Authors: REKAYA AYADI, RAYDA BEN AYED, NEJLA LASSOUED, HICHEM BEN SALEM, MOHAMED LARBI KHOUJA, LAMIA HAMROUNI, MOHSEN HANANA
Abstract: It is due to the lack of renewable fiber sources for industrial purposes that the need for finding available and alternative material has become imperative. Kenaf (Hibiscus cannabinus L.), a fast-growing industrial crop, would be a potential solution for valorizing salinized lands and/or soils irrigated with saline water. With the aim of selecting and valorizing salt-tolerant species with high fiber yields and industrial values, we launched the assessment of the performance of kenaf culture (var. Guangdong 743-2) under salinity constraints. Germination and vegetative stages were considered in the present study to better evaluate the whole life cycle of the species. Several NaCl concentrations (0, 3, 6, 9, 12, and 15 g L-1) were applied to seeds cultivated in petri dishes and to 4-month-old plants growing in hydroponics. Germination rates (germination capacity and coefficient of velocity), growth characteristics (biomass production and relative growth rate), physiological parameters (ionic content and water status), and fiber yields (neutral detergent fiber, acid detergent fiber, and acid detergent lignin) were evaluated to better understand the salt stress and toxic effects on germination, growth, and fiber yield. Multivariate analyses were used to identify the major characteristics pertaining to salinity tolerance. The obtained results have shown that kenaf variety Guangdong 743-2 is able to germinate and grow under high salinity levels (up to 15 g L-1 NaCl), deploying several mechanisms of adaptation. Kenaf could withstand salt stress by germinating smoothly, preserving root and stem biomass, maintaining relative growth rate, stabilizing root water content, producing new leaves while sacrificing older ones, and behaving as a halophyte species through the inclusion of toxic ions within the aerial part, most probably compartmentalized inside vacuoles to ultimately keep its fiber yields unchanged.
Keywords: Cellulose, germination, lignin, salt stress, principal component analysis, multiple linear regression
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