Abstract

In order to study the effect of pruning lateral branches on four varieties of castor bean yield, growth, and development, an experiment was conducted at the Agricultural Research Station of Saatlo in Urmia, Iran, during 2010 growing season. Experimental design was split plot, completely randomized block design with three replications. The main plots were varieties of castor bean (that is, 80-23, 80-29, 80-12-1 and 80-17), and sub plots included three types of pruning (that is, no pruning, pruning of two lateral branches, and pruning of four lateral branches). The plant characteristics were studied in terms of main panicle length, number of seeds per plant, 100 seed weight, seed weight per main panicle, weight of main panicle, grain yield, biological yield, harvest index, days from planting to maturity and oil yield. Results of the data review showed that, the effect of the varieties was significant on all of the characteristics. Also, the effects of pruning and interaction of two factors (variety and pruning) were significant on seed weight per main panicle, weight of main panicle and days from planting to maturity. Maximum grain yield (1307.78 kg ha^-1) was in 80-12-1 variety, and minimum yield (770.83 kg ha^-1) observed in 80-17 variety. According to the results, the variety of 80-12-1 and pruning of four lateral branches in this region were recommended for cultivation.

Key words: Castor bean (Ricinuscommunis L.), growth, pruning, varieties, yield.