GROWTH ANALYSIS OF CRAMBE

Growth analysis of crambe (Crambe abyssinica Hochst. ex R. E. Fries) i s important for the use of proper production practices and adequate pe st management strategies. This study evaluated the heat unit requireme nts and quantitative characteristics of crambe growth [leaf area index (LAI), leaf area duration (LAD), yield, and total biomass] and the im pact of defoliation on yield using artificial infestation with diamond back moth (Plutella xylostella L.) (DBM) in 1993 and 1994 and manual d efoliation in 1995. The heat unit accumulation from planting to physio logical maturity was approximately 1350 degree-days (DD) above 2.5 deg rees C. The maximum LAI and generally the maximum daily increase of bi omass occurred at the onset of flowering. The yield was proportional t o 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 defo liation 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.