Efeitos da restrição hídrica na anatomia foliar de poáceas com metabolismos C3, C3 Proto-Kranz e C4

Abstract

Studies related to evolution, plants distribution and ecology aim to understand how climatic changes and abiotic stress affect plants with different photosynthetic metabolisms. The aim objective of this study was to determine the influence of water availability on leaf anatomy variations of C3, C3 proto-Kranz and C4 poaceae. In this research, three species representatives the carbon assimilatory pathways, Oryza sativa, Homolepisisocalycia and Andropogongayanus, respectively, were submitted to three water regimes. The design was completely randomized design in a 4x3 factorial scheme, considering twoo rice varieties, susceptible and the drought tolerant – Soberana and Douradão, respectively. The following variables were determined: distance and number of cells between vascular bundles (μm), area covered by vascular bundle sheath cells (BFV), area covered by mesophyll cells (M), total epidermis area (AEPID), thickness of the upper and lower epidermis on the adaxial (EADAX) and the abaxial (EABAX) face, area covered of the buliform cells (CB), intercellular space area (EI), xylem area (X) and phloem area (F). Was determined the percentage of buliform cells (pBULIF), percentage of intercellular space (pEI), percentage of carbon assimilation area in the mesophyll cells, percentage of carbon reduction area in the vascular bundle sheath and ratio of carbon assimilation area in the mesophyll for carbon reduction area in the vascular bundle sheath (M:BFV).The data were submitted to analysis of variance (ANOVA) followed by the Tukey test (P <0.05) using R Studio software. It was possible to verify that the more specific the leaf anatomy of the species is, as in the case of A. gayanus (C4), less anatomical variations it occur, regardless of the water condition. The foliar anatomical behavior of the intermediate species H. isocalycia resembled both C3 and C4 species in certain characteristics analyzed, such as the mesophyll area, number of cells, stomatal density, abaxial epidermal thickness, phloem area and intercellular space. When subjected to water deficit, anatomical rearrangement was similar to rice plants at the distance between vascular bundles and buliform cells area; and similar to C4 plants in the ratio of mesophyll cells to vascular bundle sheath cells (M: BFV).