
%0 Journal Article
%A Halse, NJ 
%A Greenwood, EAN 
%A Lapins, P 
%A Boundy, CAP 
%T An analysis of the effects of nitrogen deficiency on the growth and yield of a Western Australian wheat crop
%J Australian Journal of Agricultural Research
%D 1969/12/01
%V 20
%N 6
%P 987-998
%K 
%R https://doi.org/10.1071/AR9690987
%U https://www.publish.csiro.au/paper/AR9690987 
%X A wheat crop was grown on a nitrogen-deficient sandy soil. Urea was supplied at rates of 0 (N0), 56 (N1), and 336 (N2) kg nitrogen/ha. In general, the relative growth rate (R) decreased with time. During the first half of the growing season R for N2 > N1 >> N0, but in August deficient plants recovered rapidly. The recovery was associated with the emergence of the second tiller, an increase in net assimilation rate and nitrogen uptake, and a decrease in nitrogen stress. There was no evidence that the recovery was due to an increase in mineralization of soil nitrogen. Nitrogen stress in treatment N0 decreased from 48&#37; in July to 14&#37; in September. By contrast, stress in treatment N1 increased rapidly from 6 to 23&#37; during July and fell to 5&#37; by September. Flower initiation in N0 plants was delayed 14 days and ear emergence was delayed 8 days compared with N1 plants. The grain yields of N0 and N1 plants were 30 and 60&#37; respectively of those of N2 plants. The decrease was due mainly to differences in the number of heads per sq metre, although nitrogen deficiency also reduced the number of grains per head and the weight per grain. The duration of photosynthetic activity after anthesis was not affected by nitrogen treatments. Harvest index was highest on N0 treatment and similar on N1 and N2 treatments. 
