Effects of gamma-irradiated seeds on germination and growth in Capsicum annuum L. Plants grown in a greenhouse

Gamma irradiation of Capsicum seeds is useful for inducing heritable mutations for breeding or for generating research material for heritability studies on agronomic traits. This study evaluated the effects of gamma-irradiated seeds on germination and plant development in a native cultivar of landrace 'Chile de Agua' (C. annuum L.) that was donated by a farmer in Oaxaca, Mexico. The seed lots were germinated at 20, 40, 60, 80, 100 and 120 Gy, along with a control without irradiation, in substrates of peat moss. The seedlings were transplanted in a greenhouse under a randomized complete block design with four replications. The results showed neither significant differences in the total germination and emergence index nor specific patterns between irradiated and non-irradiated seeds. In this trial, in general, the seed lots had low germination rates, 41% in the control and 24 to 44% in irradiated seeds. The analysis of variance revealed that the gamma radiation doses evaluated did not significantly increase plant phenotypic expressions and agronomic traits such as fruit length, plant height, and flowers per axil. The doses of 40 and 80 Gy negatively affected the average number of fruits per plant (6.2 and 7.4 fruits, respectively), while the control had 9.5 fruits. In the vegetative traits, there were no significant differences between the gamma radiation doses of 20 to 120 Gy and the control; except in plant height at 30 days after transplanting. In physiological traits, flower and fruit, in terms of the average number of fruits per plant, the 60 Gy dose had the highest value (12 fruits) and the 40 Gy dose the lowest (6.2 fruits), however, both do not differ significantly from the control (9.5 fruits).