Mixtures of Commercial Lentil Cultivars Show Inconsistent Results on Agronomic Parameters but Positive Effects on Yield Stability

Abstract

Cultivar mixtures are a useful tool to enhance cultivated biodiversity to buffer crop biotic and abiotic stresses. There are multiple pieces of evidence of mixture advantages in terms of pathogen control and increase in yield amount, stability and quality. Lentil represents a founder crop in the Mediterranean, yet it experiences strong yield fluctuations in the face of abiotic stresses. The present study aims to assess the mixing ability of four Italian commercial lentil lines in terms of yield amount and stability, nodule number, total lentil biomass and sensitivity to weeds. Since there is very limited information on lentil genotype traits, two-, three- and four-cultivar mixtures were designed with a trait-blind approach and compared to sole cultivars. The nodule number was mainly influenced by cultivar and weather; no interaction between cultivars was observed. Treatments were differently sensitive to weeds, but the effect of spatial heterogeneity prevailed over that of the cultivar. The average yield stability of all mixtures was significantly higher than pure stands, but in terms of yield amount, individual mixtures either outperformed or were outperformed by pure stands. Against our expectations, cultivar mixtures showed the most advantages in the most productive year: likely, the reason lies in the supposed low genetic diversity of commercial lentil lines in Italy. We encourage further research, taking into account the diversity of Italian lentil landraces, in order to gain a broader genetic base for the implementation of a trait-based approach, which may lead to better-performing mixtures.