ABSTRACT
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.
Key words:
Cucurbita pepo L.; growth-promoting bacteria; agricultural sustainability; protected environment; B vitamin
HIGHLIGHTS:
Foliar application of nicotinamide, alone or combined with A. brasilense, increases the number of female flowers.
Nicotinamide increases gas exchange and plant growth in a hydroponically grown pumpkin.
A. brasilense applied via foliar is capable of doubling root volume.
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A - Sowing date; B - Date of transfer of seedlings to the hydroponic system; C - Date of treatment application; D - Date of harvest and measurement
Bars with the same lowercase letter do not differ by the Tukey test (p ≤ 0.05). AZF - 2 mL L-1 of A. brasilense applied via foliar spray; AZFN - 300 mg L-1 of nicotinamide combined with 2 mL L-1 of A. brasilense applied via foliar spray; AZS - 2 mL L-1 of A. brasilense applied to the hydroponic solution; AZSN - 300 mg L-1 of nicotinamide applied via foliar spray combined to 2 mL L-1 of A. brasilense applied to the hydroponic solution
Bars with the same lowercase letter do not differ from each other by the Tukey test (p ≤ 0.05); AZF - 2 mL L-1 of A. brasilense applied via foliar spray; AZFN - 300 mg L-1 of nicotinamide combined with 2 mL L-1 of A. brasilense applied via foliar spray; AZS - 2 mL L-1 of A. brasilense applied to the hydroponic solution; AZSN - 300 mg L-1 of nicotinamide applied via foliar spray combined to 2 mL L-1 of A. brasilense applied to the hydroponic solution
Bars with the same lowercase letter do not differ from each other by the Tukey test (p ≤ 0.05); AZF - 2 mL L-1 of A. brasilense applied via foliar spray; AZFN - 300 mg L-1 of nicotinamide combined with 2 mL L-1 of A. brasilense applied via foliar spray; AZS - 2 mL L-1 of A. brasilense applied to the hydroponic solution; AZSN - 300 mg L-1 of nicotinamide applied via foliar spray combined to 2 mL L-1 of A. brasilense applied to the hydroponic solution
Bars with the same lowercase letter do not differ from each other by the Tukey test (p ≤ 0.05); AZF - 2 mL L-1 of A. brasilense applied via foliar spray; AZFN - 300 mg L-1 of nicotinamide combined with 2 mL L-1 of A. brasilense applied via foliar spray; AZS - 2 mL L-1 of A. brasilense applied to the hydroponic solution; AZSN - 300 mg L-1 of nicotinamide applied via foliar spray combined to 2 mL L-1 of A. brasilense applied to the hydroponic solution