Studies on Micromorphology and Karyotype Analysis of Three Mulberry Genotypes (Morus spp.)

The study of karyotype is of great value in modern taxonomy for evolving progeny of different ploidy levels of hybridization. Stomatal frequencies are important parameters while selecting drought resistant genotypes as being correlated with drought and disease resistant. Micro-morphology, chromosome numbers and characters of three indigenous mulberry cultivars were studied. S₁₃ and V₁ are diploid with 2n=28 and Tr-₈ is triploid with 2n=42 somatic chromosomes numbers respectively. Somatic chromosome length ranges from 1.29μm to 2.59μm where as an arm ratio ranges from 0.49 to 0.97μm. Their karyotypes were commonly bi-modal, decreasing in length from the longest to the shortest chromosomes. Experimental results have confirmed that, out of three varieties studied two are diploids with 2n=28 and one variety showed 2n=42 chromosomes. Lesser frequency of stomata in triploid than diploid varieties. Stomatal frequency and size decrease with increase in ploidy level. It can be suggested that triploid with lesser stomatal frequency are suitable for breeding triploids resistant to drought conditions.

Author(s): K.H. Venkatesh

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