YIELD COMPARISON OF RICE GENOTYPES IN HUM ID AND IRRIGATED LOWLAND

Competition tests between F-6 lines from two rice crosses selected the F-4 generation were conducted in humid and irrigated lowland cultivat ion systems, for two years. From the F-2 generation, segregating gener ations of each cross were conducted independently in each environment. The objectives were to verify if the same genotypes could be used for both cultivation systems and if only one environment could be used fo r preliminary selection of rice Lines adapted to both cultivation syst ems, in order to reduce operational costs of lowland rice genetic impr ovement programs. The results showed that: 1) the same lines can be us ed indiscriminately in the humid lowland and in the irrigated lowland systems; and 2) in the selection of rices lines for lowland, the segre gating populations can be conducted only in the irrigated condition, a nd then the final evaluations should be done in the irrigated and non irrigated conditions.