This study was conducted to evaluate morphological and physiological characteristics of red rice biotypes in rice fields in the state of Rio Grande do Sul. An experiment was carried out at the Rice Experimental Station of Instituto Rio-Grandense do Arroz, during the 1996/1997 growing season. The treatments included the following red rice biotypes, according to their grain characteristics: fine-lengthy grains, with clear husk, with or without awn; fine-lengthy grains, with dark husk; medium grains, with clear husk from two locations (Santo Antônio da Patrulha and Cachoeira do Sul); short grains, with clear or dark husk. The rice cultivars BRIRGA 410 and IRGA 417 were tested as standards. Variables evaluated were: plant height, tillering, flag-leaf area, leaf area per plant, panicle length, number of spikelets and grain per panicle, spikelet sterility, grain length/width relation, grain weight, grain yield per plant, and seed germination. The red rice biotypes evaluated differed from rice cultivars in the morphological and physiological characteristics investigated. In general, for such characteristics, there were no relevant differences between biotypes presenting short grains; between biotypes with medium grains; and between those with fine-lengthy grain and clear husk. Similar dormancy characteristics presented by red rice biotypes (with fine-lengthy grains and clear husk) and the rice cultivars allow to infer that the former underwent crossing with cultivated rice genotypes.
Oryza sativa; morphologic characteristics; seed dormancy
