Gas Exchange, Chloroplast Pigments and Growth of Passion Fruit Cultivated With Saline Water and Potassium Fertilization 1

Abstract

The objective of this study was to evaluate the gas exchange, chloroplast pigments and growth of ‘BRS Rubi do Cerrado’ passion fruit as a function of irrigation with saline water and potassium fertilization in the seedling formation stage. The experiment was conducted under greenhouse conditions in the municipality of Pombal-PB, Brazil. A randomized block design was used in 5 x 2 factorial scheme, corresponding to five levels of water electrical conductivity - ECw (0.3, 1.1, 1.9, 2.7 and 3.5 dS m-1) and two doses of potassium - KD (50 and 100% of the recommendation), with four replicates and two plants per plot. Water salinity from 0.3 dS m-1 reduced the stomatal opening, transpiration, CO2 assimilation and inhibited the growth of ‘BRS Rubi do Cerrado’ passion fruit plants, at 40 days after sowing. There was no CO2 restriction in the substomatal cavity of passion fruit plants grown under water salinity from 0.3 dS m-1. Potassium dose of 150 mg kg-1 of soil, corresponding to 100%, intensified the effect of salt stress on the assimilation rate and instantaneous carboxylation efficiency in 'BRS Rubi do Cerrado' passion fruit. There was interaction between water salinity levels and potassium doses for the chlorophyll a and b contents of 'BRS Rubi do Cerrado' passion fruit.

Potassium Does Not Attenuate Salt Stress in Yellow Passion Fruit Under Irrigation Management Strategies

“…The lower values of stomatal conductance in plants irrigated with saline water occur due to the reductions in leaf turgor and atmospheric vapor pressure, which are ways to reduce the lag between the absorption of water by the roots and the transpiration, consequently leading to partial closure of the stomata as a strategy to avoid excessive dehydration of the guard cells (SUASSUNA et al, 2014), and can be attributed to stomatal and non-stomatal causes associated with the osmotic and toxic effects of excess salts (LÚCIO et al, 2013). Lima et al (2020a), when evaluating the gas exchange of 'BRS Rubi do Cerrado' passion fruit as a function of irrigation with saline waters (ECw ranging from 0.3 to 3.5 dS m -1 ), observed that gs decreased dramatically as the levels of irrigation water electrical conductivity increased. In another study, Silva et al (2019) evaluated the gas exchange of 'Sugar Baby' watermelon plant, under irrigation strategies with saline waters (VE, VE/FL, FL, FR and MAT) and verified that the use of water with ECw of 3.2 dS m -1 during the vegetative/flowering and maturation stages inhibited stomatal conductance.…”

Cell damage, gas exchange, and growth of Annona squamosa L. under saline water irrigation and potassium fertilization

“…Thus, a lower transpiration rate contributed to the lower accumulation of Na + and Clin the plant. Lima et al (2020), in an experiment conducted with sour passion fruit (Passiflora edulis Sims) cv. BRS Rubi do Cerrado irrigated with saline water (ECw from 0.3 to 3.5 dS m -1 ) under greenhouse conditions, concluded that water salinity higher than 0.3 dS m -1 reduced plant transpiration.…”

“…Atenuação. of drought and annual irregularity of rainfall, causing water deficit in plants because evaporation rates exceed rainfall in most of the year, a situation that favors the occurrence of water sources with high concentrations of salt, mainly sodium, resulting in restrictions for use in agriculture (Lima et al, 2015;Lima, Fernandes, Soares, Gheyi, & Fernandes, 2020).…”

“…However, excess salt in water is one of the abiotic stresses that limit the growth and yield of most crops due to the imbalance in the water and nutritional relationships of plants and the accumulation of ions considered toxic (Schossler, Machado, Zuffo, Andrade, & Piauilino, 2012). Plants that grow under saline conditions are exposed to various unfavorable conditions, which include low soil water potential and nutrient imbalance, with excessive accumulation of sodium and/ or deficiency of Ca 2+ , Mg 2+ , and K + in the plants (Cuin & Shabala, 2007;Lima et al, 2020). However, many plant species have developed several adaptation mechanisms that allow them to grow under saline conditions, including low absorption of Na+ and minimization of the concentration of salts in the cytosol (Arzani & Ashraf, 2016).…”

Gas exchange, growth, and quality of passion fruit seedlings cultivated with saline water

“…In addition, the reduction in the growth in leaf area may be related to the decrease in CO 2 assimilation rate and excessive absorption of salts, affecting the production of specific metabolites that directly inhibit growth (Acosta-Motos et al, 2017). Lima, Fernandes, Soares, Gheyi and Fernandes (2020a), in a study with the passion fruit cv. 'BRS Rubi do Cerrado' under irrigation with saline waters (ECw from 0.3 to 3.5 dS m -1 ), found that ECw from 0.3 dS m -1 reduced the growth in leaf area by 10.36% per unit increase in ECw, at 40 days after sowing.…”