Investigation of the effect of growth period duration on quality and quantity yield of sugar beet (Beta Vulgaris L.) under autumn cultivation in Ilam province

Modification of planting season from spring to autumn in order to use green water, has been introduced as an effective and consistent agronomic strategy with climate change. For this purpose and in order to increase the cultivation of autumn sugar beet as a strategic crops in increasing the self-sufficiency of sugar in the country, it is necessary to implement research programs including determining the appropriate growth period duration, that recognition of them is needed to achieve optimal yield. Therefore, an experiment was conducted as split plot based on randomized complete block design (RCBD) with three replications at Darreh shahr, Ilam, Iran, in 2015-2016 growing seasons. Investigated factors were three planting dates (5 October, 19 October, 16 November) and two harvest dates (8 May and 17 June) in main plots and sub plots respectively. Results of the study showed that white sugar yield in the range of early- to late October and harvested in late June (Growth period 255 and 240 days) showed increase about %73 compared with cultivation in November and harvest in early June(Growth period duration 192 days). Results of this research were recounted the dramatic role of duration growth elongation in improving white sugar yield of autumn sugar beet followed by increasing root yield increase (%69), pure sugar percent (%23), sugar content (%12) and reduction of molasses (%37). More attention to crop management in sugar beet production under autumn swoing can play a key role in increasing sugar beet production in these areas.