Abstract:
The present study on "Reproductive biology and enzyme studies in
Ocimum spp." was undertaken at the Department of Plant Breeding and Genetics,
College of Horticulture, Vellanikkara during the period 1994-1996 with a view to
make a comparative evaluation of the reproductive biology and phosphorylase
enzyme activity of different species of Ocimum. The four species of Ocimum viz. O.
tenuiflorum, o. gratissimum, o. canum and o. basilicum collected and maintained
in the Department were used for the study.
The different species of Ocimum varied significantly in the time taken for
inflorescence development, completion of anthesis in an inflorescence, number of
flowers per inflorescence and distance between verticils. Species level variations
were also observed in seed moisture content, seed density, l000-seed weight and
seed dormancy period.
Flowers of the four selected species were identical in basic structure
although there existed variation in size, colour, hairyness and shape of floral parts.
Anthesis occurred earlier in o. canum than the other three species. Pollen grains of
Ocimum were hexacolpate and reticulate. However, species level difference existed
in the size, shape and fertility of pollen grains. No self incompatibility mechanism
existed in the four species studied. The floral morphology and protandrous nature
makes the species adapted to cross pollination. Insects and ants are the main agents
of pollination. Comparison of Sanctum and Basilicum groups revealed that Sanctum
group which includes o. tenuiflorum and O. gratissimum required longer time for
inflorescence development than Basilicum group which includes o. canum and
O. basilicum. Verticils were closer in the inflorescence of Sanctum group than
Basilicum group. Sanctum group produced less conspicous flowers with sessile
bracts and yellow pollen grains. In this group anther dehiscence occurred in bud
stage. Basilicum group produced conspicous flowers with pedicellate bracts and
white pollen grains. Anther dehiscence was after flower opening in this group.
Dormancy break was sudden in Sanctum group and gradual in Basilicum group.
Moisture content of Ocimum seeds was positively related to
phosphorylase enzyme activity. Phenol content was negatively related to both
moisture content and phosphorylase enzyme activity of the seeds.
