Sweet cherry fruit quality under fertigation

It is generally accepted that nitrogen fertilization must be ceased a month before the cherry fruit ripening because of the negative effects of nitrogen on the fruit quality. On the other hand, fertigation, an indispensable element of the intensive cherry production, requires frequent fertilizer applications and any breach of the regimes of nutrient supply may become limiting to both growth and yield of cherry trees. The objective of this study is to investigate the effect of fertigation on fruit quality under both continuous and interrupted fertilizer supply during the month prior to fruit harvest. For this purpose an experiment was carried out with 'Burlat'/Mazzard and 'Lapins'/'Gisela5' combination (12^th and 13^th leaf) under the conditions of fertigation, respectively through microsprinkling and drip irrigation. Fertigation was ceased one month before fruit harvesting. Results were compared to ones from a drip-irrigated control where the fertigation (including nitrogen) was continuous. Fruit quality was estimated based on measurements of mass, height, width, thickness and firmness, as well as by analyzing fruit flesh content of N, P, K, Ca, Mg, Fe, sugars, acids, vitamin C, juice pH, and dry mass. Before the second experimental vegetation the trees of the 'Lapins'/'Gisela5' combination were severely pruned in order to provide proper leaf-to-fruit balance. According to the obtained results, there were no significant differences between the variants, both with and without interruption of the nitrogen supply before fruit harvest. Hence, fertigation, especially with nitrogen, may be applied continuously without negative effects on the cherry fruit quality.