Evaluation of the Effectiveness of a Humic Substances-Based Product for Lettuce Growth and Nitrogen Use Efficiency under Low Nitrogen Conditions

Santiago Atero-Calvo, Francesco Magro, Giacomo Masetti, Eloy Navarro-León (), Juan Jose Rios and Juan Manuel Ruiz
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Santiago Atero-Calvo: Department of Plant Physiology, Faculty of Sciences, University of Granada, 18071 Granada, Spain
Francesco Magro: Sofbey S.A., Via San Martino 16/A, CH-6850 Mendrisio, Switzerland
Giacomo Masetti: Sofbey S.A., Via San Martino 16/A, CH-6850 Mendrisio, Switzerland
Eloy Navarro-León: Department of Plant Physiology, Faculty of Sciences, University of Granada, 18071 Granada, Spain
Juan Jose Rios: Department of Plant Physiology, Faculty of Sciences, University of Granada, 18071 Granada, Spain
Juan Manuel Ruiz: Department of Plant Physiology, Faculty of Sciences, University of Granada, 18071 Granada, Spain

Agriculture, 2024, vol. 14, issue 9, 1-17

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: R-HS 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, NO 3 − 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.

Keywords: biostimulant; humic substances; lettuce; nitrogen deficiency; nitrogen use efficiency; photosynthesis (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2024
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