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).

Concentration of Cd in soils varied widely. Elevated values of 10mg/kg soil or more were found.

During 1991 (MNL66:61, 1992) and 1992 we have studied some characters during germination of maize grains in controlled conditions without soil to assess the comparative behaviour of the progeny and the progenitors treated with elevated amounts of Cd. As in 1991, we have employed two flint type inbred lines, SC66 and SC75, and the hybrid SC66 x SC75. Grains of similar weight (244.5mg) were individually put into vials with cotton-wool and 2ml of distilled water with 0, 44.5 or 89µM of Cd2+ (as Cl-) and were grown at 28 C.

Relative mean Cd concentrations (µg Cd g DW-1) and dry matter diminution obtained in seedlings, 10 days after germination, presented the same tendencies observed in 1991: Cd concentrations among the various plant parts mark the pre-eminence in the roots in relation to grains or aerial parts; SC75 showed lesser DM diminution in relation to SC66 or the hybrid. We measured the absolute Cd uptake (µg cadmium into each tissue) (Table 1).

Table 1. Absolute Cd uptake (µg) 10 days after germination. Control: no Cd. N=5. For each parameter (root, grain, aerial parts, total DM) means with the same letter are not statistically different (P=0.05).
 
Treatments Root Grain Aerial parts Total DM Genotype
Cd 45µM 2.99e  4.74e 4.92b 12.65d  SC66
6.70bc 5.74d 5.54b 17.98bc SC66 x SC75
6.12cd 6.64c 3.06c 15.82cd SC75
means 5.27  5.71  4.50  15.48 
Cd 89µM 5.68d  9.74b 6.74a 22.16b SC66
11.72a  13.62a 7.44a 32.78a SC66 x SC75
7.12b  13.22a 2.28c 22.62b SC75
means 8.17  12.19  5.49  25.85 

Absolute Cd uptake was directly related to Cd concentration in the medium. Cd uptake by the hybrid was greater than Cd uptake by SC66. 

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