Gas exchange and production of sunflower (Helianthus annuus L.) irrigated with water of different salinity, cationic nature and nitrogen doses

Abstract

This study aimed to evaluate the gas exchanges and production components of sunflower, cv. BRS 324, as a function of irrigation with water of different salinity levels and cationic nature associated with doses of nitrogen (N). The study was conducted in pots adapted as lysimeters, under field conditions, in an eutrophic Grey Argisol of sandy loam texture. The experimental design was randomized blocks, in 5 x 5 factorial scheme, with three replicates, corresponding to five combinations of water salinity and cationic nature -S (S 1 -Control; S 2 -NaCl; S 3 -CaCl 2 ; S 4 -KCl and S 5 -NaCl+CaCl 2 +MgCl 2 ) and five N doses (50; 75; 100; 125 and 150 mg of N kg -1 of soil). Irrigation was applied using water with electrical conductivity -ECw of 0.5 dS m -1 for the control (S 1 ) and 5.0 dS m -1 for the other treatments (S 2 ; S 3 ; S 4 and S 5 ). Gas exchange through stomatal conductance, transpiration, CO 2 assimilation rate, internal CO 2 concentration and intrinsic water use efficiency were evaluated and the production components were determined by the internal diameter of the capitulum, the phytomass of the capitulum with achenes and dry matter of the capitulum. The gas exchange of sunflower cv. BRS 324 were significantly influenced, being the biggest decrease due to the variation in the ECw when compared with the cationic nature of irrigation water. Among the evaluated cations, potassium promoted the highest value of stomatal conductance and CO 2 assimilation rate. Irrigation with saline water negatively affected the production components of sunflower, regardless of the cation present in the irrigation water.

Biochemical, Physiological and Anatomical Mechanisms of Adaptation of Callistemon citrinus and Viburnum lucidum to NaCl and CaCl2 Salinization

“…To the best of our knowledge, there are no comparative studies on the responses of ornamental shrubs to iso-osmotic saline irrigation with NaCl and CaCl 2 , whereas only few reports on vegetable species are available on the CaCl 2 salinity (Colla et al, 2012, 2013; Ntatsi et al, 2017; Rabhi et al, 2018). In particular, 40 mM CaCl 2 significantly reduced the root, stem and leaf dry weight of saffron plants compared to control (Rabhi et al, 2018), while in sunflower plants, saline irrigation with NaCl or CaCl 2 at EC of 5.0 dS m -1 induced a similar decline in flower size and biomass (de Sousa Júnior et al, 2017). The two ornamental species differently responded to the salinity treatments in the ratio between below- and above-ground biomass.…”