Induction of genetic variability in guinea grass (Panicum maximum Jacq.) Var.Makuenii

Abstract

Guinea grass (Panicum maximum J.) being a facultative apomicts under continuous vegetative propagation carry very little variability. The cross incompatibility also restricts attempts to produce variability through conventional methods of plant breeding. The main objective of the study is to induce variability through mutations in guinea grass variety Makuenii using gamma rays at four doses ranging from 15 Krad to 30 Krad and EMS at four concentrations ranging from 0.25 percent to 1.00 percent. The effect of the mutagens in M1 and M 1 V1 generations were studied. The observations in the M1 generation indicated that germination of seeds was progressively reduced with increase in the dose of mutagens. The survival and early growth of seedlings were adversely affected by the mutagen treatments. The seedlings appeared to suffer from the transplanting shock as indicated by high mortality of the plants in the field. Higher doses of mutagens induced height reduction. However the tillering ability of the plants did not seem to have been affected but higher doses of mutagens inhibited flowering initiation. Pollen sterility in M1 generation exihibited dose dependence. A few chlorophyll chimeras were observed in the M1 generation. Morphological abnormalities induced dwarf, tall, semi open and open types with leaf and inflorescence modifications. The means of M1 V1 clones exhibited both positive and negative shifts from the population means with respect to plant height. Treatments 20 Kard gamma rays and 0.25% EMS caused positive shifts in the means of girth at internode and leaf area index. Certain clones were identified to have higher green fodder yield than the control. These clones also had higher girth at internode and higher leaf area index. The study revealed that variability with respect to plant height, girth at internode, leaf area index and green fodder yield can be induced by mutations using appropriate doses of gamma rays and EMS. A medium dose of 20 Krad gamma rays and a relatively lower dose of 0.25 percent EMS were found to induce more useful variations.