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sur le développement des zones arides et semi-arides

Titre : Effect of water stress, salt stress and their combination on the cultivated tomato Solanum lycopersicum and its halophyte wild relative Solanum chilense

Auteur : Grosjean, Aurélie

Université de soutenance : Université catholique de Louvain

Grade : Master : bioingénieur en sciences agronomiques, à finalité spécialisée 2022

Résumé
Drought and salinity are a growing global concern that affects plant productivity, including the cultivated tomato Solanum lycopersicum. The cultivated tomato is the second most consumed vegetable in the world. It is therefore important to improve its resistance to these abiotic stresses. Its relative wild species, Solanum chilense, originated from the Atacama Desert is known for its resistance towards dry and salty growing conditions. Its resistance to salinity is conferred by its halophyte properties. This study analyzes the response of S. chilense and S. lycopersicum under water stress, salt stress and also the combination of both stresses. It focuses on morphological, reproduction related, physiological and biochemical features with a special focus on tolerance mechanisms of the species in relation to the type of stress. The experiment took place in a greenhouse and plants were grown in soil in pots. Water stress was applied by a decrease in watering intensity. Salt stress was applied by subjecting the plants to 75 mM NaCl. Water stress mostly impacted the vegetative growth of S. lycopersicum by decreasing fresh and dry weight and the number of ramifications but only had few impacts on S. chilense. Salt stress impacted vegetative growth of both species and also reproductive growth. Water stress delayed flowering time and reduced the number of inflorescences of S. lycopersicum but did not affect S. chilense. Salt stress impacted both species by a delay in flowering time, a decrease in inflorescence production but an increase in inflorescence and flower fertility. The combination of the stresses was less detrimental than the individual stresses as it even counteracted some negative effects. Water stress caused osmotic adjustment in S. lycopersicum while salt stress decreased stomatal conductance and photosynthesis in S. chilense. Salt stress increased Na concentration throughout the plants. S. chilense accumulated more Na in its shoot compared to S. lycopersicum which mostly accumulated Na in its roots. Salt stress did not interfere with essential mineral (K, Mg, Ca) accumulation. These results show that water stress affects S. lycopersicum more than S. chilense. It also shows that the tolerance mechanism differs between species, and that the combined effects of the two stresses are less detrimental than the individual stresse

Mots clés : Solanum lycopersicum, Salt stress, Water stress, Solanum chilense

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