Increasing Cold Tolerance in Rice by selecting for high polyamine and gibberellic acid content

Increasing cold tolerance in rice by selecting for high polyamine and gibberellic acid content Publication No. 05/090 Project No. UQ-99A The information contained in this publication is intended for general use to assist public knowledge and discussion and to help improve the development of sustainable industries. The information should not be relied upon for the purpose of a particular matter. Specialist and/or appropriate legal advice should be obtained before any action or decision is taken on the basis of any material in this document. The Commonwealth of Australia, Rural Industries Research and Development Corporation, the authors or contributors do not assume liability of any kind whatsoever resulting from any person's use or reliance upon the content of this document. In submitting this report, the researcher has agreed to RIRDC publishing this material in its edited form. iii Foreword Cold stress affects rice crop at seedling stage, leading to poor seedling establishment, which accounts for Australian productivity losses of up to $30 million per annum. About once in every four years, the rice crop also suffers from cold damage at the reproductive (microspore development) stage leading to spikelet sterility, which accounts to up to $120 million loss. Hence, breeding for cold tolerance is one of the research priorities for the Australian rice industry. Previous RIRDC funded projects revealed that external application of Osmoprotectants and Gibberellic Acid (GA) played a pivotal role in increasing rice cold tolerance. The results of this project revealed that there are genetic differences in rice for spermine (osmoprotectant)-and GA-accumulating ability associated with cold tolerance. This project also demonstrates that cultivars with higher cold tolerance at the seedling establishment stage will also have higher cold tolerance at reproductive stage. These findings are highly useful for the agronomists and plant breeders involved in developing cold tolerant rice cultivars. This report, an addition to RIRDC's diverse range of over 1200 research publications, forms part of our Rice R&D program, which aims to improve the profitability and sustainability of the Australian rice industry. Most of our publications are available for viewing, downloading or purchasing online through our website: iv Acknowledgments We thank Dr. R. Reinke of NSW Agriculture for the supply of rice seed of various genotypes, and for his valuable suggestions.