Simultaneously maximizing root/mycorrhizal growth and phosphorus uptake by cotton plants by optimizing water and phosphorus management

BACKGROUND: There are two plant phosphorus (P)-uptake pathways, namely the direct P uptake by roots and the indirect P uptake through arbuscular mycorrhizal fungi (AMF). Maximizing the efficiency of root and AMF processes associated with P acquisition by adjusting soil conditions is important for simultaneously ensuring high yields and the efficient use of available P. RESULTS: A root box experiment was conducted in 2015 and 2016. The aim was to investigate the effects of different P and soil water conditions on root/mycorrhizal growth and P uptake by cotton plants. Hyphal growth was induced in well-watered soil, but decreased with increasing P concentrations. Additionally, P fertilizers regulated root length only under well-watered conditions, with the longest roots observed in response to 0.2 g P(2)O(5) kg(− 1). In contrast, root elongation was essentially unaffected by P fertilizers under drought conditions. And soil water in general had more significant effects on root and hyphal growth than phosphorus levels. In well-watered soil, the application of P significantly increased the cotton plant P uptake, but there were no differences between the effects of 0.2 and 1 g P(2)O(5) kg(− 1). So optimizing phosphorus inputs and soil water can increase cotton growth and phosphorus uptake by maximizing the efficiency of phosphorus acquisition by roots/mycorrhizae. CONCLUSIONS: Soil water and P contents of 19–24% and 20–25 mg kg(− 1), respectively, simultaneously maximized root/mycorrhizal growth and P uptake by cotton plants. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12870-018-1550-8) contains supplementary material, which is available to authorized users.