Andhra Pradesh Agricultural University, Rajendranagar, Hyderabad-30, A. P.
1Submitted in fulfilment of requirements for M. Sc. degree, Andhra Univ. This work was initiated at the Agric. Coll., Bapatla, by the introduction of malesterile lines, their counterparts and fertility-restorer lines by Dr. T.V. Reddy, the then milled specialist and present Director of Agriculture.
In cytoplasmic male-sterile Sorghum, the degeneration of male gametes was not confined to any particular stage. It occurs at any stage before the first mitotic division of microspores. About 40 per cent, of the cells degenerate at PMC stage, 15 to 20 per cent, at dyad stage, 20 to 65 per cent, at tetrad stage, and 2 to 15 per cent, during the developmental stages of microspores. No chromosomal abnormalities were noticed. The cytoplasm shrank and degenerated resulting in collapsed cells.
The tapetum in normal fertile plants was cellular till the completion of microspore development. In sterile plants, tapetum was of the peri-plasmodium type. In semisterile hybrids, the tapetal cells enlarged radially with large vacuoles and enlarged nuclei. Such hypertrophied cells were either unilateral appearing towards one side or alround the sporogenous tissue. In either case, they occluded the entire anther cavity crushing the sporogenous tissue at the centre.
