The choice of a suitable system such as pruning is an important factor for achieving a profitable balance between labor costs and crop yield without loss of quality. A field trial was conducted for manipulation of castor bean growth by pruning and its effect on some characteristics at the Agricultural Research Station of Saatlo in Urmia, Iran, during 2010 growing season. The experiment was a split-plot design, arranged in randomized complete block with three replications. Main plots including four varieties of castor bean (i.e. 80-23, 80-29, 80-12-1, and 80-17), and sub plots including three types of pruning (i.e. no pruning, pruning of 2 lateral branches, and pruning of four lateral branches). The plant characteristics were studied in terms of number of capsules in primary raceme, secondary raceme length, number of branches per plant, weight of capsules per plant, days from planting to emergence of secondary raceme and oil percent. Results of the data review showed that, the effect of the varieties was significant on most of the traits and the effect of the pruning was significant just on the days from planting to emergence of secondary raceme trait. Also, the effect of interaction between two factors (variety and pruning) was significant on number of capsules in primary raceme and number of branches per plant. Based on our results, manipulation of castor bean growth showed different response on some characteristics.
