[Effects of arbuscular mycorrhizal fungi on growth and iron uptake of Poncirus trifoliata under different pH]

Abstract

Objective: We studied the effects of arbuscular mycorrhizal fungus ( Glomus versiforme) on growth and iron uptake of trifoliate orange [Poncirus trifoliata (L.) Raf.] at different pH levels of nutrient solution.

Methods: P. trifoliata seedlings were grown in substrates watered by nutrient solution with 50 microM Feethylenediaminetetraacetic acid (EDTA) at pH values of 5.0, 6.0 (as control), 7.0 and 8.0 with a sand culture. Mycorrhizal colonization was tested by trypan blue staining method. Chlorophyll concentratration and root Fe (III) chelate reductase activity were determined by spectrophotometer. Potassium and active iron contents were quantified by atomic spectrometry, and phosphorus contents was through phospho-vanado- molybdate colorimetry.

Results: The colonization of Glomus versiforme significantly increased the plant height, stem diameter, leaf numbers, and dry mass. Arbuscular mycorrhizal fungus significantly enhanced the accumulation of chlorophyll, active iron, total iron and root Fe(III) chelate reductase activity, and decreased P/Fe and 50 (10P + K)/Fe ratios. All biomass, iron contents and root Fe(III) chelate reductase activities of P. trifoliata seedlings at pH 6.0 level were the maximum both in inoculated and non-inoculated treatments.

Conclusion: Arbuscular mycorrhizal fungi could remedy chlorosis caused by iron-deficiency in citrus, and 6.0 was the optimal pH value for the growth of P. trifoliata seedlings.