Journal Article

Journal article

Identification of thermosensitive genic male sterile lines with low critical sterility point for use in commercial hybrid rice  [2002]

Sanchez, D.L.; Virmani, S.S. (International Rice Research Inst., Los Banos, Laguna 4031 (Philippines). Plant Breeding, Genetics and Biochemistry Div.);

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Purity of hybrid rice seeds utilizing the two-line system is increased when thermosensitive genic male sterile (TGMS) line possesses a low critical sterility point (CSP), which minimizes self-fertility due to temperature fluctuations during hybrid rice seed production. To identify TGMS lines with low CSP at IRRI, Norin PL12, ID24, IR32364 (TGMS) and six IRRI-bred TGMS lines derived fron Norin PL12 were sown in three-week intervals from June to December 1999. Heading date, pollen fertility and spikelet fertility were obtained from each line in every planting interval. Correlation analysis between spikelet fertility and maximum, minimum and daily mean temperatures at 1-30 days before heading were done to determine the critical stage where temperature influences the sterility/fertility expression of the TGMS lines. CSP of the TGMS lines were identified through regression analyses between spikelet fertility and maximum and daily mean temperatures at the critical stage. The critical stage for most TGMS lines occurs at the developmental stages between the differentiation of secondary branch primordium to ripe stage of pollen, or approximately 23-4 days before heading Norin PL12, ID24, IR32364 (TGMS), IR32093 and IR72096 were identified to have low CSP (T mx+ 29.1-30.8 deg C; T mean = 25.5-26.5 deg C). Evaluating for sterility during the wet season is more effective in identifying TGMS lines with low CSP than in the dry season. TGMS lines developed using this new
strategy were found to be more stable in terms of sterility expression. Preliminary evaluation of two-line hybrids from these low CSP-TGMS lines showed a high frequency of heterotic combinations (77%)

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Philippine Journal of Crop Science (Philippines)

ISSN : 0115-463X