Fertigation Management and Growth-Promoting Treatments Affect Tomato Transplant Production and Plant Growth after Transplant

Abstract

Plant biostimulants are of interest as they can stimulate plant growth and increase resource utilization. There is still no information on the use of plant growth-promoters under variable nutritional conditions in the nursery and the effects on tomato seedling growth and plant performance after transplant. This study aimed to evaluate the suitability of gibberellic acid (GA3) or bacterial biostimulant treatments to enhance the growth and quality of greenhouse-grown tomato (Solanum lycopersicum ‘Marmande’) seedlings, fertigated with increasing nutrient rates and to assess the efficacy of these treatments on the early growth of tomato plants. During autumn 2019, tomato seedlings were inoculated with 1.5 g L−1 of TNC BactorrS13 (a commercial biostimulant containing 1.3 × 108 CFU g−1 of Bacillus spp.) or sprayed with 10−5 M GA3 and fertigated with a nutrient solution containing 0, 1, 2 and 4 g L−1 of NPK fertilizer (20-20-20) when they reached the 11th BBCH growth stage for tomato. Subsequently, the seedlings were evaluated in greenhouse cultivation for 60 days until at least the 61st BBCH growth stage (January 2020). The growth of the tomato seedlings increased curvilinearly in relation to the fertigation rates. The GA3-treated seedlings showed similar or even higher growth parameters than the control seedlings fed with 4 g L−1 of fertilizer but with half of the nutrients. The inoculation of the substrate with Bacillus spp. had negative effects in the absence of fertigation but determined a greater growth at the highest fertigation rate. The bacterial inoculum of seedlings had longer-term effects than the GA3 treatment during the plant growth, but these effects were noticeable mainly when the bacterial biostimulant was associated with the highest fertigation rate.

Alleviation of Salt Stress by Plant Growth-Promoting Bacteria in Hydroponic Leaf Lettuce

“…Many species of Bacillus and Paenibacillus, like those present in Bactor S13 , can exert plant growth-promoting activity through different mechanisms like the production of growth-promoting phytohormones or inhibition of plant ethylene synthesis, nitrogen fixation, phosphate solubilization and mobilization, production of siderophore and antibiotics, and induction of systemic resistance to pathogens in plants [60,61]. Bacillus strains application proved to be effective in enhancing plant growth crops under greenhouse or field conditions for several vegetable crops like broccoli, cucumber, pepper, tomato, and lettuce [50,62,63]. The inoculation of lettuce plants with Bacillus subtilis can determine the increase of the cytokinin content of shoots and roots, and influence the content of abscisic acid (ABA) and indole acetic acid (IAA) [64].…”

Importance of crop phenological stages for the efficient use of PGPR inoculants

“…Particularly, the enhanced root development (tomato: + 22.7% root fresh weight, 14.8% root length; bell pepper: + 57% root fresh weight, 21.8% root length) are expected to contribute to the recovery of these seedlings after transplant and in their early growth and flowering 19 .…”

Use of Microbial Biostimulants to Increase the Salinity Tolerance of Vegetable Transplants

“…The main growth-promoting mechanisms of these bacteria involve the production of growth-promoting phytohormones (cytokinin, gibberellins, indole-acetic acid) or the rebalancing of endogenous hormone content, inhibition of plant ethylene synthesis, solubilization and mobilization of phosphate, promotion of nitrogen uptake, production of siderophore, antibiosis, and induction of plant systemic resistance to pathogens [69,70,77,79]. Bacillus strains application showed to be successful in improving plant growth under greenhouse or field conditions for several vegetable crops (broccoli, cucumber, pepper, tomato, and lettuce) [8,9,43].…”

“…Thus, growing seedlings under a scarcity of good quality water is a challenge for the nursery vegetable industry. The aim of vegetable transplant growers is to obtain well-developed and vigorous seedlings [7] that can establish and grow fast after transplanting [8,9]. The negative effects of irrigation water salinity on seedling growth can make it hard for the vegetable nursery to reach these goals.…”