Evaluation of the Effectiveness of a Humic Substances-Based Product for Lettuce Growth and Nitrogen Use Efficiency under Low Nitrogen Conditions
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Atero Calvo, Santiago; Magro, Francesco; Masetti, Giacomo; Navarro León, Eloy; Ríos Ruiz, Juan José; Ruiz Sáez, Juan ManuelEditorial
MDPI
Materia
Biostimulant Humic substances Lettuce
Date
2024-09-01Referencia bibliográfica
Atero-Calvo, S.; Magro, F.; Masetti, G.; Navarro-León, E.; Rios, J.J.; Ruiz, J.M. Evaluation of the Effectiveness of a Humic Substances-Based Product for Lettuce Growth and Nitrogen Use Efficiency under Low Nitrogen Conditions. Agriculture 2024, 14, 1492. https://doi.org/10.3390/agriculture14091492
Sponsorship
PAI program (Plan Andaluz de Investigación, Grupo de Investigación AGR282); Grant from the FPU of the Ministerio de Universidades grant number [FPU20/05049]Abstract
Increasing crop yield with low-N supplies has become one of the main aims of current
agriculture to reduce the excessive use of chemical fertilizers. A sustainable strategy to improve crop
productivity, N assimilation, and N Use Efficiency (NUE) under limit-N growth conditions is the
application of biostimulants, such as humic substances (HS). Here, we evaluated the effectiveness
of an HS-based biostimulant, BLACKJAK®, in improving lettuce growth and NUE under N-deficit
conditions. Thus, BLACKJAK® was applied radicularly (R) and foliarly (F) at the following doses: RHS
0.40 mL/L, R-HS 0.60 mL/L, F-HS 7.50 mL/L, and F-HS 10.00 mL/L. Three N levels were applied:
optimal (7 mM) and N-deficit (3 mM and 1 mM). The results showed that shoot dry weight (DW) was
reduced at 3 mM N (−32%) and 1 mM N (−42%). However, R and F BLACKJAK® enhanced plant
growth at all three N levels, especially with F-HS at 10.00 mL/L, which showed an increase of 43% in
shoot DW at 3 and 1 mM N, compared to plants not treated with HS. BLAKCJAK® also improved
photosynthesis, NO3− and organic N accumulation, the activity of N assimilation enzymes, and the
concentration of amino acids and proteins, regardless of the N level. In addition, HS enhanced NUE
parameters under all N conditions, except for R-HS 0.60 mL/L at 1 mM N. Hence, our study suggests
that the HS-based product BLACKJAK® could be a good candidate for reducing chemical fertilizer
use and improving lettuce growth and NUE under low N conditions, although further research
is required.