Effect of Roots Pruning upon the Growth and Fruiting of Apple Trees in High Density Orchards

Abstract

The influence of roots cutting on growth and fruiting of five apple cultivars ‘Gala’, ‘Jonica’,‘Topaz’, ‘Florina’, ‘Granny Smith’), under the climatic conditions of Cluj-Napoca, Romania, in 2009-2010, was studied. The trees were grafted on M9 rootstocks, trained as slender spindle and the orchardhad a density of 3174 trees/ha. Roots were cut twice annually, at 60 cm distance from the trunk and 30cm depth, as followed: first time, to the autumn fall leaves on one side of the row and the second time,in spring, at blooming time. The treatments had a strong influence, statistically assured, upon the shootgrowth, number of bearing branches, cumulative yield, trunk cross sectional area, the ratio of the yieldto a trunk cross-section. Root pruning reduced the average length of shoots. The longest shoots, inmean values, gave unpruned root variant (52.07 cm). Root pruning decrease the average length ofannual growth (29.47 cm). The biggest average trunks cross sectional area with the unpruned systemwere obtained (34.82 cm2). Also root pruning influenced the yield of the trees. The best cumulativeyield was obtained in variant of root pruning system (98.75 t/ha) followed by unpruned root system(97.8 t/ha). Finally, root pruning increased productivity. The biggest value in ‘Topaz’ with root prunedwas registered (1.79 kg/cm2). The lowest value of productivity index in unpruned system variant wasobtained.