Interactions between phosphorus supply and total nutrient availability on mycorrhizal colonization, growth and photosynthesis of cucumber

Abstract

The effects of arbuscular mycorrhizal (AM) infection by Glomus mosseae (Nicolson & Gerdemann) Gerdemann & Trappe on growth, photosynthesis and nutrient concentration of cucumber ( Cucumis sativus L. var. Telegraph Improved) were studied in sand culture with three different nutrient solutions based on the Long Ashton formula. These were high P+high concentrations of the other essential nutrients (full-strength solution containing 1.3 mM P), low P (0.13 mM)+ high concentrations of the other nutrients and low P+low concentrations of the other nutrients (10% of the full-strength nutrient solution). AM infection was found to depend on both P supply and the availability of other nutrients. Plants grown at low P with high concentrations of other nutrients had the highest AM infection, and a higher biomass due to an enhanced maximum net photosynthetic rate ( P m). Although this was unrelated to the N concentration of leaves, there was evidence that the higher P m was associated with a low leaf P concentration and the significance of these results is discussed. With high P and high concentrations of the other nutrients, a growth depression was found with +AM plants, although this was not due to a reduction in photosynthesis or an increase in leaf dark respiration rate. It was, however, associated with a reduction in photosynthetic nitrogen use efficiency. Overall, the present study indicates that any advantages or disadvantages associated with AM infection in cucumber are a result of complex interactions between P supply and the availability of other essential nutrients.