利用珈瑪線處埋椪柑砧木誘導抗黃龍病突變之研究

Studies on Utility of Gamma Ray To Treatment Ponkan Rootstock For Inducing Mutation To Resist Quick Decline (Tristeza)

台灣氣候溫暖，雨量充沛，頗適於柑桔之生產。據農林廳近年之統計，栽培面積已超過一萬公頃，年產約六千七百餘萬公斤，光復初年，栽培面積已增至一萬公頃以上。惟於民國四十四年前後，忽為黃龍病所侵襲，危害最嚴重者為新竹之新埔，許多柑桔園為之完全摧毀，否則今日之產量，當更可觀。

The only Ponkan rootstock is Citrus sunki and had been used for handred years in Tankon. Unfortunately this rootstcck suffers from quick decHne since s.everal years ago and many citrus groves have been destroyed. Right now we have not found resistance rootstock which may be adopted to ponkan as Citrus sunki. As we know for many crops may make use of radiation in inducing mutation for disease resistance and this work is successful in many countries. So we try to use this method to induce the Citrus sunki mutations hoping that a new strength for resisting quick decline will be found in the mutations, This test was caried out in 1963, treatment with Gamma Ray on two years old citrus sunki seedlings. the dosage was used as 500r, lOOOr, 3000r, 5000r, and 8000r, after the radiation treatment the seedlings were planted in an one-foot pot. while the buds have been stopped thier elongation growth, Serious observation was done for determining the variations, and than a inoculation was done by tissue grafting for observing thier disease resistance. The Preliminary results are Summarized as follows. (1) The prelininary investigation indicated that the Gamma Ray radiation treatmentwith the dosage of 5000r and 8000r Were More effective to induce the bud varia tions, but showed a few inhibited to the bud sprout and forced some died.