Information on the release of N from sulfur‐coated urea (SCU) as affected by soil moisture in the aerated range is lacking. Laboratory incubation experiments were therefore conducted on two soils to study the release of N from SCU as affected by soil moisture in the aerated range, coating weight (SCU‐28 and SCU‐9), and method of placement (on one soil only).In the calcareous Princes Town soil the release of N from SCU increased with increasing moisture throughout the 9 weeks of study. In acid Talparo soil similar trends were present up to 3 weeks, but at 6 and 9 weeks maximum release of N occurred at medium moisture (soil moisture at pF 2.4) and minimum release at low moisture (soil moisture at pF 3.5).In Princes Town soil the difference in release of N from SCU‐28 and SCU‐9 remained throughout the 9 weeks. By 9 weeks SCU‐9 (heavy coat) released more N at high moisture level (soil moisture at pF 1.0) than SCU‐28 (light coat) at low moisture. In Talparo soil the effect of coating weight on the release of N at three moisture levels was considerably reduced from 6 weeks onwards.Ammonia volatilization losses were recorded only with Princes Town soil but they never exceeded 2.5% of the total N applied. The release of N from SCU was faster when the granules were mixed with the soil rather than surface applied. This difference between surface and mixed application was greater at high soil moisture levels.

The Tobacco cut worm (Spodoptera litura Fab.), a polyphagous defoliating insect is a major pest on groundnut in Asia. Screening germplasm for resistance to Spodoptera litura in the field under high infestation revealed significant genotypic variation. Low damage was observed on Mutant (28-2), NC Ac 343, ICGV 86031, R 9227 and TAG 24. In the laboratory rearing of insect, the resistant genotypes, NC Ac 343, Mutant 28-2 and R 9227 affected larval growth and survival, pupal development, adult emergence and fecundity indicating antibiosis as the principal mechanism of resistance. The reduction in larval weight reared on ICGV 86031 could be due to the toughness of leaves. Though the genotype TAG 24 suffered low damage in the field, the larval and pupal development was normal in the laboratory revealing avoidance/non-preference as the mechanism of resistance. Based on the insight gained from the growth and development of the insect on resistant genotypes, the gain in weight (GIW) of the pre-starved larvae was assessed for its suitability in rapid screening. GIW in 24 h by III instar larvae fed with fully expanded II leaf was found suitable in screening for resistance based on antibiosis. The method could be adopted for screening large breeding populations in a short time under laboratory conditions. The resistant genotypes with different mechanisms of resistance could be hybridized to pool the resistance genes for enhancing the level and effectiveness of resistance.

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