Effects of glauconitic sandstone on growth, nutrients content and some physiological traits of canola plants grown under two differents pH levels

Glauconite is a micaceous mineral that could be source of potassium. The aim of this study was evaluation of the effects of glauconitic sandstone and potential of iron relase and toxicity in case of using as a potassium fertilizer for canola plants. The plants cultivation experiments were carried out in growth chamber in sand culture with completely randomized design as factorial. The first factor was potassium with three levels including Hoagland nutrient solution, Hoagland nutrient solution lack of potassium and Hoagland nutrient solution lack of potassium accompanied with glauconitic sand stone powders. The second factor was pH of culture medium contained 6 and 7.5. The results indicated that potassium deficiency in Hoagland nutrient solution without potassium treatment caused severe reduction in growth traits, contents of K+, soluble protein, starch and chlorophylls and increased total amino acids in canola plants. Application of glauconitic sand stone powders could release potassium in solution medium as plants treated with Hoagland without + glauconite did not indicated significant differences in fresh and dry mass and potassium content with Hoagland-treated ones. Iron content was higher in roots of Hoagland without potassium + glauconite treated canola plants compared treatments, however, pH reduction from 7.5 to 6 did not increase iron content in this treatment. The reduction of pH of nutrient medium imposed significant decrease of soluble protein, starch and chlorophyll contents that lead to growth retardation of canola plants. The results indicated that glauconitic sandstone has certain potential to release potassium. Iresspective pH of nutrient solution, no toxicity symptom was observed in canola plants following glauconite application.