Genetic analysis of seedling vigor in rice for direct-seeded culture

• Published in: Philippine Journal of Crop Science (Philippines) Vol. 23; no. 1
• Main Authors: Redona, E.D, Ocampo, T.D, Manangkil, O.E, Pacada, I.G. (Philippine Rice Research Inst., Munoz, Nueva Ecija 3119 (Philippines))
• Format: Journal Article
• Language: English
• Published: 01.04.1998
• Subjects: BREEDING METHODS; DIRECT SOWING; FILIPINAS; GENETIC MARKERS; GENETIC VARIATION; GENOTIPOS; GENOTYPE; GENOTYPES; MARCADORES GENETICOS; MARQUEUR GENETIQUE; METHODE D'AMELIORATION GENETIQUE; METODOS DE MEJORAMIENTO GENETICO; ORYZA SATIVA; PHILIPPINES; PLANTULAS; PLANTULE; SEEDLINGS; SEMIS DIRECT; SIEMBRA DIRECTA; VARIACION GENETICA; VARIATION GENETIQUE
• ISSN: 0115-463X

Direct-seeding is increasingly being practised by Filipino rice farmers but all modern varieties released so far have been bred far and selected under transplanted rice culture. Seedling vigor (SV) is important for optimum field establishment and increased weed-competitiveness under direct-seeded conditions. The genetic variation for SV traits was analyzed in 49 promising parents for breeding direct-seeded rice using conventional and molecular assays. Substantial quantitative variation was observed for shoot, root, mesocotyl and coleoptile lengths in slantboard tests. High SV genotypes were identified in addition to known SV genetic donors - Italica Liverno (IL) and Black Gora (BG). Molecular markers, identified earlier in both indica and japonica rice to flank quantitative trait loci (QTL) underlying SV traits, were used to characterize genetic diversity in the test materials. Cluster analysis using 39 RAPD loci flanking 11 SV QTL revealed genotypic differences at SV QTL regions and discriminated the test varieties into eight major clusters. High SV genotypes that grouped differently from IL and BG may possess alternative SV QTL alleles. This was supported by the different grouping pattern that resulted when 70 randomly selected RAPD markers were used in cluster analysis. Crossing high SV genotypes from different clusters may lead to new populations segregating for the maximum number of high SV alleles, thereby facilitating the development of superior varieties for direct-seeded rice culture