Role of nitrogen fertigation in sweet cherry fruit quality and consumer perception of quality: at- and postharvest

Abstract

The management of nitrogen (N) is key for commercial orchard production as N plays an important role in the quality of sweet cherry fruit. Whilst fertigation is commonly practised by cherry growers in Australia, research into optimal N supply to meet tree demands is limited and the effects of oversupply of preharvest N on fruit quality are virtually unknown. This study aims to investigate (i) the role of preharvest N application on fruit N concentration and the implications for fruit quality postharvest; (ii) consumer perception of stored fruit produced under a relatively high N supply compared with high grade export quality fruit and; (iii) how consumer perception aligns with objective quality measures of firmness (compression test by FirmTech and puncture text by Guss Texture Analyser), sugar and acid composition. Nitrogen treatments, applied as calcium nitrate, were imposed preharvest to 10 year old 'Lapin' trees on F12 rootstock in southern Tasmania through a drip irrigation system. Nitrogen concentration in cherry fruit at harvest significantly increased under the high N treatments. Fruit firmness at harvest and in storage was significantly reduced under increased N supply. Results demonstrate an immediate effect of increased N supply on cherry N concentration and fruit firmness. Sensory analysis demonstrated that consumers strongly preferred export grade over high N fruit and that perception generally matched instrumental fruit quality assessments for the range of parameters tested with the exception of firmness. Preharvest N application must be carefully managed to avoid over-supply of N and consequent detrimental impacts on fruit quality at- and postharvest.