Performance and stability of homogeneous and heterogeneous broccoli (Brassica oleracea L. var. italica Plenck) varieties in organic and low-input conditions

Abstract

Organic (OA) and low-input (LI) farming rely on genotypes with high adaptability that maintain good performance over a broad range of agronomic and environmental conditions. Two synthetic varieties of Brassica oleracea var. italica Plenck (broccoli) were developed from a landrace. Their performance and stability under LI and OA farming conditions were then assessed and compared to a F1 hybrid variety. Identical experiments were carried out over a period of 2 years in three locations in Italy having different management and pedo-climatic conditions. Initially, an analysis of variance, carried out using a linear mixed model (LMM), with “Genotype” (“G”) and “Location” (“L”) as fixed factors and “Year” (“Y”) as a random factor, showed that the “Genotype” effect was significant for days to heading (DH), head number (HN), plant diameter (PD), plant vigour (PV) and plant height (PH). The “L” effect was significant for PD and PV. “G × L” interaction was significant for DH, PV and for yield. To obtain a better understanding of entry performances across years and locations, each location—year combination was considered as “Environment” and the additive main effects and multiplicative interaction analysis was used to dissect the “G × E” interaction. Synthetic varieties had good performances and always had a higher stability than the F1 hybrid. The data discussed in this study suggest that heterogeneous varieties developed from adapted materials are suitable for OA and LI because of their stability.