The effect of superphosphate and rock phosphate on the growth of Lupinus angustifolius and Vicia faba: A dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Science with Honours at Lincoln University

Abstract

To determine the ability of faba bean (Vicia faba) and narrow leafed lupin (Lupinus angustifolius) to utilise rock phosphate as a P source, a glasshouse pot trial was established on 10 May 2002 at Lincoln University, Canterbury, New Zealand (45 °S). There were six phosphate treatments; triple superphosphate (21 % P) applied at 30 and 60 kg P ha⁻¹ , North Carolina rock phosphate (13 % P) applied at 30 and 60 kg P ha⁻¹ , a 0 P control and a control provided with complete nutrient solution, including soluble N and P. At 60 kg P ha-1 , superphosphate produced 10.8 g of total dry matter (TDM) plant⁻¹ This was 104 % more than the 0 P control (5.3 g plant⁻¹ ) and 73 % higher than the mean of the two rock phosphate treatments (6.0 and 6.5 g plant⁻¹ for 30 and 60 kg P ha⁻¹ respectively). Superphosphate at 30 kg P ha⁻¹ gave a TDM of 9.1 g plant⁻¹ , which was not significantly different to superphosphate at 60 kg P ha⁻¹ . The response of shoot and root DM production to P treatment followed a similar pattern to TDM production. Superphosphate increased nodulation and leaf area, but did not affect pod yield or shoot N and P concentrations compared to the 0 P control. In both species rock phosphate did not increase total, shoot or root DM production, pod yield, nodulation, leaf area or shoot N and P concentration over the 0 P control at any time. Faba bean had a higher TDM production than lupin at 42 (3.2 and 0.6 g plant⁻¹ respectively) and 64 days after sowing (DAS) (3.2 and 1.3 g plant⁻¹ respectively). Faba bean leaf area developed at a rate of 5.8 m² day⁻¹ , which was much faster than lupin (2.2 cm² day⁻¹ ). By 124 DAS there was no difference between species in total, root or shoot DM production. It was concluded that, under conditions of severe nutrient deficiency, lupin and faba bean were unable to utilise rock phosphate as a source of P for growth