Sensitivity to winter and spring frost of sweet cherry cultivars on Gisela 5 rootstock

Abstract

The influence of winter and spring frost on injury of flower buds and flowers was studied in 18 sweet cherry cultivars during 2012 year. The experimental orchard was planted in 2004 in the region of Šabac (Western Serbia). The rootstock is 'Gisela 5', the training system is slender spindle, and the tree spacing is 4 x 1.5 m. Winter frost intensity of -25.2°C, which occurred on 9th February, caused the average injury of 31.2% of flower buds for all studied sweet cherry cultivars. Frost damage was highest in cultivar 'Skeena' (68%) and lowest in cultivar 'Penny' (7%). The winter cold hardiness was highest in cultivars 'Penny', 'Early Star', 'Regina', 'Summit', 'Kordia' and 'Chelan', and lowest in cultivars 'Skeena', 'Noir de Meched', and 'Sylvia'. Spring frost intensity of -3.7°C occurred on 10th April, when the cherry cultivars were in the stage of full bloom or the end of blooming. It caused the average injury of 95.2% of flowers. The damage was lowest in cultivar 'Penny' (85.2%), and the highest in cultivar 'Early Lory' (99.3%). Cultivars of later flowering time showed a lower level of injury compared to the cultivars of earlier flowering time. Due to the occurrence of winter and late spring frosts, there was a drastic reduction in yield of sweet cherry. The average yield for all cultivars was only 0.26 kg per tree. Slightly higher yield (from 0.6 to 1.4 kg per tree) was found only in cultivars 'Penny', 'Kordia', 'Regina', and 'Summit'.

Kod 18 novijih sorti trešnje kalemljenih na podlozi Gizela 5 na području Šapca u toku 2012. godine ispitivan je uticaj zimskog mraza (-25,2°C od 9. februara) na izmrzavanje cvetnih pupoljaka, kao i uticaj poznog prolećnog mraza (-3,7°C od 10. aprila) na izmrzavanje cvetova. Prosečno izmrzavanje cvetnih pupoljaka od zimskog mraza iznosilo je 31,2%, sa variranjem od 7% kod sorte Peni do 68% kod sorte Skina. Najveću otpornost na zimski mraz pokazale su sorte Peni, Erli Star, Regina, Samit, Kordia i Čelan, dok su najosetljivije bile sorte Skina, Noar de Mečed i Silvija. Pozni prolećni mraz koji se javio u fenofazi cvetanja doveo je do prosečnog izmrzavanja od 95,2% cvetova, sa variranjem od 85,2% kod sorte Peni do 99,3% kod sorte Erli Lori. Sorte kasnijeg vremena cvetanja imale su manji stepen izmrzavanja u odnosu na sorte ranijeg vremena cvetanja. Usled pojave zimskog i poznog prolećnog mraza, došlo je do drastičnog smanjenja prinosa, koji je iznosio samo 0,26 kg po stablu u proseku za sve ispitivane sorte.