Yield, Vegetative Growth, and Fiber Length of Kenaf Grown on Saline Soil

Abstract

Abstract Kenaf ( Hibiscus cannabinus L.) is an excellent supplement to wood as a source of fiber for paper pulp. With the introduction of kenaf into the western USA, plantings may be on soils where salinity problems already exist or may develop from the use of saline irrigation water. Because of the lack of salt‐tolerance information on mature vegetative growth and yield, a 2‐yr field‐plot study was conducted at Brawley, CA. Two cultivars (Everglades‐41 and 7818‐RS‐10) were grown with six salinity treatments imposed on a Holtville silty clay [clayey over loamy, montmorillonitic (calcareous), hyperthermic Typic Torrifluvent]. Electrical conductivities of the irrigation waters, containing NaCl and CaCl 2 (1:1 by weight), were 1.1, 2.0, 3.0, 4.0, 5.0, and 6.0 dS m −1 . Soil salinity (electrical conductivity of the saturated‐soil extract, K c ) ranged from 5.4 to 12.6 dS m −1 the first year, and from 6.0 to 14.9 dS m −1 the second year. Vegetative growth, stem yield, and fiber length were measured. The mean dry weight yields of the stems during the 2‐yr experiment were reduced 11.6% for each unit increase in soil salinity above 8.1 dS m −1 . These results place kenaf in the salt tolerant category. Yield reduction resulted from both a reduction in plant height and stem diameter. Increased salinity did not significantly affect fiber length. Excessive Cl accumulation occurred in the leaf tissues at high soil salinity levels.