In this study, we evaluated the salt resistance level of seven tomato cultivars Akikon, Tounvi, Thorgal, F1 Mongal, Padma, Petomech and TLCV15 at young plant stage. The experiment was laid out as a Randomized Complete Design (RCD) with four replications in a greenhouse. Three-week old plants from the seven cultivars were submitted in pots containing a mixture of potting soil and sand to five NaCl concentrations: 0; 30; 60; 90 and 120 mM NaCl corresponding respectively to an electric conductivity of 0.221; 3.827; 6.47; 10.56 and 14.02 dS.m-1 by irrigation every two days. Plant growth parameters were evaluated after two weeks. Salt effect caused a reduction of young plant growth whatever the growth parameter considered with a significant difference among cultivars. Growth of cultivars Padma, Akikon and Petomech was more affected by salt stress with two or three growth parameters significantly reduced at 30 mM NaCl whereas no growth parameter was significantly affected at less than 60 mM NaCl for cultivars Thorgal and Tounvi. Thus, cultivars Akikon, Petomech and Padma appeared as the most sensitive to salt stress. In contrast, cultivars Tounvi and Thorgal appeared as the most salt-resistant. Cultivars F1 Mongal and TLCV15 had intermediary behavior.

Effet améliorateur d'un apport extérieur de calcium et de potassium sous différentes formes sur la tolérance à la salinité de l'amarante (Amaranthus cruentus L.)

Évaluation de la résistance à la salinité au stade jeune plant de quelques cultivars de piment (Capsicum spp.) du Benin

Salt stress is one of the major environmental constraints limiting agricultural productivity and influencing the concentration of bioactive compounds of vegetables. In this study, we assessed the effect of NaCl salt stress on flowering, fructification and fruit nutritional quality of a local cultivar of chili pepper. The experiment was carried out in a screen house as a completely randomized design (CRD) with three replications. Three weeks old plants were submitted in pots containing a mixture of potting soil and sand, to five NaCl concentrations; 0, 30, 60, 90 and 120 mM NaCl by irrigation every two days for 94 days. Salinity retarded significantly flowering and fruit ripening, and reduced significantly the fruit number, as the NaCl concentration increased with no fruit obtained at 90 and 120 mM NaCl. Fruit size and fresh mass were also significantly reduced by salt stress. Capsaicinoids contents increased significantly for about 389% in comparison to the control at 60 mM NaCl, whereas vitamins B6, B12 and C contents decreased significantly with increasing NaCl concentration. Thus, salt stress retarded flowering and fruit ripening; reduced fruit number, size and mass; enhanced fruit tangy appearance and deteriorated fruit nutritional values in chili pepper.

Objectifs : Le stress salin constitue un des stress environnementaux majeurs qui agit négativement sur la croissance des plantes. L’effet positif d’une application exogène de calcium et de potassium a été déterminé sur la croissance des plants de tomate soumis à la salinité. Méthodologie et résultats : Les plants de trois cultivars de tomate ont été exposés à six traitements comprenant le témoin sans NaCl ; 120 mM de NaCl et une combinaison entre 120 mM de NaCl et un apport de 40 mM de CaSO4 ; CaCl2 ; KNO3 ou K2SO4. La croissance des plantes a été déterminée après quinze jours d’exposition. L’application exogène de potassium n’a pas amélioré la croissance des plants stressés tandis que celle du calcium a atténué significativement les effets du NaCl sur les plantes du cultivar sensible Akikon. Aucun effet améliorateur n’a été observé chez les cultivars Tounvi et F1 Mongal. Conclusion et applications des résultats : Seule l’application exogène des deux formes de calcium a atténué les effets de la salinité sur la croissance des plantes du cultivar sensible Akikon. Le CaSO4 s’est révélé comme le meilleur composé pouvant atténuer les effets néfastes du sel chez la tomate, suivi par le CaCl2 notamment au niveau de la partie aérienne alors qu’au niveau de la partie racinaire, le CaCl2 a été plus efficace. Ainsi la réponse des plants de tomate cultivés sous stress salin à une application exogène de composés dépend non seulement du cultivar, de l’organe pris en compte mais aussi de la nature des composés apportés. Des études complémentaires sont nécessaires pour déterminer les mécanismes physiologiques impliqués dans l’effet améliorateur du calcium. Le CaSO4 et CaCl2 seront utiles pour la gestion de la salinité dans les zones de production de tomate Akikon. Mots clés : tolérance à la salinité, tomate, potassium, calcium, biomasse fraîche, biomasse sèche. Henry et al., J. Appl. Biosci. 2021 Réponse des plantes de tomate (Lycopersicon esculentum Mill.) cultivées sous stress salin a une application exogène de calcium et de potassium 16364 Response of tomato (Lycopersicon esculentum mill.) plants cultivated under salt stress to exogenous application of calcium and potassium ABSTRACT Aims: Salt stress is one of the major environmental stresses that have a negative effect on plant growth. The ameliorative effect of exogenous application of calcium and potassium was determined on the growth of tomato plants subjected to salinity. Methodology and results: Plants of three tomato cultivars were exposed to six treatments including the control without NaCl; 120 mM NaCl and a combination of 120 mM NaCl and an input of 40 mM CaSO4; CaCl2; KNO3 or K2SO4. Plant growth was determined after 15 days of exposure. The exogenous application of potassium did not improve the growth of stressed plants while that of calcium significantly attenuated the effects of NaCl on plants of the susceptible cultivar Akikon. No ameliorative effect was observed in cultivars Tounvi and F1 Mongal. Conclusions and applications of the results: Only exogenous application of both forms of calcium attenuated the effects of salinity on plant growth of the susceptible cultivar Akikon. CaSO4 has proven to be the best compound that can mitigate the harmful effects of salt in tomatoes, followed by CaCl2 especially in the aerial part, while in the root part, CaCl2 has been more effective. Thus, the response of tomato plants grown under salt stress to an exogenous application of compounds depends not only on the cultivar and the organ taken into account, but also on the nature of the compounds used. Further studies are needed to determine the physiological mechanisms involved in the ameliorative effect of calcium. CaSO4 and CaCl2 will be useful for the management of salinity in Akikon tomato production areas. Keywords: tolerance to salinity, tomato, potassium, calcium, fresh biomass, dry biomass.