Crop management strategies to improve forage rape seed yield

Abstract

In New Zealand, forage rape (Brassica napus L.) is an important supplementary feed crop in animal production systems. Detailed investigations on seed production are limited and strategies for maximising seed production are not well understood. The objective was to increase seed yield of forage rape by manipulating crop architecture using combinations of mechanical topping, plant growth regulators (difenoconazole and paclobutrazol) and sowing date. Data were collected for components of yield, including dissection of plants into four seed fractions. Topping at yellow bud or delaying sowing until April significantly (P<0.05) increased seed yield by 40-60% compared with control treatments. On average, 85% of seed was from secondary racemes with 60% coming from middle and lower racemes. Plant height was significantly (P<0.05) different among treatments. Seed yield of forage rape can be influenced by manipulation of crop architecture through mechanical topping and sowing date. There is therefore scope for forage seed growers to improve seed yield of forage rape through adoption of simple improvements in practice.