Cadmium toxicity during germination

--Jaime R. Jatimliansky, Otmaro E. Roses* and Daniel González*

*Buenos Aires, Cát. de Toxicología, Fac. Fcia y Bioquímica, UBA

Numerous data from a number of sources have demonstrated that different cultivars of the same plant show differences in their Cd absorption characteristics. Different plant parts (leaves, stems, roots) accumulate different amounts of Cd (SCOPE 31:141, 1987).

Information on the relationship between the cadmium content in an organism and the biological effects is needed (Ravera, Experientia 40:2-14, 1984). Concentration of Cd in soils varied widely. Elevated values of 10mg/kg soil or more were found.

We have studied some characters, in controlled conditions without soil, during germination of maize grains to assess the comparative behavior of the progeny and the progenitors treated with elevated amounts of Cd. We have employed two flint type inbred lines, SC66 (B) and SC75 (A), and the hybrid SC66 x SC75 (F1). Grains of similar weights (F1=B=284.5mg; A= 254.5mg) were individually put into vials with cotton-wool and 2ml of distilled water with 0; 44.5 or 89uM of Cd2+ (as Cl-) and were grown at 28 C.

Some results obtained 8 days after germination were:

Table 1. Dry matter diminution. DMD = 100 (initial DW - final DW)/initial DW. Initial DW: F1 = B = 250.4 mg; A = 224 mg.
 
  F1 B A
Controls 14.1 13.1 8.6
Cd 44.5uM 12.5 11.7 6.5
Cd 89.0uM 10.8 10.7 6.2

Table 2. Mean Cd concentrations (ug Cd g DW-1) in seedlings. Controls: no amounts.
 
  F1 B A
roots 328 351 536
aerial parts 48 43 81
grains 51 112 66
mean 142 168 211

Cadmium concentrations among the various plant parts analyzed mark the pre-eminence in the roots in relation to grains or aerial parts. Cd root concentrations were inversely related to growth rate expressed as DM diminution. Cd has affected the growth of all treatments and populations.


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