Sélection des génotypes tolérants au stress salin pendant la germination, la croissance, et le développement chez le blé dur (Triticum turgidum subsp., durum Desf.)

Abstract

Salinity is a serious threat to agriculture, especially cereal, causing inhibition and alteration of germination, growth and development. Durum wheat (Triticum durum Desf) is a widely consumed cereal in the world, we chose it to conduct our study. In the present experiment, a germination test was performed for 70 genotypes showing a high germination rate were used for salinity test. This test was conducted under various salinity levels (NaCl 45, 90, 135 mM). It would be exposed to different levels of stress to determine their degree of salt tolerance. In order to achieve this objective, a new experimental protocol was carried out to develop an effective method for screening the salt tolerance of wheat. In a first step, we succeeded in determining the median concentration LC50 (45mM) on only 4 genotypes, then we submitted the 70 selected genotypes to increasing salt concentrations; 0, 45, 90, 135 mM NaCl, which allowed us to assess their degree of tolerance during the growth and development stage. In a second step, we evaluated the chlorophyll level, the plant size and the number of dry leaves for the 70 genotypes. The results obtained showed that high NaCl concentrations would lead to a reduction in germination rate, chlorophyll content, plant size, an increase in the number of dry leaves, and the death of the most sensitive genotypes. The salt tolerance screening test during germination is not very effective, but it is reliable during the growth and development stage of the plant. Phenotypic characterization during this study showed that some genotypes were tolerant, while others were sensitive to salt stress. The data on tolerance to saline stress could be useful in selecting crops with the greatest production potential in highly saline waters.