| dc.description | In sweet cherries, accumulated nitrogen (N) stores from the previous fall support early spring growth. To complement the N supply in the soil, Chilean growers use foliar urea applications after harvest. Information on the effectiveness of foliar N applications in sweet cherry is lacking. To study the canopy distribution of N applied as urea foliar sprays, an experiment using a "Bing"/"Gisela®6" ("GI®6") sweet cherry orchard was carried out in 2009/2010 in Chile (35° 09' 53'' S, 71° 20' 43'' W). The objective was to investigate N distribution and recycling in 3-year-old fruiting branches. A total of 120 branches (one per tree) were labeled using 15N-urea. 15N-urea was applied to the whole branch on four separate dates or treatments (TR) after fruit harvest: TR1=Jan, TR2=Feb, TR3=Mar and TR4=Apr. For each TR, a group of 15N-labeled branches (10 replications) was destructively harvested at 3 times/stages: 15 days after the urea foliar application (DAA), dormancy and stage I of fruit development. Branches were divided into the various organs, dried (70 °C), ground and processed for GC-MS analysis. In all TR, labeled urea was taken up by the leaves and translocated to various organs. The highest N levels were observed in the fruiting section. TR1 exhibited the highest N use efficiency (NUE%). Buds and bark showed the highest N derived from fertilizer (NDDF%) values. In all TR, stored N was recovered in the flowers, immature fruits and young leaves during the following spring. According to the results, urea sprays after fruit harvest constitute an alternative to complementing the N supply in the soil in sweet cherry trees using "GI®6". | |
