Effect of growing media on morpho-physiological quality attributes of Tetraclinis articulata seedlings

Abstract Tetraclinis articulata (Vahl.) Master or thuya is facing several constraints to its successful natural regeneration in Morocco. Containerized seedlings plantation is the only method adopted in thuya forest restoration programs and post-transplant water stress produces high seedling mortality after the first summer following outplanting. There is thus a real need to improve nursery seedlings quality, especially enhancing the growth of the root system by improving the water holding capacity of the root plug. Our aim was to assess the effects of clay on the water holding capacity of the growing media and on various morphological and physiological traits of T. articulata seedlings in the nursery. T.articula seedlings were raised in nursery using nine composite substrates; seedlings quality was evaluated according to their morpho-physiological and performance attributes. This investigation determined that a clay content of 20–25% constitutes an optimum for obtaining seedlings with a good root growth potential and high root viability. Excessive clay content in the growing media resulted in water-logged root plug decreasing root growth potential. This investigation found that morphological attribute as Root Collar Diameter and Root/Shoot ratio could be considered good predictors of Root Growth Potential.