Biostimulant use in pangolão grass Digitaria pentzii subjected to saline stress ¹

Utilização de bioestimulante no capim-pangolão Digitaria pentzii submetido a estresse salino

HIGHLIGHTS:

Pangolão grass is moderately salinity tolerant.

Biostimulant did not favor growth and production of pangolão grass in any salinity.

Accumulation of sodium in leaves reduced phytomass production of pangolão grass.

ABSTRACT

Salinity caused by excess salts in soil solutions is one of the most limiting environmental stresses in agriculture worldwide. In this scenario, among strategies that favor the expression of the genetic potential of plants, the use of biostimulants stands out. The objective of this study was to evaluate the influence of a seaweed-based biostimulant on growth, forage production, gas exchange, and accumulation of sodium and potassium ions in pangolão grass (Digitaria pentzii) under saline stress. The experiment was conducted from March to July 2019 using a randomized block design, in a 2 × 3 factorial scheme with two concentrations of biostimulant (0 and 8 mL L^-1) and three electrical conductivities of irrigation water (0.03, 2 and 4 dS m^-1), with four replicates. The accumulation of 50 µmol g^-1 of sodium in leaves corresponded to a reduction of 0.3 g of dry matter in the leaf blade production per plot. The biostimulant did not influence the structural characteristics, phytomass accumulation, or stomatal conductance of the pangolão grass, regardless of salinity. At the level of 4 dS m^-1 in irrigation water, the ionic stress toxicity due to the accumulation of salts in the aerial part of pangolão grass was more severe. This is the first evidence of the “moderate” salinity tolerance of pangolão grass in semi-arid regions.

Key words:
abiotic stress; phytomass accumulation; salinity; seaweed extract; sodium content