Effect of different nitrogen fertilization approaches on the quality of the \u27summit\u27 sweet cherry tree variety

Od leta 2015 do 2019 je v nasadu Sinič 1 na območju UKC Pohorski dvor potekal poskus na češnjah (Prunus avium L.) sorte \u27Summit\u27, cepljenih na podlago Gisela 5, posajenih leta 2010. Izvzeli smo tri leta (2016, 2018, 2019) ter primerjali vpliv različnega odmerka (80 kg N/ha, 120 kg N/ha) in časa njegove prve aplikacije dušika (jesen, pomlad), dodanega z gnojilom KAN (kalcijev amonnitrat) na pridelek in parametre kakovosti plodov (masa 100 plodov, suha snov, titracijske kisline in čvrstost plodov). Ugotovili smo, da je na količino pridelka pozitivno vplival manjši odmerek dušika s prvo aplikacijo v jesenskem času. Na parameter masa 100 plodov je v večini let pozitivno vplivala prva aplikacija gnojila jeseni, ne glede na odmerek dušika. Na vsebnost suhe snovi v izbranih letih noben dejavnik ni izkazal pomembnega konsistentnega vpliva. Na vsebnost skupnih titracijskih kislin je pomembno vplivala interakcija leta, odmerka dušika in časa gnojenja. Od posameznih dejavnikov sta večji spomladanski odmerek in manjši jesenski odmerek povečala vsebnost skupnih titracijskih kislin v plodovih. Čvrstost plodov je bila v veliki meri odvisna od pridelovalne sezone, nanjo pa je pomembno vplivala tudi interakcija leta, odmerka dušika in časa gnojenja. V letu 2019 s 50 % manj padavin v času jesenskega gnojenja in v času zimskega mirovanja ter s 100 mm manj padavin v času rastne dobe (med aprilom in junijem) je bila čvrstost plodov 15 % večja kot leto prej, glede na odmerek dušika pa so bili plodovi najmanj čvrsti pri spomladanskem gnojenju, medtem ko so boljšo čvrstost v več letih poskusa običajno dosegli plodovi z manj intenzivno pognojenih dreves.From 2015 to 2019, an experiment was carried out on cherries (Prunus avium L.) of the \u27Summit\u27 variety, grafted on the basis of Gisela 5, planted in 2010, on the Sinič 1 plantation in the area of UKC Pohorski dvor. The harvest of three years (2016, 2018, 2019) were exempted and the effect of different doses (80 kg N / ha, 120 kg N / ha) and time of first application of nitrogen (autumn, spring), added with KAN fertilizer (calcium amonnitrate) on yield and fruit quality parameters (weight of 100 fruits, dry matter, titratable acids and fruit firmness) were compared. The amount of crop was positively affected by a lower dose of nitrogen with the first application in the fall. The parameter of 100 fruit weight was positively influenced in most years by the first application of fertilizer in autumn, regardless of the nitrogen dose. No factor has shown a significant consistent effect on the dry matter content in the selected years. The content of total titratable acids was significantly influenced by the interaction of the growing year, nitrogen dose and fertilization time. Of the individual factors, a higher spring dose and a lower autumn dose of nitrogen increased the content of total titratable acids in the fruit. Fruit firmness largely depended on the growing season and was also significantly influenced by the interaction of year, nitrogen dose, and fertilization time. In 2019, with 50 % less precipitation during autumn fertilization and winter dormancy, and with 100 mm less precipitation during the growing season (between April and June), fruit firmness was 15 % better than in the previous year, and depending on the nitrogen dose, the fruits were the least firm in the spring fertilization, while the fruits with less intensively fertilized trees usually achieved better firmness in several experimentation years