Impact of cyanobacteria as a bioelicitor on the morphological and physiological characteristics of wheat plant (Triticum aestivum L.)

Blue-green algae or cyanobacteria have a crucial role in the agriculture. In particular, heterocystous cyanobacteria which are increased plants growth through the production of hormonal and non- hormonal stimulants and also the ability to fix nitrogen. Considering the special role of these microorganisms in production of biofertilizers, in present study the impact of cyanobacteria on plant growth was evaluated through the study of morphological and physiological characteristics of Triticum aestivum L. seedlings treated with six isolates of terrestrial cyanobacteria. These studied cyanobacteria were four isolates of Nostoc spongiaeforme var. tenue, one isolae of Anabaeana vaginicola and one isolate of Hapalosiphon fontinalis. It should be noted that these taxa were isolated from the bed soil of medicinal plants of Guilan Province. Among the evaluated characteristics, we can mention the seed germination percentage, morphological characteristics such as shoot and root length and physiological parameters such as quantity of chlorophyll a, chlorophyll b, total chlorophyll and carotenoids. For this purpose, 30 air-dried seeds of Triticum aestivum L. were soaked in algal extracts (2.0 g fresh algal material in 1000 mL of distilled water; experimental) for 24 h. For controls, seeds were soaked in distilled water for 24 h. Then, the seeds were placed on filter papers wetted with distilled water (control samples) or with 5 mL of algal suspension (treatment samples). The experiment was carried out in three replications based on a randomized design. Based on the results of this study, all treated plants showed a significant increase in the rate of germination and growth parameters at the 0.05 level. In other words, cyanobacteria, in addition to increasing the seed germination rate, significantly increased the root and stem growth parameters of treated plants. Among the treatments, the maximum vegetative growth of root and stem was related to the seedlings treated with Nostoc spongiaeforme var. tenue respectively. The result of pigment evaluation also showed the significant increase of photosynthetic pigments such as chlorophyll a, b and total chlorophyll in treated plants compared to controls at the 0.05 level, which the highest amount of them were meseaured in the plants treated with Hapalosiphon fontinalis and Anabaena vaginicola. Altogether, our findings suggest that the selected cyanobacteria, isolated domestically, can serve as potential biofertilizer candidates to promote economic plants growth.

Keywords:

Cyanobacteria , Biofertilizer , pigmentation measurement