INFLUENCE OF Trichoderma harzianum FROM SEMI-ARID SOILS ON MAIZE SEED GERMINATION AND EARLY SEEDLING GROWTH UNDER WATER STRESS

Abstract

Water stress is one of the major constraints on plant productivity worldwide and is projected to aggravate with climatic changes while human population is at its exponential phase. On the other hand, Trichoderma spp. are plant symbionts that have been widely used as seed treatments to control diseases and to enhance plant growth and yield. However, few recent works have been published with regards to their abilities to improve abiotic stresses in plants. The present study sought to assess the effect of T. harzianum from semiarid soils on maize seed germination and seedling growth under water stress. Trichoderma harzianum from semiarid soils (Marigat rangeland) was isolated using macro and micro-morphological characteristics. The present study employed a three factor factorial (3×4×4) design, arranged in a completely randomized design (CRD) with three replications. Three maize varieties (H614, H629 and H62 10) were treated with four concentrations of T. harzianum (0, 1x105 , 1x107 and 1x1010 spore/ml), and thereafter grown under 0, -0.3, -0.6 and -0.9 MPa osmotic potentials. Results showed that, 105 , 107 and 1010 spore/ml concentrations of T. harzianum had a significant effect (p<0.05) on seed germination, seedling length, seedling fresh weight, root dry weight and shoot dry weight compared to control under water stress. Precisely, 107 spore/ml of the T. harzianum recorded maximum seed germination and seedling growth under all water stress levels. However, there were no significant (p>0.05) differences between 107 and 1010 spore/ml of T. harzianum in terms of maize seed germination and seedling growth. It was observed that under normal conditions (0MPa), T. harzianum did not enhance either maize seed germination or seedling growth. The activity of superoxide dismutase (SOD) and catalase (CAT) was also significantly enhanced by T. harzianum in all the three varieties of maize. Optimum SOD and CAT activity was recorded in seeds treated with 107 spores/ml of T. harzianum. Under normal growth conditions (0MPa), SOD and CAT activities were not enhanced by T. harzianum. However, under severe water stress (- 0.9MPa), maximum activity of the enzymes was registered in all the three varieties of maize. It was also noted that the three concentrations of the T. harzianum (105 , 107 and 1010 spores/ml) significantly promoted growth in all the three varieties of maize. However, in response to the fungus, there was no significant interaction (p>0.05) between maize variety and the concentration of T. harzianum in terms of seed germination and early seedling growth under water stress. Therefore, the study ascertained that the activity of T. harzianum was not dependent on the genotype of the maize plant. Taken together, the study recommends that for enhanced maize seed germination and seedling growth, 107 spores/ml of T. harzianum isolated from semi-arid soils should be used as seed treatment regardless of the maize variety, since the beneficial, activity of T. harzianum is not dependent on the maize plant variety