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|Title:||Comparison of different protocols for indirect measurement of leaf area index with ceptometers in vertically trained vineyards|
|Authors:||LOPEZ LOZANO RAUL; CASTERAD M. Auxiliadora|
|Citation:||AUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH vol. 19 no. 1 p. 116-122|
|Type:||Articles in periodicals and books|
|Abstract:||Background and Aims Most optical devices to indirect leaf area index (LAI) measurements from canopy transmitted light are tailored to be used in homogenous canopies, thus limiting a priori their application to discontinuous ones such as vertical trained vineyards. This work evaluates the influence of sun position in the reliability of LAI estimations provided by a ceptometer, and propose a measurement protocol for the use of this instrument on vineyards under direct light illumination. Methods and Results An experimental plan comprising ceptometer readings at different sun elevation and azimuth angles was conducted in two fields. LAI estimated by ceptometer at different sun positions were then compared against destructive leaf area measurements. Best overall results were obtained when sun position departs from zenith (sun elevation <40°) and the light transmittance measurements integrates all the inter-row space. Conclusions The homogeneity of transmitted Photosintetically Active Radiation (PAR) values along ceptometer is critical in de accuracy of indirect LAI estimation. The pattern of SunScan ceptometer readings and sun position revealed critical for the accuracy of LAI determination. Significance of the Study Provide guidelines to reducing LAI uncertainties associated to vineyard canopy structure in LAI estimation with optical devices like Sun SCAN ceptometer.|
|JRC Directorate:||Sustainable Resources|
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