Studies on Gamma Rays Induced Cyto-Morphological Variations and Procurement of Some Induced Novel Mutants in Kalmegh [Andrographis paniculata (Burm. f.) Nees]

In order to increase genetic variability for improvement and better adaptation in the present days' changing climate, present investigation has been done in Andrographis paniculata (Burm. f.) Nees (also known as Kalmegh in Ayurveda), an ethno-medicinal wild plant with highly immune-boosting properties. For the purpose, healthy, dry and homogeneous seeds were treated with four doses of gamma rays from Co-60 sources at the dose rate of 1.55 Gy per second; selected on the basis of LD 50 i.e. 25 Gy (gray), 50, 100 and 200 Gy along with one set of non-irradiated seeds and sown in triplicates in a completely randomized block design (CRBD). Higher doses were detrimental hence not suggested for further mutation breeding experiments. However, lower doses (viz. 25 and 50 Gy) of gamma rays were stimulatory; had induced some significant ( p > 0.5) variations in several lucrative traits of Andrographis paniculata (Kalmegh) viz. Plant height, leaf area, number of branches per plant, length of internodes, fruit length, and seeds per fruit. Some induced novel mutants (viz. bushy, dark green leaves mutant and tricotyledonous leaf mutant in M 2 generation) have also been procured. This is, to the best of our knowledge, first report on induction of tricotyledonous leaf mutant in A. paniculata using gamma rays.