Effect of sowing dates on quantity and quality of castor bean (Ricinus communis L.) under semi-arid condition in Iran

Abstract

The sowing date is often used to overcome environmental constraints on crop production.<br><br>Information on the effect of this agronomic technique on the oil quality of castor bean<br><br>(Ricinus communis L.) is scarce. An experiment was conducted on the basis of randomized<br><br>complete blocks with three replicates for two years (2008, 2010) to evaluate the effect of<br><br>different sowing dates on the oil content and fatty acid composition of castor bean under<br><br>the semi-arid conditions of Tehran-Iran. The treatments were six sowing dates including 5th<br><br>and 20th of April, 5th and 20th of May and 5th and 20th of June. The results showed that the<br><br>seed yield, oil content and fatty acid composition were influenced by the sowing date. An<br><br>earlier sowing date resulted in higher seed yield, oil content and oil yield in either year. Based<br><br>on the results of the fatty acid analysis by gas chromatography (GC), fifteen fatty acids<br><br>were observed in castor oil with ricinoleic acid (18:1 Δ9c-12OH) being the major oil fatty<br><br>acid. The highest content of this fatty acid was obtained at the 20th of June, followed by the<br><br>5th of April, as sowing date. A delay in sowing decreased the oleic and stearic acid content<br><br>but increased the ricinoleic, linoleic and linolenic acid levels in both years. Conclusively,<br><br>plants sown at the 5th of April encountered favorable environmental conditions resulting in<br><br>significantly high economic yield compared to other sowing dates.