Structural Features of Some Wheat (Triticum Spp.) Landraces/Cultivars Under Drought and Salt Stress

Seven local landraces of common and durum wheat (Triticum aestivum L. and T. durum L.) from the arid and semi-arid areas of the Sultanate of Oman were examined for specific leaf and stem structural features for water conservation. On the basis of shoot fresh and dry weights (g plant^-1), degree of tolerance to drought and salt stresses in these wheat landraces/cultivars can be ranked as S-24 > J-305 > Sarraya > Senain > Cooley > MH-97 > Missani>Hamira > Shwairaa. Modifications related to water conservation were found to be high degree of sclerification, succulence in leaf and stem, low resistance to water conductance in vascular tissue, and pubescence on leaf surface. The salt and drought tolerant cultivar S-24 showed high proportion of chlorenchyma and intensive sclerification in stem structure, and well-developed bulliform cells and dense pubescence on the leaves. These modified features were poorly developed in lesser stress tolerant Omani wheat landraces like Hamira and Shwairaa. Accession Senain also showed stem succulence (solid stem), an important xeromorphic feature. Structural modifications in landrace Missani were found to be increased sclerification in vascular tissue and high number of metaxylem vessels and high proportion of parenchyma in stem, and highly developed bulliform cells in leaf. Overall, the promising anatomical traits in highly stress tolerant landraces/cultivars were chlorenchyma in stem, rigorous sclerification in parenchyma and around vascular tissue, stem and leaf succulence, and enhanced ratio of major conducting tissue.