缺硼槟榔幼苗的生理反应和根系发育特征

  【目的】  探究缺硼对槟榔幼苗生理特征和根系形态的影响，以期为槟榔缺硼（B）诊断提供理论依据。  【方法】  以‘热研1号’槟榔幼苗为材料进行了砂培试验。设置营养液中不加B (B0，0 μmol/L) 和添加常规硼 (B50，50 μmol/L) 两个浓度处理。生长3个月后，测定了槟榔幼苗生物量、株高、硼含量、叶片糖类物质以及抗氧化酶活性、丙二醛含量、光合速率，观察了不同处理下根尖及根尖细胞的形态。  【结果】  与B50处理相比，B0处理显著降低了槟榔幼苗株高、地下部鲜重和干重、总鲜重、地上部和地下部硼含量；B0处理槟榔叶片蔗糖和淀粉含量下降，可溶性总糖含量无显著变化，叶片光合速率降低，且MDA含量、POD活性显著升高。在B0条件下，槟榔根系变短，根尖明显膨大，细胞壁明显增厚，且内壁上积累了大量的颗粒物，根系活力显著降低。  【结论】  缺硼导致槟榔幼苗根尖解剖结构受到破坏，养分吸收运转能力降低，叶片抗氧化系统受到损伤，光合能力下降，最终抑制植株生长。

Physiological response and root development of areca-nut seedlings under boron deficiency

  【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.