Peach flower bud development

Thinning is indispensable practice in peach cultivation aiming to reduce fruit number per plant, promoting sink-source balance and reducing competition among fruit, which results in bigger fruit and the improvement of other fruit-quality parameters. Inhibition of floral induction by GAs has been largely demonstrated and commercial products based on GAs have been used to this aim. We tested a product GA4/7 based in different moments after full bloom in peach to reduce the number of flowers in the following season. Return to bloom and transcriptome analysis were performed to identify the best moment for the treatment, increasing the product efficacy and understanding the product action at genetic level. The main field trial has been carried out in 2019 on the flat-nectarine cultivar Platinet 1 (Prunus persica var. platycarpa). This cultivar is harvested approximately 22 days before the reference cv RedHaven. The experiment was conducted at Vivai Zanzi’s farm in Ferrara, Italy (44°46’56.355”, 11°39’55.419”). A suitable number of homogeneous trees with a suitable fruit load, all protected by anti-hail nets, were selected and marked among 40 trees in total in order to build a single block experiment with 5 trees per block. Blocks were separated by two untreated trees to avoid drift effects. The experimental formulation FAL900 (10 g/L GA7) was sprayed at 100 ppm by using a shoulder sprayer until run-off, at 45 (T1), 51 (T2), 58 (T3), 65 (T4), and 79 (T5) days after full bloom (DAFB). Before spraying, a suitable number of shoots were collected in three biological replicates and the buds from the top and the bottom halves of the shoot excised separately, frozen in liquid nitrogen and stored at -80°C for following analyses.