Relationship between Pigments and Seed Fall Rate of Iranian Castor Genotypes and Genetic Diversity

This study aimed to examine the relationship between pigments and seed fall rate of Iranian castor genotypes and genetic diversity, specifically 28 castor genotypes (27 native and 1 modified), a randomized complete block design with three replications was conducted in 2014 and 2015 at the Research Farm of Islamic Azad University in Damghan, northern Iran. During the growth period, the following traits were sampled: seed length; seed width; weight of 1,000 seeds; color of seed coat; number of leaves in the bush; leaf, nervure, and stem color; seed fall rate; growth type; seed performance; oil percentage; and chlorophyll fluorescence rate. After data collection, variance analysis was conducted through SAS and mean comparison was performed through Duncan test at 5% probability level. Correlation coefficients were calculated to find correlations, and cluster analysis was used to group the genotypes. Finally, graphs were drawn with Excel. The results indicated diversity in the investigated traits. Differences were observed among the native castor genotypes so that they were divided into five groups in terms of grain fall rate. A significant negative correlation at 1% probability level between the grain fall rate and the leaf color (r= –0.71**), nervure color (r= –0.56**), and stem color (r= –0.57**) indicated that in all of these three traits, when the color changed to dark red, the rate of grain loss decreased. Thus, the color trait can be used as a reference in breeding programs so that grain fall in the castor plant can be prevented in the future.