Number of sowings: A line—one, B line-- two
1. Do differential sowing of A and B lines are done to have synchronized flowering.
2. Begin the sowing sequence by sowing the A line on the first day.
3. The first sowing of the B line is done 3 days after sowing of the A line.
4. The second sowing of the B line is done 3 days after the first sowing of the B line.
5. The two sowings of the B line will supply pollen grains for a prolonged duration during the flowering period of the A line.