Division of Entomology Indian Agricultural Research Institute, New Delhi-110 012 (India).
The relationship between stem borer, Chilo partellus (Swinhoe) damage to 12 moderately resistant sorghum cultivars and CSH-1 (susceptible), and grain yield was worked out. The damage was based on leaf injury (%) and stem tunnelling (96). The simple correlations between leafinjury and grain yield, and stem tunnelling and grain yield, determined separately for each of the three years were significantly not different within the years. The pooled data for three years showed highly negative correlations between grain yield and stem tunnelling (−0.95), and grain yield and leaf injury (−0.86). Positive correlation (+ 0.89) was obtained between stem tunnelling and leaf injury. The variation removed by the regression was 90.30 per cent. The multiple regression analysis revealed that a unit increase in stem tunnelling resulted in decrease of 0.59 unit of grain yield. Further, one unit increase in leaf injury caused decrease of 0.002 unit of grain yield. Stem tunnelling appeared to be more important parameter as compared to led injury and contributed more towards reduction in grain yield.
