Objectives The physiological characteristics were measured and the root morphology of areca-nut seedlings under boron (B) deficiency were observed, in order to provide theoretical basis for diagnose of B deficiency in areca-nut.

Methods A sand culture experiment was conducted using areca-nut cultivar of ‘Reyan No.1’ as the research material. Treatments of B deficient (B0) and normal B supplies (B50) were done by adding 0 and 50 μmol/L of B in the nutrient solution. The plants were harvested after grown for 3 months, the biomass, plant height, B concentration, carbohydrate content, antioxidant enzyme activities, malondialdehyde content, photosynthetic rate were determined, and root tip morphology were observed with electron microscopy.

Results The plant height, fresh weight and dry weight of root, B concentration of shoot and root, and the sucrose and starch content of leaves were significantly decreased, the soluble total sugar showed no obvious change, the content of malondialdehyde, the photosynthetic rate was also decreased, while the activities of peroxidase increased markedly under B deficiency (B0). And the roots became shorter, root tips were obviously enlarged and the cell walls were thicker, a large amount of particulates were accumulated on the inner walls, and the root activity was significantly decreased under B deficiency (B0).

Conclusions B deficiency leads to the deformation of the apical structure of the areca-nut seedling roots, which reduces nutrient absorption capacity and result in the impairment of the antioxidant system of the leaves and the reduction in the photosynthetic capacity, and ultimately inhibit the growth of the whole plant.