Abstract:
Ionizing radiation, particularly gamma rays, is widely used to induce genetic
mutations for improving morphological traits and enhancing genetic diversity in
plants. In citrus plants, such mutations can be achieved by irradiating leaves and
propagating the resulting mutants through vegetative methods. This study was
conducted at the BINA research farm with the objective of developing Citrus limon
mutants using gamma radiation and analyzing their morphological characteristics
through visual inspection, alongside genetic diversity assessment using hierarchical
clustering. A total of 400 fresh leaves were collected from the mother plant (BINA
Lebu-1) and exposed to different doses of gamma radiation (0, 60, 80, and 100 Gy),
divided into four treatment batches. The irradiated samples were planted in unit
plots following a Randomized Complete Block Design (RCBD). Root and shoot
development were monitored visually after 3 to 4 months. Maximum root length
was observed at 100 Gy, the highest root quantity at 60 Gy, and the highest success
rate at 80 Gy. After 7–8 months, mature plants were further assessed, and leaves
were collected for genomic analysis. Genetic relationships among the different
treatment groups were evaluated using a Dendrogram generated through simple
hierarchical clustering. The results indicated clear genetic dissimilarities between
irradiated (60, 80, and 100 Gy) and non-irradiated (0 Gy) plants, with the 100 Gy
group showing the greatest genetic distance from the others. Due to time
constraints, fruit production could not be observed. Nonetheless, the study
demonstrates the effectiveness of combining visual inspection and genetic distance
analysis in evaluating gamma-induced citrus mutants developed via the leaf-cut
method.
