Cool Temperature Increases Spikelet Number per Panicle in Oryza sativa L. “Tachiayaka”, a Short-Panicle Rice for Whole-Crop Silage Use

Abstract

Rice cultivars with short panicles are in demand for whole-crop ensilage because they yield fewer spikelets, which are hard for cattle to digest. However, methods for efficient seed production need to be developed. Factors that are effective for seed production have been elucidated in “Tachisuzuka”, but they may not be effective in ‘Tachiayaka’. Here, to elucidate the factors that affect spikelet number per panicle in “Tachiayaka”, we examined the effects of crop management. Comparison of the samples transplanted at various periods and harvested at different altitudes or latitudes revealed negative correlations between spikelet number per panicle and average of daily minimum air temperature from 30 days to 11 days before heading. Plants grown in cold water from 29 days to 10 days before heading had significantly more spikelets per panicle than plants grown in warm water. These results showed that spikelet number per panicle in “Tachiayaka” was greater at lower temperatures during young panicle development.