Fariba Bagheri; Abdolhosein Rezaei Nejad; Mohammad Reza Raji
Abstract
Waterlogging may be imposed by intense rainfall, excessive irrigation, or poor drainage. In Iran, besides the northern parts of the country with high precipitation, waterlogging may occur due to over-irrigation, or inadequate drainage especially for landscape use of ornamentals. In this study, the joint ...
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Waterlogging may be imposed by intense rainfall, excessive irrigation, or poor drainage. In Iran, besides the northern parts of the country with high precipitation, waterlogging may occur due to over-irrigation, or inadequate drainage especially for landscape use of ornamentals. In this study, the joint effects of growth stage (four-leaf stage, full growth and start flowering), at which waterlogging is encountered, and the duration of the episode (0, 6, 12, and 24 h) on flowering induction, plant growth, and external quality were investigated in zinnia (Zinnia elegans Jacq.). Waterlogging generally downgraded visually-perceived quality (stem length, flower size, leaf coloration), increased the risk of buckling (lower stem strength) and shortened flower bud longevity. Waterlogging adversely affected biomass accumulation, through decreases in both light capture (leaf area), and photosynthesis. Besides disturbed water relations, waterlogged plants underwent oxidative damage as indicated by reduced chlorophyll content, and elevated lipid peroxidation level. Waterlogging was further associated with increased activity of antioxidant enzymes (ascorbate peroxidase, peroxidase). The waterlogging-induced effects were generally more prominent as waterlogging duration increased, and the growth stage of application was less advanced, so that the plants waterlogged in four-leaf stage for 24 h showed the most negative effects and their plant dry weight reduced to 75 percent of that in controls. In conclusion, the obtained results offer a quantitative analysis of how both growth stage and duration determine the waterlogging-induced injury in zinnia.
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.
Hamid Alipour
Abstract
Understanding mechanisms of salt tolerance, physiological responses to salt stress, and screening genotypes for breeding programs are important scientific issues remained to be investigated in pistachio. Therefore, current study was carried out to investigate response of different pistachio cultivars ...
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Understanding mechanisms of salt tolerance, physiological responses to salt stress, and screening genotypes for breeding programs are important scientific issues remained to be investigated in pistachio. Therefore, current study was carried out to investigate response of different pistachio cultivars (G1, G2, Kaleghochi and UCB1) to salinity treatments (0.6 as control, 10, 20 dS m-1 using saline underground water) as a factorial experiment based on randomized complete block design with three replications in greenhouse of Iranian Pistachio Research Institute (Rafsanjan) in 2014-2015. Some physiological and nutrition properties of the pistachio cultivars measured in this study. Results showed decreased stomatal conductance, photosynthesis rate, chlorophyll content, and Fv/Fm in response to salinity treatments. The main cause of these changes was related to the altered ion contents along with the competition among ions for being absorbed by plant. Despite of sufficient amount of potassium in the soil, high concentrations of sodium and other associated elements such as calcium and magnesium decreased the ability of pistachio plants to absorb adequate amount of vital ions such as potassium. As a result of sodium accumulation and deficiency of potassium, K+/Na+ ratio was decreased in pistachio leaves. Consequently, toxicity of sodium ions in the plant cells reduced stomatal conductance and the rate of photosynthesis. Comparison between cultivars showed that for the most of the traits the difference between control and moderate salinity (10 ds m-1) in all cultivars was not significant. However, G2 cultivar showed higher ability to accumulate potassium and absorbed lower concentration of sodium, calcium, and magnesium under sever salinity treatment (20 ds m-1). These result suggested that G2 could be considered as a potential tolerant cultivar for cultivation in saline area.
