National Research Centre for Sorghum, IARI, Regional Station, Rajendranagar, Hyderabad-500 030, India
Seed set pattern in reciprocal crosses in two apomictic grain sorghum lines, ‘R 473’ and ‘302’, was investigated. The seed set in ‘R 473’ was very limited in crosses. Plant to plant variation for seed set in crosses is present in ‘R 473’ indicating possibility for existence of different strains, some cross sterile obligate apomictic and others with varying degrees of facultadve apomixis.
‘R 473’ carries the fertility reducer (—) cytoplasm and fertility promoter (+) nuclear genes, whereas ‘302’ carries fertility promoter (+) cytoplasm and fertility reducer (—) nuclear genes. Therefore, ‘R 473’ as pollinator results in higher seed set in ‘302’ cytoplasm while seed set in ‘R 473 × 302’ is the least.
‘302’ was also cross-sterile like ‘R 473’, but after several generations of selling and selection for better yield (seed set), the cross fertility status of ‘302’ has considerably improved. Changes in cross fertility status of ‘R 473’ even after several generations of selfing is low probably due to its cytoplasmic control. There is evidence of some seed set under emasculation without pollination.
