Comparative observations on the pest and disease incidence and yield losses of Japonica, Indica and Japonica × Indica rices

Abstract

Comparative field observations of pest incidence on five selected varieties each of Japonica, Indica, and Japonica × Indica rice types indicated that tungro incidence was relatively higher on Japonica varieties, while stem borer incidence at heading stage was higher on Indica varieties. No differences in the relative abundance of other pests on these rice types were observed. Insecticide treatment and caging of plants reduced pest incidence on all varieties. Plant growth and yield of insecticide-treated plants were significantly higher than unprotected plants. Caging reduced the number of tillers but the yields remained higher than unprotected plants. Yield loss estimated by the insecticide protection method was higher at 39% than that by the caging method at 25% overall. There was a significant positive correlation between yield loss estimated by the two methods in Indica and Japonica × Indica varieties and no such relationship in Japonica varieties.

Genetic Behavior of Yield, Grain Quality, Stem Borer and Storage Insect Infestation Traits for Some Rice Genotypes at Different Sowing Dates.

“…It was found that the japonica types were more resistant to stem borer. This was previously conformed by Pathak (1967), Tantawi (1985) and Bleih et al (1991) who concluded that rice verities belonging to Indica type are more susceptible to stem borer than those belonging to japonica or Indica x Japonica types. Djamin and Pathak (1967) concluded that japonica rices have more silica content than Indica rices.…”

Genetic Variability, Insect and Disease Resistance of some Promising Rice Genotypes

“…By contrast, the japonica rice genotypes showed the lowest values of infestation. The obtained results are in accordance with those found by Bleih et al,(1991), who reported that rice varieties belonging to indica or indica/japonica sub-species are more susceptible to rice stem borer infestation than those belonging to japonica one. Resistance of japonica rice varieties to the stem borer could be attributed to its higher silica content than indica types.…”