Male sterility induced by low temperatures during reproductive development is the major constraint on rice production in Ethiopia, which generally lies at high elevations. Because of a lack of phenotyping facilities, limited information is available on the cold tolerance of Ethiopian germplasm. We evaluated the genotypic variation in cold tolerance of 18 Ethiopian rice cultivars in two phenotyping facilities and characterized their cold tolerance in relation to their reproductive morphology in a 2-year trial in Japan. Genotypic variation in spikelet fertility was high after exposure to cold during reproductive development at both facilities, with fertility ranging from 0% to 90 %. ‘Andassa’ and ‘Tana’ had the highest fertility and ‘Fogera 2’ and ‘Getachew’ had the lowest. The two cold-tolerant germplasms had tolerance similar to that of the Japanese ‘Hitomebore’ (strong), whereas the susceptible germplasms had tolerance similar to that of the Japanese ‘Sasanishiki’ (weak). The variation in spikelet fertility was explained by both anther length and number of fertile pollen grains per anther under cold stress, and by anther length under unstressed control conditions in both years of the study; longer anther length and higher fertile pollen number leads to stronger cold tolerance. Our results suggest that anther length under unstressed conditions offers a pre-screening criterion for cold tolerance without requiring phenotyping facilities for screening.

生殖发育过程中低温引起的雄性不育是埃塞俄比亚稻米生产的主要制约因素，埃塞俄比亚通常处于高海拔地区。由于缺乏表型鉴定工具，有关埃塞俄比亚种质的耐寒性的信息有限。我们在日本进行了为期2年的试验，评估了两个表型分析设施中18个埃塞俄比亚水稻品种的耐冷性的基因型变异，并表征了其耐寒性与生殖形态的关系。在这两个机构的生殖发育过程中，暴露于寒冷后，小穗繁殖力的基因型变化都很高，繁殖力范围为0％至90％。“ Andassa”和“ Tana”的生育率最高，“ Fogera 2”和“ Getachew”的生育率最低。这两种耐寒种质的耐受性与日本“ Hitomebore”（强）相似，而易感种质的耐受性与日本“ Sasanishiki”（弱）相似。在这两年的研究中，小穗受精率的变化既可以通过在冷胁迫下的花药长度和每株花药中可育花粉粒的数量来解释，又可以通过在无应力控制条件下的花药长度来解释。较长的花药长度和较高的可育花粉数目导致较强的耐寒性。我们的结果表明，在无压力条件下的花药长度为耐寒性提供了预筛选标准，而无需进行表型筛选。在这两年的研究中，小穗受精率的变化既可以通过在冷胁迫下的花药长度和每株花药中可育花粉粒的数量来解释，又可以通过在无应力控制条件下的花药长度来解释。较长的花药长度和较高的可育花粉数目导致较强的耐寒性。我们的结果表明，在无压力条件下的花药长度为耐寒性提供了预筛选标准，而无需进行表型筛选。在这两年的研究中，小穗受精率的变化既可以通过在冷胁迫下的花药长度和每株花药中可育花粉粒的数量来解释，又可以通过在无应力控制条件下的花药长度来解释。较长的花药长度和较高的可育花粉数目导致较强的耐寒性。我们的结果表明，在无压力条件下的花药长度为耐寒性提供了预筛选标准，而无需进行表型筛选。