QUELQUES POPULATIONS SAHARIENNES DE LUZERNE PERENNE (Medicago Sativa L.) FACE A UN STRESS HYDRIQUE

Abstract

This topic covers some Saharan populations and an introduced variety of perennial alfalfa (Medicago sativa L.) subjected to moisture stress materialized by different concentrations of PEG-400 in order to compare their degree of drought resistance. For this, we selected fourteen (14) populations and a variety introduced (Italian) for 05 irrigation solutions with different concentrations of PEG (1%, 5%, 10%, 20% and 50%) in addition to the control (distilled water). The results show that the threshold for adaptation to drought depends on the growth phase and the population itself. Similarly, an osmotic pressure of approximately 142.8682 bar (50% PEG) of irrigation solution shows a total cessation of all development processes in most populations, although there is that growth stops well before others and beyond. Also, most people are more sensitive (low levels of the used parameters) to zero pressure (distilled water) at low osmotic pressures. We found very highly significant differences between populations for the studied parameters. Subsequently, the Principal Component Analysis (PCA) and hierarchical ascending classification (HAC), allowed us to identify 04 groups of population based on their resistance to drought, taking into consideration all the results obtained for the different parameters: · Group 1 (very low resistance): Italy; · Group 2 (low resistance): Janet, In Salah, Hassi Laabid, Ouargla and Saudia; · Group 3 (medium resistance): Aoulef and Tamentit; · Group 4 (high resistance): Chott, Hassi Ben Abdallah, Blidet Amor, Temacine, Nezla, Meggarine and Lioua