Light conditions measurement in 3D digitized apple trees to evaluate their influence on fruit quality | Pommiers digitalisés pour mesurer l'influence du microclimat lumineux sur la qualité des fruits
2012
Monney, Ph. | Potel, A.-M., Agroscope Changins-Waedenswil (ACW), Nyon (Switzerland) | Sinquet, H. | Sonohat, G. | Lauri, P.-E.
3D plant models of 13 to 14 year-old apple trees were created with computer programs, considering the variety Golden Delicious and three training systems (Vertical Axis, Drilling, Ycare). These models helped calculating light conditions within a tree and consequently their influence on sugar content of individual fruits. Within a tree, the sugar content was related to the STAR (Silhouette to Total Area Ratio, i.e. the ratio of exposed to total leaf area during a day) of the leaf area near the fruit. High correlation coefficients (r2 = 0.75 in 2004 and 0.88 in 2005) could be achieved between STAR categories and sugar content of the respective fruits. However, for individual fruits the correlation coefficients were rather low (r2 0.2 for over a half of the trees in 2004 et 2005), suggesting that light conditions nearby fruit were not sufficient to explain alone its sugar content. Other factors, such as shoot lengths which affects the leaf area, may also play a role. This information is useful for trailing and pruning the trees to improve fruit quality. Differences in average sugar content of the fruits between training systems and apple trees could not be related to light conditions. The fruit to leaf area ratio was better suited to explain those differences in fruit sugar content between the trees.
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