Tomato Cultivar Evolution and Traits
This project evaluates the evolution of processing tomato cultivars during the past 80 years, and how morphological, physiological and phenological traits have changed according to new crop management practices and the need to increase yields. For many crops, breeding has played an important role in increasing yields, but the mechanisms by which particular traits contribute to these higher yields are not well understood. In California processing tomatoes, water use efficiency (WUE) has inadvertently increased in the past 30 years. Evapotranspiration rates (i.e., water loss via evaporation and plant use) have kept constant at an average of 648 mm, but yields have increased more than 50% since the 1970s to currently over 81 Mg/ha (Hanson and May 2006). This study compared 8 tomato cultivars released from 1936-2002 to identify particular traits, e.g., stomatal conductance, photosynthetic capacity or root depth, that may have evolved during the breeding process for maximizing yields, or alternatively, improving pest resistance to tomato cultivars. The preliminary results suggest that canopy architecture, leaf area per plant, and stem biomass has decreased along with an increase in photosynthetic rates and more fruits per branch, i.e., harvest index. These findings can contribute to the understanding of traits involved in the increased WUE in processing tomato and serve for breeding programs as information on which specific physiological, phenological or morphological traits may further increase WUE in tomatoes as well as other crops.
Barrios-Masias, F.H. and L.E. Jackson. 2014. California processing tomatoes: Morphological, physiological and phenological traits associated with crop improvement during the last 80 years. European Journal of Agronomy 53:45-55. Barrios Masias and Jackson 2014