In Northeast Thailand, sandy soil is prevalent, in which the growth of teak (Tectona grandis L. f.) is suppressed. Sandy soil is characterized by low pH, poor fertility, and low water holding capacity. To determine the factors that suppress teak growth, we planted teak seedlings in sandy soil at two sites. One of the sites exhibited suppressed teak growth but the other did not. We compared growth, photosynthetic rate, leaf water potential, and the concentrations of elements in plant organs between the two sites.
The site where teak growth was suppressed showed low concentrations of nutrients in the soil, especially Ca. The average tree height at this site was only 40 cm after 16 months, whereas tree height at the other site was over 300 cm at same time point.
The site with low teak growth was characterized by low uptake of nutrients, and especially Ca deficiency. The low growth rates correlated with decreases photosynthetic rate and drought stress in the dry season. Moreover, Mg accumulated in the leaves of teak with low growth, and this accumulation was considered as a factor in the decreased photosynthetic rate and drought stress. We concluded that the concentration of Ca in soil was important for teak growth, and the site with low Ca showed drastic suppression of teak growth and Mg toxicity caused by Ca deficiency.