A relationship between increasing midday canopy PAR intercepted by orchard tree canopies and increasing productivity has been well documented (Jackson, 1980; McFadyen et al., 2004, Robinson and Lakso, 1991; Wagenmakers and Callesen, 1995). However, collecting data on canopy light interception in orchards is time-consuming, and it is difficult to measure large areas. Several different methods of estimating canopy light interception have been used including fisheye photography (Robinson and Lakso, 1991). Wunsche et al. (1995) used a series of light sensors moved on a trailer through the orchard, while Giuliani et al. (2000) used a portable light bar with 48 phototransistors and a Teflon diffuser. A commercially available PAR-sensing bar (Ceptometer; Decagon Devices, Pullman, WA) was used by Grossman and DeJong (1998) and McFadyen et al. (2004) to take multiple readings in a regular pattern under the trees. Although all of these methods can provide useful data, they are all time-consuming, which makes it difficult to measure light interception in large areas of the orchard.
The authors have used the methods described by Grossman and DeJong (1998) to collect PAR interception data using a hand light bar (unpublished). However, the area covered by the hand light bar is small. Since both almonds and walnuts are mechanically harvested, it is difficult to cover large enough areas with the hand light bar to coincide with areas harvested. Therefore, the areas covered with the light bar and harvest data were often not equal.
The mobile platform described here was designed to automate the collection of canopy PAR data. This allowed much larger scale mapping of variability in orchard light interception and better comparison with mechanically harvested yield data.
DanylukM.D.Nozawa-InoueM.HristovaK.R.ScowK.M.LampinenB.HarrisL.J.2008Survival and growth of Salmonella Enteritidis PT 30 in almond orchard soilsJ. Appl. Microbiol.10413911399
GiulianiR.MagnaniniE.FragassaC.NerozziF.2000Ground monitoring the light-shadow windows of a tree canopy to yield canopy light interception and morphological traitsPlant Cell Environ.23783796
GrossmanY.L.DeJongT.M.1998Training and pruning system effects on vegetative growth potential, light interception and cropping efficiency in peach treesJ. Amer. Soc. Hort. Sci.12310581064
McFadyenL.M.MorrisS.G.OldhamM.A.HuettD.O.MeyersN.M.WoodJ.McConchieC.A.2004The relationship between orchard crowding, light interception, and productivity in macadamiaAust. J. Agr. Res.5510291038
RobinsonT.L.LaksoA.N.1991Light interception, yield and fruit quality of ‘Empire’ and ‘Delicious’ apple trees grown in four orchard systemsActa Hort.243175184
VerheijE.W.M.VerwerF.L.J.A.W.1973Light studies in a spacing trial with apple on a dwarfing and semi-dwarfing rootstockSci. Hort.12542
WagenmakersP.S.CallesenO.1995Light distribution in apple orchard systems in relation to production and fruit qualityJ. Hort. Sci.70935948
WunscheJ.N.LaksoA.N.RobinsonT.L.1995Comparison of four methods for estimating total light interception by apple trees of varying formsHortScience30272276