Calcium pyruvate as a salt stress mitigator in yellow passion fruit seedlings¹

Piruvato de cálcio como mitigador do estresse salino em mudas de maracujazeiro amarelo

HIGHLIGHTS:

Foliar spraying of pyruvate at a concentration of 50 µM improves the morphophysiology of passi-on fruit seedlings.

Application of calcium pyruvate in passion fruit seedlings reduces the effects of salt stress on photosynthesis.

Pyruvate supplementation protects against electrolyte leakage and improves water relations.

ABSTRACT

Although the semi-arid region of Northeast Brazil is a major producer of yellow passion fruit, the problems of salts in the soil and water sources, in many areas have limited the growth and production of this crop, which highlights the importance of studies aimed at reducing such effects. In this context, the objective of this study was to evaluate the effect of foliar application of pyruvate, as a mitigator of salt stress, on the morphophysiology of yellow passion fruit, in seedling phase. The treatments consisted of three electrical conductivities of irrigation water (EC_w: 0.8, 2.4, and 4.0 dS m^-1) and three concentrations of pyruvate (0, 25, and 50 mM), distributed in a randomized block experimental design in a 3 × 3 factorial scheme, with four replications and two plants per plot. Irrigation with EC_w of 4.0 dS m^-1 reduces growth variables, phytomass, Dickson quality index, and increases electrolyte leakage in passion fruit seedlings cv. Redondo Amarelo. Exogenous application of calcium pyruvate (25 and 50 mM) increased growth, phytomass, Dickson quality index, relative water content and leaf succulence and reduced electrolyte leakage in the leaf blade in passion fruit. Exogenous application of pyruvate attenuates salt stress, with beneficial effects on CO₂ assimilation rate, transpiration, instantaneous carboxylation efficiency, intrinsic water use efficiency, and root dry mass.

Key words:
Passiflora edulis f. flavicarpa Deneger; salt stress; physiology