HIGHLIGHTS:
Differences caused by cationic natures are even more evident than an increase in concentration up to a certain threshold.
The prevalence of Na+ in water caused less damage to the photosynthetic appa-ratus than the prevalence of Ca2+or Mg2+.
There is no influence of the cationic nature at high levels of salt concentration in the nutrient solution.
ABSTRACT
The analysis of chlorophyll fluorescence is one of many ways to quantify the salt damage to photosynthetic performance and crop production. Thus, the present study aimed to evaluate the photochemical efficiency and production of coriander, cultivar ‘Verdão’, as a function of the electrical conductivity levels of the nutrient solution and the cationic nature. The experimental design was in randomized blocks, in a 4 × 3 factorial scheme, with four replicates. The treatments consisted of four electrical conductivities of the nutrient solutions (ECns = 1.6, 3.2, 4.8, and 6.4 dS m-1) and three kinds of water of different cationic natures (Na+; Ca2+; Mg2+), which were prepared with the dissolution of different salts - NaCl, CaCl2.2H2O, and MgCl2.6H2O in supply water (ECw = 0.12 dS m-1), that is, three predominant cationic natures. The study was carried out in a greenhouse between November and December 2019 at the Fertigation and Salinity Laboratory of the Agricultural Engineering Department of the Universidade Federal Rural de Pernambuco. It was found that the increase in the electrical conductivity of the nutrient solution affected reaction centers, photochemical activity, and carboxylation efficiency and resulted in reductions in stomatal conductance, CO2 assimilation rate, and therefore, in the biomass production of coriander. Different cationic prevalence in water causes differences in the intensity of salt damage, especially with increasing concentration.
Key words:
Coriandrum sativum L.; gas exchange; chlorophyll a fluorescence
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Vertical bars represent the standard error of the mean (n = 4). Means followed by the same letters indicate no significant difference between treatments by the Tukey test (p ≤ 0.05) with respect to the cationic nature at the same electrical conductivity of the nutrient solution
Vertical bars represent the standard error of the mean (n = 4). Means followed by the same letters indicate no significant difference between treatments with respect to cationic nature by the Tukey test (p ≤ 0.05)
Vertical bars represent the standard error of the mean (n = 4). Means followed by the same letters do not differ by the Tukey test (p ≤ 0.05) with respect to the cationic nature at the same electrical conductivity of the nutrient solution