Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: February 1, 1996
Publication Date: N/A
Technical Abstract: Semi-dwarf varieties exhibit significantly less seedling vigor than traditional, tall varieties. A more vigorous semi-dwarf variety would compete better with weeds, allow earlier planting, and allow planting to moisture thereby reducing water costs. A set of 'Lemont'/'Teqing' Recombinant Inbred Lines were used to collect data on various components of fseedling vigor. A slant board technique was used to grow replicated sample of 15 seedlings under warm (25C) and cool (20c) conditions. Data was collected on percent germination and lengths of roots, mesocotyls, coleoptiles, and shoot. Lab data was compared to data on seed weight and to two year's field data on plant height and percent germination. All lab measures showed poor correlation (r2 equal to or less than 0.2) with percent germination in the field, due in part to the shallow planting depth used in the field (20 mm) typical for modern semidwarf varieties. Neither plant height nor seed weight were strongly correlated (r2 < 0.2) with any of the components of seedling vigor suggesting the ability to locate vigor QTL not associated with these characters. Interestingly, while both Lemont and Teqing have almost no mesocotyls, several RILs developed mesocotyls of significant length. One RIL developed mesocotyls nearly as long as those produced by the vigorous check line, 'Labelle'. This supports previous reports of linkage rather than pleiotropism causing low seedling vigor in the semi-dwarf varieties. Also, several RILs produced coleoptiles of significantly longer length under cool conditions than under warm growing conditions, as did 'Italica livorno', and two RILs produced shoots as long as those of Italica livorno indicating possible genes for cold tolerance.