Soraya Karami; Sakine Faraji; Tayebeh Basaki; Sedighe Ghanaei
Abstract
The present research considered identifying drought-tolerant genotypes through an index-based analysis of stress tolerance and physiological traits in pomegranates. Ten local pomegranate genotypes in Iran were evaluated for drought stress tolerance in two different irrigation regimes, i.e., normal conditions ...
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The present research considered identifying drought-tolerant genotypes through an index-based analysis of stress tolerance and physiological traits in pomegranates. Ten local pomegranate genotypes in Iran were evaluated for drought stress tolerance in two different irrigation regimes, i.e., normal conditions and severe drought stress (SDS). The experiment was arranged in a randomized block design with three replications and took two consecutive years to accomplish (2019- 2020). Indices for stress tolerance were estimated from the fruit yield of a single tree under each irrigation regime. There were significantly positive correlations among several parameters, including Yp (fruityield under normal conditions), Ys (fruit yield under SDS), mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI), and proline (Pro) content. Therefore, these indices can be applied when identifying drought-tolerant genotypes under SDS and normal conditions. The Pro content was introduced as the best physiological index to assist in indirectly selecting drought-tolerant genotypes. A negative correlation occurred between Ys and stress susceptibility index (SSI). This index may assist in identifying susceptible genotypes. Based on principal component analysis (PCA), two genotypes (MTS and PSS) performed best in fruit yield and showed a high Pro content under the SDS condition.
Mina Zahedi; Mehdi Sarcheshmehpour; Homayoun Farahmand
Abstract
Arbuscular mycorrhizal fungi (AMF) have a mutualistic relationship with a great number of plants. This can offer promising approaches to managing arid ecosystems. In the present study, the effects of native AMF inoculums were evaluated on morphological and physiological traits of Cercis siliquastrum ...
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Arbuscular mycorrhizal fungi (AMF) have a mutualistic relationship with a great number of plants. This can offer promising approaches to managing arid ecosystems. In the present study, the effects of native AMF inoculums were evaluated on morphological and physiological traits of Cercis siliquastrum and Prosopis cineraria seedlings under drought stress conditions. The study was carried out in two independent experiments as a full factorial design with two factors: AM fungal (non- AMF and AMF) and three levels of drought stress (80%, 50%, and 30% of field capacity). The results showed that shoot dry weight and root growth were reduced in response to an increase in drought stress levels on Prosopis cineraria. In C. siliquastrum, however, the shoot dry weight, root volume and root dry weight increased moderately as a result of AMF but decreased in response to severe drought stress. Native AMF inocula increased proline content by about two-fold, while also increasing root and shoot dry weight and root volume of the inoculated plants of both species. Drought stress increased proline content in both AMF plants and in uninoculated C. siliquastrum seedlings. The native AMF colonized the roots of C. siliquastrum and P. cineraria, by at least 80% and 70%, respectively, which was significantly higher than AMF from soils. Drought stress reduced catalase activity (CAT) in P. cineraria, but this was lower in inoculated plants than in uninoculated plants. In response to moderate and severe drought stress, ascorbic peroxidase (APX) activity increased by over 29 and 44%, respectively, compared to well-watered and inoculated P. cineraria seedlings. P. cineraria seedlings tolerated drought stress by both enzymatic and non-enzymatic ways, while C. siliquastrum accumulated osmotic solutes such as proline under drought stress. In conclusion, both species were recommended for xeriscaping purposes, although mesquite proved to be more reliable in adverse conditions.
Lavin Babaei; Mohammad Mehdi Sharifani; Reza Darvishzadeh; Naser Abbaspour; Mashhid Henareh
Abstract
To investigate photosynthetic response of some pear (Pyrus spp.) species to drought stress, a pot experiment was conducted using as factorial experiment based on completely randomized design (CRD) with three replication under greenhouse condition. The factors included five pear species including: P. ...
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To investigate photosynthetic response of some pear (Pyrus spp.) species to drought stress, a pot experiment was conducted using as factorial experiment based on completely randomized design (CRD) with three replication under greenhouse condition. The factors included five pear species including: P. biossieriana, P. communis, P. glabra, P. salicifolia and P. syriaca and three levels of drought stress [(100%, 60% and 30% of field capacity (FC)]. According to the obtained results, different levels of drought stress significantly restricted morphological and physiological responses in all studied species. Increasing drought stress intensity reduced leaf relative water content (RWC), net photosynthetic rate, stomatal conductance, transpiration rate and intercellular carbon dioxide concentration when compared to their values in control plants. However, root/shoot dry weight ratio, specific leaf weight and stomatal density per unit of area were increased. In P. glabra exposed to severe stress (30% of FC), the values of root/shoot dry weigh ratio (0.85 g), specific leaf weight (23 mg cm-2), stomata density per unit of area, relative water content (73%) and net photosynthetic rate (3.9 µmol CO2 m-2 s-1) were significantly higher than the other species. P. syriaca, P. salicifolia, P. biossieriana and P. communis were placed in the next ranks, respectively based on their response to drought. In conclusion, P. glabra is reported as a more effective species in mitigating the adverse effects of drought by boosting its protective mechanisms than the other pear species.
Nasser Abbaspour; Lavin Babaee
Abstract
Adaptation and defense responses are the consequences of exposure to drought stress in plants. Salicylic acid (SA) as a natural signaling molecule poses a significant impacts on various aspects of plant growth and development. This study investigates the effects of SA on carotenoids content, lipid peroxidation ...
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Adaptation and defense responses are the consequences of exposure to drought stress in plants. Salicylic acid (SA) as a natural signaling molecule poses a significant impacts on various aspects of plant growth and development. This study investigates the effects of SA on carotenoids content, lipid peroxidation rate and antioxidant enzymes activities. A pot experiment was conducted using a factorial pattern based on a randomized complete block design with three replications under greenhouse conditions. The variables in the experiment included grapevine cultivars (‘Rasheh’ and ‘Bidane Sefid’), irrigation periods (5, 10 and 15 day intervals) and SA concentrations (0, 1 and 2 mM). Results showed that with increasing the drought stress levels, increase in carotenoids, malondialdehyde (MDA) contents, catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) enzymes activities were detected. Carotenoids content, catalase (CAT) and ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) enzymes activities were higher in the Rasheh cultivar compared with the ‘Bidane Sefid’ cultivar. Carotenoids content, CAT, APX and GPX enzymes activities increased by application of salicylic acid. . According to the obtained results, the Rasha cultivar showed a greater tolerance to water stress in comparison with Bidane Sefid cultivar, suggesting that SA is capable of inducing drought stress tolerance in plants.
Hamid-Reza Fallahi; Morteza Ghorbany; Alireza Samadzadeh; Mahsa Aghhavani-Shajari; Amir-Hassan Asadian
Abstract
In this study effect of irrigation managements including irrigation after 100 and 200 mm pan evaporation as normal and deficit irrigation respectively was investigated in Roselle plants. Effects of humic acid (including 0 and 4 kg ha-1) and mycorrhizal inoculants (including Glomus versiforme (GV) and ...
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In this study effect of irrigation managements including irrigation after 100 and 200 mm pan evaporation as normal and deficit irrigation respectively was investigated in Roselle plants. Effects of humic acid (including 0 and 4 kg ha-1) and mycorrhizal inoculants (including Glomus versiforme (GV) and Rhizophagus irregularis (RI)) were also studied on growth, yield and mycorrhizal symbiosis index of Roselle plants. Drought stress reduced the amounts of morphological indices and yield components, while mycorrhizal treatment particularly RI inoculation and to a lower extent humic acid application reduced the negative impacts of water deficit on growth and yield of Roselle plants. Both inoculants of mycorrhizal fungi increased the economical yield of Roselle under drought stress condition, where the amount of calyx yield for RI, GV and control in 200 mm pan-evaporation treatment was 130, 127 and 66 kg ha-1, respectively. In addition, the highest root mycorrhizal frequency was obtained at normal irrigation × humic application × RI (95%) and the lowest value was observed at deficit irrigation × no-humic × no-mycorrhizal inoculation (31.6%) treatment. In conclusion, combined effects of experimental factors showed that seed inoculation of plants by mycorrhiza and to some extent application of humic acid are two reliable strategies for Roselle production under deficit irrigation.