Growth patterns of Phragmites karka under saline conditions depend on the bulk elastic modulus

Abstract

Salt stress is known to hamper steady-state water flow, which may reduce plant growth. This research was aimed to study the roles of leaf turgor, osmotic adjustment and cell wall elasticity under saline conditions which may reduce biomass production in Phragmites karka (Retz.) Trin, ex. Steud. (a marsh grass). Plants were grown in 0, 100 and 300 mM NaCl and harvested on 3, 7, 15 and 30 days to observe periodic changes in growth and water relations. Leaf number, relative growth rate, and relative elongation rates were higher in the non-saline control than in the plants grown under saline conditions. Plants showed a rapid decline in leaf growth rate (7–15 days) in 300 mM NaCl compared with a delayed response (15–30 days) in 100 mM NaCl. Leaf water potential decreased with increases in salinity after the third day of exposure whereas osmotic potential decreased after the fifteenth day. Low leaf turgor (Ψp) on the third day indicated an initial phase of osmotic stress under saline conditions. Plants maintained higher Ψp in 0 and 100 mM than in 300 mM NaCl. Differences between mid-day and pre-dawn water potential and water saturation deficit were higher in 300 mM NaCl than with other treatments. Water potential and hydraulic capacitance at turgor loss point decreased whereas bulk elastic modulus increased in 300 mM NaCl. Maintenance of turgor and growth at 100 mM NaCl could be related to efficient osmotic adjustment (use of K+ and Cl–), higher WUEi, and lower bulk elasticity whereas poor growth at 300 mM NaCl may have been a consequence of low turgor, decreased cell hydraulic capacitance and higher bulk elastic modulus.

Salinity stress improves antioxidant potential by modulating physio-biochemical responses in Moringa oleifera Lam.

“…Decrease in OP requires excessive solute uptake, to create sufficient turgor for cell growth and elongation 15 , 96 . No change in leaf succulence indicate the water-conserving strategy of the plant that helps in retaining cell wall integrity and maintaining growth, especially under moderate salinity 97 , 98 . To achieve workable OP, most plants accumulate ions as cheap osmoticum 99 , because synthesizing organic osmolytes require a high cost of energy 100 , 101 .…”

Respostas fisiológicas do girassol em fase reprodutiva ao estresse hídrico e salino

“…A eficiência instantânea de carboxilação obteve comportamento semelhante com A, com maiores eficiências quando irrigado com água salina, prioritariamente nos maiores níveis de água (tabela 3). Este comportamento pode ser explicado devido essas plantas que vivem em ambientes com estresse salino responderem diferentemente ao potencial hídrico do solo do que aquelas que crescem sob condições não salinas (Shoukat, et al, 2018), através de importantes mecanismos de defesa presente em algumas espécies ou materiais genéticos melhorados, sendo um deles o ajuste osmótico, através do acúmulo de solutos que podem ajudar a alcançar o equilíbrio osmótico, a captação de água para manter o crescimento (Flowers e Colmer, 2008) e alteração do módulo de elasticidade da parede celular, pois plantas com tecidos mais elásticos mantêm maiores quantidades de água na saturação total e, portanto, no ponto de perda do turgor, elas podem ter maior capacitância hidráulica em relação ao volume da célula (Lambers et al, 2008;Bartlett et al, 2012).…”

Phytoremediation of Potentially Toxic Elements from Contaminated Saline Soils Using Salvadora persica L.: Seasonal Evaluation

“…Following complete hydration, bags were removed in the early morning (pre-dawn), leaves were cut from the branches, and their hydrated weights were taken immediately. A 5 mm leaf disc was then punched from each sample and quickly inserted in a sample chamber of a Wescor HR-33T thermocouple psychrometer (Wescor, Inc., Logan, UT, USA) to minimize air exposure [ 43 ]. Water potential was determined after thermal equilibration.…”

“…Between 8–10 repetitive measurements, leaf samples (along with leaf discs) were subjected to bench drying (1–20 min) and re-inserted in the sample chamber to note subsequent water potential readings. A Pressure-volume curve (PVC) was obtained by the method of Shoukat et al [ 43 ], and the following water relation parameters were derived: water and osmotic potential at full turgor ( ΨS o and ΨW o ), water potential at turgor loss point ( ΨTLP ), and bulk elastic modulus ( ε ) (Bartlett et al, 2012) [ 44 ].…”