S16 - Session P1 - Apple orchard row orientation and light exposure to optimise quality and yield of apple fruit

Authors: Madeleine Peavey *, Lexie McClymont, Alessio Scalisi, Ian Goodwin

Row orientation is an important factor in the creation of a new orchard, and once established cannot be altered. The direction of orchard rows affects the angle of incoming solar radiation to the tree canopy, changing the potential for light interception and distribution throughout the canopy m two key features of orchard productivity. The amount of light intercepted by the leaves on fruiting spurs is directly linked to carbohydrate assimilation in the nearby fruit. Orchard design, thus far, has striven to maximise both light interception and distribution, leading to the widespread implementation of north n south orientated rows. Excessive light exposure, however, can be detrimental to photosynthetic rate and cause sunburn damage, yet light exposure is often needed for improved colour and fruit development. In a climate of high light intensity and extreme heat events, such as that in South-Eastern Australia, and with climate change likely to place current orchard systems at risk, altering row orientation offers an adaptation strategy to optimise yield and fruit quality. The aim of this study was to investigate the influence that row orientation has on vegetative growth, canopy light interception and distribution, yield and fruit growth, quality and colour development of the Australian apple cultivar 'ANABP 01'. Trees were grown in a multidirectional orchard (east-west, northwest-southeast, north-south, northeast-southwest row orientations) and canopy light interception and distribution were measured monthly, and yield assessed at harvest. Exposure of fruit to photosynthetically active radiation was measured monthly. Vegetative shoots were monitored weekly for length and fruit were monitored weekly from 42 DAFB until harvest for fruit growth and colour development, and assessed at harvest for soluble solids concentration, flesh firmness, starch index and dry matter concentration. The effects of row orientation and their implications for orchard management decisions are discussed.