Morphometric description and genetic diversity in 208 monoecious and pistillate castor (Ricinus communis L.) germplasms/genotypes: an unexplored industrial oil crop in semi-arid tropics

It is axiomatic that castor (Ricinus communis L.) is an industrially important oil crop with wide use. Though it is possible to augment oil yield by selecting appropriate parental lines, seed yield of the parents should also be given due weightage to meet out the increasing oil demand. Hence, it is imperative to improve the seed yield by breeding elite hybrids/varieties. Morphological description of 208 castor genotypic population for eight qualitative traits was carried out and considerable polymorphism existed among the collection. Maximum genotypes were R2 and R3 morphotypes because of the dominant nature of red stem color and blooming nature. K means clustering separated the genotypes into 20 clusters with cluster 4 and 20 as well separated ones. Cluster 4 could serve as female parent since the cluster was composed of pistillate lines and cluster 20 as male parent during hybridization. Path coefficient analysis supported the correlation coefficient that effective spike length and capsule weight showed high positive direct effects with seed yield. Also, the analysis revealed primary spike length and effective length of primary spike as the variables with the largest weightage. The first four components accounted for 75.95% of the variation cumulatively. The components were rotated with varimax rotation and the variability contribution was similar to the normal (76%). High communality values specified the reliability of the studied variables in explaining the total variation. Considering both cluster analysis and PCA, the genotypes SKP 84, DPC 19, JP 65, JC 3, JC 26, RG 27, ICS 210 and RG 3477 possessed superior agronomic performance. Hence, these genotypes/germplasms had immense value as parents in breeding varieties/hybrids to meet out the global oil demand.