TITLE:
Soil and Leaf Micronutrient Composition in Contrasting Habitats in Podzolized Sands of the Amazon Region
AUTHORS:
María Antonieta Sobrado
KEYWORDS:
Acid Soils; Amazon Caatinga; Ionome; Leaf Nutrient Homeostasis; Micronutrients; Toxic Elements
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.4 No.10,
September
25,
2013
ABSTRACT:
Plant
macronutrient distribution in podzolized sands of the Amazon caatinga has
received attention in several studies; however, the distribution of
micronutrients has not been assessed. Soil micronutrient availability has been
hypothesized to reflect contrasting habitat characteristics as well as
fundamental differences in substrate, and leaf micronutrient composition may
reflect the macronutrient content needed to maintain balance for leaf cell
functions. In this study, soil and leaf samples were obtained in a toposequence
(valley, slope, and mound). Available soil micro- and macronutrients as well as
total leaf content were measured by inductively coupled plasma-atomic emission
spectrometer and mass spectroscopy. Soil Zn (-1)
and B (-1) as well as Cu (-1)
levels were very low. Soil Mn was low in the valleys and slopes (0.62-0.87 mg·kg-1),
but higher in the mound (6.59 mg·kg-1). Soil Fe (11.48-21.13 mg·kg-1)
was well above the critical level in all of the habitats. Leaf micronutrients
Cu, B, Zn, and Fe were below the critical levels for tropical crops of 3-7, 20-70, 15-20, and 72 mg·kg-1,
respectively. Leaf Mn (88 mg·kg-1) and Al (-1) were below the accumulators level. A strong relationship
between leaf micro- and macronutrients suggests the maintenance of a
homeostatic elemental composition, which may favour photosynthetic function.
Therefore, the local distribution of species may be shaped by their abilities
to maintain a balance of micronutrient collected through roots under critically
low levels of available Zn, B, and Cu whilst excluding potentially deleterious
ions of Mn, Fe, and Al.