PT - JOURNAL ARTICLE AU - Johanna Döring AU - Manfred Stoll AU - Randolf Kauer AU - Matthias Frisch AU - Susanne Tittmann TI - Indirect Estimation of Leaf Area Index in VSP-Trained Grapevines Using Plant Area Index AID - 10.5344/ajev.2013.13073 DP - 2013 Nov 07 TA - American Journal of Enology and Viticulture PG - ajev.2013.13073 4099 - http://www.ajevonline.org/content/early/2013/12/04/ajev.2013.13073.short 4100 - http://www.ajevonline.org/content/early/2013/12/04/ajev.2013.13073.full AB - Leaf area index (LAI) and canopy structure are important parameters affecting grape quality and yield of grapevines. Two different experimental protocols as well as the average LAI value of the different protocols for indirect estimation of LAI by gap fraction analysis in VSP trained grapevines (Vitis vinifera L. cv. Riesling) were tested in this study using plant area index (PAI). Measurements were performed using the Plant Canopy Analyzer (PCA, LAI-2200, LI-COR, Lincoln, NE, USA). Directly measured LAI and estimated PAI were compared. Protocol SFC (sensor facing the canopy) gave accurate estimates of LAI by measuring PAI along a diagonal transect including eight vines on each side. The correlation between directly measured LAI and estimated PAI was very high (R2 = 0.93) and the root mean square error was lowest of the methods tested here (RMSE = 0.21). It was shown that eight measurements below the canopy were enough to accurately estimate LAI. By applying the empirical calibration equation the measurements provide accurate LAI estimates. Nevertheless local calibration is required. The method presented provides a useful tool for rapid and precise LAI estimation in VSP training systems and for supporting canopy or management decisions based on LAI.