Abstract
Changes in pectic substances and calcium during ripening of tomato fruits on vine and after harvest were followed.
(1) Firmness and viscosity of the ripening fruits decreased. Protopectine also decreased, while soluble pectine increased.
(2) The total Ca content in tomato fruits was almost the same at all stages of maturity. There was a marked increase in the water soluble fraction and decrease in the 1 N-NaCl soluble and 2%-acetic acid soluble fraction between breaker and light pink stages. The increase of the water soluble form of Ca was attributable to an increase of Ca2+
(3) 45CaCl2 solution was administered to tomato fruits through the peduncle at each ripening stage. In immature fruits, high specific activity was observed mostly in 2%-acetic acid soluble and 5%-HCl soluble fractions. The percentage distribution of incorporated 45Ca in the water soluble fraction increased during ripening.
(4) After applying 45Ca at the mature green stage, the tomato fruits were ripened off the tree. The specific activity of 45Ca increased in the water soluble fraction and decreased in the 2%- acetic acid soluble fraction between mature green and breaker stages.
