Persistence and efficacy of bifenthrin (25 and 50 g ai ha(-1)), fipronil (50 and 100 g ai ha(-1)) and indoxacarb (70 and 140 g ai ha(-1)) has been studied in okra fruits. The initial deposits varied from 0.259-0.382 microg g(-1) at low and 0.461-0.688 microg g(-1) at high rate of application. The residues persisted upto 10 days with half-life of 1.32-1.58 days for bifenthrin, 0.65-1.12 days for fipronil and 0.58-1.02 days for indoxacarb. Based on ADI, the suggested waiting period was 1 day for bifenthrin and indoxacarb and 3 days for fipronil. All the insecticides were found effective against leafhopper and shoot and fruit borer.

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The effects of salt stress on growth, nodulation, and nitrogen accumulation in cowpea (Vigna sinensis) and mung beans (Vigna aureus) were studied in sand culture. Salinity (NaCl) retarded the growth of leaves, stem and roots of both the crops. Root growth of mung beans was more sensitive to the increase in salt stress than that of cowpea. The relative growth rates of stressed plant parts declined initially but were subsequently higher than those of control for a period, suggesting that the plants tended to adapt to unfavourable environment even while being stressed. The total nodule number, weight and nitrogen content per plant decreased due to salt treatment, which interfered with the initiation of nodules but not with their further development. There was a considerable fall in the nitrogen fixation efficiency of mung beans under saline environment; it was not so in cowpea.