Sunflower in Zambia is planted following the rainfall pattern. The actual planting dates follow the onset of the rain season and also can vary depending on the materials being handled, that is if they are early or late maturing. A rule of thumb for sunflower is that at least three and half months is required for a crop to reach physiological maturity. Yield reductions have been observed with delayed planting, hence it is important to plant sunflower at appropriate dates to have maximum favourable soil water status. Planting dates should take full advantage of the season.
This is usually determined by the seed. Sunflower seed is of medium size
A: S-1 has sterile cytoplasm and N-1 has normal cystoplam. A cross between S-1
and N-1 gives an S-1 plant. This way sterile plants are maintained. S-1 and N-1 are isogenic.
B: Once an R-line RfRf is identified through progeny test, perpetuating the line is by selling. In a similar manner the B-line can be maintained.
Maintenance of male lines carrying restorer genes is not a problem in the sunflower breeding programme in Zambia as the genes are already incorporated in the breeding population.
Despite this situation, the usual way by which the restorer lines (R-line) would be mainted is similar to the maintenance of B-line (Figure). Genetic contamination can be addressed through mass selection.
compared to other field crops. If planting is done by hand, then caution should be taken to ensure that the holes do not exceed 7 cm in depth. Plant depth to 3 to 5 cm is ideal for good emergence. In sandy soil, however, planting should be slightly deeper because the top soil dries quickly.
Planting density, spacing and pattern
For all sunflower seed in Zambia the planting rate is recommended at 5-8 kg/ ha to yield a plant population between 40,000 and 44,000 plants/ha. This is achieved by sowing 2 to 3 seeds per station which would be thinned to one plant per station at the 3