Nourredine Yahia
Publications et Ouvrages : Nourredine Yahia
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Salt stress is a major environmental constraint most limiting plant productivity. Seeking salt-tolerant crops requires an examination of the behavior of the plant development including seed germination stage. The effects of NaCl stress (100 mM) combined or not with different solutions of phytohormones ABA (0.005 mM), GA3 (0.005 mM) and SA (0.5 mM) on germination of two processing tomato cultivars named Rio Grande (Rg) and Imperial (Ip) were investigated. Seeds were subjected to salt stress, combined or not with hormones, at two stages of development (48 and 96 hours). The results shows that the germination rate and germinate value of the two processing cultivars of tomato were influenced by the different treatments. On the other hand, salicylic acid as GA3 attenuate the effect of NaCl. Instead, the middle enriched with ABA inhibits seed germination. Moreover, the tested stress conditions had shown a significant variability in the germination and handling between the two germination stages. Nevertheless, the effect of GA3 and SA on the germination of two processing tomato varieties to improve the inhibitory effect of ABA and salinity was discussed.
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Effect of cold on antioxidant responses in aerial (shoots and leaves) and roots tissues of two contrasting accessions of M. ciliaris Krockers (Cil 126, tolerant and Cil 123, sensible) were investigated. Ten-day-old grown seedlings were subjected at different periods of cold acclimation (4℃) 2, 4, and 6 days. Peroxidases (POD) (EC 1.11.1.7) activities and isoenzymes expression of plantlets treated and control (23℃) of the aerial (shoot+leaves) and root vegetative tissues were carried. Global peroxidase activity under low temperature stress was higher in tolerant ecotype than sensible one. The same trend was also observed at expressed isoenzymes. On the other hand, whether in tolerant or sensitive, activity and isoenzymes peroxidase was more pronounced at the roots than in aerials tissues system.
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Les especes annuelles du genre Medicago presentent un interet economique
Ires important. Ces plantes fourrageres sont souvent utilisees dans les
systemes de rotation "cereales-luzeme». En Algerie, !'integration cerealiculture
paturage temporaire d'especes annuelles de Medicago necessite Ia disponibilite
d'ecotypes adaptes et ce, au depend des jacheres, peu productives en zones
cerealieres. Les objectifs de cette etude consistent a examiner les rapports entre
Ia variabilite genetique et Ia tolerance au froid d'ecotypes locaux appartenant a
des especes annuelles de Medicago vivant dans des etages climatiques dillerents.
Le developpement de jeunes plants issus de germination, sous un regime
de basse temperature, differe d'une espece a une autre. M. acu/eata et M. ci/iaris
presentent une tolerance au froid plus importante que celle de M. polymorpha
et M. sativa. A l'interieur des especes, les ecotypes originaires des sites de
haute altitude affichent une tolerance superieure a ceux originaire des sites de
basse altitude. La teneur des proteines est plus prononcee chez les ecotypes
tolerants que chez les ecotypes sensibles.