Cytological implications in interspecific cross of Arachis involving Arachis hypogaea var VRI 2 and Arachis stenosperma

Abstract

Unstable triploid and sterile derivatives were obtained upon inter-specific hybridization of Arachis hypogaea var VRI 2 (2n=4x=40) and Arachis stenosperma (2n=2x=20). Chromosomal doubling was resorted using colchicine enabling doubling the ploidy level of this triploid (3x) to get an unstable hexaploid derivative. The manuscript presents the cyto-morphological features of the unstable derivatives to frame a suitable breeding strategy for evolving the stable culture tolerant to major foliar diseases. Phenotypic traits like leaf colour, length and width of calyx tube, poor pollen fertility and abortive ovarian system were found to be dominant in the triploid. Chromosome doubled triploid progeny possessed leaves with larger veins, semi spreading habit, slow growth, shriveled anthers and improved pollen fertility as compared to triploid. While the normal meiotic behaviour witnessed among parents, the abnormal meiotic system as evidenced from the formation of trivalents and quadrivalents among triploid and hexaploid derivatives. Abnormal sporads also recorded among triploid and hexaploid leading to formation of sterile pollen grain.