Dinamika rodnosti jabuke Idared u uvjetima fertirigacije s dušikom

Istraživanja su obavljena sa sortom jabuke Idared (Malus x domestica Borkh), koja je cijepljena na slabo bujnu podlogu M 9, i uzgajana u gustom sklopu (3000 stabala/ha). U pokusu je bilo pet tretmana (fertirigacija s 45 kg N/ha, 60 kg N/ha, 120 kg N/ha, natapanje bez gnojidbe i kontrola – bez natapanja i uporabe gnojiva), u dvije varijante (tretmani za vrijeme vegetacije: od 1. svibnja do 20. lipnja – varijanta A, i od 1. svibnja do 1. kolovoza – varijanta B). Pokus je trajao sedam godina počevši od druge godine poslije sadnje (1992-1998.). Istraživanjima nije utvrđen konzistentan utjecaj primijenjenih tretmana na dinamiku rodnosti, kumulativan prirod i učinkovitost rodnosti. U svim varijantama pokusa dinamika rodnosti slijedila je sličan trend uz slabo izraženu tendenciju alternativnoj rodnosti, a puna rodnost postignuta je u petoj godini nakon sadnje. Dobiveni rezultati istraživanja potvrđuju da je sorta Idared vrlo prikladna za intenzivan uzgoj u sustavu gustog sklopa.
The trial was conducted in an ‘Idared’/M9 orchard (3000 trees/ha), designed as split-block comprising five treatments (fertigation with 45 kg N/ha, 60 kg N/ha, 120 kg N/ha, irrigation without fertilisers, and control - without irrigation and without fertilisers), and two timing variants (treatments during vegetation period from 1 May to 20 June - variant A, and treatments from 1 May to 1 August – variant B). The treatments began in the second year after planting and lasted seven years (1992-1998). Fertigation with different amounts of nitrogen had no consistent effect on the dynamic of cropping, cumulative yield and regularity of bearing. Tendency to biennial bearing was low, dynamic of yield increasing followed the same trend in all treatments, and full productivity was achieved in the fifth year after planting. This means that ‘Idared’ is a very suitable apple cultivar for growing in the system of high density planting.