Analisi della plasticità temporale e spaziale in genotipi contrastanti di Populus nigra L.
Author(s)
Russo, Giuseppe
Date Issued
March 10, 2011
Type
Doctoral Thesis
Abstract
The work deals with two opposing genotypes of Populus nigra L., one from North of Italy and the other from South and it is divided in several fields of research: study of temporal plasticity (growing season 2008) including at canopy level (growing season 2009), study of genotypes in a multi-site evaluation and observations about particular micro-morphological traits. In the case of spatial plasticity progeny of the opposing genotypes (parent clones) was analyzed too. Species like black poplar (continuous growth) can show a modification of features in leaves along the growing season; considering different generations of leaves each leaf become a sort of regulatory valve mixing the intrinsic water use efficiency (Wi), considered an instantaneous process, a resultant in which it’s possible to identify the concept of temporal plasticity. Stable carbon isotopes utilization has shown higher and constant efficiency of 58-861 genotype (northern) than Poli one (southern). Lab measurements in standard conditions have highlighted the different behaviour in the two poplars, confirming that they use different adaptive strategies by leaf traits (both morphologycal and stomatal) as drivers to acclimate (a form of plasticity). Moreover differences would be caused by a different nitrogen uptake in the opposing genotypes, a trait strongly correlated to leaf traits and isotopic composition too. The next year was charctarized by the morpho-physiologic evaluation of canopy; by this set it was possible to improve field measurements. Three levels of genotypes were analyzed, by leaf parameters; at the end of season (September) isotopic composition of leaves was compared with corresponding section of stem at the base of leaves. Results have confirmed the different behaviour of genotypes about the canopy profile, both in morphology and physiology; thus higher water use efficiency of 58-861 genotype was confirmed.Third part of thesis work deals with comparison of two experimental plantations (common garden) in different places. Results have confirmed the hypothesis that leaf traits “drive” physiological ones cause in 58-861, though there are no morphologycal differences in the sites, there is a different WUE (measured by stable carbon
isotopes) not strong as difference carried out from progenies compared and in which morphologycal differences exist. By this way Poli results as a stable genotype, able to face in the same manner different environment (canalization at spatial level). In the final part PhD thesis presents a spin-off about giant stomata, observed during the other activities of research. They represent a morphologycal leaf trait so little studied yet but it would be fundamental to clarify aspects of ontogenesis and evolution in black poplar by a physiological study approach. In perspective of analysis and studies that could be improve the entire set of the present thesis work, it is possible to catch the necessary suggestion to detect new breeding strategies in cultivation of poplars.
Additional information
Dottorato di ricerca in Ecologia forestale
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