Foliar anatomical and morphological variation in Nothofagus pumilio seedlings under controlled irradiance and soil moisture levels

IVANCICH, HORACIO; LENCINAS, MARIA VANESSA; MARTÍNEZ PASTUR, GUILLERMO; SOLER ESTEBAN, ROSINA MATILDE; HERNÁNDEZ, LUIS; LINDSTROM, IVONE

TREE PHYSIOLOGY

OXFORD UNIV PRESS

Año: 2012 vol. 5 p. 554 - 564

0829-318X

Foliar anatomy and morphology is strongly related to physiological performance, therefore phenotypic plasticity in leaves to variations in environmental conditions, as irradiance and soil moisture availability, can be related to growth rate and survivorship, mainly during critical growth phases as establishment. The aim of this work was to analyze changes in the foliar internal anatomy (tissue proportions and cell dimensions) and external morphology (leaf length, width and area) of Nothofagus pumilio seedlings growing in a greenhouse under controlled irradiance (three levels) and soil moisture (two levels) along one growing season (measured three times), and relate them to physiological traits. Three irradiance levels (4%, 26% and 64% of the natural incident light) and two soil moisture levels (40% and 80% soil capacity) were evaluated during November, January and March. Internal foliar anatomy of seedlings was analyzed using digital photographs of histological cuttings, while leaf gross morphology was measured using digital calipers and image analysis software. Most internal anatomical variables presented significant differences under different irradiance levels along the growing season, but differences were not detected between soil moisture levels. Palisade parenchyma was the most sensitive tissue to irradiance levels, meanwhile high irradiance levels (64% natural incident light) produced greater values in most of the internal anatomical variables than lower irradiance levels (4%-24% natural incident light). Complementary, larger leaves were observed in medium and low irradiance levels, as well as under low soil moisture levels (40% soil capacity). Relation with eco-physiological traits was discussed. Foliar internal anatomical and external morphological plasticity allows quick acclimation of seedlings to environmental changes (e.g., during harvesting). These results can be used to propose new forest practices that consider soil moisture and light availability changes to maintain high physiological performance of seedlings.