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United States Department of Agriculture

Agricultural Research Service

Research Project: Enhancing Production and Ecosystem Services of Horticultural and Agricultural Systems in the Southeastern United States

Location: Soil Dynamics Research

Title: Soil fertility affects elemental distribution in needles of the conifer Araucaria angustifolia: A microanalytical study

Author
item Barbosa, Julierme
item Constantino, Valdeci
item Zanetti, Flavio
item Motta, Antonio
item Prior, Stephen - Steve

Submitted to: Cerne
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/5/2017
Publication Date: 6/21/2017
Publication URL: http://handle.nal.usda.gov/10113/5763053
Citation: Barbosa, J.Z., Constantino, V., Zanetti, F., Motta, A.C., Prior, S.A. 2017. Soil fertility affects elemental distribution in needles of the conifer Araucaria angustifolia: A microanalytical study. Cerne. 23(2):257-266. doi:10.1590/0104776020172302313.

Interpretive Summary: Araucaria angustifolia is a conifer species found in South American subtropical forests that comprises less than 3% of the native vegetation. Thus, little is known concerning the accumulation of nutritional elements in its needles. In this study, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) was used to assess the elemental accumulation in needles. Research indicated that soil P and K levels affected the locations of elements in needles of Brazilian pine. The type of plant tissue and formation of crystals were important to nutrient dynamics in needles. Under low soil P and K, low amounts of these elements were found in the epidermis, mesophyll, and crystals. Under low soil K, increases in Ca and Mg in needles promoted higher Ca increases in the spongy mesophyll and crystal formation with more Ca and Mg. Under low P conditions, K and Ca accumulated in the spongy mesophyll with a small increase in crystals. The other elements detected in specialized tissues (C, O, S, Al) and in crystals (C, O, Fe, Al, Si, Cl, S, Na) showed no changes due to soil nutrient availability.

Technical Abstract: Araucaria angustifolia is a conifer species found in South American subtropical forests that comprises less than 3% of the native vegetation. Thus, little is known concerning the accumulation of nutritional elements in its needles. In this study, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) was used to assess the elemental accumulation in needles. Needles were selected from 28 month-old plants grown in a fertilization experiment supplied with: 1) N, P, and K; 2) N and P; and 3) N and K. In microanalysis, four types of specialized needle tissues (adaxial epidermis, palisade mesophyll, spongy mesophyll and abaxial epidermis) were evaluated for elemental composition (C, O, P, K, Ca, S and Al). When crystals were detected, the concentrations of 12 elements were determined (C, O, P, K, Ca, S, Al, Fe, Mg, Na, Si, and Cl). Under low soil P and K, these elements were found in low concentrations in the epidermis, mesophyll, and crystals. Under low soil P, Ca and K accumulated in the spongy mesophyll while under low soil K only Ca accumulated in this tissue. In addition, low soil P or K availability favored the formation of crystals; crystals under low soil K availability had more Ca and Mg. Soil P and K availability affected the accumulation of elements in needles of A. angustifolia.

Last Modified: 09/23/2017
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