Morpho-physiological traits of sugar beet exposed to salt stress

Selection of traits increasing salt (NaCl) tolerance would improve the cultivation of sugar beet (Beta vulgaris L. subsp. vulgaris) in salty soils, by reducing or avoiding the usually linked losses in sugar yield and processing quality. This study analysed some adaptive morpho-physiological mechanisms in genotypes grown under controlled conditions in different salt concentrations. Parents and F1 hybrids obtained from a diallel cross were analysed for: i) mid-parent heterosis of root; ii) root length and its morphological components; and iii) length and dry weight of shoot (leaf + stem). Physiological traits such as: i) antioxidant enzyme activities in leaves; ii) root plasma membrane (pm) H+-ATPase activity; iii) leaf relative water content; and iv) shoot Na/K ratio, were also investigated. Through principal component analysis (PCA), it was possible to group the single morpho- physiological traits. This permitted discrimination of hybrids in relation to their response to salinity. The hybrid Hy-1 in presence of medium salt concentration performed well in terms of root morphology and enzyme activities, which were linked to the cell growth process. These findings evince a better understanding of the salt tolerance mechanisms in sugar beet and the identification of useful physio-biochemical traits useful for sugar beet breeding