Diagnosis of nitrogen deficiency and toxicity of Eucalyptus globulus seedlings by foliar analysis

Abstract

The relationship between shoot growth and foliar nitrogen (N) in E. globulus seedlings was studied in the glasshouse to determine standard values for N deficiency and toxicity diagnosis . Seedlings were grown for 9 weeks in yellow sand, at 10 rates of N, applied as ammonium sulphate, calcium nitrate or ammonium nitrate . Shoot dry weight (DW) increased linearly with N rate for all forms of N in the deficiency range . Seedlings continued to respond to higher rates of ammonium and ammonium nitrate than to nitrate . Maximum shoot DW for nitrate fed plants and ammonium nitrate fed plants were 51 % and 84% respectively of ammonium fed plants . Total N concentration in the youngest fully expanded leaf (YFEL) ranged from 1 .0% to 3 .3% in deficient and adequate plants . The critical N concentration for deficiency diagnosis (corresponding to 90% maximum yield) in the YFEL, determined from these growth response curves averaged over all N forms, was 2 .6% N. For ammonium nitrate fed plants, total N concentration in the YFEL for the severely deficient, deficient, adequate, and toxic ranges were < 1 .4%, 1 .4-2.5%, 2 .6-3 .5%, > 4.3% . High total N concentrations were associated with growth depression and toxicity symptoms, which differed with N form . For nitrate fed plants, a total N concentration above 3 .3% in the YFEL was associated with severe growth depression, and leaf tip necrosis . The adequate concentration range for ammonium nitrate was similar to values found on a field trial with 7 month old E. globulus trees grown on an exforest site .

Kinetics of ammonium and nitrate uptake by eucalypt roots and associated proton fluxes measured using ion selective microelectrodes

“…In that case the V max for NO 3 was reduced from 69% to 23% of the NH 4 + value. The closely related eucalypt, E. globulus, achieved higher growth rates with NH 4 + as the sole N source compared with both NH 4 + and NO 3 together or solely NO 3 - (Shedley et al 1995). It seems that patterns of uptake found here could partly explain this growth difference.…”

“…Even with reduced NO 3 uptake rates when both NH 4 + and NO 3 are present, the total N uptake is still greater than with just NH 4 + present. Thus, it is difficult to explain why, in the work of Shedley et al (1995), plants grew better on solely NH 4 + . The majority of the literature would suggest that, for almost all plants, growth is increased when both NH 4 + and NO 3 are present (Haynes and Goh 1978).…”

“…Studies have suggested that E. nitens and E. globulus may, like temperate coniferous species, have a preference for NH 4 + over NO 3 -as an N source (Shedley et al 1995;Garnett and Smethurst 1999;Garnett et al 2001). However, until now there has not been a kinetic characterisation of NH 4 + and NO 3 uptake by a eucalypt species.…”

Inoculation of Eucalyptus urophylla with spores of Scleroderma in a nursery in south China: Comparison of field soil and potting mix

“…H 2 SO 4 at 21 8C, digested in conc. H 2 SO 4 and H 2 O 2 at 360 8C (Shedley et al, 1995) and N determined spectrophotometrically using the Berthelot reaction (Issac and Johnson, 1976). Total P and K were analyzed by digesting samples in nitric acid followed by ICP-AES spectrometry (Zarcinas et al, 1987).…”

Optimum nitrogen fertilization of Calophyllum inophyllum seedlings under greenhouse conditions

“…Regression equations between nutrient concentration or ratio and total biomass of the seedlings were fitted and then diagnostic equations were accepted that were statistically significant. The critical value and the optimum concentration range were calculated using the nutrient concentration which corresponded to 90% maximum biomass from the equation [26,27] .…”