A Study of the Environmental Factors Affecting some of the Biological Characteristics of Flower in Four Iranian Commercial Apricot Cultivars

Apricot belongs to the Rosaceae family and is considered as an economically important Fruit among others. Irregular bearing is a shortcoming in apricot production which is partly due to its limited ecological adaptation. The aim of this study was to investigate the effects of temperature prior to flowering stage on some characteristics as related to flowering organs. In two consecutive years, some traits were recorded in four commercial apricot cultivars namely: ‘Nasiri’, ‘Noori’, ‘Jahangiri’ and ‘Shahroudi’.Results indicated that temperature influenced the plant’s flower reproductive organs, pollen and pistil performance which in turn played an important role on flower fertility. During the first year, pollen germination was considerably low due to a very cold winter while in the second year the final development stage of pistil failed because of becoming confronted with a warm winter. Pistils with shorter style and non-swollen ovaries were observed in some cultivars including ‘Jahangiri’ and ‘Noori’. The two other cultivars produced a higher percentage of normal pistils during the second year. Differences between cultivars would be attributed to carbohydrate storage and sensitivity of ‘Jahangiri’ to warm winters. In ‘Nasiri’ double pistil and multiple ovule percentage decreased during the second year. On the other hand, in year 2007-2008cultivars exhibited early flowering due to easily meeting the chilling requirement but faced spring frost damage. According to the obtained results, temperature fluctuation affected flower quality in either on year. Continuous cold winter provided more suitable conditions for organogenesis and fruit set in year 2006-2007. In this year, pollen germination decreased because of cold winter but, in total, fruit set was at its optimum level because of good pistil’s performance.