The all-wave radiant energy absorbed by the canopy (Rnc) of trees is one of the main variables of interest in water studies and crop growth of woody species, but its direct determination is not an easy task, being limited to experimental work. Scanning the top of trees along plant hedgerows by moving net radiometers around them is a technique that renders possible spatiotemporal integration of Rnc values, allowing the tests of physico-mathematical models and establishing of correlations of Rnc with routine measurements of incoming solar radiation (Rg) and grass net radiation (Rng). Integrated values measured by this technique in a stretch of rows of a coffee plantation and an acid lime orchard were correlated with Rng and Rg. For the coffee crop, linear and quadratic polynomial equations fitted well for the relationship of Rnc with Rg and Rng for autumn, winter and spring in 15 min, hourly and diurnal time-scales, but for the summer only in the diurnal scale this occurred. For the lime orchard, good fits were obtained in the three timescales in the winter, but only for the diurnal timescale in the summer.
net radiation; orchard; citrus; coffee
