Influence of two soil fungal inocula on growth of Abelmoschus esculentus (L.) Moench. plants grown in arsenic-treated soils

Abstract

In this study, growth of Abelmoschus esculentus (L.) Moench. was investigated in soils treated with arsenic ions and inoculated with two fungi two weeks after planting. Aspergillus niger and Aspergillus terreus were selected out of five isolated fungi from a heavy metal contaminated soil and used to inoculate soils treated with, 50,100 and 150 ppm As³⁺ ion solutions. Abelmoschus esculentus plant growth was measured, where data were collected for germination, morphological and reproductive characters, chlorophyll content, activities of nitrate reductase, catalase (CAT), and super oxide dismutase (SOD). Soil enzymes i.e., urease, phosphatase, dehydrogenase and cellulases were monitored. Results showed that the two fungal inocula increased number of leaves. Plant height was increased in both 100 and 150 ppm As³⁺ treated soils from 19.50 cm to 26.86 cm and 17.60 cm to 30.97 cm in uninoculated and Aspergillus terreus inoculated soils, respectively. Delayed flowering was observed in plants grown in the As³⁺ treated soils. The fungal inocula affected SOD and CAT activities in leaves of Abelmoschus esculentus, in As³⁺ treatments. At 50ppm and 100ppm, inoculation with A. nigerand A. terreus significantly reduced SOD activity. Fungal inoculation stimulated phosphatase and cellulases production in the As³⁺ treated soils. This study clearly shows that the soil inoculants immensely contributed to alleviating heavy metal stress encountered by plants.