Screening and differential physiological responses of tomato ( Solanum lycopersicum L.) to drought stress
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ORIGINAL ARTICLE
Screening and differential physiological responses of tomato (Solanum lycopersicum L.) to drought stress Rowland M. Kamanga1
Received: 3 January 2020 / Accepted: 20 July 2020 Ó Indian Society for Plant Physiology 2020
Abstract Water deficit stress remains an important agricultural threat worldwide, thereby identifying germplasm with proven tolerance to drought stress is imperative. Tomato (Solanum lycopersicum L.) is a prominent fruit vegetable whose growth is considerably hampered by drought stress. This study evaluated physiological responses of 14 commercial tomato cultivars subjected to drought stress. Multivariate analysis and drought susceptibility index were employed to assess differential drought tolerance among cultivars, resulting into selection of Star 9003 and Rodede as tolerant and sensitive cultivars respectively. Subsequent physiological experiments showed that cultivar Star 9003 maintained better photosynthetic parameters as opposed to Rodede under drought stress, but had lower intercellular carbon dioxide concentration indicating that available CO2 was efficiently assimilated as also shown by its higher carboxylation and instantaneous transpiration efficiencies (CE and ITE). Lower stomatal limitation values in sensitive cultivar Rodede hint at a possibility that the major photosynthetic limiting factors were non-stomatal such as oxidative stress-induced photoinhibitory damage. The present study reports that tolerance in Star 9003 was unrelated to avoidance in stomatal water losses, but in part through development of morphologically thicker leaves, accumulation of organic osmolytes for osmotic adjustment and attainment of higher efficiencies in photosynthetic water use and carbon assimilation.
& Rowland M. Kamanga [email protected] 1
Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima, Japan
Keywords Tomato Drought stress Photosynthesis Carboxylation efficiency Stomatal limitation Osmotic adjustment
Introduction Tomato (Solanum lycopersicum L.) is amongst the most commercially important fruit vegetables globally (Jangid and Dwivedi 2016; Schwarz et al. 2014), yet remains considerably sensitive to drought stress (Ijaz et al. 2017; Saadi et al. 2015) as shown by its higher yield response factor to water stress (Johl et al. 2013; Smith and Steduto 2012; Steduto et al. 2012). Soil is said to be droughted or in a state of water stress when soil water potential and consequently plant’s turgor fall below a threshold such that normal plant functioning is perturbed (Kramer and Boyer 1995). Tomato has substantial genetic wealth with a number of wild relative species, landraces and cultivated varieties (Shamim et al. 2014) having differential tolerance to water stress. Recent advances in molecular research have made important revelations in tolerance mechanisms in this species (Albaladejo et al. 2017; Egea et al. 2018; Ijaz et al. 2017). This understanding is an important prerequisite in development of tolerant cul
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