Comparative yield and chemical composition of two varieties of narrow-leafed lupin (Lupinus angustifolius) when harvested as whole-crop, moist grain and dry grain

An experiment was conducted to determine the yield and chemical composition of narrow-leafed or blue lupins (Lupinus angustifolius) when harvested as whole-crop silage, crimped grain and dry grain. A branching variety (cv. Bordako) and a single-stemmed variety (cv. Borweta) were sown in spring. The crops were harvested for whole-crop silage at growth stage 4.5 (green pod, septa split). Following a 24 h wilt and inoculant (Lactobacillus plantarum) application the forage was ensiled in 10 kg mini-silos for 90 days. The moist grain was harvested when the crop reached a target grain DM of 700 g kg−1. After crimping an acid additive was applied, and the grain ensiled in 10 kg mini-silos. The dry grain was harvested when the DM content of the grain had reached 850 g kg−1. The chemical composition of the whole-crop silages was similar, with CP concentrations of over 190 g kg−1 DM. However, the forage yield of Bordako (8446 kg DM ha−1) was significantly higher than that of Borweta (6622 kg DM ha−1). In contrast, the yields of moist and dry grain were higher for Borweta due to lodging of the Bordako stand (3666 kg DM ha−1 versus 1707 kg DM ha−1 and 2863 kg DM ha−1 versus 1442 kg DM ha−1 for moist and dry grain, respectively). The CP concentrations of the moist and dry grain produced by Bordako (both 360 g kg−1 DM) were significantly higher than that produced by Borweta (300 g kg−1 DM). The results suggest that while the branching variety Bordako is better suited to whole-crop production because of its substantially higher DM yield, the earlier ripening and more robust stand of the single-stemmed Borweta make this variety more appropriate for grain production.