Effect of Bacillus methylotrophicus on Tomato Plug Seedling

Abstract

Tomato production is gradually shifting to modern production, which requires the factorization of tomato seedlings to shorten the seedling cycle and improve the seedling quality. Bacillus methylotrophicus, as a biofertilizer for plant growth-promoting rhizobacteria, can promote plant growth and enhance native plant defenses. However, reports on the role of this type of bacterial agent in horticultural crop seedlings are limited. We investigated the effects of different dosages of Bacillus methylotrophicus (0.00, 0.25, 0.50, 0.75, 1.00, 1.25, and 1.50 g/strain) on tomato plug seedlings and aimed to screen out the suitable dosage of Bacillus methylotrophicus for tomato seedlings in 50-hole cavity trays. In this experiment, with the increase in Bacillus methylotrophicus, the number of leaves, plant height, stem thickness, leaf area, dry matter accumulation in each organ, growth function (G value), and seedling strength index of tomato seedlings showed an increasing trend, followed by a decreasing one. The appropriate dosage (0.50–1.25 g/strain) of bacterial agent increased the activities of the substrates urease, sucrase, and catalase, thus forming a good microbial community to maintain the balance of organic and inorganic carbon and guaranteeing the normal development of the root system. Meanwhile, under the treatment of 1.00 and 1.25 g/strain of inoculum, the absorption range of tomato roots increased, more nitrogen, phosphorus, and potassium were absorbed from the substrate, and more nutrients were transported from the underground to the above-ground parts, which promoted shoot elongation and thickening of the shoots, increased the leaf number and dry matter accumulation, and improved the seedling quality. In this study, the mechanism of action of this microbial product on tomato seedlings was studied from the perspective of nutrient uptake and supply, and a sowing root application of 1.00 g/strain of Bacillus methylotrophicus in 50-hole cavity trays can improve the quality of tomato seedlings.