Monitoring spatial variability in an apple orchard under different water regimes

R. Rud, J. Käthner, J. Giesser, R. Pasche, A. Giebel, J. Selbeck, C. Shenderey, D. Fleury, M. Zude-Sasse, V. Alchanatis
Precision fruticulture addresses site or tree-adapted crop management. In the present study, soil and tree status, as well as fruit quality at harvest were analysed in a commercial apple (Malus × domestica 'Gala Brookfield'/Pajam1) orchard in a temperate climate. Trees were irrigated in addition to precipitation. Three irrigation levels (0, 50 and 100%) were applied. Measurements included readings of apparent electrical conductivity of soil (ECa), stem water potential, canopy temperature obtained by infrared camera, and canopy volume estimated by LiDAR and RGB colour imaging. Laboratory analyses of 6 trees per treatment were done on fruit considering the pigment contents and quality parameters. Midday stem water potential (SWP), normalized crop water stress index (CWSI) calculated from thermal data, and fruit yield and quality at harvest were analysed. Spatial patterns of the variability of tree water status were estimated by CWSI imaging supported by SWP readings. CWSI ranged from 0.1 to 0.7 indicating high variability due to irrigation and precipitation. Canopy volume data were less variable. Soil ECa appeared homogeneous in the range of 0 to 4 mS m-1. Fruit harvested in a drought stress zone showed enhanced portion of pheophytin in the chlorophyll pool. Irrigation affected soluble solids content and, hence, the quality of fruit. Overall, results highlighted that spatial variation in orchards can be found even if marginal variability of soil properties can be assumed.
Rud, R., Käthner, J., Giesser, J., Pasche, R., Giebel, A., Selbeck, J., Shenderey, C., Fleury, D., Zude-Sasse, M. and Alchanatis, V. (2018). Monitoring spatial variability in an apple orchard under different water regimes. Acta Hortic. 1197, 139-146
DOI: 10.17660/ActaHortic.2018.1197.19
apple, CWSI, precision agriculture, management zone

Acta Horticulturae