Effect of Biochar And Hydrochar Produced from Potato Plant Residue on Bean Growth Indices and Mycorrhizal Symbiosis in Drought Stress

A study was conducted as split plot layout with three replications at the research greenhouse of Bu-Ali Sina University, Hamedan in 2017 in order to investigate the consequences of using biochar and hydrochar, produced from potato plant residue on bean plant growth indices, chlorophyll content, and root mycorrhizal symbiosis in drought stress. The main plot and subplots in this study have been two drought levels and four amendment treatments, respectively. The study shows that the drought stress and the application amendments in various forms have had significant effects on plant growth indices, chlorophyll content, and root mycorrhizal colonization. Drought stress reduces root and shoot dry weights up to 39.8, 46.1%, leaf chlorophyll a (Chl a) content up to 52.6%, chlorophyll b (Chl b) content up to 58%, and total chlorophyll up to 54.52%. Although the number of rhizobium nodule on the root of plant decreases in drought stress, the rate of root mycorrhiza rises by 19.2% in drought stress. The use of biochar increased the mycorrhizal symbiotic indices significantly. It increases root colonization 11.34% and Glomeromycota spore number 50.5% in soil. The application of raw residue in soil has had the most positive effects on the plant growth indices and the leaf chlorophyll contents, leading to increased shoot dry weights (49.8%) and chlorophyll a, b and total contents (3.54%, 36.8%, and 14.5% respectively). The findings of this study show that among the treatments, the best plant growth index has been obtained in the use of potato biochar, which reduces the harmful effects of drought stress on the bean plant.