Inheritance patterns of morphological Characters and the karyotype of crotalaria Species in kenya

Abstract

Slender leaf (Crotalaria spp.) is an African indigenous leafy vegetable with high nutritional benefits. However, despite these benefits, this vegetable has been neglected in terms of research, and information on breeding techniques is scanty. This study aimed to determine the inheritance patterns of morphological characters and the karyotype of Crotalaria. Crotalaria accessions from Kakamega, Bungoma, Vihiga, Busia, Siaya, Homa Bay, Kisumu, Migori and Kisii were subjected to inheritance studies under similar field conditions. The experiments were carried out at the University of Embu Farm. Two landraces FKK 0039 and FHB 0211 were used to develop an artificial pollination protocol. The experiment was set up in a completely randomized design (CRD) in a greenhouse with Crotalaria ochroleuca as the female parent and Crotalaria brevidens as the male parent. Six plants were planted in pots replicated three times for both male and female parents. Six-day-old flower buds of the female parent were emasculated and pollen from a freshly opened flower was rubbed over the stigma of the emasculated flower. The pollinated stigma was inserted back into the keel petal and covered by the wing and standard petal. Data on crossing success rate, pod and seed production was subjected to analysis of variance. Eleven parents of Crotalaria were used in a diallel cross to determine genetic control of morphological traits. The experiment was laid out in a triple lattice design with 110 hybrids and 11 parents. The data were evaluated for the inheritance of six traits using Hayman’s method and Griffing’s model 1 for estimation of gene action, general and specific combining abilities. A mean separation was done by Tukey’s HSD test at 5% probability level. Twenty Crotalaria seeds were grown in petri dishes for karyotype studies. Chromosome morphology was observed and the chromosome numbers were noted. Chromosome positioning at different mitotic stages were observed under a compound microscope. The developed artificial pollination method showed 75% success rate in the interspecies cross of C. ochroleuca and C. brevidens. Time of crossing did not significantly influence the success rate, pod and seed production. Data showed significant additive and dominance gene effects for two and six traits, respectively. The general combining ability and specific combining ability were significant for plant height and leaf length. This study recorded a diploid chromosome number of 2n = 2x = 16 for five Crotalaria species; C. trichotoma, C. brevidens, C. ochroleuca, C. spectabilis and C. intermedia. The diploid chromosome number of 2n = 2x = 16 was reported for the first time in C. trichotoma. The study demonstrated artificial interspecific pollination of Crotalaria by rubbing method involving keel petal incision. This protocol lays the foundation for genetic studies and improvement of Crotalaria spp. The study showed the importance of general combining ability for parental selection and specific combining ability in hybrid production.