An alternative dormancy-breaking agent to hydrogen cyanamide for sweet cherry (Prunus aviumL.) under low chilling accumulation conditions in the Central Valley of Chile

Abstract

In areas with mild winters and low chill accumulation, the application of budbreak promoters such a hydrogen cyanamide (HC) is used to overcome insufficient winter chilling in sweet cherry (Prunus avium L.). Despite HC efficiency, its toxicity to human health and environment has become a serious issue. A potential alternative to HC is Erger®, an organic nitrogen compound. Erger® might promote a more concentrated and uniform bloom, early vegetative growth and higher fruit size, without toxic effects. The objective of this study was to compare the effect of applications of Erger® and HC on fruit production and vegetative growth in combination 'Santina®'/'Pontaleb'. The experiment was carried out in Colina (Lat. 33°13'; Long. 70°42'), Metropolitan Region, Chile. The treatments (TR) included: TR1 = Control (H2O); TR2 = Erger® (6%) + calcium nitrate (9%) [Erger®+Ca(NO3)2]; TR3 = Erger® (6%); TR4 = calcium nitrate (9%) [Ca(NO3)2]; TR5 = hydrogen cyanamide (2%) + oil at (0,015%) [HC+oil]. TRs were sprayed with 520 chilling hours (Modified Richardson model). Erger®+Ca(NO3)2 and HC+oil treatments advanced bloom. [Erger®+Ca(NO3)2] concentrated bloom and increased the number extension shoots. Pollen viability was negatively affected by most TRs with exception of Erger®+Ca(NO3)2. Fruit set was similar among TRs. Budbreak promoters increased significantly fruit weight, however, [Erger®+Ca(NO3)2] not only increased fruit size, but it also shifted the distribution curve to the larger sizes.