Physico-chemical basis of insect-resistance of traditional rice varieties against Sitophilus oryzae (L.)

Abstract

Based on popularity and specialty, seven traditional rice varieties were tested for resistance reactions in terms of physico-chemical properties against rice weevil, Sitophilus oryzae and compared with the improved high yielding rice varieties during 2019-2021. The result revealed that the aromatic rice variety Kon joha was the least suffered (11.67%) under the husked condition, whereas the aromatic traditional rice variety Bokul joha was the least suffered (53.00%) under the de-husked conditions at 18 days after infestation. Amongst the traditional varieties, the Black rice variety suffered maximum weight loss of 60.16% under de-husked conditions. All tested physical and biochemical parameters revealed a significant positive correlation with weight loss (r=0.87), total soluble protein (r=0.86), 1000 grain weight (r=0.74), moisture content (r=0.54), germination loss (r=0.89) and seed vigor loss (r=0.54) at 180 days of infestation under husked condition, while significant positive correlation with weight loss (r=0.91), starch content (r=0.98), crude protein content (r=0.94), L/B ratio (r=0.88), 1000 grain weight (r=0.50) and moisture content (r=0.87) at 180 days of infestation under de-husked condition. The rice grains possessing a high percentage of starch and protein, but a low per cent of crude fat was found more prone to infestation by S. oryzae.