Document Type : Research Paper
Authors
1
PhD Student, Department of Plant Breeding and Biotechnology, Faculty of Agriculture, University of Zabol, Zabol, Iran
2
Professor, Department of Plant Breeding and Biotechnology, Faculty of Agriculture, University of Zabol, Zabol, Iran
3
Associate Professor, Ramsar Citrus and Subtropical Fruits Research Center, Ramsar, Iran
4
Assistant Professor, Department of Agronomy and Plant Breeding, Faculty of Agricultural Sciences, University of Guilan, Rasht, Iran
Abstract
Most of the plants in the citrus family are sensitive to cold stress. Therefore, the inevitable occurrence of periodic frost causes extensive damage to their functions. With the purpose of comparing 110 citrus genotypes’ reaction to the two levels of cold stress (-3°C and -6°C), 76 unknown natural genotypes and 34 known genotypes from Ramsar citrus and sub-tropical fruits research institute were studied based on the split-plot design with three replications. The results of variance analysis for the eight traits related to cold tolerance showed that there was a significant difference between the examined accessions. According to cluster analysis, the genotypes in each temperature demonstrated a relatively different grouping pattern after the employment of Euclidean distance squares and the furthest neighbors’ method. The highest amount of electrolyte leakage (55.84%), leaf water soaking (2.70) and lipid peroxidation (2.12 μg/g leaf fresh weight) were estimated at -6°C and recorded at -3°C for other traits. The relationship between the studied panels was determined by considering the common group and the traits in question. G32 and G71 genotypes were merely found to be close to the tolerant genotypes. Regarding the negative deviation from the standardized mean for electrolyte leakage (-1.367), leaf water soaking (-1.423) and lipid peroxidation (-0.684), along with the positive values of other traits (proline content, antioxidant capacity, total soluble carbohydrates and antioxidant enzymes), genotypes Poncirus, Citrumelo, off type sour orange, Sour orange, Satsuma mandarin, and Okitsu are of great usage value in cold tolerance breeding programs.
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