Improvement of tuber yield in yam bean by mutation induction

Full text: The genus Pachyrrhizus, a native of Mexico and Central America is now widely distributed throughout the tropics. Pachyrrhizus erosus (L.) Urb., commonly known as the yam bean is cultivated in many parts of India for its edible tubers. The young tubers have a crisp and juicy flesh and can be eaten raw or cooked. Genetic variability for agronomically important characters is rare. It was therefore felt desirable to increase it by mutation induction. Seeds of a locally adapted variety were subjected to gamma irradiation (10, 15, 20 and 25 kR). Evaluation of the M3 raised from the different treatments unveiled mutants possessing significantly higher yields than the control. While the control plants showed a mean tuber yield of 168 g, one of the higher yielding mutants from the progenies of 10 kR treatment recorded 415 g. Two other mutants selected from the 25 kR treatment showed yields of 401 and 411 g. These mutants, first identified in M2, were found to breed true in M3-M5 generations. Yield trials conducted in M5 generation showed more than two-fold increase in yield by the mutants. Apparently there are remarkable possibilities of improving the yield potential in yam bean by mutation induction. (author)