Dear Jakty,

It is unlikely that anyone can give a direct answer. there is no literature on the response of this species to gamma rays. You should first test this by irradiation of batches of seeds with different doses (I suggest 0, 50, 100, 150, 200, 300, 400 Gy), grow those in about 3 replicates. Then take the germination count, seedling height (after about 1 month) and other characters such as pollen fertility and seed set. Use the 50% reduction in these values for irradiating a larger batch of seeds. In the meantime, you can use the plants from the growth reduction study also for the breeding programme. Details of how to sample the M1 population and selection in M2 can be found in literature. 

I have a review on mutation breeding in my ResearchGAte page you can download.

Good luck!

Thank you very much for your answer.

Unfortunately, it is uncommon way if we grew those Patchouli plants from the seed, since the plant is vegetatively propagated. I will try to use the doses you suggest, though.

BR

Dear Jakty, I fully agree with Ranjith. You may try with cuttings as well. As Ranjith suggested, in a very empirical way you have to test different radiation doses of gamma rays with the batches of cuttings. Make sure you use the cuttings of same stage and age for your pilot experiment. Good luck.

Sorry, I did not realise that yours is a vegetatively propagated species. Treating buds will result in chimeras that you will have to clean up in several propagation cycles. If you have a good somatic embryogenesis protocol or callus-based regeneration system, you can avoid that by treating embryogenic cultures or callus. A good example you will find in literature is banana, but there are other species also. If you are treating vegetative buds, please use a reduced dose, not more than 200 Gy or even less.