Unfertilized flowers drop off within 24 hours after anthesis and the unfertilized ovary may remain attached for 48 hours after anthesis. You can make a good check on the success of a cross three days after anthesis.
Moderate temperature and increased humidity appear to increase the percentage of fruit setting in hand emasculated crosses, and results in seasonal variations in the success of hand crossing. At Ibadan, the percentage of successful crosses is higher during the cooler, humid months.
An automatic misting system can be installed over the crossing benches to maintain high humidity and lower temperatures during hot periods.
The rate of setting varies enormously with environmental conditions, genotype and manipulative technique. With the use of the IITA technique, an average 50% success may be expected with some specific combinations as high as 90%.
For unexplained reasons, male sterile (MS2 MS2) plants as seed parents seem to produce a high average set (75-95%) under IITA greenhouse conditions throughout the year, in spite of variation in temperature and humidity. Moreover, male sterile plants appear to accept and hold hand-fertilized fruits more readily than hand crossed fertile plants, producing about as many crossed fruits per plant as unmanipulated fertile plants of similar type.
In crosses between fertile plants it is seldom practical to
attempt more than two or three crosses per plant or
Pods are ready for harvest 18-22 days after pollination at Ibadan.
|Objectives, Study materials, Practicals|
|1||Principles of cowpea crossing|
|7||Suggestions for trainers|