Plant growth and production are greatly affected by water deficit worldwide and particularly in Tunisia. In this context, a study was conducted to analyse the response of three vetch species (Vicia narbonensis, V. sativa and V. villosa) to four water treatments: 100% (Control), 80%, 60% and 40% of field capacity. Water stress led to important changes of both leaf physiology and anatomy. V. narbonensis kept cells turgor by adjusting the osmotic potential without changes in cell walls elasticity. V. sativa showed the most pronounced reductions of leaf water potential and the lowest osmotic adjustment under water stress although cell walls elasticity has not changed. However, V. villosa kept a higher fraction of apoplastic water over V. sativa that allowed it to maintain cells turgor despite the rigidity of its cell walls. Drought did not affect lamina thickness but increased the palisade parenchyma at the expense of spongy parenchyma. It was characterised by leaf lamina increase and constant thickness of the spongy parenchyma: a strategy to cope with drought. Moreover, stomata were reduced in size but were increased in number in order to avoid water loss.

The current challenge of agriculture is to get the best yields while overcoming frequent water deficit conditions. The objective of this study was to compare performances of three vetch species (Vicia narbonensis L., V. sativa L., and V. villosa Roth) subjected to water stress. Plants were sown in pots under rainout shelter and submitted to four water regimes: control (100% field capacity [FC]), 80%, 60%, and 40% FC through 3 yr experiment. Results showed that V. narbonensis had the smallest declines in all the studied variables in response to water restriction but the highest water use efficiency (WUE) and stress tolerance index (STI) in both control and water-treated plants. This indicates the greater tolerance of this species to water constraint and its better water use. Vicia villosa was characterized by drastic declines in leaf area and DM yield (75% and 64%, respectively). It had also the smallest WUE and STI suggesting its low adaptation to water stress. Vicia sativa showed severe reductions in seed yield and yield components; accordingly, it was the most sensitive species in terms of seed yield. The three species implied avoidance strategies to cope with water stress. The different levels of drought tolerance explain the species ecological distribution in Tunisia.

Citrus production is increasingly constrained worldwide by rising soil salinity, particularly in arid and semi-arid regions. In Tunisia, the expansion of saline soils represents a major abiotic stress limiting orchard productivity. The identification of salt-tolerant rootstocks has therefore become a priority, especially as alternatives to sour orange (SO, Citrus aurantium L.), which is highly susceptible to Citrus tristeza virus. In recent years, several outbreaks of the disease have been reported in the Cap Bon citrus-growing region, posing an imminent threat to the sustainability of citrus production in Tunisia. This study evaluated the salt tolerance of commercial cultivars (HER, MAR, WN, NH) grafted onto Citrus volkameriana Ten. & Pasq. (CV, Citrus aurantium × Citrus limon (L.) Burm.f.) and three Poncirus trifoliata hybrids (CC, C35, CTR) under irrigation water salinity ranging from 1.1 to 4.1 mS/cm and soil salinity between 1.8 and 3.8 mS/cm. Data were collected between 2020 and 2021 in five young citrus orchards (KHB, OSN, BKN, BSJ, CHK) located in the main citrus-producing region of Tunisia, with key physiological measurements conducted during the high-evaporation period. Salinity increased across most sites during summer 2021, affecting ion homeostasis, Na⁺/K⁺ selectivity, stomatal traits, photosynthetic performance, and growth. The highest leaf Cl⁻ concentration (0.4 meq g⁻¹ dry weight) was recorded in the sensitive HER/CC combination at the OSN site. Increased salinity at OSN was associated with a 0.86% reduction in canopy growth compared to BSJ. Rootstock tolerance was strongly linked to the ability to restrict Cl⁻ accumulation in leaf tissues. Under higher salinity conditions, CV showed superior performance and represents a suitable alternative to SO.