Growth Response and Nutrient Concentrations of Sago Palm under Aluminum Stress
The growth response, nutrient concentrations in different plant parts and some physiological features under Al treatment were investigated to evaluate the Al resistance of sago palm under acidic conditions. Seedlings at the 7th leaf stage were used for the treatment of 0, 10, 20, 100 and 200 ppm Al in culture solution at pH 3.6 for 4.5 months. The study revealed that the growth of sago palm increased at low Al concentrations in the growth media under acidic conditions. This result might be attributed to a positive effect on the uptake of major nutrients, such as P, N and Ca2+. Nevertheless, the total dry weight and leaflet area significantly decreased under the 200 ppm Al treatment. This result might be associated with a significant decrease of the Ca2+ and Mg2+ uptake. The critical value at which the growth of sago palm was inhibited is considered to be approximately 200 ppm Al in the growth media. In addition, sago palm maintains a low Al3+ concentration in the leaflets by storing Al3+ mainly in the roots, especially in the lateral roots, and the Al3+ concentration in the whole plant did not increase significantly even under the 200 ppm Al treatment. We conclude that Al resistance of sago palm might be due to the avoidance mechanism via the Al exclusion ability under acidic condition.
Keywords: acidic condition; aluminum resistance; nutrient accumulation; physiological characteristic; sago palm.