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Effect of external nitrate supply on nodulation of lupins II. comparison of eighteen lines of lupinus angustifolius

A.L. Cowie, R.S. Jessop and D.A. MacLeod

Department of Agronomy and Soil Science, University of New England, Armidale 2351.

Modulation of lupins is inhibited by increasing external nitrate supply (1). No information is available regarding the relative tolerance to nitrate of different lupin lines. In this experiment, growth and nodulation of 18 lines were compared.


A description of the method, including the composition of the nutrient solution, is given elsewhere (1). Nitrate treatments of 2 and 8m14 were used, as this represents the range typically encountered in the field. Treatments were replicated three times and plants were harvested after 7 weeks.

Results and discussion

Nodule weight; at. 8 mtl nitrate averaged 5.57 mg per plant compared with 12.52 mg at 2 mM (P<.001). Although there was large variability in nodulation within lines, it was apparent that nodulation of some lines, including Chittick and Illyarrie, was less sensitive to external nitrate

than that of others, such as Wandoo (Table 1). Thus, there is potential for the selection of L. angustifolius lines capable of fixing nitrogen in soils of high N status.

Table 1. Variation in nodulation between 18 lupin lines.

Means followed by the same letter are not significantly different (P>.05) using Duncan's Multiple Vence Test. Lower case letters refer to columns, upper case refer to rows. Nodule weight in 8 mM nitrate as a percentage of average nodule weight for that line in 2 mM nitrate.

1. Cowie, A.L., Jessop, R.S. and MacLeod D.A. 1987. Proc. 4th. Aust. Agron. Conf., Melbourne.

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