Crop load and rates of nitrogen effects on performance of 'Gala' apple.

The trial was conducted in 'Gala'/M9 orchard with 5100 trees/ha.The experimental design was as split-block comprising three rates of nitrogen (N) as broadcast fertilization with 60 kg N/ha, 90 kg N/ha and 120 kg N/ha, and three crop load [(9, 6 and 3 fruits/cm 2 trunk cross sectional area (TCSA)].The treatments with different rates of applied N lasted two years beginning in the 6 th year after planting.In the 6 th growing season crop load was adjusted by hand thinning whereas in the next year fruits were not thinned (control year).The major effect of excessive crop load of 'Gala' apple was reduced flowering in the following year.A positive relationship was found between the rates of N in year of applied treatments and return blooming in control year.The results showed no significant effect of N treatment on the TCSA and fruit size.Key words: Malus x domestica, growth, return blooming, yield, yield efficiency, fruit size SAŽETAK Pokus je izveden sa sortom Gala, cijepljenom na podlozi M9, u gustoći sklopa od 5100 stabala po hektaru.Pokus je postavljen po metodi split-blok, a obuhvaćao je 3 razine gnojidbe sdušikom (60 kg N/ha, 90 kg N/ha i 120 kg N/ha) i 3 razine opterećenja rodom (3, 6 i 9 plodova na cm 2 površine porečnog presjeka debla na visini od 20 cm iznad cijepljenog mjesta.Pokus je proveden u dvije uzastopne godine počevši u u šestoj godini nakon sadnje.U šestoj vegetaciji opterećenje rodom određeno je ručnim prorjeđivanjem plodova, dok u sljedećoj godini nije obavljeno prorjeđivanje plodova (kontrolna godina).Glavni utjecaj većeg opterećenja rodom očitovao se kao smanjenje cvatnje u kontrolnoj godini.Pri tom su povećane doze dušićnih gnojiva imale pozitivan utjecaj na obilnost cvatnje u kontrolnoj godini.Rezultati istraživanja nisu pokazali značajni utjecaj doza dušika na prirast debla i krupnoću plodova.