Selection of improved genotypes in M4 mutants of Tarom Mahalli, Hasani and Anbarboo local varieties

Development of improved rice varieties for paddy fields relies on the assessment of genetic resources and the selection of the superior plant material (Kiani & Nematzadeh, 2013). One of the best methods for improving the high quality but low yielding rice local varieties, which are highly appreciated by customers, would be mutation breeding, as it changes only rather small parts of genome and there are high chances that the good quality of these varieties would remain unintact (Majad et al., 2003). Gamma irradiation has been reported to be highly successful in rice breeding (Wani & Anis, 2008).
Material and In order to study yield and agronomic traits in gamma-induced rice mutants, 133 M4 mutants from Tarom Mahalli, Hasani and Anbarboo local varieties, along with their parents, were planted under an augmented design with 6 blocks. Measurements were made on the number of days to flowering, plant height, number of panicles per hill, yield and yield components.
Results showed that mutation produced significant genetic diversity in mutants for all of the studied traits. Cluster analysis divided the mutants from Tarom Mahalli, Hasani and Anbarboo varieties into 5, 3 and 4 groups, respectively. On average, mutants were earlier than their respective parents and had a shorter plant height. Although most of the mutants had a yield similar to their parents, but the selected mutants had yields 10 to 27% higher than their respective check. The improvement in yield was attributed to the higher number of grains per panicle. Based on the results, eight lines with high yield, and 12 lines with same yield as checks but with early maturity and short plant stature, were selected.
Wani & Anis (2008) reported that improvements in morphological traits such as number of grains per pod and number of pods were the main reasons for the higher performance of three gamma-induced pea mutant lines. Esfahani & Fotokian (2003) found a rice mutant line from Domsiah local variety which was 15 days earlier than the original variety. Zenalinajad et al. (2003), using cluster analysis based on morphological traits, divided their 100 rice genotypes into four groups.
Days to 50% flowering of Hasani and Tarom mahali were 95 days, while in Anbarboo variety it was 108 days. The yield of Hasani variety was lower than the other varieties. The range of plant height in the mutants was between 100-135 cm. Only one mutant of Anbarboo had163 grains per panicle, which it was significantly higher than the other Anbarboo mutants. The genetic gain of yield in mutants was between 11 to 17 percent over Anbarboo check. 20 Mutant liness were selected based on higher yield than checks and shorter growth duration, and most of them were from groups 3 and 4. They had lower height and more filled grains per panicles than check vareties.