Anther culture response of some rice genotypes with varying amylose content to nitrogen fertilization

The influence of nitrogen fertilization of anther donor plants on callus formation and plant regeneration of seven rice genotypes differing in amylose content was evaluated during the 1996 dry and wet seasons. Physiological condition of donor plants and environmental conditions under which the plants were grown influenced the embryogenic ability of the cultured anthers. However, the optimum conditions (e.g. level of nitrogen and season) for growing the seven genotypes (e.g. IR64, IR65, IR65489H, IR68, UPLRi-1, UPLRi-7 and Taipei 309) varied. Once the optimum level of nitrogen fertilization was reached, both callus formation and green plant regeneration of all the genotypes decreased. When cultivated under optimum conditions, Taipei 309 and IR65489H had the highest anther culture efficiency. Except for IR65, all genotypes had higher anther culture efficiency during wet season when solar radiation and time of exposure to sunshine were lower. Plant regeneration was also affected by the quality of the formed calli. Embryogenic type of callus, the general type of callus produced by Taipei 309, exhibited excellent ability of plant regeneration while the non-embryogenic type had poor plant regeneration ability. In an attempt to find a potential marker for screening rice genotypes responsive to anther culture, the correlation between amylose content in the grains and callus formation and plant regeneration was investigated. Weak association was observed. As possible source of energy, amylose content in the anthers did not contribute significantly to both callus formation and plant regeneration. The relationships between amylose content in the anthers and callus formation, green and albino plant regeneration were not significantly correlated, suggesting that amylose content can not be used as potential marker in predicting and/or choosing genotypes responsive to anther culture