Growth analysis of crambe

Growth analysis of crambe (Crambe abyssinica Hochst. ex R. E. Fries) is important for the use of proper production practices and adequate pest management strategies. This study evaluated the heat unit requirements and quantitative characteristics of crambe growth [leaf area index (LAI), leaf area duration (LAD), yield, and total biomass] and the impact of defoliation on yield using artificial infestation with diamondback moth (Plutella xylostella L.) (DBM) in 1993 and 1994 and manual defoliation in 1995. The heat unit accumulation from planting to physiological maturity was approximately 1350 degree-days (DD) above 2.5 degrees C. The maximum LAI and generally the maximum daily increase of biomass occurred at the onset of flowering. The yield was proportional to LAD: 238 g m(-2) versus 1187 DD in 1993, 190 g m(-2) versus 1010 DD in 1994, and 117 g m(-2) versus 774 DD in 1995, No reduction in yield or thousand seed weight was observed in any of the infestation or defoliation experiments. The artificial defoliation experiment showed that crambe can withstand substantial injury after the start of anthesis (25-50% of leaf area lost) without a significant yield loss.