| Abstrakt: |
Tasar silkworm quality seed in adequate quantity is vital for raw silk production and BSM&TCs cater the need of basic seeds in the country. In recent years, environmental rigors like very high summer temperature have hampered seed production especially during first crop. The present study deals with the impact of abiotic factors viz. temperature, humidity and rainfall on the seed production of Daba (trivoltine) tasar silkworm at BSM&TC, Pali during 1st crop grainage taking into account last five years data. The year 2022 was very harsh for diapausing cocoons as the highest temperature from 1st April to 23rd May was above 400C and average was above 350C accompanied with humidity much below threshold lower limit as the rainfall was scarce. The preservation loss calculated before sorting of cocoons for processing was 19.22%. Again out of 1,52,432 cocoons processed dfls production was 21,450 @ 7.11 cocoons required for production of one dfl although 45,469 couplings were obtained. Out of the couplings 3,652 (8.03%) did not lay eggs and 4,332 (9.53%) were rejected due to very less eggs laid. A total of 1,23,119 (80.7%) moths emerged thus with a tally of about 20% death of pupae. Average realized fecundity was only 123 and depression in eggs was observed. So, the number of unfertilized eggs was determined on the basis of froth floatation during washing immediate after moth testing and also on 6th day of coupling. It was found that about 39 % of eggs were unfertilized. More number of female moths emerged in first phase in comparison to males indicating towards the death of male cocoons. The grainage data of last five years were superimposed with the atmospheric data. It was found that the high average temperature (33 to 360C) with continuous highest temperature above 400C with average humidity (30% or below) over a period of 40 days preceding the grainage operation result in adverse impact on egg production. The lethality or death of sperm is also suspected which need to be studied further. The intermittent rain fall during four preceding months is beneficial for diapausing cocoons. [ABSTRACT FROM AUTHOR] |
