EVALUATION OF SOME SELECTED TOMATO VARIETIES FOR RESISTANCE AGAINST WHITEFLY, BEMISIA TABACI GENNADIUS

Abstract

The experiment was conducted at the experimental tieid of Sher-e-Bangla Agricultural University, Dhaka during the period from October. 2006 to March 2007 to screen some tomato varieties/genotypes for their resistance to whitefly, J3emisia uthacE Gennadius. Incidence and abundance of whitefly as well as Tomato yellow leaf curl virus (TYLCV) disease and several morphological traits of the tomato varieties were studied to identify resistance source(s) among nine released tomato varieties. Out of nine tomato varieties. 13AR1-2 showed the most preferred host followed by RARI-S, whereas BINA-3. I3ARI-7 and BINA-1 performed as least preferred host for whitefly, Bnnisia jahaci in terms of adult whitefly incidence. Considering the TYLCV infection transmitted by whitefly, 110110 of' them were found to be free from TYLCV infection. Disease incidence varied from 22.57 to 53.04%. Only three tomato varieties were resistant, which include BARI-2 (Ratan), DART-S and BARI-9. The varieties BARI-3, I3ARI-7 and BINA-) and B1NA-2 were found as moderately resistant to TYLCV infection and the varieties BINA-3 and BINA-4 were found as moderately susceptible. In this study. the incidence of TYLCV infected leaves and plants were not directly proportional to the density of vector (whitefly) population, but were related either with the proportion of the virulif'erous whitefly rather than total number of whitefly or the morphological and or physiological properties of the host plant. Considering mean whitefly infestation, cumulative TYLCV infection and comparative yield of different tomato varieties, it was observed that the tomato BARI-2 had significantly the highest whitefly infestation (25.95 per plant) and but with the lowest TYLCV infection (22.57%) and the highest yield (73.00 t/ha) On the other hand, flower per bunch, the maximum number (99 33 and 5.67) were produced by the variety BINA-2, which was statistically similar with the variety BARI-2 (79.33 and 5.33). The number of fruits was not positively related to the yield exce BINA-2 showed significantly the second lowest whutefly infestation (16.90 per plant) and second highest TYLCV infection (46.7 1%) and yielded the highest (73.24 t/ha). The variety BARI-7 showed significantly maximum height (2904 cm) per plant but produced lowest yield (54.98 t/ha), whereas BARI-2. (265.5 cm) and BINA-2 (250.3 cm) showed third highest height as well as produced significantly highest yield (73.00 and 73.24 t/ha, respectively). In consideration of number of branch and leaves per plant, the maximum numbers (13.78 and 86.77 respectively) were produced by the variety BARI-2. In terms of the number of flower bunch per plant and number of flower per bunch, the maximum number (99 33 and 5.67) were produced by the variety BINA-2, which was statistically similar with the variety BARI-2 (79.33 and 5.33). The number of fruits was not positively related to the yield except few cases. The increase in yield per hectare due to the increase of single fruit weight was justifiable.