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Stability of the Nitrogen Concentration of Inoculated White Lupins during Pod Development
C. DUTHION and ALIX PIGEAIRE
Annals of Botany
Vol. 72, No. 1 (July 1993), pp. 55-61
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/42758889
Page Count: 7
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The general pattern of decrease of the 'critical' plant N concentration (i.e. minimum concentration required for maximum growth rate) during growth has been described for several C₃ non grain-legume species, and this can be used as a reference curve for diagnosis of N nutrition in these species. The present study was undertaken to investigate changes of N concentration during growth of a grain legume, in different conditions of N nutrition. White lupin (Lupinus albus L.) was grown for six crop seasons in field trials in which inoculation with Rhizobium lupini, nitrogen fertilizer rate, cultivar and plant density were manipulated. The yield and dry matter production of noninoculated plants were lower than, or at the best similar to, those of inoculated plants, whatever the level of N supply. From anthesis to the beginning of seed filling, the N concentration of shoots of inoculated plants was found to be remarkably stable between years, N fertilization regimes, cultivars, and for individual plants within a plot. Nitrogen concentration only varied with plant density. By contrast, the N concentration of noninoculated plants was highly variable and generally lower than that of inoculated plants, whatever the level of N supply. The high and stable N concentration of inoculated plants did not appear to be necessary for maximum growth rate but seemed to be required for maximum production of seed dry matter and N. The potential use of these results to diagnose, in any white lupin crop, an inefficiency of the white lupin—R, lupini interaction is evaluated.
Annals of Botany © 1993 Oxford University Press