Low temperature resistance mechanisms are complex during dormancy. Plants can use several biochemical processes to counteract the direct and indirect effects of low temperatures. In order to investigate the seasonal changes of some biochemical compounds in flower buds of three domestic almond cultivars, a split plots in time experiment was conducted in a randomized complete block design with three replications, in 2017-2018. Experimental treatments included three domestic almond cultivars (early flowering chr('39')Mohebchr('39'), medium flowering chr('39')Mamaiechr('39') and late flower chr('39')Rabichr('39')) and 5 time periods of 20 days during the endodormancy until after breaking the endodormancy. The results showed that the proline amino acids accumulation increased during endodormancy and endodormancy release in cultivars, and chr('39')Mohebchr('39') cultivar had lower proline content compared to chr('39')Mamaiechr('39') and chr('39')Rabichr('39'). At the beginning of the experiment, the maximum starch content was observed before the cold accumulation in the studied cultivars, but it showed a decreasing trend in all three cultivars with the progress of the dormancy and the increase in the cold accumulation. Non-enzymatic antioxidant compounds (total phenols and flavonoids) increased during the dormancy and approaching to dormancy release in all cultivars. On the other hand, the antioxidant capacity decreased at low temperatures. The results of biplot showed a clear and positive relationship between proline amino acid and non-enzymatic antioxidant compounds at low temperature. Different cultivars of a species also showed different responses during the dormancy. Therefore, it is important to consider biochemical changes during the dormancy periods in the selection of resistant and cold-sensitive almonds to spring frost.
 

Keywords: proline, cold, antioxidant capacity, flavonoids, phenol total.

Full-Text [PDF 424 kb]   (501 Downloads)