M. A. Nejatian,
Volume 3, Issue 7 (6-2013)
Abstract
One of the main problems in vineyards of Iran is sensitivity of grape cultivars to winter cold. Considering the rich genetic diversity of grape cultivars in Iran vineyards and severe cold winter in 2007, this situation was used as a natural treatment in order to identify cold tolerance and assess damages in 21 Iranian grape varieties and 8 European grape varieties in a factorial experiment, based on completely randomized blocks design with four replications and three plants per unit. In each plant, four branches (one year old) were selected and the number of healthy and damaged sprouts were counted. Then, statistical and cluster analysis was performed. Descriptive statistics (coefficient of variation of phenotypic traits) of the obtained data from assessment of grape cultivars was calculated. Using the correlation coefficient (Pearson r), bilateral relationship between traits was measured and the attributes which their selection could increase the efficiency were determined. The results indicated that grape cultivars were located in four groups of sensitive, semi-sensitive, semi-tolerant and completely tolerant. Ghermez Bidaneh, Fakhri, Siyah Gazvin, Khalili and Rish Baba cultivars showed the highest tolerance. Most of the European cultivars including Ruby Seedless, Superior, Fiesta, Black Seedless, Perlette, Flame Seedless, Tompson Seedless and Torkmanistan 4 were in semi-tolerant to susceptible groups. Tolerance threshold against winter cold was was 15 ±1 ◦C in normal varieties and 20 ±1 ◦C in tolerant cultivars. There was a significant phenotypic correlation between the studied traits.
S. Farhadfar, M. Keshavarzi, A. Ladan, N. Bouzari, D. Atashkar,
Volume 9, Issue 3 (11-2019)
Abstract
Winter cold is a significant damaging factor in fruit trees specially stone fruits. Relative resistance of 20 local and introduced sweet cherries (Prunus avium) to winter cold in artificial cold condition and its association with electrical conductivity and a number of morphological traits including trunk diameter, shoot diameter, anthocyanine and lenticels frequencies was studied in year 2011. In February, dormant shoots and buds were collected and treated in a freezer with temperatures decreasing from 4 OC to -24 OC and increasing from -24 OC to 4 OC. Then, cold damage was determined based on percentage of discoloration from green to brown. Results showed variability of shoot and bud cold tolerance among different genotypes/cultivars. Cold damage to buds was higher than shoots and they showed significantly positive correlation. In both organs, Albaloogilas Daneshkadeh was rated as the most resistant and Meshkinshahr as the most susceptible genotypes. According to the observed responses to the low temperature treatment, the germplasm was divided in three relative susceptibility groups including highly susceptible (10%), relatively susceptible (15%) and relatively resistant (75%) and no genotype was completely resistant. Accordingly, it is concluded that most genotypes/cultivars studied were relatively tolerant to winter cold. A correlation existed between cold damage and shoot diameter, indicating that this species is more cold-susceptible at the seedling stage. Considering low correlation between cold damage and lenticel numbers/anthocyanin pigment intensity, these traits are not appropriate criteria for winter cold tolerance selection in cherry.
