Soil salinity and water status affect growth of Phoenix dactylifera seedlings

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.