Irradiation effect on leaf sclerophylly, gas exchange and stomata in sweet orange (Citrus sinensis)

The study was carried out in mutated population of sweet orange [Citrus sinensis (L.) Osbeck] cv. Mosambi developed from varying dose of gamma rays (10-35 Gy) to determine its effect on leaf sclerophylly, photosynthesis and leaf anatomical characters at the Division of Fruits and Horticultural Technology, ICAR-Indian Agricultural Research Institute, New Delhi during 2017 and 2018. As compared to wild type leaf area, fresh and dry mass was stimulated by 19.53, 18.42 and 20.37% in mutant GS-3 developed from 10 Gy, while in the mutants GS-33 and GS-35 developed from 35 Gy >50% inhibitory effects were noticed. Leaves were however, 82.06% more succulent in the mutant developed from 30 Gy. Mutated population showed dose dependent effect with regard to SLA, SLW and DFT. A significant decline in the photosynthetic rate and stomatal conductance was noticed at 35 Gy in GS-32, whereas mutant GS-34 developed from the same irradiation dose had the minimum transpiration rate. Stomata length and width in the mutants GS-17 and GS-15 as compared to wild type registered an increase of 25.50% and 15.96%. A general reduction in stomata number was observed in the mutated populations. Our result indicated alteration in traits of the mutated population which are of significance and can be used as a selection criterion for improvement of sweet orange.

Automated summary

This study investigated the effects of varying doses of gamma rays on mutated populations of sweet orange, showing significant alterations in leaf characteristics, photosynthesis, and anatomical features. The mutations displayed dose-dependent responses, with varying impacts on leaf traits and physiological processes. These findings suggest potential criteria for selecting improved sweet orange varieties.