Response of narrow-leafed lupin (Lupinus angustifolius L.) to foliar application of growth regulators in Western Australia

Abstract

Four experiments were conducted during 1991-93 in the south coastal and lakes regions of Western Australia, to test the hypothesis that foliar application of a range of growth regulators will improve the pod set and seed yield of narrow-leafed lupins (Lupinus angustifolius L.). The chemicals tested (not all in any 1 year) were: Cultar (250 g paclobutrazol/L), Pursuit (240 g imazethapyr/L), Cytokinin (21 g 6-benzyladenine/L), Legumex (400 g 2,4-DB/L), Cytolin (20 g gibberellins A4 and A7/L and 20 g 6-benzyladenine/L), Bladex (500 g cyanizine/L), Diuron 500F (500 g diuron/L), Lexone (750 g Metribuzin/kg), NAA (40 g 1-napthalene acetic acid/L), Pix (38 g mepiquat chloride/L), Gesatop 500 (500 g simazine/L), High Yield (unknown active ingredient), Lontrel (300 g clopyralid/L), a Cultar-Lontrel mix, and a Lexone-Brodal(500 g diflufenicad) mix. Chemicals were applied from as early as 6 weeks before flowering on the main stem to as late as flowering on the 1st-order branches. Any gross physical effects were visually assessed. Canopy height and components of yield were measured at some of the experimental sites. In 2 experiments, no chemical had any significant effect on seed yield (P>0.05). At the 2 remaining sites, Cultar, Lontrel, and the Lexone-Brodal mix increased seed yield of lupins by 230-250 kg/ha. Seed yield increases were related to improvements in pod set. No chemical had any significant effect (P>0.05) on dry weight production. Timing of application was critical, with application 6 weeks before flowering giving the most consistent positive responses.