RESPOSTAS MORFOFISOLÓGICAS DE MUDAS DE PINHA SOB DIFERENTES LUMINOSIDADES E REPOSIÇÃO HÍDRICA

Abstract

The pinecone is a fruit tree adapted to tropical climates, so, it is very promising in Brazil. However, it is important to understand this crop and how edaphoclimatic factors influence the physiology/gas exchange during the plant growth and development. Studies regarding luminosity and water replacement are important to provide the most efficient protection and irrigation to it. Thus, this paper aimed to evaluate the physiology/gas exchange during the growth of the pine tree under different shading environments and irrigation blades. The experiment was carried out in the experimental area of the Goiano Federal Institute, Ceres Campus, Goiás State (GO), Brazil, from May to July 2021. The statistical design was completely randomized in split-plot, consisting of three protection or shading environments (full sun, 50% and 70% shade screen) and four volumetric water contents [25%, 50%, 75%, and 100% of evapotranspiration (ETc) blades], and five replicates. The seedlings were produced from seeds at the Institute. Plant height (PH), number of leaves (NL), fresh and dry mass (leaves, stem, spindle root, and secondary root), and volume (spindle root and secondary root) were the morphological variables analyzed. Gas exchange, leaf and air temperature, vapor pressure deficit, relative chlorophyll content (Soil Plant Analysis Development - SPAD index), fluorescence, stomatal conductance, and photosynthesis physiological variables were analyzed. Full sun cultivation resulted in higher active photosynthetic radiation. Leaf temperature and vapor pressure deficit increased with 100% water replacement. The best results for photosynthesis occurred under 70% shading and 100% water replacement. The plant height, leaf fresh mass, and stem dry mass variables showed interaction between environments and water replacement. The physiological variables in general showed statistically different responses, regarding to water replacement, except for the dry and fresh stem mass that have responded to different protection environments.