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  • Author or Editor: Ali Nikbakht x
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Traffic stress is one of the major abiotic stresses that limits grass growth in lawn fields. The severity of losses depends on several factors, including the number of events per season, the athletic field size, and the soil moisture content during the traffic incident. Trinexapac-ethyl (TE) is considered to influence plant tolerance to traffic stress. Therefore, the physiological responses of the wheatgrass (Agropyron desertorum L.) and tall fescue (Festuca arundinacea L. cv. Rebel) species to different levels of TE and traffic stress were investigated. A factorial experiment including combination of TE application and traffic stress treatments was performed based on a randomized complete block design (RCBD) with three replications in 2014 and 2015. The treatments, including traffic stress (traffic and nontraffic stress) and TE at three levels (0, 0.25, and 0.5 kg·ha−1), were applied once every 3 weeks. The simulated traffic stress was imposed using a Brinkman traffic simulator (BTS). The results showed that traffic stress reduced the turf quality, relative water content (RWC), total chlorophyll content, and antioxidant activity and increased electrolyte leakage (EL), soluble sugar content (SSC), and malondialdehyde (MDA) in both species. Conversely, TE increased the turf quality, RWC, SSC, and total chlorophyll and resulted in less EL and MDA in both species. Furthermore, TE application increased the superoxide dismutase (SOD) (EC 1.15.1.1), ascorbate peroxidase (APX) (EC 1.11.1.11), and peroxidase (POD) (EC 1.111.1.7) activities, especially under traffic stress conditions. TE application enhanced the resistance to traffic stress in both species by improving the osmotic adjustment and antioxidant activity.

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Desert wheatgrass (Agropyron desertorum L.), tall wheatgrass (Agropyron elongatum L.), and crested wheatgrass (Agropyron cristatum L.) are native cool-season grass species that exhibit potential as a low-input turfgrass. An increased understanding of the biochemical and physiological responses of wheatgrass species and genotypes to salt stress conditions is important for developing genotypes with enhanced tolerance to salinity. The objective of this study was to characterize the physiological and antioxidative properties in 20 Iranian wheatgrass genotypes and to observe their responses to salinity stress during seed germination and seedling growth stage. A completely randomized factorial design was used with two types of factors, four levels of salinity (0, 50, 100, and 150 mm of NaCl), wheatgrass genotypes, and three replicates. In this experiment, the results demonstrated that salinity limits the germination of Iranian wheatgrass genotype seeds. The result of this study showed that among the wheatgrass genotypes, ‘AD1’, ‘AD3,’ ‘AC6’, and ‘FA’ took the shortest average time to germinate. Higher levels of final germination percentage (FGP) were observed in ‘AD2’, ‘AD3’, and ‘AE5’ under salinity stress than other genotypes throughout the experiment. During a prolonged period of study, ‘AD1’ had greater rate of germination (GR) than other genotypes. Out of the 21 genotypes, five genotypes (‘AD1’, ‘AD2’, ‘AD3’, ‘AE5’, and ‘FA’ genotypes) were in the range of “salinity tolerant genotypes” cluster. The ‘AD1’, ‘AD2’, ‘AD3’, ‘AE5’, and ‘FA’ genotypes generally performed better than other genotypes under salinity conditions, mainly through maintaining higher enzymatic activities such as superoxide dismutase (SOD) (EC 1.15.1.1), catalase (CAT) (EC 1.11.1.6), ascorbate peroxidase (APX) (EC 1.11.1.11) and peroxidase (POD) (EC 1.111.1.7), and nonenzymatic antioxidant activities by glutathione (GSH). The ‘AD1’, ‘AD2’, ‘AD3’, ‘AE5’, and ‘FA’ genotypes also had higher proline levels and more of total nonstructural carbohydrates (TNC) content, lower malondialdehyde (MDA) content, and lower hydrogen peroxide content (H2O2).

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Lisianthus is one of the most important specialty cut flowers in the world. Various greenhouse conditions and inadequate evapotranspiration can disturb the transport of calcium and impair its uptake by plants. This study aimed to compare the effects of calcium amino acid chelates and calcium chloride (CaCl2) on flower production, quality, and postharvest life of cut ‘Cinderella Lime’ lisianthus. Therefore, nutrient solutions containing calcium amino acid chelates (1%) were prepared using calcium and equal concentrations of lysine, threonine, or methionine. The control treatment was a solution without amino acids and calcium. Calcium concentrations of flowering stems were significantly higher in plants treated with calcium amino acid chelates than those treated with amino acids or the control treatment. Treatment with calcium methionine chelate led to significantly higher flower numbers compared with treatment with free amino acids and the control treatment. Moreover, calcium amino acid chelates effectively improved the fresh and dry mass of the flowering stems in comparison with the control plants. In summary, among all calcium sources, calcium lysine chelate could most effectively enhance the postharvest life of lisianthus cut flowers.

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