EFFICIENCY OF USE OF PHOTOSYNTHETICALLY ACTIVE RADIATION BY AÇAIZEIRO IN THE MICROMETEOROLOGICAL CONDITIONS OF CASTANHAL - PARÁ
Radiation, Productivity, Photosynthesis
The açaizeiro (Euterpe oleracea Mart.) is a species of palm native to the Amazon region, belonging to the botanical family Arecaceae, and is considered the most important palm of the Euterpe genus in Brazil. Therefore, the most valuable and commercially recognized products of the açaí tree, which supply the human food market, are the palm heart and, above all, the juice of its fruit, açaí. Photosynthetically Active Radiation (PAR) is the solar radiation that plants absorb or assimilate to carry out their biochemical processes, and is one of the major factors influencing crop productivity. The aim of this study was to analyze the efficiency of use of photosynthetically active radiation in the açaizeiro crop under the microclimatic conditions of Castanhal-PA. The study was conducted in the municipality of Castanhal in an area of 0.6 ha-1 of commercial açaí plantations (1°19'10.40" S and 47°35.94" W). The agrometeorological variables were collected using instruments fixed to a 17 m high micrometeorological tower installed within the commercial açaí plantation area. The intercepted RFA radiation (RFAint ) was obtained as a result of comparing the photosynthetically incident radiation (RFAinc ) and the radiation transmitted to the ground (RFAts ). The average monthly incident global solar radiation flux was 16.97 (±2.21) MJ m-2 day-1 in 2018. PAR above the canopy averaged 8.13 (±0.87) MJ m-2 day-1, with a minimum of 6.78 and a maximum of 9.24 MJ m-2 day-1. It was observed that the photosynthetically active radiation intercepted during the 7 months of the harvest has a direct influence on the productivity of the açaí crops, in addition to the meteorological elements that influence this development, such as rainfall, relative humidity, global radiation and minimum air temperature.