Genetics parameters and path analysis in Cannabis sativa L.

Abstract

The ostracism to which the species was subjected in the last century generated a weak use of genetic variability in the genetic improvement of characteristics of interest. This study aimed to estimate genetic parameters, correlation, and path analysis for 13 agronomic traits, cannabidiol (CBD) and tetrahydrocannabinol (THC) content in 10 cannabis genotypes from different departments of Colombia. The study was conducted under greenhouse conditions with a polycarbonate cover and anti-aphid mesh at the La Esperanza farm in Pueblo Bello, Cesar (North Colombia). A randomized complete block design with 10 treatments (genotypes) and three replicates was used. Each experimental unit consisted of 20 plants obtained from mother plants and transplanted at 14 cm between rows and between plants. Significant differences (P≤0.01) were detected between genotypes for all traits and THC and CBD content. Heritability in a broad sense showed values higher than 82% for all the traits studied. Genetic variability between genotypes was detected for number of leaflets, internode length of main stem, length of petiole, central leaflet-length, width of central leaflet, number of stems per plant, CBD, and THC, which allowed obtaining genetic gains higher than 30%. There was a high, inverse, and significant phenotypic and genotypic correlation between the percentage of CBD and THC (r=-0.93**). Overall, width of central leaflet direct and indirect effects explains the association level between CBD and THC with the correlated traits. It is possible to increase CBD and THC by selecting genotypes with higher width of central leaflet.