Influence of phosphorus nutrition and vesicular–arbuscular mycorrhizal fungi on growth and yield of greenhouse cucumber (Cucumis sativus L.)

Abstract

This study determined whether beneficial effects obtained with infection by vesicular–arbuscular mycorrhizal (VAM) fungi during early growth of cucumber are maintained through to maturity. Greenhouse cucumbers (Cucumis sativus L. 'Corona' and 'Carmen') were grown in VAM-inoculated (Glomus intraradices Schenck & Smith) or noninoculated autclaved sandy soil with supplemental phosphorus (P) ranging from 90 to 720 mg P plant−1 wk−1. These P treatments resulted in leaf P levels that spanned the range from deficient to sufficient, based on published data for mature cucumber plants. Leaf and mainstem development, number of fruit per plant, and harvest index were enhanced by increasing P levels in all studies. Low levels of P nutrition resulted in deficiency symptoms that were well correlated with deficient concentrations of leaf P. Mature plants maintained a relatively high level of infection by G. intraradices at low and moderate levels of P nutrition; however, depending on the cultivar, VAM infection either had no effect, or slightly depressed leaf and stem growth. The VAM infection stimulated earlier flowering and fruit production, but a longer fruit abortion period precluded increases in final fruit yield. The reduced shoot development and longer interval of fruit abortion characteristic for VAM-infected plants may be due to increased stress imposed by the collective sink requirements of the fungus and developing fruit. Key words:Cucumis sativus L., growth, phosphorus, vesicular-arbuscular mycorrhizal fungi, yield