Phenotypic variability of plant architecture, easy destemming, and yield for accelerated selection for mechanical harvestability in chile pepper

In recent years, chile pepper (Capsicum annuum L.) production in the US has shown a decline due to higher costs associated with manual harvesting and unavailability of skilled labor. Chile pepper breeding programs have incorporated mechanization as a long-term breeding objective alongside historically significant traits such as yield, disease resistance, and fruit quality. Nevertheless, information on the genetic landscape of traits crucial for chile pepper mechanization and their relationships with other agronomic traits remain limited. This study employed multivariate approaches, phenotypic and genetic correlations, hierarchical cluster analysis (HCA), and principal component analysis (PCA) to investigate the genetic architecture of mechanical harvestability traits using a diverse C. annuum L. population evaluated in field conditions in New Mexico, USA. Fruit morphology and fruit destemming force were the most discriminating traits that accounted for most of the observed phenotypic variation in the population. Medium to high narrow-sense heritability estimates (0.53-1.0) indicated the predominance of additive genetic effects for traits relevant for mechanical harvesting. Negative genetic correlations (r_g; -0.28 to -0.67) were observed between fruit destemming force and plant architecture traits demonstrating the challenge in breeding New Mexican pod type chile peppers suitable for mechanical harvesting. Ten genotypes identified through HCA were further validated for mechanization potential using PCA. These genotypes could be used as potential parental lines in breeding programs aimed at developing chile pepper varieties amenable to mechanical harvest. The findings of the study provide valuable insights to breeders on the genetic architecture of traits critical for mechanization, thereby aiding informed decision-making and improving breeding and selection accuracy for the development of new mechanically harvestable chile pepper cultivars.