Sage is an important aromatic crop, extensively cultivated worldwide. Drought stress affects yield and composition of secondary metabolites such as fatty acids, essential oils, antioxidants (Bettaieb et al. 2009, Munné-Bosch et al. 2001), changing the essential oil composition profile with respect to the ISO 9909 standard. Drought tolerance may differ at the infraspecific level, so we compared the response of Salvia officinalis L. and S. officinalis L. var maxima grown under two different irrigation regimes to highlight differences in leaf growth, water potential and gas exchange. Potted plants were grown in the greenhouse at 100% or 50% of field water capacity for three months. Monthly measurements of 3rd node leaf length, width and area were taken using ImageJ software. Midday leaf water potential was measured using a pressure chamber (SKPM 1400, Skye Instruments) and leaf stomatal conductance, transpiration and net photosynthesis were measured using a portable infrared gas analyzer (HCM-1000, Walz). Drought stress reduced leaf area in both taxa, but the effect was less pronounced in S. officinalis (-67%) than in S. officinalis var. maxima (-76%) . Also leaf water potential was almost 2 bar lower in this variety than in S. officinalis under water deficit. In irrigated S. officinalis var. maxima plants transpiration and stomatal conductance rates were more than twice those of S. officinalis, while under water deficit the difference between the taxa was not significant. Interestingly, net photosynthesis in S. officinalis was about twice that measured in S. officinalis var. maxima, both in irrigated and in stressed plants. Furthermore, in S. officinalis water deficit resulted in only a slight reduction of photosynthetic rate, while in in S. officinalis var. maxima the reduction was around 50%. Both taxa are affected by drought stress, responding with a reduction in leaf expansion and in transpiration, in order to reduce water loss. However, S. officinalis appears to have a higher efficiency, maintaining higher levels of carbon assimilation.
|Stato di pubblicazione||Published - 2017|
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