The present invention relates to a method for enhancing growth of plants which comprises contacting a Trichoderma strain with the plant or a plant seed under conditions effective for the Trichoderma strain to colonize the roots of the plant or a plant grown from the plant seed, thereby creating a plant-Trichoderma system. The plant or plant seed is grown under conditions effective to sustain the plant-Trichoderma system in a planting medium and to enhance plant growth, where the Trichoderma strain is selected from the group consisting of Trichoderma atroviride strain WW10TC4 (ATCC accession number PTA 9707), Trichoderma harzianum strain RR17Bc (ATCC accession number PTA 9708), Trichoderma harzianum strain F11Bab (ATCC accession number PTA 9709), and combinations thereof. Also, disclosed are methods of enhancing resistance of plants to abiotic stress, increasing nitrogen use efficacy in plants, reducing nitrous oxide emissions in air, reducing leaching of nitrates into soil and water, and enhancing sequestration of carbon from air.