Photochemical efficiency of basil cultivars fertigated with salinized nutrient solutions

Abstract

Reduction in plant growth under salt stress is due, among other factors, to changes in photochemical efficiency and, consequently, in photosynthesis. The objective of this study was to evaluate the effect of salt stress on the chlorophyll fluorescence variables in cultivars of basil (Ocimum basilicum L.). The experiment was conducted in a greenhouse, using a randomized block design in a 5 x 3 factorial scheme, corresponding to five basil cultivars (‘Grecco a Palla’, ‘Alfavaca Basilicão’, ‘Alfavaca Verde’, ‘Lemoncino’ and ‘Roxo’) and three salinity of the nutrient solution (2.0, 3.5 and 5.0 dS m-1), with three repetitions, and the experimental plot was represented by three pots containing 3.0 dm3 of coconut fiber. At the full flowering stage, plants were evaluated for chlorophyll fluorescence, when adapted to the dark, as well as under saturating light conditions. In general, there were changes in fluorescence variables only at salinity above 3.5 dS m-1. Fertigation using high-salinity water promotes strong changes in the chlorophyll a fluorescence of sensitive basil cultivars. The cultivars ‘Grecco a Palla’ and ‘Alfavaca Verde’ were little affected by the increase of salinity, being the most tolerant to salt stress. In the cultivars ‘Alfavaca Basilicão’, ‘Lemoncino’ and ‘Roxo’, chlorophyll fluorescence was strongly affected by salinity, being the most sensitive. The tolerance ranking based on chlorophyll fluorescence is: ‘Grecco a Palla’ = ‘Alfavaca Verde’ > ‘Alfavaca Basilicão’ > ‘Lemoncino’ > ‘Roxo’.

Sweet Basil Functional Quality as Shaped by Genotype and Macronutrient Concentration Reciprocal Action

“…Although numerous studies underlined how the composition and concentration of the nutrient solution affects growth and yield [ 35 , 36 , 37 ], in this case, the average nutrient solution effect did not lead to differences in fresh production, leaf number and dry matter percentage. It can be partly attributed to the moderate salinity tolerance of basil [ 38 , 39 ] but, above all, to the short growing cycle (34 DAT), which minimizes the influence of macronutrients concentrations in the solution on growth parameters [ 26 ]. These results are also confirmed by the Fv to Fm ratio that showed a similar efficiency of the PSII system for all the applied treatments [ 40 ] without any evidence of stress or deficiency.…”

“…Identically to the observation of Maggio et al [ 41 ], an interaction between the genetic background of the different cultivars and the different concentrations of the nutrient solution was obvious, specifically in the case of fresh and dry biomass. Each cultivar achieved the best production with a specific nutrient solution, highlighting how tolerance to the concentration of salts in the nutrient solution is highly dependent on the genotype [ 38 , 42 ]. The use of nutrient solution 2 dS m −1 determined on average an increase of Aroma 2 fresh biomass of about 30% compared to those recorded with the other two nutrient solutions, confirming how the yield is negatively affected by nutrient solutions that are too concentrated and/or too diluted [ 43 ].…”

Photosynthetic Responses, Growth, Production, and Tolerance of Traditional Varieties of Cowpea under Salt Stress

“…This photoprotective mechanism is efficient in cowpea bean plants once the Fv/Fm values are greater than 0.75, indicating a lack of degradation of the photosynthetic apparatus [17]. Compared with the control, the Fo values were lower under salt stress, corroborating the absence of damage in the PSII reaction centers [20].…”

“…Increases of Fv and ETR in cowpea bean varieties under salt stress compared with control demonstrated an increased ability to transfer energy from the excited electrons of chlorophyll molecules to assemble NADPH and ATP and had reduced ferredoxin (Fdr). This increased energy transfer was vital for preventing the decrease in photosynthesis or improving photosynthesis under salt stress once the quantum efficiency of photosystem II ( Y(II) ) in cowpea bean varieties decreased under salt stress, indicating a decrease in the fraction of energy absorption by chlorophyll in PSII [ 20 ]. However, some varieties susceptible to salt stress, e.g., Boquinha, Roxão, Feijão Branco, Canapu Miúdo, Coruja, and Paulistinha, exhibited decreased A N and A/Ci , despite this mechanism for increasing the photochemical energy transfer.…”

Physiological responses of sugar-apple seedlings under saline wastewater irrigation and NPK doses

“…In the present study, there was an increase in Tl, and consequently, part of the accumulated energy was dispersed in the form of heat. Another part was dissipated by regulated photochemical quenching (Y( NPQ )) and by energy losses due to damage to the photosynthetic apparatus (Fo') (KRAMER et al, 2004;OXBOROUGH;BAKER, 1997;SANTOS et al, 2020;SILVA et al, 2021).…”