This study was conducted to evaluate the effect of sowing date on morphology, yield parameters, as well as oil percentage and fatty acids composition of castor bean. The experiment was carried out at research farm of TarbiatModaresUniversity, in randomized complete blocks design with three replications during 2010. Plants were grown at six sowing dates of 5th April, 20th April, 5th May, 20th May, 5th June and 20th June. The results showed that morphological traits and yield traits were influenced by sowing dates. The highest seed yield (1590.67 kg/h), oil yields (774.43 kg/g) were obtained at 5th April, and delay in sowing date, led to significant reduction in these traits. Fifteen fatty acids were detected in oil. Nevertheless, the highest amount of fatty acid belonged to Ricinoleic acid. Results showed that fatty acid composition of castor oil influenced by sowing date. Therefore, it can be concluded, that 15th April could be recommended as an appropriate sowing date in the studied location and similar climates for achieved high oil yield of castor bean.
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