Yield And Competitive Ability Against Weeds Of Mixtures Between Old And Modern Wheat Varieties

Durum wheat is the keystone of the agro-ecosystems in the arable land of the Mediterranean environments and an important part of its area falls within organic farms. For this crop competition exerted by weeds for the use of resources (natural and auxiliary) can determine drastic yield and quality reductions (Ruisi et al., 2015). In organic farming such critical issue is often addressed through a remodelling of several techniques such as soil tillage management, sowing time, plant density and genotype choice. With regard to the latter, there is a growing interest by organic farmers towards the old varieties as they, compared to the modern varieties, have a definitely greater competitive weed abilities thanks to some morpho-physiological plant traits (establishment speed, tillering capacity, plant height) (Röös et al., 2018); moreover, the old varieties/landraces are often characterized by a greater protein and gluten content and for peculiar sensory properties (Newton et al., 2010; Vita et al., 2016). On the other hand, the new varieties have a much higher production potential and technological characteristics of the grain often more responsive to the needs of the processing industry (De Vita et al., 2007). This study, carried out in a organic farming system, aimed to answer the following questions: 1) can the mixture of old and modern durum wheat varieties offer advantages over the monovarietal crop, combining the qualities of the different genotypes? 2) Which mixing ratio should be used in order to maximize the potential advantages of the mixture?