Leaf anatomy and morpho-physiological mechanisms of acclimation to high irradiance in heliconia genotypes

ABSTRACT The amount of solar irradiation available in the growing environment can cause significant changes in physiology and leaf anatomy that enable crops to acclimate to different light conditions. In this sense, the objective was to characterize the leaf anatomy and to elucidate the morpho-physiological mechanisms of acclimation to high solar irradiance of heliconia genotypes during the initial stage of development under semiarid conditions. The experiment was conducted in the municipality of Petrolina, Pernambuco state, Brazil (09° 19’ 14” S, 40° 32’ 40” W, and 387 m of altitude) and the behavior of three heliconia genotypes (Heliconia rauliniana; H. bihai cv. Lobster Claw Two, and H. rostrata) grown in full sun and shading (50%) environments were evaluated. At 30 days after the implementation of the experiment, leaf anatomy, chlorophyll index, plant height, number of leaves, and number of tillers were analyzed. Heliconia leaves are characterized as amphistomatous with tetracytic stomata. In its main vein there are aerenchyma structures and hypodermis on the abaxial and adaxial sides. The responses to different light conditions in plants of H. bihai, H. rauliniana, and H. rostrata are genotype-specific. Furthermore, the anatomical structures and physiological changes observed in H. bihai and H. rauliniana plants demonstrate that these genotypes present greater plasticity and consequently greater potential for acclimation to high solar irradiation conditions. Thus, the genotypes H. rauliniana and H. bihai emerge as a potential alternative for cultivation in gardens or in open areas and for exploration as cut flower in regions with high solar irradiation availability. RESUMO A quantidade de irradiação solar disponível no ambiente de cultivo pode causar alterações significativas na fisiologia e anatomia foliar que possibilite á aclimatação das culturas a diferentes condições de luminosidade. Nesse sentido, objetivou-se a caracterização anatômica foliar e a elucidação dos mecanismos morfofisiológicos de aclimatação a alta irradiância solar de genótipos de helicônias durante o estágio inicial de desenvolvimento em condições semiáridas. O experimento foi conduzido no município de Petrolina-Pernambuco (09°19’14” S, 40°32’40” O e 387 metros de altitude) e foram avaliados o comportamento de três genótipos de helicônias (Heliconia rauliniana; H. bihai cv. Lobster Claw Two e H. rostrata) cultivadas em ambientes de pleno sol e sombreamento (50%). Aos 30 dias após