2Department of Agriculture, Gujarat State.
3Division of Vegetable Crops, Indian Institute of Horticultural Research, Bangalore-6.
University of Udaipitr, Jobner Campus
1A part of the M. Sc. thesis submitted by the senior author to University of Udaipur.
Investigations on floral biology in watermelon parents viz., Crimson Sweet, New Hampshire Midget, and their F1, F2 and backcross generations were carried out during the summer season of 1968. Under the arid and semi-arid conditions of Jobner parent New Hampshire Midget (P2) was first to flower, while parent Crimson Sweet (P1) and back-cross (BCi) were last to flower and other cross combinations were intermediate. Flowering continued for about four months with its peak during the second fortnight of June in the second flush. All the watermelon lines and crosses were monoecious and bore flowers singly in leaf axils.
There were eight distinct morphological bud developmental stages in both, male and female buds. The whole period of bud development was completed in 12–16 days by the male bud and in 11–13 days by the female bud of parent Crimson Sweet and in 11–13 days by the male bud and in 9–11 days by the female bud of parent New Hampshire Midget. In BC1 male bud took 12–16 days and female bud took 10–12 days for its complete development, while F1(A), F1(B) and F2(A) were intermediate to their parents.
The increase in size of the male as well as female buds was associated with the bud development. The rate of increase in size was more rapid in earlier stages, i.e., upto 8–12 days, thereafter it decreased and during the post-developmental period remained more or less constant.
The anthesis started in the early hours of morning at 6.00 AM and continued upto 7.30 AM., with the peak between 6.30 AM to 7.00 AM. Anthesis was prolonged with the decrease in relative humidity and decrease in minimum temperature.
The dehiscence of anthers started one and quarter hours before anthesis, i.e., 5.15 AM in all the cases with the exception of Crimson Sweet in which it always started at 5.30 AM., and continued upto 6.30 AM. The peak period of dehiscence varied in all the cases from 5.15 to 5.45 AM.
The stigma was receptive from 2 hours before to 3 hours after anthesis. Maximum receptivity of 83.33 per cent was observed just after anthesis in New Hampshire Midget and minimum receptivity of 14.28 per cent in F1(B), 2 hours before anthesis. However, fruit set percentage varied in all the lines and crosses at each level of pollination but the same was higher in all the cases when flowers were pollinated just after anthesis.
