Growth and nodulation of alfalfa-rhizobia symbiosis under salinity: electrolyte leakage, stomatal conductance, and chlorophyll fluorescence

Abstract

The present work was a study on the adverse effects of salinity on growth, nodulation, and some physiological parameters in 4 symbiotic combinations involving 2 Moroccan alfalfa (Medicago sativa L.) populations (Demnate and Tata) and 2 rhizobial strains (rhLAr 1 and rhLAr 4). The experiment was conducted in the greenhouse at 32/22 °C day/night, 50%-80% relative humidity, and a photoperiod of 16 h. The seedlings were separately inoculated with suspensions of 2 rhizobial strains and grown under 2 NaCl treatments, 0 mM (control) and 100 mM (salt stress), in plastic pots filled with sterile sand and peat at 9/10 and 1/10 ratios, respectively. The salt stress was applied for 5 weeks and some agro-physiological and biochemical parameters related to salt tolerance were assessed. The results showed that salinity significantly reduced the height of plants, their dry biomass, and nodulation. This constraint has also negatively affected the relative water content of leaves, the membrane permeability, the stomatal conductance, the maximum quantum yield of photosystem II, and the chlorophyll contents. Comparison among the symbiotic combinations tested showed that their behavior was significantly different. Plants inoculated with rhizobial strain rhLAr 4 were more tolerant to saline conditions. Their tolerance was associated with the maintaining of adequate levels in terms of physiological and biochemical parameters studied.

Study of effects of seawater salt spray on growth, chlorophyll fluorescence and chlorophyll content in three coastal species of Morocco

“…Under this condition, those plants curl their leaves and reduce area in order to avoid salt deposits, and to minimize the water loss by transpiration. Some authors, Latrach et al and Kekere et al [12,20], published similar findings for Medicago sativa, Kyllinga peruviana and Paspalum vaginatum respectively. A. heterophylla was more tolerant to stress due to its high survival rate (more than 90%) under salt treatment, this could be explained by the structure of their leaves (leavesscales), which permit it to resist the seawater spray [21].…”

“…It is well known that salinity negatively affects plants growth and metabolism. In fact, similar effects of salt spray treatment on plant height and growth has been observed in many plants species such as P. rigida and Q. rubra [3,12,18]. The survival rate of the tree-studied species was 94%, 91% and 83% for A. heterophylla, L. patersonii and S. terebinthifolius respectively.…”

“…Mouradi et al, [14] and Fghire et al, [15] proved the efficiency of this tool for determining more drought tolerant genotypes of alfalfa and quinoa respectively. As well as drought, PSII performance decreased under salinity reflected by the decrease in the F v /F m ratio [12]. These results are essentially linked to the photosynthetic state engendered by seawater spray as results of stomatal closure and water loss by osmotic stress [25].…”

Osmopriming improves seeds germination, growth, antioxidant responses and membrane stability during early stage of Moroccan alfalfa populations under water deficit

“…Efficient seed germination, rapid and uniform seedlings emergence lead to successful culture establishment (Chen and Arora, 2011). The Moroccan alfalfa populations are considered as moderately tolerant to drought and salinity but there is a variant behavior within a lot of them (Bouizgaren, 2007;Latrach et al, 2014;Mouradi et al, 2016). In addition, many species and sub-species of Medicago also exhibit traits of agronomic interest, such as tolerance to grazing (rooting ability and regrowth) and disease (Bouizgaren, 2007).…”

Effect of Microbially Enriched Vermicompost on the Growth and Biochemical Characteristics of Okra (Abelmoschus Esculentus (L.) Moench)

“…The maximum chlorophyll a, chlorophyll b and total chlorophyll, carbohydrate and protein content found in plants treated with biofertilizers enriched vermicompost in Vigna unguiculata (L.). Increased amount of chlorophyll contents seems to correlate the increased photosynthetic properties [26,27,28]. The application of vermicompost highly enhanced the carbohydrate content in tomato plants [29].…”