Impact of Sorghum Aphid, Melanaphis sacchari Population on Sorghum Yield

The substantial genetic variability for resistance to sorghum aphid was studied and the results indicated that genotypes 61526 and 61558 among aphid resistant lines, RSV 458, RSV 792 and RSV 807 shoot fly resistant lines, RS 29 and C-43 R-lines, RSE 3, Lakadi, M 35-1, local cultivars and Selection 3, Swati, and CSV 8R and CSV 216R national/state varieties had a low population build-up of aphids with < 2 score indicating their least preference with < 10 aphids per leaf. But considering the leaf chlorosis rating of < 2 score consistently during Rabi 2005/06 as well as Kharif 2006 season in the genotypes, 61526, RSV 161, C-43, IS 2312, RSE 3 and CSV 216 R were promising indicating good resistance with only a portion of the leaf found killed by the pest. Among these, 61526, RSV 807 and CSV 216R were most promising with a plant damaging score of < 3 invariably during Rabi 2005/06 and Kharif 2006 season implying that < 40% of the leaf area was dead.

A divergent yield performance of the different sorghum genotypes was also observed despite the aphid infestation during the two seasons. The aphid resistant lines varied in their yield performance in the range of 15.5 g to 31.1 g/plant in Rabi and 14.1 g/plant to 46.1g/plant in Kharif, and the best line was 61526. The shoot fly resistant lines also recorded a yield range of 17.3 g to 36.6 g/plant in Rabi and 7.4 g/plant to 46.1 g/plant in Kharif. Among the shoot fly resistant lines, RSV 807 was the most productive. The performance of R lines in both the seasons was reverse except RS 629, where in yield recorded was more in Kharif than Rabi and C43 was the highest yielder. IS 2312 from the germplasm lines was the highest yielder both in the Rabi and Kharif seasons. Selection 3 was the best among all the sixty genotypes screened in this investigation.