Physical mutagenesis is an effective mutational breeding method for improving various morphological characteristics of ornamental plants. The experiment was undertaken to investigate the effect of various dosages of gamma irradiation on seed germination of Catharanthus roseus (Madagascar periwinkle). The experiment was conducted at UCIARS, Weligatta to find out the appropriate gamma dosages for selecting planting materials for C. roseus with the purpose of crop improvement under gamma irradiation. Healthy matured dry seeds were exposed to 60 CO Gamma irradiation source at Horticultural Crops Research and Development Institute (HORDI), Gannoruwa, Sri Lanka. Treatments included six different gamma dosages such as (T0-control) 0 Gy, (T1) 100 Gy, (T2) 200 Gy, (T3) 300 Gy, (T4) 400 Gy and (T5) 500 Gy.
A Completely Randomized Design with four replicates and twelve samples per replicate was employed under shade house conditions. Data on germination were collected daily until constant germination was observed for up to 10 days, while other management practices were maintained. Data were analyzed using Minitab 17 statistical software with one-way ANOVA and Tukey's test to identify significant differences among treatments at a 0.05 significance level. The results revealed that the higher dosages of 60 CO Gamma irradiation significantly decreased the germination ability of C. roseus seeds (P<0.05). Specifically, 400 Gy and 500 Gy treatments resulted in significant reductions in germination, whereas lower dosages less than 400 Gy did not exhibit such effects. Seed germination started on day 3 after planting for all treatments except for T5 (500 Gy). Indicating a delayed germination initiation, seeds subjected to the T5 treatment began germination on day 5 after planting and exhibited a significantly lower overall germination percentage when compared to other treatments.
The highest germination rate (84%) was observed in the control seeds, which were not subjected to gamma irradiation, whereas the lowest germination rate (8%) occurred in seeds treated with 500 Gy of gamma irradiation. High doses of gamma irradiation negatively impact germination by potentially inducing oxidative stress, which leads to cellular damage and reduced germination efficiency. At higher doses, such as 400 Gy and 500 Gy (as in T4 and T5 treatments respectively) radiation can cause significant damage to the DNA and cellular membranes, leading to delayed germination initiation and reduced overall germination percentages. These findings have practical implications for the use of gamma irradiation in plant breeding and seed preservation, emphasizing the need to carefully optimize irradiation doses to avoid adverse effects on seed germination of C. roseus.
Sriwarnsinghe, Nelka & Vidanapthirana, Nisansala & Silva, Tara & Subasinghe, Siripala & Dahanayake, Nilanthi. (2024). EFFECT OF GAMMA IRRADIATION ON SEED GERMINATION OF Catharanthus roseus (MADAGASCAR PERIWINKLE).