Can water stress lead to water excess?

Fruit cracking in sweet cherries is a significant problem for growers world-wide. Recent research has indicated that uptake of water through the vascular system can increase large cracks in fruit following rainfall. It is likely, therefore that irrigation water could impact on fruit cracking. To assess the impact of high irrigation rates on water uptake and cracking, irrigation volumes in a commercial orchard were manipulated to either over or under-irrigate cherry trees compared to the orchard standard. The standard was set by a pre-determined soil moisture level on an automated system. Fruit cracking, and fruit cracking index were determined at harvest maturity from trees subject to high, medium and low irrigation volumes. Results showed that fruit from trees under the low volume exhibited both a greater susceptibility rating (according to the cracking index), and a higher incidence of cracking following rainfall. This result supports previous studies into fruit cracking and highlights the importance of disallowing fruit and trees to create potential gradients that will drive water movement when increased water is supplied. Furthermore, the diurnal growth patterns of fruit from each of the irrigation treatments support the link between adequate water supply through irrigation and increased uniformity of fruit growth. Fruit from water stressed trees were less able to support expansion, showed higher daily fluctuations in diameter compared to total growth, and could not withstand excess water after rainfall.