Growth and metabolism of germinating rice (Oryza sativa L.) seeds as influenced by toxic concentrations of lead

Abstract

Summary The effects of toxic concentrations of neutral lead acetate (CH 3 COO) 2 Pb, 3 H 2 0 on the germination and growth of rice ( Oryza sativa L.) seeds are reported. Elongation inhibition was first detected at lead acetate concentration of 10 −3 M and became more pronounced with increasing concentrations. Root growth was more strongly inhibited than shoot growth and no germination occurred at 10 −1 M. Various hormones, viz. indole-3-acetic acid (IAA), gibberellic acid (GA 3 ), 6-furfurylaminopurine (kinetin), adenosine 3,5-cyclic monophosphate (cAMP), various organic acids and ethylene diamine tetraacetic acid (EDTA) were partially capable of relieving lead inhibition, whereas cations were ineffective. The activity of catalase, peroxidase, IAA oxidase, IAA synthase and ascorbic acid oxidase incresed in response to lead addition. It was apparent that reduced growth was associated with increased enzyme activity. The stimulated activity of these enzymes was probably due to an enhanced protein synthesis.