The effect of Dual Application of Arbuscular Mycorrhizal Fungi and Polyamines upon Growth and Nutrient Uptake on Trifoliate Orange (Poncirus trifoliata) Seedlings

Abstract

The experiment was carried out to study the dual application effects of Arbuscular Mycorrhizal Fungi (AMF) and polyamines on growth and nutrient uptake of trifoliate orange (Poncirus trifoliata) seedlings. The seedlings were colonized by Glomus versiforme and irrigated with 320 mL 100 mg/L putrescine, spermidine and spermine, respectively. Two months after exogenous polyamines treatments, both putrescine and spermine applications significantly increased the mycorrhizal colonization, whereas spermidine supplement did not alter the colonization rate. The sole AMF inoculation significantly increased total dry weight, leaf P, K, Ca, Mg, Fe, Cu and Mn contents and root P, K, Ca, Fe, Cu and Zn contents of the seedlings, compared to the non-AMF control. Compared to the sole AMF inoculation, additional putrescine and spermine markedly increased total dry weight, and elevated leaf P and K contents and root P, Mg, Fe and Zn contents. These increases were more significantly in the mycorrhizal seedlings supplied with putrescine than in the mycorrhizal seedlings supplied with spermine. All these polyamines applications did not affect root Cu and Mn contents, but enhanced leaf Mn uptake and root Ca uptake. Spermidine treatment had almost no effects on nutrient uptake and growth of the seedlings. These results suggest that dual application of G. versiforme and putrescine could be a feasible procedure for better citrus cultivation.