Studies on population dynamics of aphids on wheat cultivars
2001
Bhutto, A.H.
Homogeneous seeds of 45 cultivars/lines including both progeny (coded lines) and commercial varieties were planted in row trial. Each line was 10 meter long, keeping 30 cm distance between row to row. Cultural practices were adopted as per recommendations of the Department except use of agrochemical this was avoided for proper exploitation of pest. Aphid population recorded on 2-2-99 averaged 0.091 plus-minus 0.011, 22-2-99 (1.716 plus-minus 0.027), 1-3-99 (4.670 plus-minus 0.046), 8-3-99 (4.750 plus-minus 0.03) and 15-3- 99 (0.7487 plus- minus 0.008) per 30 liters respectively. Varieties 1, 3, 4, 5, 14, 32, 37 were found susceptible while rest were resistance to aphid. Leaf length average was 28.12 plus-minus 0.166 cm, leaf breadth (1.410 plus-minus 0.021 cm) and total leaf area (39.650 plus-minus 0.752 cm2). Tillering capacity averaged 13.03 plus-minus 0.261/plant, grains 34.68 plus-minus 0.186 per spike respectively. Correlation work out indicated that mean aphid population had negative significant correlation with leaf length (r=-0.279), negative non significant with leaf breadth (r=-0.107) total leaf area b(r=-0.182), while positive and significant with tillers/plant (r=0.308) and negative highly significant with grains/spike (r=0.569). On the basis of present studies it may be concluded that all varieties were not equal infested by aphids, few were found resistant. It was further found that March 1st was the critical period of aphid infestation, at this stage plant acquire high chlorophyll also the climatic factors such as temperature and humidity favour the pest. As for as correlation of aphids with morphological characters are concerned a negative response of aphid population was observed toward leaf area, grain number and grain weight respectively.
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