholic fermentation and ethylene evolution of fruit compared with those supplied with calcium, but the opposite trend occurred with sucrose accumulation.
A significant difference of calcium concentrations in the fruit between treatments was observed at the developing stage of the fruit (P<0.05), but the difference became smaller as fruit matured.
In the mesocarp tissue from the basal hemisphere, calcium concentrations in the NaCl soluble fraction at ripe fruit stage differed significantly (P<0.05) between calcium treatments but no significant difference was detected in the inner mesocarp of the distal hemisphere.
Calcium exclusion did not lead to the development of water-soaked symptoms in the mesocarp tissue of ripe fruit.
Uronic acid concentrations in ionically bound pectin fraction did not differ between calcium treatments throughout fruit development.
In covalently-bound pectin fraction, however, uronic acid concentration of ripe fruit was significantly lower in calcium-excluded plants than in calcium-supplied plants (P<0.05). Our results suggest that: first, accelerated fruit softening under calcium deficient conditions might result from promoted ethylene evolution rather than from the shortage of ionically-bound calcium in cell walls, second, calcium deficient condition does not necessarily lead to water-soaked symptoms in tissue of ĎAndesuí melon fruit.
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