Investigation of some Physiological Indices Related to Frost Damage in Almond Genotypes with Different Flowering Time

Early flowering and frost in native genotypes are among causes of reduction in almond production in most years. Therefore, a proper understanding of the resistance mechanisms is necessary for developing varieties with high quality and resistant to frost. In this research, four different genotypes were selected out of 40 genotypes based on flowering time and resistance to frost, including late flowering and susceptible to frost (Sh12) medium to late flowering and resistant to frost (H), early flowering and resistant to frost (G19) and medium flowering and susceptible to frost (D99). These genotypes were evaluated in terms of physiological characteristic related to frost resistance at full-bloom stage in a controlled condition. The results showed that the early flowering genotype (G19) and the medium flowering genotype (D99) had the highest and lowest damages, respectively. In the most cases, the amount of soluble sugars and amount of minerals (N, P, and K) were higher significantly in resistant genotypes compared with susceptible genotypes. The correlation between amount of frost damages and soluble sugars and minerals was negative and significant. These results imply that these characters are important in conferring frost tolerance to the genotypes. On the other side, the correlation between frost damage and ion leakage was positive and significant. According to the results shown in Bi-plot diagram, resistance to frost genotypes was accompanied with soluble sugars and minerals. Meanwhile susceptible genotypes were accompanied with ion leaking. In addition, cluster analysis classified different genotypes within different groups. In conclusion, these criteria could be used for detecting resistance genotypes, by the way the genotypes G19 and H both are recommended as frost resistant genotypes.