The application of biostimulants in agriculture has been studied to increase production while using smaller physical spaces and agricultural inputs to increase sustainability in production systems. Despite the promising results, there is a need to study the effects of joint applications of these products, identifying possible interactions during crop development. Thus, this study aimed to verify the biostimulant potential of the isolated and combined use of nicotinamide and Azospirillum brasilense during the initial growth of pumpkin plants in hydroponic cultivation. A completely randomized design with six treatments and four replicates was performed. The treatments were composed by the combination of the application of nicotinamide (foliar) and A. brasilense (foliar or applied in the hydroponic solution). Treatments increased the gas exchanges, particularly the assimilation rate and carboxylation efficiency, being superior to the control treatment. However, for growth characteristics, the isolated application of nicotinamide favored the development of the shoot and, when combined with A. brasilense via foliar, increased root growth. Thus, the application of nicotinamide and A. brasilense alone or together enhances the growth and gas exchanges of pumpkin plants grown in a hydroponic system, especially when using foliar application of A. brasilense. Whereby its action can be referred to as a biostimulant effect. Furthermore, the application method affects the efficiency and compatibility of the products applied. Therefore, foliar application is recommended.

The objective of the work was to evaluate the effects of nicotinamide application via seed immersion on seed physiological quality and initial growth characteristics. Two experiments were carried out, in the laboratory (seed physiological potential) and another in a randomized block design, in a greenhouse (initial growth). Treatments consisted of immersion of seeds in six solutions with different concentrations of nicotinamide (0, 100, 200, 300, 400, and 500 mg·L⁻¹). Characteristics related to primary root protrusion speed, average protrusion time, protrusion rate, and primary root length were evaluated under different temperature conditions (18°, 25°, and 35°C), and gas exchange, plant height, stalk diameter, number of leaves, aerial fresh weight, aerial dry weight, and root dry weight were evaluated. It was found that the use of nicotinamide, despite delaying the process of radicle protrusion, increases its development under stressful temperature conditions and results in an increase in gas exchange processes and gain in initial growth, mainly in the aerial part. Thus, it is concluded that the use of nicotinamide in maize seeds has the potential for use in stressful environments, as well as for obtaining greater initial growth, in which concentrations between 200 and 300 mg·L⁻¹ are suitable for the crop.

Technologies once applied exclusively in conventional systems have maximized gains in hydroponic systems; however, they still need information for proper use. Thus, the study aimed to evaluate the effect of foliar application of thiamine and niacin on growth and gas exchange activities in two lettuce cultivars in an ebb and flow hydroponic system. The completely randomized design (CRD) was used with four treatments and eight replications. The treatments were as follows: T1 - control, T2 - thiamine at a concentration of 200 mg L^-1, T3 - niacin at 200 mg L^-1, and T4 - thiamine and niacin combined at 100 mg L^-1 of each vitamin. Each experimental plot consisted of a lettuce plant. The combined application of thiamine and niacin stood out, increasing the activity of gas exchange of lettuce plants and increasing by about 30% the fresh mass, concerning the control, for both cultivars, followed by the isolated application of niacin. For thiamine, the application alone did not result in significant changes. The vitamins affect the morphophysiology of lettuce, where the use of niacin has the potential for use in hydroponic production systems. Its combined use with thiamine increases this potential, with a synergistic effect between the compounds being verified.

The exchange of technologies used in field cultivation for hydroponic systems can potentially increase plant development and grain production, requiring studies to verify the best management forms, such as growth‐promoting bacteria and biostimulant compounds. With this in mind, the study aimed to evaluate the effect of the application of thiamine and niacin, alone and combined, to soybean plants in the absence and presence of inoculation with B. japonicum on the agronomic and physiological characteristics of the crop grown in an ebb and flow hydroponic system. Eight treatments were evaluated using t‐test (LSD) and Tukey’s test, both at 5% probability (P < 0.05), in addition to Pearson correlation and canonical variables. The treatments consist of inoculation with B. japonicum at 1 mL 500 g⁻¹ seeds (with and without) and foliar application of four solutions (water, niacin (0.1 g·L⁻¹), thiamine (0.1 g·L⁻¹), and niacin + thiamine (0.05 g·L⁻¹ + 0.05 g·L⁻¹)). We found that inoculation significantly improved the parameters evaluated and resulted in a gain of approximately 84.8% in yield when compared by t‐test (P < 0.05). In addition, the action of the vitamins was more significant when they were applied without the presence of B. japonicum, especially niacin, either alone or combined with thiamine, which increased yield parameters in this condition, identified when the Tukey’s test (P < 0.05) was applied. We conclude that inoculation with Bradyrhizobium japonicum in soybean seeds grown in a hydroponic system significantly benefits the development and grain yield, mainly when combined with vitamin solutions. Niacin also has the potential to be used alone or combined with thiamine in noninoculated or inoculated hydroponic soybean crops, respectively.

Cultivating microgreens in central-southern Chile in unheated greenhouses offers a viable and productive alternative to growers. In 2023, two experiments were conducted in autumn and spring. These experiments involved the production of microgreens of eleven vegetable species. The tray system with the substrate was employed. Subsequently, agronomic, nutritional, and sensory perception variables were assessed. Despite notable fluctuations in external temperatures between these seasons, a diverse array of microgreens can be successfully cultivated, meeting local consumer preferences. Research indicates that microgreens grown under these conditions exhibit high nutritional quality, serving as a rich source of essential nutrients and bioactive compounds beneficial to human health. This nutritional value remains consistent across autumn and spring, establishing microgreens as a reliable and valuable food option. The observed acceptance and purchasing intentions among the surveyed population suggest a promising market opportunity for introducing these products regionally. Consumers appreciate microgreens’ quality and nutritional advantages, underscoring their potential.

The use of water with a high concentration of salts has been increasingly frequent in vegetable production. This reduces the development and productivity of vegetables, raising the importance of the search for techniques to mitigate deleterious effects. In this sense, vitamins have the potential to improve conditions for plant development. The study was conducted to evaluate the effects of the application of B vitamins in lettuce plants submitted to irrigation with saline water. The treatments consisted of Control: irrigated with water and without application of vitamins; NaCl: irrigated with saline solution (50 mM NaCl, equivalent 5.18 dS m-1) and without application of vitamins; NaCl+B1: irrigated with saline solution and application of vitamin thiamine (100 mg L-1); NaCl+B3: irrigated with saline solution and application of vitamin niacin (100 mg L-1). These treatments were applied to two lettuce cultivars, “Pira Roxa” and “Valentina”. Both vitamins increased net photosynthesis when compared to the NaCl treatment. However, only the application of thiamine resulted in a mitigating effect on the losses of plant dry mass accumulation. Thus, the exogenous application of these vitamins alleviates the effects caused by salinity in lettuce plants, reducing stress on photosynthetic mechanisms and increasing photosynthetic activity. In addition, thiamine helps to reduce the deleterious effects of salinity on the accumulation of biomass.