
%0 Journal Article
%A Pinkerton, A. 
%T Critical sulfur concentrations in oilseed rape (<emph type="2">Brassica napus</emph>) in relation to nitrogen supply and to plant age
%J Australian Journal of Experimental Agriculture
%D 1998/09/18
%V 38
%N 5
%P 511-522
%K 
%R https://doi.org/10.1071/EA97103
%U https://www.publish.csiro.au/paper/EA97103 
%X Summary. Oilseed rape was grown in a sand culture experiment in a glasshouse to derive values for plant testing for the diagnosis of sulfur (S) deficiency and for the prediction of seed yield. Five rates of S, combined factorially with 4 rates of nitrogen (N), maintained constant throughout the experiment, were used to determine critical concentrations of S fractions and ratios (total S, St; sulfate-S, SO4; total N/total S, N/St; SO4/St). The most satisfactory indices of rapeseed S status for diagnosis or prediction were St and SO4. Whole shoots and youngest fully expanded leaves exhibited similar critical values in plants at the rosette stage, and critical values (St = 0.20&#8211;0.25%; SO4 = 230&#8211;460 mg/kg) changed little with time. Critical values for N/St changed with time, required 2 analyses, and gave no indication of the degree of deficiency when used to predict yield. Critical values of SO4/St depended on N supply, so 3 analyses were needed. It is argued that high critical values reported previously for prediction of seed yield have been obtained when there was a decline in soil-available S and plants relied on S taken up during early growth. 
