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.

Keywords:

• Rice varieties
• Japonica
• Indica
• Japonica × Indica crosses
• insect damage
• tungro
• yield loss
• insecticide protection
• caging method

Notes

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