Anatomical studies of in vitro raised haploid and diploid citrus plants obtained through gamma irradiated pollen

Abstract

Histological studies of stem, root and leaf of ovule and embryo cultured haploid and diploid plantlets of Citrus grandis × C. sinensis and Citrus grandis × C. limetta crosses were carried out. Area of xylem and phloem in stem increased gradually with increasing age of explants in both cross combinations; however, it was measured minimum in haploid plantlets (1.95 and 1.62 mm2, respectively) as compared to diploid ones. Similar trend was also observed for the area occupied by xylem and phloem in root section of those plantlets. A negative relation was obtained between the ploidy level and per cent area of xylem and phloem within the stem and root of those plantlets. No cuticular and epicuticular wax was observed on the leaf surface in any plantlets irrespective of ploidy level and age of cultured explants, although the leaf thickness increased gradually with the increasing age of the explants with minimum in haploid one. Although, the area of all the parameters evaluated in stem, root and leaf under this experiment were reduced in haploid plantlets but they were well developed as similar to diploid ones which confirmed that these haploid plantlets can also grow normally under open field condition, if intensive care is taken during acclimatization.