Evaluation of salinity tolerance in Buxus spp.

Urban green area design and management require deep knowledge of the environmental context. Many abiotic stresses can compromise plants vitality and aesthetic value, such as salinity. Especially in the Mediterranean regions, characterized by hot, dry summers and cool, wet winters, several urban green areas are on salt-affected soils, caused by saline water, sea aerosol or contaminated by antifreeze solutions. This work aimed to investigate the response to saline stress in two species of Buxus L. commonly used in Mediterranean green areas. One-hundred twenty plants of B. sempervirens L. and B. microphylla Sieb. & Zucc. ‘Faulkner’ were grown from December 2005 to April 2006 at the Experimental Centre of the Faculty of Agriculture of the University of Turin (Italy) and submitted to two NaCl solutions (0.125 N and 0.25 N), applied every two weeks by immersion or perfusion. Colour variation, determined by means of spectrophotometer and visual check, SPAD values, and leaf chlorophyll content were evaluated every two weeks. Differences between NaCl applications and between species were observed. Perfusion with NaCl, but only at the highest concentration at the 4th application, negatively affected plant growth and ornamental characteristics. Overall, Buxus appeared to be an interesting genus for saline environment. Between species, B. sempervirens resulted more resistant than B. microphylla.