Leila Baghazadeh Daryaii; Davoud Samsampour; Abdoolnabi Bagheri; Jelveh Sohrabipour
Abstract
Bacterial endophytes grow symbiotically inside plants and improve the growth of their hosts. We evaluated the effects of inoculating macroalgae bacterial endophytes, introduced formerly by our group, Bacillus aquimaris strain OD14, B. megaterium strain AM25, B. zhangzhouensis strain Tv91C, individually ...
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Bacterial endophytes grow symbiotically inside plants and improve the growth of their hosts. We evaluated the effects of inoculating macroalgae bacterial endophytes, introduced formerly by our group, Bacillus aquimaris strain OD14, B. megaterium strain AM25, B. zhangzhouensis strain Tv91C, individually and in combination with each other on the reactive oxygen species (ROS) of scavenging and antioxidant functions, as well as growth characteristics of Mexican lime seedlings under salinity stress. Accordingly, Mexican lime (Citrus aurant-ifolia Swingle.) seedlings were subjected to four salinity levels, i.e. 0, 2000, 4000 and 6000 µs cm-1 in the presence or absence of bacterial endophytes. The results indicated that salinity stress significantly reduced growth, chlorophyll, and carotenoid content of plants lacking endophytes. Combinatory applications with bacterial endophytes significantly improved the above-mentioned parameters under salinity stress. Lipid peroxidation levels were significantly reduced in plants inoculated with bacterial endophytes. Salinity stress significantly increased the activities of ascorbate peroxidase (APX), superoxide dismutase (SOD), glutathione reductase (GR), peroxidase (POD), and catalase (CAT) in salinity conditions. Overall, the inoculation with bacterial endophytes improved salinity tolerance and reduced the accumulation of ROS by increasing their scavenging via an enhanced redox state of glutathione and more effective antioxidant enzyme activities.
Maryam Chavoushi; Khosrow Manoochehri Kalantari; Mohamad Javad Arvin
Abstract
Salinity stress is one of the main limiting factors for optimum agricultural productivity of safflower, Carthamus tinctorius L., in arid and semi-arid regions. It could leads to significant changes in plant biochemical, physiological, and growth traits. Salinity induced endogenous rise in jasmonic acid ...
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Salinity stress is one of the main limiting factors for optimum agricultural productivity of safflower, Carthamus tinctorius L., in arid and semi-arid regions. It could leads to significant changes in plant biochemical, physiological, and growth traits. Salinity induced endogenous rise in jasmonic acid and its methyl esters (MeJA) has been reported. In the present study, effects of salinity stress (6 and 12 ds m-1) and the exogenous application of MeJA (0.1 and 0.5 mM) on the leaf number, shoot fresh weight, shoot length, chlorophyll a/b, soluble sugar, proline, and malondialdehyde (MDA) contents were investigated in two safflower varieties (Isfahan and IL111). Salinity stress negatively affected the growth of both varieties. Lipid peroxidation was not observed in Isfahan variety, but it significantly increased in the salinity resistant safflower, IL111. Soluble sugar and proline as the important osmoprotectants and free radical scavengers were elevated by salinity stress. Exogenous application of MeJA to the salinity stress-imposed plants slightly improved the growth due to inductions in the rate of photosynthesis; however, MeJA application impaired the growth of non-stressed plants because of induction of stomatal closure and as a result reduced photosynthesis.
Majid Rajaie; Mohammah Ebrahim Motieallah
Abstract
To investigate interaction effects of salinity and nitrogen on growth, mineral composition and salinity tolerance of lemon seedlings, a greenhouse experiment with four sodium chloride concentrations (0, 250, 500 and 1000 mg kg-1 soil) and four nitrogen levels (0, 50, 100, and 200 mg kg-1 soil ammonium ...
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To investigate interaction effects of salinity and nitrogen on growth, mineral composition and salinity tolerance of lemon seedlings, a greenhouse experiment with four sodium chloride concentrations (0, 250, 500 and 1000 mg kg-1 soil) and four nitrogen levels (0, 50, 100, and 200 mg kg-1 soil ammonium sulfate) was carried out. Experiment was conducted in a completely randomized design with three replications. Sodium and chloride ions in plant tissues were increased to toxic levels with increase in salinity which resulted in a significant reduction of plant dry weight. Nitrogen consumption up to 100 mg kg-1 soil increased plant dry weight. As the concentration of sodium chloride was increased, the improvement effect of nitrogen on plant growth was decreased. Although nitrogen had no considerable effect on sodium concentration in root and shoot, it made a decrease in chloride concentration in shoot and an increase in root concentration of this element. Salinity decreased essential nutrients concentration in plant shoot. Therefore, it can be concluded that adverse effect of salinity is to some extent due to reduction of required elements to suboptimal ranges in plant tissues. Nitrogen improved the adverse effects of salinity on plant nutrients by increasing their concentration in plant tissues. Therefore it can be inferred that part of the ameliorative effects of nitrogen on salinity adverse effects is related to the maintenance of essential nutrient concentrations in plant tissues. The results of the present study indicate that nitrogen can be applied in amounts higher than optimal level to reduce the harmful effects of salinity.
