Characterization of second generation colchiploids in sweet orange (Citrus sinensis) cv. Mosambi with respect to morpho-physio-biochemical traits

Abstract

Induction of tetraploidy in citrus is aimed for the development of triploid seedless cultivars, which are needed for meeting the requirements of the citrus industry. The present study was carried out during 2020 and 2021 at ICAR-Indian Agricultural Research Institute, New Delhi to identify suitable tetraploids in vegetatively propagated second generation of the colchiploids in sweet orange [Citrus sinensis (L.) Osbeck] cv. Mosambi. The 3-year-old, 20 2nd generation colchicine treated (0.05, 0.10, 0.15 and 0.20%) plants, developed from the putative tetraploid branches of the first generation colchiploids of sweet orange cv. Mosambi, budded on Jatti khatti rootstock along with their wild (parent) type, were characterized based on morphological and physiological traits. Leaf area, fresh weight and succulency increased, but density of foliar tissue and leaf dry weight reduced in majority of the colchiploids. Leaf length, width and thickness also increased in colchiploids in comparison to their wild type. Fruit weight, length, width and rind thickness also increased in the colchiploids in comparison to their wild type. Juice TSS reduced, but acidity increased in majority of these Mosambi colchiploids. Seed number was lowest in M-3 (7.33) colchiploid. Total carotenoids and chlorophyll fractions also increased in majority of the colchiploids. On the basis of morpho-physio-biochemical trait characterization, 8 solid tetraploids (M-1, M-3, M-2, M-5, M-4, M-7, M-13 and M-16) of Mosambi were identified, which can be used in future breeding programmes for the development of seedless triploids of Mosambi.