Twenty three varieties of soybean were sown in two experiments in the experimental area of Oilseed Programme, National Agricultural Research Centre, Islamabad in a randomized complete block design. The experimental unit was 5x1.8m. The varieties in Experiment No.1 attained maturity in ten weeks while they took eight weeks in Experiment No.2. The whitefly population was usually observed on the upper fresh leaves of soybean whereas no or very little whitefly population was observed on the lower and middle leaves of the plant. Heavy rains proved to be lethal for whitefly and a sharp decline in its population was recorded after rains. The significant differences were recorded in the whitefly population amongst the varieties in both the experiments. The susceptibility and resistance of different varieties against whitefly varied in different weeks. In the first week, CO-1 proved to be most resistant in Experiment No.1, while G-9956 showed maximum resistance to whitefly in the 2nd and 3rd weeks. As a whole, AGS-129 was the most susceptible variety with an average seasonal population of 0.74 whiteflies per leaf in Experiment No.1 while G-9956 proved to be most resistant with an average seasonal population of 0.19 whiteflies per leaf. Among the 11 varieties sown in Experiment No.2. RAWAL-1 was recorded as the most susceptible variety with an average seasonal population of 1.08 whiteflies per leaf. AGS-344 proved to be most resistant with an average seasonal population of 0.10 whiteflies per leaf. The data on plant growth revealed no direct relation between number of nodes per plant and their respective plant heights. A plant having more number of nodes may have less height and vice versa. Similarly, a plant having maximum number of nodes or height in the initial stages of growth may not have maximum number of nodes or height at maturity.
Abdul Khaliq , Waseem Akbar and M. Amjad , 2000. Studies on the Relative Resistance of Some Soybean Varieties Against Whitefly and
its Population Fluctuations During the Crop Season . Pakistan Journal of Biological Sciences, 3: 1658-1661.