Phosphorus stress strongly reduced plant physiological activity, but only temporarily, in a mesocosm experiment with Zea mays colonized by arbuscular mycorrhizal fungi

[摘要] Phosphorus (P) is an essential macronutrient for plant growth andone of the least available nutrients in soil. P limitation is often a majorconstraint for plant growth globally. Although P addition experiments havebeen carried out to study the long-term effects on yield, data on P additioneffects on seasonal variation in leaf-level photosynthesis are scarce.Arbuscular mycorrhizal fungi (AMF) can be of major importance for plantnutrient uptake, and AMF growth may be important for explaining temporalpatterns in leaf physiology. In a nitrogen (N) and P fertilizationexperiment with Zea mays , we investigated the effect of P limitation on leafpigments and leaf enzymes, how these relate to leaf-level photosynthesis,and how these relationships change during the growing season. A previousstudy on this experiment indicated that N availability was generally high,and as a consequence, N addition did not affect plant growth, and also theleaf measurements in the current study were unaffected by N addition.Contrary to N addition, P addition strongly influenced plant growth andleaf-level measurements. At low soil P availability, leaf-levelphotosynthetic and respiratory activity strongly decreased, and this wasassociated with reduced chlorophyll and photosynthetic enzymes. Contrary tothe expected increase in P stress over time following gradual soil Pdepletion, plant P limitation decreased over time. For most leaf-levelprocesses, pigments and enzymes under study, the fertilization effect hadeven disappeared 2 months after planting. Our results point towards a keyrole for the AMF symbiosis and consequent increase in P uptake in explainingthe vanishing P stress.

[学科分类] 大气科学