Effect of Trichoderma harzianum on microelement concentrations and increased growth of cucumber plants

The potential of the biocontrol agent Trichoderma harzianum strain T-203 to induce a growth response in cucumber plants was studied in soil and under axenic hydroponic growth conditions. When soil was amended with T. harzianu m propagules, a 30% increase in seedling emergence was observed up to 8 day s after sowing. On day 28, these plants exhibited a 95 and 75% increase in root area and cumulative root length, respectively, and a significant incre ase in dry weight (80%), shoot length (45%) and leaf area (80%). Similarly, an increase of 90 and 30% in P and Fe concentration respectively, was obse rved in T. harzianum inoculated plants. To better characterize the effect o f T. harzianum during the early stages of root colonization, experiments we re carried out in a gnotobiotic hydroponic system. An increased growth resp onse was apparent as early as 5 days post-inoculation with T. harzianum, re sulting in an increase of 25 and 40% in the dry weight of roots and shoots, respectively. Similarly a significant increase in the concentration of Cu, P, Fe, Zn, Mn and Na was observed in inoculated roots. In the shoots of th ese plants, the concentration of Zn, P and Mn increased by 25, 30 and 70%, respectively. Using the axenic hydroponic system, we showed that the improv ement of plant nutritional level may be directly related to a general benef icial growth effect of the root system following T. harzianum inoculation. This phenomenon was evident from 5 days post-inoculation throughout the res t of the growth period, resulting in biomass accumulation in both roots and shoots.