
%0 Journal Article
%A Pinkerton, A 
%A Spencer, K 
%A Govaars, AG 
%T Assessment of the phosphorus status of oilseed rape by plant analysis
%J Australian Journal of Experimental Agriculture
%D 1989/12/01
%V 29
%N 6
%P 861-865
%K 
%R https://doi.org/10.1071/EA9890861
%U https://www.publish.csiro.au/paper/EA9890861 
%X Phosphorus (P) concentrations in young plants of rapeseed (Brassica napus cv. Wesway) were related to seed and oil yields to develop a tissue test for the diagnosis of P deficiency. Critical P concentrations were defined as those concentrations required to sustain 90% of maximum yield.  In 2 field experiments in successive seasons on a P-deficient soil, rates of triple superphosphate from 2.5 to 120 kg/ha were banded with the seed. The lowest P concentration in young shoots (17-19 weeks from sowing) associated with a P supply that was adequate for plant growth was approximately 0.31%. The youngest fully-expanded leaf was a reliable plant part to sample, its P concentration being about 0.05% lower than the concentration of the whole shoot.  Critical P concentrations in young plants for sustaining 90% of maximum seed and oil yields were higher, namely 0.33 and 0.28% for whole shoots and youngest fully-expanded leaves respectively. The critical P concentration in seeds was about 0.35%. 
