Effects of cyanobacteria producing microcystins on seed germination and seedling growth of several agricultural plants

Abstract

The effects of cyanobacteria aqueous extracts containing Microcystin-LR (MC-LR) on the seed germination and growth of Pisum sativum, Lens esculenta, Zea mays and Triticum durum were investigated. Experiments were carried out on a range of doses of the extract (equivalent to 0, 1.6, 2.9, 5.8, 8.7 and 11.6 μ g MC-LR/mL). The results confirm that these plants were sensitive to cell-free extracts of a toxic Microcystis and that germination inhibition was dose dependent. One-way analysis of variance (ANOVA) showed that P. sativum is the most sensitive tested species with a 97% germination rate reduction and L. esculenta was the most resistant. At the 8th day, the exposure to the microcystins (MC) resulted in a significant decrease of plant epicotyls length, roots length and a net inhibition of lateral root formation. It is concluded that MC could affect also terrestrial plants seedling germination and growth. Therefore, the use of water for irrigation contaminated by MC could exert negative biochemical effects on seed and plant metabolism which might influence the agricultural crops.

Keywords:

• Cyanobacteria
• Microcystis aeruginosa
• microcystins
• germination inhibition
• root inhibition
• impact on agriculture

Acknowledgments

Authors thank B. Sbiyyaa, B. Sabour, I. El Hadrami, J. Oswald, R. Martins, M. Saker, M. Vale, F. Teles for help and technical assistance. This work was carried out within the framework of the cooperation Morocco-Portuguese collaboration (convention of cooperation CNRST-Morocco/ GRICES-Portugal; Prof. Brahim Oudra/Prof. V.M. Vasconcelos).