Potentials of Pseudomonas aeruginosa and Trichoderma harzianum in the Growth of Solanum lycopersicum in Heavy Metal Contaminated Soil

Abstract

This study determined the growth and yield of Solanum lycopersicum in heavy metal contaminated soil and the heavy metal uptake of the harvested S. lycopersicum fruit. Experimental pots containing 3000 g of sterilized soil was used for this experiment whereby 60 sample pots were used with various treatments in this study. Solanum lycopersicum seeds were raised in the nursery for a period of 3 weeks and treatments applied just before transplanting into the experimental pots. The plants were left for a week so as to be established properly and overcome transplanting shock before watering with the contaminated stream water. Heavy metal analysis using Atomic Absorption Spectroscopy (AAS) method was carried out on the contaminated stream water to determine the amount of heavy metal in the stream water before the commencement of the experiment. The contaminated stream water was applied to the pots in measured quantities; 0, 5 and 0%. Growth and yield data from the experiment were obtained and the results were subjected to ANOVA and descriptive analysis. The results showed that heavy metals were present in high concentration in the stream water sample. The values of the heavy metals in the stream water sample used for watering were Iron – 138.15 mg/L, Zinc – 68.4 mg/L, Lead – 7.89 mg/L and Copper – 8.98 mg/L. The effect of P. aeruginosa were found to be more pronounced among all the treatments as it enhanced the growth and yield of the plants when compared with other treatments. Also, tomato plants with T. harzianum inoculation had higher mean plant height of 66.7 ± 2.3 cm, higher number of leaves 78.0 ± 8.0 and leaf area of 77.5 ± 4.5 cm2. Highest fruit yield was produced in tomato plants treated with P. aeruginosa at 5% and 10% level of contaminated stream water sample concentration. The study concluded that the use of contaminated stream water for irrigation could be a potential source of heavy metals in tomato. However, inoculation of microorganisms for the treatment of the heavy metal contaminated sites was effective for increased health, growth and yield of tomato fruits.