Abstract

Some sweet cherry cultivars are susceptible to producing double fruits or fruits with deep suture in warm climates. Photo-selective nets can be used to reduce solar radiation and temperature in these orchards, however, they can collaterally affect vegetative growth. This study aims to characterize the vegetative growth of 'Sweetheart' under a permanent photo-selective net. The trial was conducted during the 2021 season in a commercial orchard in central Chile. Two treatments were applied from dormancy to harvest: a control under full sunlight and a shading treatment under a pearl-gray net (24% of shading). Five trees per treatment were randomly selected. Subsequently, 43 days after budbreak (DAB), six shoots and six spurs per tree were chosen. Shoot length, internode number, and relative growth were evaluated weekly. Likewise, spurs were monitored at harvest, recording the proportion of new shoots or old spurs. Intercepted fraction of photosynthetically active radiation (fPARi) by the treatments (fPARi) and the canopy at midday were measured at 51 DAB and harvest (91 DAB). The results indicated that pearl-gray net induced a delay in vegetative development, which was compensated at 65 DAB. fPARi was higher in the treatment under net; however, no differences were found in fPARi at midday. In addition, 67% and 20% of the spurs grew as shoots under full sunlight and shading treatments, respectively. There were no significant differences in final shoot length between treatments. Therefore, the pearl-gray net generated a delay in shoot development and a spur-generating effect. Knowledge of these effects is relevant to regulate the fruit load and ensure balanced vigor in orchards under photo-selective nets.