Stigma exsertion trait in rice (oryza sativa l.) and comparison of two phenotyping methods

A practical option to address food security of South-east Asian countries with rice as staple is to exploit yield heterosis through hybrid rice technology. Several traits contribute to hybrid rice seed production efficiency, and stigma exsertion is a trait increasing the opportunity of pollination and thereby enhancing hybrid seed set. Few rice stigma exsertion types are enumerated but phenotyping methods are not systematic and well compared. This study reports the extent of variability for the trait in parental lines of some popular rice hybrids, identifies the opportunity for enhancing the trait in some of them, and identifies good donors, namely BF16B and BF96B for the trait. During phenotyping, sample processing was improved for non-distortion of spikelet characters and longer storability between sampling and phenotyping. Method comparison analyses between the two modified phenotyping methods for stigma exsertion indicate that the whole panicle and the panicle zone methods are statistically on par in quantitative assessment of stigma exsertion and are interchangeable. However, the latter being less resource demanding, may be the choice for stigma exsertion phenotyping in rice.