Cadmium effects on valerian (Valeriana officinalis L.) morphology and Cd uptake in relation to substrate acidity/alkalinity

Abstract

Experiments were conducted on valerian (Valeriana officinalis L.) grown under glasshouse conditions to evaluate the effect of Cadmium (Cd) on plant morphological characteristics and Cd uptake. Valerian plants were grown in pots containing a uniform mixture of either moderately acidic or slightly alkaline substrate consisting of peat and perlite (1:1 v/v) over two periods. Pots were arranged in a completely randomized block design within two groups (moderately acid substrate and slightly alkaline substrate) with four Cd treatments (0, 1, 2 and 5 mg Cd L-1) and six replications per treatment. Cadmium was applied as CdSO4*8/3H2O. No visual symptoms of toxicity or nutrient deficiency were attributed to Cd application irrespective of the growth stage or substrate in either experimental period. Cadmium did not affect the dry mass of shoots or roots. Cd concentration in both shoots and roots increased with increasing Cd application, indicating valerian to be a Cd accumulator with accumulation occurring mainly in the roots both in moderately acidic or slightly alkaline substrates. The amount of Cd extracted by Diethylene triamine penta acetic acid-triethanol amine (DTPA-TEA) increased with increasing Cd doses and significantly correlates with the Cd concentrations within the shoots and roots indicating that this extractant could be used to predict Cd concentrations within the plant parts.

Keywords

• cadmium; DTPA-TEA; roots uptake; shoots uptake; valerian