Worm castings-based growing media with biochar and arbuscular mycorrhizal fungi for producing organic tomato (Solanum lycopersicum L.) in greenhouse.

Organic vegetable production has specific research and innovation requirements which are not shared by other parts of the food and farming sector. A pot experiment was conducted to investigate the interactive effects of few permitted organic inputs such as arbuscular mycorrhizal fungi, biochar, and different ratios of peat:worm casting on tomato (Solanum lycopersicum L.) growth, mycorrhizal dependency, biomass production, fruit yield, and soil respiration. The experimental design was a factorial arrangement based on completely randomized design with three replicates. Factors included worm casting at three levels (0, 15 and, 30% of the media volume), organic peat-based potting soil at three levels (70, 85, and 100% of the media volume), two Glomus intraradices treatments (inoculated at sowing or un-inoculated), and two biochar levels (10% of total weight of the media or unlamented). Results indicated that worm casting × peat combination significantly affected all measured traits except for the number of fruits in plant and mycorrhizal dependency. Mycorrhizal symbiosis had a significant effect only on shoot dry weight and mycorrhizal dependency. Moreover, biochar application significantly affected shoot dry weight, stem diameter and carbon mineralization. Among the different ratios of worm casting and peat in the growing media, 15% worm casting × 85% peat formed the most suitable medium condition for plants and 100% peat without worm casting was the least suitable. The highest fruit fresh weight (228.7 g/plant) was achieved in 15% worm casting × 85% peat and the lowest fruit fresh weight (175.1 g/plant) was achieved in 100 peat treatment.