Water potential and gas exchanges in sugarcane irrigated with saline waters

Abstract

In Pernambuco, state in the northeastern region of Brazil, in the coastal areas, due to the intrusion of seawater, the waters used for sugarcane irrigation can have high salt contents and cause serious problems to soil and plant. The present study aimed to evaluate the effects of irrigation with saline water on the physiology of sugarcane, variety RB867515, irrigated under five salinity levels of 0.5; 2.0; 3.5; 5.0 and 6.5 dS m-1 in a completely randomized design, with four replicates in drainage lysimeters. The study was conducted in the period from December 2014 to June 2015, at the Federal Rural University of Pernambuco (UFRPE). Salinity levels were obtained by dissolving NaCl and CaCl2 in water from the local supply system (ECw = 0.5 dS m-1). Leaves were analyzed for stomatal conductance, transpiration and photosynthesis at 140, 229 and 320 days after planting (DAP) and for water potential at 137, 243 and 318 DAP. Increase in irrigation water salinity inhibited all variables at the respective plant ages and with greater intensity in the first evaluations (140 and 229 DAP) for stomatal conductance and transpiration. Photosynthesis and water potential showed the greatest linear reductions at the last data collection (320 and 318 DAP), respectively. Increase in salinity of irrigation water hampered water potential and gas exchange in the leaves of RB867515 sugarcane.

Growth and Gas Exchanges of Cotton Under Water Salinity and Nitrogen-Potassium Combination

“…Thus, it is evident that the longer exposure of plants to salt stress has contributed to the intensification of deleterious effects on the growth in plant height, as verified at 107 DAS. According to Acosto-Motos et al (2017), in the long term, salt stress affects the photosynthetic process, due to the accumulation of salts in the leaves. Bezerra et al (2018) state that the decrease is a response to the reduction in the osmotic potential of the soil due to the increase in irrigation water salinity and accumulation of Cland Na + ions.…”

“…Stomatal conductance decreased linearly with the increase in irrigation water salinity (Figure 5A), with losses of 9.48% per unit increase in ECw and of 60.91% between plants irrigated with waters of 6.7 dS m -1 and 0.7 dS m -1 . The limitation in water availability in response to osmotic stress resulting from the increase in ECw restricts stomatal conductance, constituting an important strategy of plants to avoid severe dehydration and maintain high cell water potential (LIRA et al, 2018). The results (Figures 1, 2, 3 and 4) are in agreement with Marchiori et al (2017), who concluded that the changes observed in crop growth reflect a possible state of water deficit in plants and that, in this situation, it can restrict the dilution of ions such as Na + and Clin plant tissues, causing greater accumulation of these elements to the detriment of biomass, with consequent toxicity.…”

“…The lysimeters were filled with a 0.5-kg-layer of crushed stone type zero, followed by 25 kg of a Neossolo Regolítico (Entisol) with sandy loam texture, collected from 0-20 cm depth in Lagoa Seca, PB, Brazil, with physical and chemical attributes obtained according to the methodology proposed by EMBRAPA (2017): Ca 2+ , Mg 2+ , Na + , K + , Al 3+ + H + = 2.60; 3.66; 0.16; 0.22 and 1.93 cmol c kg -1 , respectively; pH (water 1:2.5) = 5.9; ECse = 1.0 dS m -1 ; organic matter = 1.36 dag kg -1 ; sand, silt and clay = 73.29, 14.21, and 12.50 dag kg -1 , respectively; bulk density (kg dm -3 ) = 1.39; moisture content at 33.42 and 1519.5 kPa = 11.98 and 4.32 dag kg -1 , respectively.…”

Fisiologia e componentes de produção do algodoeiro sob estresse salino e aplicação de ácido salicílico

“…The study by Dias et al (2020) was developed in Campina Grande -PB, Brazil, a region characterized by milder temperatures and high relative humidity. According to Lira et al (2018), the reduction in gs in response to increases in ECw is an important strategy for plants to avoid severe dehydration and maintain high cellular water potential, since osmotic stress limits water availability.…”