Effect of nitrogen fertilization level on population density of Tetranychus urticae (KOCH) in relation with yielding ability and quality of summer squash | ||
| Journal of Pest Control and Environmental Sciences | ||
| Volume 3, Issue 2, December 1991, Pages 90-101 PDF (723 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/jpces.1991.461584 | ||
| Authors | ||
| M. Doss* ; M. Salah | ||
| Horticulture Dept. Plant Protection Dept. Faculty of Agriculture, Alexandria University, Egypt. | ||
| Abstract | ||
| Under field conditions a two years study was conducted to determine the effects of nitrogen fertilization on the population of mites attacking squash plants as well as on the total yield and yield components. Data showed significant differences among mite population under nitrogen levels. A positive correlation was detected between nitrogen fertilizer rates (soil application) and the density of mite. Total yield and fruit number per plant increased with increasing nitrogen level up to the rate of (60-120 Kg/ feddan) whereas the average fruit weigh (g) did not show a clear response. Increasing N- fertilizer rate raised the leaf contents of phenolics and chlorophyll II retention, since phenols accumulated in leaves and elevated mite population rates. These compounds could be regarded as preformed chemical resistance factors. However, only the symptoms (Senescence of leaves) caused by mite infestation was suppressed. In other words, it turned out that acquired resistance in summer squash plants, which received high nitrogen level, was effective only against the necrotic mites symptoms but not against the multiplication of mite. | ||
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