Pollination, fruit set and fruit development in Carambola (Averrhoa carambola Linn).

Anthers burst with the opening of the flowers. The optimum time for collection of pollen was between 8 A. M. and 10 A. M. The stigma was considered to be most receptive when the stigmatic surface looked bright, moist and creamy in colour. Pollen grains are sticky and look yellowish after dehiscence. An individual pollen is barrel-shaped under dry condition and becomes roundish in aceto-carmine under the microscope. The fertility of pollen was cent per cent in both varieties. The carambola is a cross—pollinated fruit. Honey bees, flies and other insects were regarded to be the chief pollinating agents. The fruit set takes place on the fourth day of opening of flower (‘sour’ and ‘sweet’). The fruit set under natural open-pollination was maximum (52.65 and 66.90 per cent in ‘sour’ and ‘sweet.’ respectively) against no set under ‘natural self-pollination’ and ‘parthenocarpy’. Fruit set under ‘hand self-pollination’ in ‘sour’ and ‘sweet’ was 32.85 per cent and 30.26 per cent respectively, while under ‘hand cross-pollination’, the set was 35.60 per cent and 38.20 per cent in the same order. The set under natural cross-pollination was negligible (8.33 per cent in ‘sour’ and 7.20 per cent in ‘sweet’ var.). Initial fruit set under natural condition per panicle was 58.9 per cent in ‘sour’ and 74.5 per cent in ‘sweet’ variety. The number of mature fruit obtained per panicle was approximately two in sour and four in sweet. Out of the growing fruits, 84 per cent dropped off from the tree and the remaining 16 per cent reached final maturity. About half of the total drop occurred during the later half period of fruit growth. Fruits matured at the end of 14th or 15th week after set and the total period required from opening of flower till maturity was 101 to 108 days. The growth of fruit continued till maturity after which it remained hardly for a week on the tree. During this period growth of the fruit remained completely ceased.