Saline-boron stress in northern Chile olive accessions: Water relations, B and Cl contents and impact on plant growth

The objective of this study was to analyze the effect of saline-boron stress on the vegetative growth, dry leaf weight, water potential (Ψ_w), relative water content, and leaf and root B and Cl- contents in 8 accessions of olive. Rooted one-year-old plants were cultivated for 132 days with 50% shading in 5-L pots containing sand substrate and watered with Jensen's nutrient solution. After eight days of uniform ferti-irrigation, the plants were exposed to saline-boron stress, which was administered in three successive stages to condition them to a final stress of 0.49 mM B(OH)3 and 200 mM NaCl. The accessions were identified by their place of origin as Suca, Chiza, San Pedro I (SPI), Taltal, Azapa, San Pedro II (SPII), Frantoio and Lluta. The results showed that saline-boron stress decreased vegetative growth and dry matter in all accessions. The levels of Cl- in leaves and roots increased significantly, although Suca and SPI experienced the least increases. B increased in leaves and roots but did not reach toxic levels. Water potential decreased except in the accession Taltal. RWC decreased in all accessions. Cv. Frantoio, known internationally for its high salt tolerance, was used as a reference for the observed responses in the other accessions.