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Effect of
cadmium on soybean (Glycine max L) growth and
nitrogen fixation
Rizwan Ali Sheirdil, Kashif Bashir,
Rifat Hayat* and Mohammad Saleem Akhtar
Department of Soil Science and
Soil Water Conservation,
PMAS Arid Agriculture University, Rawalpindi, Pakistan.
*Corresponding author. E-mail:
hayat@uaar.edu.pk.
Accepted 13 December, 2011 |
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To
study
the effect of
cadmium (Cd) on soybean growth and nitrogen (N2)
fixation, an experiment was performed in sand culture using
Hoagland nutrient solution. At the time of sowing, different
cadmium level that is 0, 4, 8 and 16 mg kg-1 sand
was created using Cd (NO3)2. Soybean
shoots and root lengths shoot and root biomass, nodule
density and Cd uptake was recorded on 2, 4, 6, 8, 10, and 12
weeks after the emergence. To calculate the relative
abundance of ureide and % Pfix (proportion of
plant N derived from N2-fixation), xylem sap was
collected and analyzed for ureide, nitrate and amino-N at
pod fill stage. The application of Cd adversely affected
soybean growth, nodulation and N2 fixation as a
function of time and increase in Cd concentration. Maximum
reduction in the root and shoot length was found with higher
Cd level that is 16 mg kg-1 sand after 10 weeks
of the growth. Similarly, nodulation and the proportion of
plant N (% Pfix) derived from N2
fixation decreased sharply as Cd concentrations increased
during the whole growth stages and the maximum reduction was
observed in the Cd level of 16 mg kg-1 sand
followed by 8 and 4 mg kg-1 sand, respectively.
Cadmium uptake increased with the highest Cd application
after each bi-weekly harvest of growth.
Keywords:
Cd, growth, nodulation, N2 fixation, soybean. |
