Soil salinity and water status affect growth of <i>Phoenix dactylifera</i> seedlings

Abstract

Abstract Effects of salinisation of soil on emergence, growth, and physiological attributes of seedlings of the date palm ( Phoenix dactylifera ) ‘Rati’ (Palmaceae) were studied. A mixture of chlorides and sulfates of Na, K, Ca, and Mg was added to the soil and salinity was maintained at 4.3, 6.0, 8.2, 10.5, 12.8, and 14.6 dS m –1 . A negative relationship between percentage seed germination and salt concentration was obtained. Seedlings did not emerge when soil salinity exceeded 12.8 dS m –1 . Results suggested that this species is salt tolerant at the seed germination stage. Seedlings survived and grew up to a soil salinity of 12.8 dS m –1 and evidently this species is salt tolerant at the seedling stage as well. Elongation of stem and root was retarded by increasing salt stress. However, this species has a tendency for rapid root penetration and roots are able to extract water from dry saline soil (6.0% moisture) below the permanent wilting percentage. Among the tissues, young roots and leaf tissue were most tolerant, whereas stem tissue was most sensitive to salt stress. This species is a halophyte and adapted to salt stress conditions by the evolution of an osmoregulation mechanism. However, osmoregulation is effective for salt tolerance only to a limited range in the continuum of salt stress. The ability of this plant to thrive in dry regions is further conferred by the xeromorphic features of its leaves.