At the northern borders of the peach-growing zone, low temperatures during winter are the critical factors for the survival of the trees and for the reliability of production. Our aim was to carry out detailed analysis of the hardening and dehardening processes of flower buds of three peach cultivars with contrasting frost tolerance and to evaluate the effects of environmental factors and of genotypic differences in two consecutive winters with very diverse weather conditions. Based on our results, the hardening process takes place in two phases in peach flower buds. In the first phase, gradual cooling is essential if the level of frost resistance characteristic of the genotype is to develop, but in the second phase, it is a prerequisite that the external temperature drop consistently below zero for reaching the maximum frost tolerance. The maximum level of frost resistance developed by peach flower buds was only maintained for a limited time and the differences between the cultivars gradually decreased as flowering time approached. At the time of leaf fall in the fall and before flowering, the difference between the mean frost tolerance values for flower buds of the extremely frost-tolerant and frost-sensitive cultivars was only 2 °C, whereas in midwinter, it was 5 to 5.5 °C.
László Szalay, Béla Timon, Szilvia Németh, János Papp and Magdolna Tóth
Attila Hegedűs, Emőke Balogh, Rita Engel, Béla Zoltan Sipos, János Papp, Anna Blázovics and Éva Stefanovits-Bányai
Fruits of four berry species (strawberry, raspberry, red and black currants) were compared in their elemental composition (Al, B, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, P, and Zn) and redox parameters involving total phenol content (TPC), ferric reducing ability (FRAP), 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, and total radical scavenger activity (TRSA). Berry cultivars contained significantly higher (P ≤ 0.05) amounts of most detected elements as compared with apple with many maximum elemental values demonstrated by the black currant ‘Otelo’. Black currant also had the greatest antioxidant capacity as demonstrated through all conducted assays. The results obtained through FRAP, TPC, and TRSA assays were closely correlated, whereas TRSA and DPPH varied independently. Our study provides valuable information on the antioxidant capacity of several berry species grown in Hungary and highlights the crucial influence of cultivar on elemental content and antioxidant power of berry fruits. This study demonstrated the ability to select berry cultivars for specific nutritional purposes or assign parental lines in functional breeding programs.