Use of plant growth regulators in fruit nursery production of plums and sweet cherries

Apple and plum cultivars are the most produced fruit nursery stocks in the Czech Republic. In 2015 372,162 plum trees were produced in nurseries in Czech Republic compared to 1.229 million apple trees and 178,720 cherry trees. It is difficult to stimulate branching of cherries and plums belonging to the Prunus domestica ssp. italica Bork. group in nurseries. Yet, well-branched nursery stocks of plums from P. domestica ssp. oeconomica Bork. group can be produced with ease. This experiment, conducted in 2015, was carried out at two locations in South Moravia (Kadov and Slup). For branching of the plum trees commercial plant growth regulator products Gibb plus, and Globaryll 100 from Globachem, Progerbalin LG from L. Gobbi, Italy were used. For branching of the cherry trees new formulations of plant growth regulators (PGRs) were used beside the commercial products (Gibb plus + 4-CPPU, ethephon + BA + putrescine HCL, TIBA + 4-CPPU, naphthylphtalamic acid + 4-CPPU, TIBA + paclobutrazol, naphthylphtalamic acid + paclobutrazol, ethephon + GA4-7 + putrescine HCL, Progerbalin + 4-CPPU + putrescine HCL, Globaryll + 24-epibrassinolide). The aim of the experiment was to verify the effect of commercial products and new formulations of PGRs on branching of nursery stocks of selected plum and cherry cultivars (plum cultivars: 'Guten von Bry', 'Cacak's Fruitful', 'Cacak's Beauty', 'Stanley', 'Domestic Plum'; cherry cultivars: 'Canada Giant' and 'Kordia'). Each treatment of commercial products was applied to 60 trees of each cultivar. The new formulations were applied to 10 trees. The commercial products and new formulations of PGRs were applied twice during the spring time (with a 12-day interval between applications). The best results were found in 'Guten von Bry' and 'Cacak's Fruitful' cultivars after application of Gibb plus (50% of 'Guten von Bry' trees and 80-90% of 'Cacak's Fruitful' trees were branched). Cherry tree cultivar 'Canada Giant' showed the best results (38% of trees were branched) after application of Globaryll + 24-epibrassinolide mixture. In 'Kordia' the best effect appeared after application of ethephon + BA + putrescine HCL (100% trees were branched).