Growth duration and hispa susceptibility [India]
1987
Datta, S.K. | Konar, D. | De, X.K. | Banerjee, P.K. (Operational Research Project, Pandua, West Bengal (India))
The effect of hispa Dicladispa armigera infestation on growth and yield of rices were evaluated with different durations: Ratna (early), Mahsuri (medium), and Kajalkalma (late). Plots were 50 x 20 m with 20- x 15-cm plant spacings. Test plots were fertilized at 40-20-20 kg NPK/ha. Recommended agronomic practices were adopted. Thionil insecticide as foliar spray was applied as needed to the control plots. Percentage of leaf water content was calculated on the basis of fresh weight of leaves at the peak period of infestation. Feeding by hispa grubs and adults cdaused leaves to turn whitish, membranous, and dry. Infestation was 20% on Mahsuri, 36% on Ratna, and 40 percent on Kajalkalma. Leaf water content of infested plants decreased for each variety. The early and medium varieties had significantly lower growth, yield attributes, and yield than the late variety. In general, hispa infestation delayed heading. The prolonged growth period after hispa infestation significantly improved seed setting in late variety Kajalkalma, but reduced seed setting in Ratna (early) and0632Mashuri (medium). In Kajalkalma, early depression of vegetative growth in hispa-infested plots favored effective tiller formation. The delay in heading favored assimilation and accumulation of reserves, promoting reproductive development and grain yi
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