Effects of increasing soil phosphorus and association with ectomycorrhizal fungi (Pisolithus microcarpus) on morphological, nutritional, biochemical, and physiological parameters of Pinus taeda L

Abstract

Phosphorus (P) is the macronutrient that most limits the growth of forest plantations. Pinus taeda L., has shown divergent responses when subjected to phosphate fertilization, probably by association with mycorrhizal fungi activity, in relation to morphological parameters, nutritional, physiological, and oxidative stress. The study aimed to evaluate if the increase of P levels in the soil and associated with ectomycorrhizal fungi and its effects on morphological parameters, nutritional status, biochemistry, and physiology of P. taeda. The experiment was conducted in a greenhouse, with Pinus taeda inoculated (With) and non-inoculated (Without) with Pisolithus microcarpus, under three soil P levels: Low P – without P addition; Medium P (30 mg P kg−1); and High P (60 mg P kg−1). Morphological parameters of the shoot and root system, nutritional status, chlorophyll a fluorescence, photosynthetic variables, photosynthetic pigments, oxidative stress indicators and antioxidant enzymes were evaluated. The addition of P to the soil increased the values of aerial and root growth parameters, P status in the plant, and photosynthetic efficiency of P. taeda. The increase of P in soil provided an increase in P uptake and development of surface area, volume, and length roots, enhanced by inoculation with P. microcarpus. The increase of P within the plant increased the values of variables related to the physiological apparatus such as A, Gs, WUE, A/Ci, and Ci and the fluorescence efficiency (i.e., ETR, Fv/Fm and Y(II)). This increased C assimilation in leaf tissues and thus increased needles and stem dry matter production, and development in height and stem diameter of P. taeda.