Studies on the Relationship between Silkworm Rearing and Tobacco Cultivation I. Tobacco Field Cultivated in Mulching System Affecting the Silkworm Rearing in Autumn Season

연초재배가 양잠에 미치는 영향에 관한 연구 I. 뽕밭 부근의 담배개량 Mulching 재배가 추잠작에 미치는 영향에 관한 시험

Silkworm is known to be damaged under the unfavorable environmental conditions. Recently, it has been often argued that nicotine is a main factor to affect the silkworm nutritional balance and to result in decrease of quantitative characters, and unbalance of larval nutrition. Especially in spring season, there is tendency to produce nicotine damage to silkworm fed with the mulberry leaf near to tobacco field early cultivated in mulching system. In these connections, the trial was made in the different pots placing by the different distance 10rn, 20m, 40m, and 60m in the direction of east-north from the tobacco field. Location of pot near to the tobacco fold is 40m below the tobacco Held and gradually higher than the tobacco field by 10 degree of slope. In addition, when the mulberry field is divided into two areas from the east-south to west-north, southern east zone is lowering down below 10 degree of slope and has 36％ of east-south wind, 21％ of south-east wind and 16％ of south wind, etc. Pots are left on the mulberry field from the completion of lower part leaf harvest to just before upper part leaf harvest is completed for 32 days. Then silkworm at 4th-5th stage was fed with the leaf grown during the period and larval characters are statistically analyzed. The results are summarized as follows： 1. 10-40m distant pot statistically at the same level has the longest larval duration and 60m distant pot is. not significant at 5％ level. Whole larval duration has same tendency as in the 5th larval duration. 2. Percentage of delayed molting larvae at the 5th stage is increased in 10m distant pot and there is no significance statistically in other pots, as compared with that of control. 3. It is not showed that there is no damage to mortality of the old larvae in 60m distant pot. 4. 10-20m distant pot produces a low pupation and others are at the same level statistically at 5％ significance, 5. It is showed that nicotine damage is occurred in single cocoon freight and cocoon shell weight up to 60m distant pot, rather higher damage in cocoon shell weight than in single cocoon weight. 6. It is showed that cocoon yield from 10, 000 molted larvae including double cocoon is decreased up to 40m distant pot far from the tobacco field in which 40％ of cocoon yield in 10m distant pot by 7kg, 26％ of cocoon yield in 20m distant pot by 3.9kg, 24％ of cocoon yield in 40m distant pot by 3.6kg, and 12％ of cocoon yield in 60m distant pot by 1.8kg, as compared with control. However, there is no significance statistically at 5％ level in 60m distant pot. With these above results, it is concluded that nicotine da mage could be occurred in cocoon yield and cocoon quality up to 60m distant far from the tobacco field.

개양 Mulching에 의한 조기재배 담배밭 부근 뽕잎이 추잠작에 미치는 영향을 알고자 뽕나무 pot 100m구를 대조로 하여 10m, 20m, 40m, 60m 구별로 담배밭으로부터 동북쪽에 배치하였으며, pot가 배치된 밭의 경사는 담배밭과 근접된 지점은 담배밭 보다 지반이 40cm 내외로 낮았으나 담배 밭에서 멀어질수록 10％ 내외 경사로 점점 높게 위치하고 있었다. 한편 담배밭은 전 면적의 1/2 정도를 동남방향에서 서북방향으로 나누어 남서편은 10％ 미만의 경사로 점점낮게 위치하고 있었다. 오독처리 기간중의 풍향은 동남풍아 36％로 주풍 이었고, 남서풍이 21％, 남풍이 16％, 기지의 순이었다. Pot는 담배 하엽수확 완료 후부터 상엽수확 완료 직전까지 32일간을 경합시켰으며 경합기간 중 신장된 뽕은 pot격리 후 33일째인 4령말기부터 상업전까지 11일간에 걸쳐 급여시험한 결과를 분석한 각각의 계량형질에 미친 영향을 요약하면 다음과 같다. 1. 5령경과는 10m구부터 40m구까지 같은 수준으로 대조보다 길었으며 60m구는 대조와 유의차가 없었고 전령경과도 대체로 같은 경향이었다. 2. 5령기잠 지면잠비율은 10m, 20m구단이 가장 높았고, 기타구는 대조와 유의차가 없었다. 3. 장잠감잠비율은 60m구까지 피해가 인정되었다. 4. 화용비율은 10m구에서 20m구까지가 가장 낮았으며, 기타구는 대조와 유의차가 없었다. 5. 전견중, 견층중은 각각 60m구까지 피해가 인정되었으며, 전견중 보다는 견층중의 피해가 크므로서 그 결과, 견층비율 역시 같은 경향의 피해를 보였다. 6. 수견량(대 소잠 1만두 옥견포함)에서는 담배밭에 가까운 구 일수록 대조에 비해 현저히 감수가 되어 고도의 유의차가 있었고 60m구는 대조와 같은 수준이었다. 단, 실제 수견량에 있어서는 10m, 20m, 40m, 60m구는 각각 7kg, 3.9kg, 3.6kg, 1.8kg으로 잔수되어 그 피해율은 40％, 26％, 24％, 12％로 감수된는 경향을 나타냈다. 이상을 종합하여 볼때 수견량과 견층의 피해거리는 60m 이상까지 있는 것으로 사려된다.