Interactive effects of treated wastewater irrigation and Trichoderma harzianum inoculation on growth and yield of tomato (Solanum lycopersicum L.)

Abstract

Water scarcity is driving the need for alternative irrigation strategies that reduce dependence on freshwater while maintaining crop productivity. This study investigated the combined effects of treated wastewater (TWW) and Trichoderma harzianum inoculation on the growth and yield of two tomato cultivars (Bobcat and Galilea) under controlled greenhouse conditions. Five TWW levels (0%, 25%, 50%, 75%, and 100% TWW) were applied with or without fungal inoculation. Seventeen agro-morphological traits were assessed, covering vegetative growth, leaf characteristics, root system, and yield. Treated wastewater (TWW) significantly improved plant performance, and the effect was amplified by T. harzianum. The highest concentration (100% TWW + inoculation) produced the strongest response, increasing plant height, leaf number, root volume, and fruit yield. In this treatment, the Galilea variety reached a height of 115.7 ± 0.60 cm with 21.3 ± 0.38 branches and 219.3 ± 0.60 leaves; whereas Bobcat attained 99 ± 0.47 cm, with 18.66 ± 0.38 branches and 206 ± 0.47 leaves. Leaf area was similar for both cultivars, averaging approximately 190 cm². However, Bobcat exhibited a root volume of 15.6 ± 0.38 cm 3, which is slightly higher compared to Galilea 14 ± 0.47 cm 3 . Bobcat outperformed Galilea, producing a high number of fruits (12.3 ± 0.54 vs . 10.33 ± 0.38), greater average fruit weight (156.4 ± 1.40 g vs. 83.64 ± 0.98 g), and a significantly higher total yield per plant (1934.22 ± 8.15 g/plant vs 863 ± 2.56 g/plant). This yield represented an increase for Bobcat of more than 520% compared to the untreated control (Tr⁻). Principal component Analysis (PCA) confirmed a synergistic interaction between TWW and fungal inoculation across most measured traits. The combined use of TWW and T. harzianum enhances nutrient availability, stimulates root development, and substantially improves crop yield. This integrated strategy reduces reliance on freshwater and synthetic fertilizers, representing a promising agroecological strategy for vegetable crop production under water scarcity conditions.