Study of Microbial Population and Enzyme Activities in Intercropped Peanut Rhizosphere with Different Nutrient Application.

The aim of this study was to investigate the effect of different levels of chemical fertilizers (CF) alone or in combination with farmyard manure (FYM) under lime or no lime amelioration on biological properties of the rhizosphere soil of peanut, grown as intercrop with sabai grass (Eulaliopsis binata (Retz.) C.E. Hubb) in an acid lateritic soil. The effect of five fertilization levels viz., no CF (F0), CF @ 20:40:30 (F1), CF @ 40:80:60 (F2) kg ha-1 NPK, F1 + 2.5 t FYM ha-1 (F3) and F2 + 5 t FYM ha-1 (F4) with (2 t ha-1) and without lime application were studied on the bacterial density, dehydrogenase and phosphatase enzyme activities (i.e. acid and alkaline phosphomonoesterases), nitrogen accumulation in nodules and phosphorus solubilizing power at 25, 50, 75 and 100 days after sowing of peanut for two years. Results showed significant effects of fertilization levels and growth stages of the crop on the microbial activities. Populations of symbiotic nitrogen fixing and phosphorus solubilizing bacteria, soil enzyme activities, nitrogen accumulation in nodules and phosphorus solubilizing power in the FYM+CF treated plots significantly increased compared to sole CF treatments under both lime and no lime application. Lime application improved the activity of dehydrogenase and alkaline phosphomonoesterase enzymes, while decreased acid phosphomonoesterase activity. This study revealed that integrated application of optimum level of inorganic fertilizer, farmyard manure along with lime could improve the biological properties of an acid lateritic soil as well as the growth of peanut under sabai grass-peanut intercropping system.

Photoperiodic effect on some enzymes and metabolites in diapausing Antheraea mylitta pupae and Philosamia ricini larvae during development.

The variation in acid phosphatase (EC 3.1.3.2) activity in Antheraea mylitta was similar in all light and dark groups exposed to different photophases (LD =0:24, 24:0, 18:6, 14:10, 10:14 and 12:12 h) maintaining all along a higher activity than its alkaline counterpart. The highest activity was recorded on day 82 in LD group 10:14 h. The non-diapausing Philosamia ricini larvae registered highest activity in LD group 0:24 h on day 5. Alkaline phosphatase (EC 3.1.3.1) activity was low all through metamorphosis in both the lepidopterans, although significantly elevated activity was observed on day 5 in larvae of all Philosamia ricini LD regimens and on day 82 in Antherae mylitta. Photoperiodic effect on Phosphorylase (EC 2.3.1.1) activity, glycogen and inorganic phosphates content have also been studied. Exposure to LD 10:14, 14:10 and 18:6 h provoked early diapause termination in Antheraea mylitta. The non-diapausing Philosamia ricini was unaffected in moth emergence but the emerged adults of LD 24:0 and 0:24 h groups were unhealthy, small and did not mate or oviposit.