Observations on the frost resistance of 'Fernor' and hybrids KMS1, KMS2, KMS3, KMS4 and KMS5, during the period January-April 2017

It is known that walnut cultivars with lateral bearing have some sensitivities to temperature variations during relative dormancy and on entering the vegetation. In the first decade of January 2017, in Dambovita County, extremely high variations in negative temperatures have been recorded, which could affect the viability of the flowering buds and vegetative buds. In late April, the nights of 21, 26 and 28, late spring frosts were registered causing necrosis of the tissue in the local genotypes and partial frostbite of buds flowering male cultivar 'Fernor', in the phenophase inflation buds. If the production of the local genotypes of 2017 was compromised in 80%, the cultivar 'Fernor' and some new hybrids (KMS1, KMS2, KMS3, KMS4 and KMS5), these late spring frosts did not affect the further development of fruit buds. 10% of male flowering buds (catkins) showed partial frostbite, without affecting their ability to deliver total pollen of 3% of female mixed buds were affected by frost. In conclusion, in addition to the genetic conditioning, the frost resistance of the observed walnuts is influenced by fertilization and irrigation.