Carbon Assimilation, Isotope Discrimination, Proline and Lipid Peroxidation Contribution to Barley (<i>Hordeum vulgare</i>) Salinity Tolerance

Barley (Hordeum vulgare L.) exhibits great adaptability to salt tolerance in marginal environments because of its great genetic diversity. Differences in main biochemical, physiological, and molecular processes, which could explain the different tolerance to soil salinity of 16 barley varieties, were examined during a two-year field experiment. The study was conducted in a saline soil with an electrical conductivity ranging from 7.3 to 11.5 dS/m. During the experiment, a number of different physiological and biochemical characteristics were evaluated when barley was at the two- to three-nodes growing stage (BBCH code 32–33). The results indicated that there were significant (p 2 and proline concentration were 200% and up to 67% higher than the sensitive varieties, respectively. However, in sensitive varieties, hydrogen peroxide and lipid peroxidation were enhanced, indicating an increased lipid peroxidation. The expression of the genes Hsdr4, HvA1, and HvTX1 did not differ among barley varieties tested. This study suggests that the increased carbon isotopes discrimination, increased proline concentration (play an osmolyte source role), and decreased lipid peroxidation are traits that are associated with barley tolerance to soil salinity. Moreover, our findings that proline improves salt tolerance by up-regulating stress-protective enzymes and reducing oxidation of lipid membranes will encourage our hypothesis that there are specific mechanisms that can be co-related with the salt sensitivity or the tolerance of barley. Therefore, further research is needed to ensure the tolerance mechanisms that exclude NaCl in salt tolerant barley varieties and diminish accumulation of lipid peroxides through adaptive plant responses

Carbon Assimilation, Isotope Discrimination, Proline and Lipid Peroxidation Contribution to Barley (Hordeum vulgare) Salinity Tolerance

Barley (Hordeum vulgare L.) exhibits great adaptability to salt tolerance in marginal environments because of its great genetic diversity. Differences in main biochemical, physiological, and molecular processes, which could explain the different tolerance to soil salinity of 16 barley varieties, were examined during a two-year field experiment. The study was conducted in a saline soil with an electrical conductivity ranging from 7.3 to 11.5 dS/m. During the experiment, a number of different physiological and biochemical characteristics were evaluated when barley was at the two- to three-nodes growing stage (BBCH code 32–33). The results indicated that there were significant (p &lt; 0.001) effects due to varieties for tolerance to salinity. Carbon isotopes discrimination was higher by 11.8% to 16.0% in salt tolerant varieties than that in the sensitive ones. Additionally, in the tolerant varieties, assimilation rates of CO2 and proline concentration were 200% and up to 67% higher than the sensitive varieties, respectively. However, in sensitive varieties, hydrogen peroxide and lipid peroxidation were enhanced, indicating an increased lipid peroxidation. The expression of the genes Hsdr4, HvA1, and HvTX1 did not differ among barley varieties tested. This study suggests that the increased carbon isotopes discrimination, increased proline concentration (play an osmolyte source role), and decreased lipid peroxidation are traits that are associated with barley tolerance to soil salinity. Moreover, our findings that proline improves salt tolerance by up-regulating stress-protective enzymes and reducing oxidation of lipid membranes will encourage our hypothesis that there are specific mechanisms that can be co-related with the salt sensitivity or the tolerance of barley. Therefore, further research is needed to ensure the tolerance mechanisms that exclude NaCl in salt tolerant barley varieties and diminish accumulation of lipid peroxides through adaptive plant responses

Field bindweed (Convolvulus arvensis L.) and redroot pigweed (Amaranthus retroflexus L.) control in potato by pre- or post-emergence applied flumioxazin and sulfosulfuron

Field bindweed (Convolvulus arvensis L.) is one of the most serious weeds in potato (Solanum tuberosum L.), but selective herbicides controlling this weed have not been reported. A field experiment was conducted in 2010 and repeated in 2011 in Greece to study the efficacy of herbicides flumioxazin and sulfosulfuron, applied pre- or post-emergence, on field bindweed and redroot pigweed (Amaranthus retroflexus L.), as well as their phytotoxicity on potato. Gas chromatography-mass spectrography (GC-MS) and high-performance liquid chromatography (HPLC) analyses were conducted for possible herbicide residues in potato tubers. Also, the efficacy of these herbicides on field bindweed generated from root fragments was investigated in greenhouse pot experiments. In pots, both herbicides provided 78% to 100% control of field bindweed generated from root fragments. In field, both herbicides when applied pre-emergence at 72 to 144 g ai ha-1 provided 65% to 100% field bindweed control. However, the corresponding post-emergence applications did not provide satisfactory weed control. All treatments provided excellent control of redroot pigweed. Potato growth was not significantly affected by herbicide application in 2010. However, in 2011, post-emergence applications of flumioxazin caused significant crop injury and yield reduction. The results of this study indicate that satisfactory control of field bindweed and redroot pigweed, as well as high potato yield can be obtained by the pre-emergence application of flumioxazin or sulfosulfuron at 72 to 144 g ai ha-1, without herbicide residues on potato tubers