seasonal change in carbohydrates, starch, proline and water status during dormancy of some apricot (prunus armeniaca l.) cultivars

dormancy in deciduous fruit trees constitutes an important factor to be considered when selecting for the appropriate species/cultivar to be cultivated in a given geographical region. the factors influencing dormancy, however, remain poorly understood. occurring in cold season, dormancy helps the plant with enduring adverse environmental conditions, especially chilling and freezing tensions. a sound understanding of dormancy and the contributing metabolic changes, thus, could help in selecting the appropriate species/cultivar to cope with environmental tensions. in this research, the quantitative changes in sugar compounds, starch, proline, as well as in water status in the buds of 6 apricot cultivars namely: pish ras tabas and noori pish ras (early-ripening), ketabi and shahroodi (mid-ripening), and shahrood 51 and shahrood 29 (late-ripening) were investigated during 2008-2009 in golmakan research station, khorasan razavi province, iran. among the cultivars, the highest dissolved sugar content (34.36 mg/g dry weight) was observed in the vegetative buds of shahroodi 51; proving statistically different from the content in other cultivars. this cultivar was also proved to contain the highest proline content (statistically different from that in the other cultivars). no statistically significant difference was observed among cultivars with respect to water status. during the experimental run-time, the highest total carbohydrate contents were observed in october and february, respectively. the lowest water content was observed during the coldest month of the year viz. january.