Modulating infestation rate of white fly (Bemicia tabaci) on okra (Hibiscus esculentus L.) by nitrogen application

Pests are major factor affecting the crop yield, quality, and esthetic value. Although pest resistance is genetically controlled, it is mediated through physiological and biochemical processes interrelated with the nutritional status of the plant. Nutrition of plant may determine its resistance or susceptibility to pests. An experiment was conducted to determine whether and up to what extent varying concentrations of N modulate the infesting rate of whitefly on Okra (Hibiscus esculentus). Twenty-one-day-old okra plants were subjected to five concentrations of 4, 8, 12, 16, and 20 mM N for 30 days. Number of eggs, nymph were counted on each plant after every 4 days. Growth and yield of okra plants increased with increasing supply of N but it decreased slightly at the highest level of N (20 mM). Leaf soluble proteins, amino acids, and soluble sugars were determined on fresh weight basis. From these results, it is clear that increasing N level increased the biosynthesis or accumulation of protein, free amino acid, and sugars that might have attracted more whitefly for feeding. © 2010 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.