Application of biostimulants enhances precocity and number of king flowers in a kiwifruit orchard in central Italy

In order to adopting sustainable agricultural methodologies, such as the incorporation of biostimulants, is a viable strategy. This study aimed to investigate the impact of a non-microbial biostimulant on the agronomic performance of Actinidia deliciosa (kiwifruit) trees. The experiment was carried out in 2018 in a 6-ha eight-year-old kiwifruit vine located in Cisterna di Latina (Lazio, central Italy), in which a plastic film covered half of the orchard. A single application of a liquid biostimulant fertilizer (24 L per treatment) was applied 30 days prior to the expected date of bud break. The foliar spraying application took place simultaneously for both covered and uncovered plots. This product, comprising a mixture of free amino acids and peptides, was used to investigate the effects on interrupting dormancy and floral biology. Comparative assessments were made between covered and uncovered sections, as well as between treated and untreated trees. The treated trees exhibited higher precocity compared to the untreated ones; in particular, a 10% higher number of 4th and 5th leaves were found for the treated trees in the covered orchard, while 9% less closed and cotton buds were observed in the uncovered. Moreover, an increase in the number of king flowers was observed in treated trees, resulting in 14 and 11% higher percentages than the covered and uncovered non-treated trees, respectively. This reduction is noteworthy as it signifies potential labor and time savings during thinning operations. While these promising outcomes provide impetus for further investigation, additional research is necessary to deepen the understanding of kiwifruit trees' response to biostimulants, considering alternative products.