The spatial distribution of phosphate in the root system modulates N metabolism and growth in Eucalyptus grandis young plants

COSTA LORENZA; FAUSTINO LAURA; GRACIANO CORINA

TREES-STRUCTURE AND FUNCTION

SPRINGER

Lugar: Berlin; Año: 2017 p. 247 - 257

0931-1890

Little is known about consequences of nutrient imbalances, i.e. when theincrease of one nutrient´s availability, in non-toxic concentration, reducesplant growth because other nutrient availability is low. In a soil with low N(nitrogen) availability, high homogeneous P (phosphorus) availability reducednitrate uptake and reduced growth of Eucalyptus grandis plants. However, if thesame availability of P was applied only in a part of the root system(localized), no depressive effect was observed. In this work it was analyzedwhich step in early assimilation of N was affected by high homogeneousP and howlocalized P counteracted this depressive effect. Inorganic forms of N andprotein in plant tissues as well as some plant hydraulic traits were analyzedin an experiment with E. grandis plants growing in perlite in a split-rootsystem fed with low N. Control plants received low P. High P was applied in twospatial distributions: localized in one part of the root system (LP) ordistributed homogeneously in both parts (HP). HP reduced growth while LP had nodepressive effect in growth. Both high P spatial distributions reducedconcentration of nitrate in roots. Since concentration of nitrate in the xylemwas similar in all treatments and nitrate in leaves were lower in high P thanin control treatment, the reduction in root N was probably due to lower uptake.Nevertheless, plants growing with LP had no depressive effect in growth becausethe decrease in N assimilation was counteracted by an increase of roothydraulicconductivity.