Liquid fertilizers on photochemical efficiency and gas exchange in yellow passion fruit under saline stress

Abstract

The Northeast region of Brazil is the primary producer of yellow passion fruit. In recent years, water scarcity has led passion fruit growers to use highly saline water for cultivation. Therefore, implementing technologies that alleviate the negative effects of salt stress on plants is a promising approach, particularly in semi-arid conditions. This study aimed to assess the efficacy of organomineral fertilizers in mitigating salt stress effects on chlorophyll-a fluorescence and gas exchange in ‘Guinezinho’ yellow passion fruit seedlings. The treatments were arranged in randomized blocks with four replicates and four seedlings per plot, following a 2 × 3 factorial design. The factors considered were irrigation using water with low (0.18 dS m-1) and high (4.0 dS m-1) electrical conductivity and three liquid organomineral attenuators (Codasal™, Aminoagro Raiz™, and a mixture of Codasal™ + Aminoagro Raiz™ at a 1:1 v/v ratio), applied through fertigation. Irrigation with water containing 4.0 dS m-1 electrical conductivity, combined with liquid fertilizers, resulted in increased substrate salinity, and reduced stomatal conductance in yellow passion fruit seedlings, particularly when Codasal™ was applied. Application of Codasal™ alone or in combination with Aminoagro Raiz™ significantly enhanced variable fluorescence, quantum efficiency of PSII, CO2 assimilation rate, and instantaneous carboxylation efficiency in ‘Guinezinho’ yellow passion fruit seedlings.

Morphophysiology of cowpea under salt stress and application of carbon-based nanobiostimulant in the vegetative stage

“…This reduction in qP may be related to both the lower chlorophyll content and the negative effects of the excessive amount of sodium ions present in cells, ultimately causing damage to the photosystems (Zhang et al, 2019). On the other hand, the increase in qN constitutes a defense mechanism for plants to protect themselves from photoinhibition, in which they begin to dissipate the excess energy of the PSII reaction center in a non-photochemical way (Guedes et al, 2023).…”

“…Regarding the impact of the nanobiostimulant, it was observed that the concentration of 272 mg L -1 resulted in the highest electron transport rate (Figure 6B) and 220 mg L -1 was the one that led to the lowest non-photochemical quenching (Figure 6D), promoting an increase of 12.7% and a decrease of 9.9% compared to the concentration of 0 mg L -1 , respectively. Thus, the effectiveness of the nanobiostimulant in increasing photosynthesis is observed, with much of the energy investment concentrated in processes that lead to increased photosystem yield (Guedes et al, 2023).…”