Seed Biopriming With Trichoderma Strains Isolated From Tree Bark Improves Plant Growth, Antioxidative Defense System in Rice and Enhance Straw Degradation Capacity

This study is a unique report of the utilization of Trichoderma strains collected from above ground parts not only for rice plant growth and its health management but also for paddy straw degradation. Seven different spp. of Trichoderma were characterized according to morphological and molecular tools. Two of the isolated strains determined as Trichoderma hebeiensis and Trichoderma erinaceum outperform the others. Both the strains controlled four important rice pathogens i.e. Rhizoctonia solani (100%), Sclerotium oryzae (84.17%), Sclerotium rolfsii (66.67%) and Sclerotium delphinii (76.25%). Seed bio-priming with the formulated strains reduced the mean germination time, enhanced the seedling vigour and total chlorophyll content which could be related to higher yield observed in two rice varieties; Annapurna and Satabdi. All the seven strains not only promote the formation of rice straw compost by producing higher straw degrading enzymes like total cellulase (0.97-2.59 IU/mL), endoglucanase (0.53-0.75 IU/mL), xylanase (145.35-201.35nkat/mL), laccase(2.48-12.60 IU/mL) but also produce higher quantity of IAA (19.19-46.28 µg/mL), inorganic phosphate (297.49-435.42 µg/mL) and prussic acid (0.01-0.37 µg/mL) which can be promote plant growth and inhibit the population of rice pathogens. The out flow of antioxidant enzymes like catalase (~250% both in shoot and root), peroxide (~ 150% in root and ~100% in shoot), superoxide dismutase (~150% in root and ~100% in shoot), polyphenol oxidase (~160% in shoot and ~120% in shoot) and total phenolics (~200% in root and ~250% in shoot) as compared to control indicates stress tolerance ability to rice crop. The expression of all the above mentioned enzymes were confirmed by the expression of prominent antioxidant defense genes like PAL (>3 fold), DEFENSIN (>1 fold), POX (>1.5 fold), LOX (>1 fold) and PR-3 (>2 fold) as compared to the non treated control plants. This investigation demonstrates that Trichoderma strains got from tree coverings might be considered as biofertilizer and decomposer for rice crop.