A Mobile Platform for Measuring Canopy Photosynthetically Active Radiation Interception in Orchard Systems

Abstract

<jats:p>A mobile platform was developed for measuring midday canopy photosynthetically active radiation (<jats:italic>PAR</jats:italic>) interception in orchards. The results presented are for almond (<jats:italic>Prunus dulcis</jats:italic>) and walnut (<jats:italic>Juglans regia</jats:italic>), but the mobile platform can be used in other orchard crops as well. The mobile platform is adjustable to accommodate orchard row spacing from 4.8 to 7.8 m and is equipped with a global positioning satellite (GPS) receiver and radar for positional assessment as well as three IR thermometers for measuring soil surface temperature. Data from the mobile platform are logged at 10 Hz and stored on a data logger. Custom software has been developed to process the data. The mobile platform was used extensively for mapping midday canopy <jats:italic>PAR</jats:italic> interception in almond and walnut orchards in 2009 and 2010. The mobile platform produced comparable results to those collected with a handheld light bar with the advantage of being able to cover much larger areas and compare these data to mechanically harvested yield data over the same area. For almond orchards, midday canopy <jats:italic>PAR</jats:italic> interception peaked at ≈70% at an orchard age of ≈12 years. For walnut orchards, midday canopy <jats:italic>PAR</jats:italic> interception continued to increase to ≈15 years of age and peaked at a level above 80%. The mobile platform was also able to follow seasonal development of midday canopy <jats:italic>PAR</jats:italic> interception in young and mature orchards. This technology has potential for evaluating new varieties in terms of productivity per unit <jats:italic>PAR</jats:italic> intercepted, in evaluating hand pruning or mechanical hedging practices in terms of impact on <jats:italic>PAR</jats:italic> interception/productivity as well as evaluating effectiveness of insect or disease management treatments. It also has potential as a reference point for grower self-assessment to evaluate orchard canopy development compared with other orchards of similar variety, spacing, etc. Finally, this technology could be used as ground truth referencing for remotely sensed data.</jats:p>

Light interception, leaf nitrogen and yield prediction in almonds: A case study

“…The results showed that canopy light interception or LAI of individual trees are poor predictors of almond yield. Making measurements over a wide range of canopy light interception values, Lampinen et al (2012) found that the correlation between MLB fPAR and yield of entire orchard rows was moderate for almonds (R 2 = 0.49-0.59 for two consecutive years) and high for walnuts (R 2 = 0.62 and 0.83).…”

“…Lampinen et al (2012) found that canopy light interception in almonds, walnuts and other tree crops correlates well with maximum potential yield. They reported that the maximum sustainable yield in commercial almond orchards of California is 56 kernel kg ha −1 per each unit percent light intercepted by the canopy.…”

Actual Evapotranspiration and Tree Performance of Mature Micro-Irrigated Pistachio Orchards Grown on Saline-Sodic Soils in the San Joaquin Valley of California

“…Specifically, the natural light in the PAR region (400-700 nm) below the canopy (PARb) was measured during the surveys using a series of AccuPAR LP-80 ceptometers (Decagon Devices, Inc., Pullman, WA, USA) connected to a datalogger (CR3000, Campbell Scientific, Logan, UT, USA) and mounted at a height of 0.4 m from the ground level on two side-arm bars of a Kawasaki Mule utility vehicle or Mobile LightBar (MLB) [48]. Measurements of light interception were taken during clear skies at solar noon ± 1 h. The MLB is normally operated at a speed of about 2.8 m s −1 , scanning the light transmitted by the canopy every 0.3 m down the orchards rows and integrating segments of 0.4 m across the rows [49].…”

Advancing Agricultural Production With Machine Learning Analytics: Yield Determinants for California’s Almond Orchards

“…Among the variables that have been shown to impact yield in almond, canopy interception of photosynthetically active radiation (PAR), is directly related to maximum potential yield of almonds (Zarate-Valdez et al, 2015). Lampinen et al (2012), reported that the maximum sustainable yield in the most productive commercial almond orchards is 56 kernel kg/ha per unit PAR intercepted by the canopy. Percent light interception at the orchard level is determined by canopy structure, e.g., total leaf area and health at the individual tree level, as well as row and tree spacing; while the location of the orchard (latitude) and cloud fraction affect the total amount of PAR incident on the canopy.…”