Diagnosis Of Nitrogen Deficiency Research Articles

FERTILIZER APPLICATIONS AFFECT FOLIAR NITROGEN, CHLOROPHYLL, SHOOT GROWTH AND YIELD OF 'QING' CHINESE CHESTNUT

Three different fertilizer treatments were applied in 2005 and 2006 at equivalent annual rates of nitrogen to determine their effect on growth and yield of 'Qing' Chinese chestnut trees. Chlorophyll meter readings were also obtained to determine their relationship to foliar nitrogen. The fertilizer treatments were: 1) 150 kg N/ha in the form of slow-release fertilizer (Pro-Grow) applied on 1 Mar.; 2) 75 kg N/ha in the form of NH 4 NO 3 applied on 1 Apr. and on 15 June; and 3) 75 kg N/ha applied on 1 Apr., 30 kg N/ha applied on 15 June, and 45 kg N/ha applied on 10 Oct. all in the form of NH 4 NO 3 . 'Qing' trees treated with two applications of NH 4 NO 3 resulted in greater yield and less terminal shoot growth than other fertilizer treatments in 2005. In 2006, yield was similar, but nut growth may have been influenced by adverse weather conditions. The SPAD-502 chlorophyll meter readings had the strongest relationship to foliar nitrogen when mid-shoot leaves from current season's growth were sampled in mid-June in both years. Thus, the SPAD meter may be a promising tool for the rapid assessment of foliar nitrogen of 'Qing' Chinese chestnut trees and for the diagnosis of nitrogen deficiency.

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

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 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.

Diagnosis of nitrogen deficiency in barley, growing in different rotation systems, by plant analysis

Nitrate concentrations were determined in stems of barley taken at the tillering stage from a 2-year rotational/N fertilizer experiment carried out at 2 locations in Cyprus. In the second year leaf laminae were also analysed for total nitrogen (N) concentration.

The diagnosis of nitrogen deficiency in wheat by means of a critical nitrate concentration in stem bases

Abstract Stem bases from wheat plants in a glasshouse pot experiment conducted under varying nitrogen and two water regimes, were analysed for nitrate (NO3) concentration. The concentration of NO3 at three stages of growth i.e. tillering, jointing and anthesis were related both to rates of applied nitrogen and to shoot dry matter yield at time of sampling. Plotted against rate of increasing nitrogen application, the response curve of NO3 concentration in wheat stem bases was sigmoidal. The level of nitrogen application at which NO3 began to accumulate in the plants was the supply at which plants reached maximum dry matter yield. The concentration of NO3 at which plant yield was 90% of maximum dry matter was taken as the critical level. This concentration was around 1000 ppm NO3‐N at all stages. Compared with plants supplied with unlimited water, plants under moderate water stress accumulated relatively more NO3 but had a similar critical NO3 concentration. Maximum grain yield was obtained from plants which stayed above the critical level throughout the growing season.