Evaluation of plant growth regulators for control of dormancy in apricot (Prunus armeniaca L.)

In an environment where fruit production is increasingly affected by unpredictable weather patterns, it is important to look for ways to minimise the impact of climate change on production. Under Central European conditions, a limiting factor for apricot (P. armeniaca L.) and Asian plum (P. salicina Lindley) growing in certain years is the occurrence of late spring frosts. One measure to eliminate their impact is to delay the actual flowering of the trees. This can be done by breeding or just by applying various plant growth regulators (PGRs). In our experiment, the effect of a total of 6 active substances in 16 different concentrations was evaluated. The results show that the application of Ethrel-based mixtures (concentrations of 0.05 and 0.5%) had the greatest influence, delaying flowering by up to 3-5 days, but also had the most destructive effect on tree health. The application of the commercial product Rhodofix (NAA - 0.3%) and the application of a proprietary mixture based on NAA 1.0% did not have a very significant effect, with a delay in flowering of just 2 to 3 days. One interesting finding was that the application of the above products had a statistically significant effect on the ripening date of apricot fruit, with a difference of up to 4 days.