Resistance of Okra against two-spotted spider mite, Tetranychus urticae Koch

Field and laboratory studies were conducted to screen test entries including varieties/hybrids/local seeds and one wild type of okra for their resistance against Tetranychus urticae. Based on the mean mite population and damage score, six entries viz., Kasturi bhendi, (R), Dharmapuri local (MR), Parbani Kranti (MR), Pusa Sawani (MR), COBhH1 (MR) and Mahyco 10 (S) were selected for further investigations. Studies were made on the physiological and biochemical components. The per cent reduction of moisture in the infested over the healthy plants was maximum (15.3 %) in susceptible check (Mahyco 10) and the depletion of total chlorophyll due to mite infestation was quite remarkable. The carbohydrate content was higher in the healthy leaves of the okra accessions tested than in the mite infested leaves. The minimum increase was observed (15. 9 %) in resistant entry. Infested plants recorded a low amount of protein than the mite free plants, whereas total free amino acids were more in infested plants than mite free plants. There was substantial increase in the quantity of polymeric phenols and tannin as a result of feeding by mites. Resistant wild type Kasturi bhendi recorded the highest level of total phenols in both healthy (6.23 mg/g) and infested (9.50 mg/g) leaves. The resistant entries recorded approximately 20 % increase in tannin over mite free plants.