SummaryChanges in rind pigments of Valencia oranges were studied in relation to plastid ultrastructure, hormone treatment and light exclusion in green, coloured and re-greened fruits. In the early phase of re-greening an increase occurred in the plastid lamellae in the two outer layers of rind cells, corresponding to decreases in carotenoids and starch. Plastids containing lamellae without grana stacks were most frequent in re-greened fruit. GA inhibited carotenoids and increased chlorophylls at the re-greening stage only, but hastened the loss of starch at the coloured stage, whereas ethephon reduced chlorophylls and increased starch contents in the plastids. It is suggested that ethephon-induced colour change is not a reversal of re-greening and that re-greening is induced by the natural seasonal increase in light during spring and early summer as the fruits reach maturity.
No takes yet. Share an insight, caveat, or question.
El-Zeftawi et al. (1978) studied this question.