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ThesisItem Open Access PHENOLOGY AND COCOON CHARACTERS OF ERI SILKWORM (Samia ricini) AS AFFECTED BY TEMPERATURE AND HUMIDITY UNDER JORHAT CONDITIONS(AAU, Jorhat, 2019-07) Das, Sudipta Kumar; Dutta, L.C.An investigation on “Phenology and cocoon characters of Eri silkworm (Samia ricini) as affected by temperature and humidity under Jorhat conditions” was carried out in the Department of Sericulture, Assam Agricultural University, Jorhat during summer, autumn, early spring and late spring seasons in the year 2018-19. The results revealed that the occurrence of the phenophases and cocoon characters varied significantly in different rearing seasons. The phenophases viz. egg laying period, incubation period, egg hatching duration, larval duration (instar-wise and total), instar-wise moulting duration and cocoon spinning period were found to be longest during early spring season followed by late spring and autumn season. The shortest duration of the phenophases was observed during summer season. Cocoon characters viz. cocoon weight and cocoon shell weight were highest in early spring season followed by late spring and autumn season while lowest values were observed during the summer season. The egg hatching percentage and instar-wise larval weights were found to be highest during early spring season followed by late spring and autumn season while the summer season registered for the lowest values. Larval accumulated growing degree days were observed to be highest during early spring followed by summer, autumn and late spring. Most of the phenophases and cocoon characters were negatively correlated with temperature and relative humidity. The accumulated growing degree days during larval period had a positive effect on the cocoon yield parameters. Predictive models for growth and cocoon yield of eri silkworm developed which indicated the most significant weather factor (temperature and relative humidity) responsible for growth and cocoon yield. Thus, from the present investigation, it can be inferred that the occurrence of different phenophases and cocoon characters of eri silkworm were largely regulated by the environmental temperature and relative humidity during the seasons. The best season for rearing was found to be early spring (March-April) considering the larval growth parameters and cocoon yield of eri silkworm. Predictive models developed on the basis of temperature, relative humidity and accumulated growing degree days can be used to estimate the growth and cocoon yield of eri silkworm in different rearing seasons. The findings of the study will help to develop agro-advisory bulletin for various seasons which will help the farmers to adapt eri culture in a proper and efficient way for quantitative and qualitative production of eri cocoon and silk.
