Growth Properties and Ion Distribution in Different Tissues of Bread Wheat Genotypes (Triticum aestivum L.) Differing in Salt Tolerance

Journal of Agronomy and Crop Science (Impact Factor: 2.44). 02/2011; 197(1):21-30. DOI: 10.1111/j.1439-037X.2010.00437.x

Four bread wheat genotypes differing in salt tolerance were selected to evaluate ion distribution and growth responses with increasing salinity. Salinity was applied when the leaf 4 was fully expanded. Sodium (Na+), potassium (K+) concentrations and K+/Na+ ratio in different tissues including root, leaf-3 blade, flag leaf sheath and flag leaf blade at three salinity levels (0, 100 and 200 mm NaCl), and also the effects of salinity on growth rate, shoot biomass and grain yield were evaluated. Salt-tolerant genotypes (Karchia-65 and Roshan) showed higher growth rate, grain yield and shoot biomass than salt-sensitive ones (Qods and Shiraz). Growth rate was reduced severely in the first period (1–10 days) after salt commencements. It seems after 20 days, the major effect of salinity on shoot biomass and grain yield was due to the osmotic effect of salt, not due to Na+-specific effects within the plant. Grain yield loss in salt-tolerant genotypes was due to the decline in grain size, but the grain yield loss in salt-sensitive ones was due to decline in grain number. Salt-tolerant genotypes sequestered higher amounts of Na+ concentration in root and flag leaf sheath and maintained lower Na+ concentration with higher K+/Na+ ratios in flag leaf blade. This ion partitioning may be contributing to the improved salt tolerance of genotypes.

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Available from: Afrasyab Rahnama, Sep 29, 2015
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    • "This finding differs to the responses observed in other cereal species, such as einkorn wheat (T. monococcum) (Rajendran et al. 2009), durum wheat (James et al. 2008; Rahnama et al. 2010) and bread wheat (Rahnama et al. 2011), where an immediate response to salt application can be seen -the shoot ion independent stress (osmotic stress) (Munns and Tester 2008). This early reduction in plant growth is not observed in either IR64 or Fatmawati, Figure 3 Projected shoot area of rice cv. "
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    ABSTRACT: Soil salinity is an abiotic stress wide spread in rice producing areas, limiting both plant growth and yield. The development of salt-tolerant rice requires efficient and high-throughput screening techniques to identify promising lines for salt affected areas. Advances made in image-based phenotyping techniques provide an opportunity to use non-destructive imaging to screen for salinity tolerance traits in a wide range of germplasm in a reliable, quantitative and efficient way. However, the application of image-based phenotyping in the development of salt-tolerant rice remains limited. A non-destructive image-based phenotyping protocol to assess salinity tolerance traits of two rice cultivars (IR64 and Fatmawati) has been established in this study. The response of rice to different levels of salt stress was quantified over time based on total shoot area and senescent shoot area, calculated from visible red-green-blue (RGB) and fluorescence images. The response of rice to salt stress (50, 75 and 100 mM NaCl) could be clearly distinguished from the control as indicated by the reduced increase of shoot area. The salt concentrations used had only a small effect on the growth of rice during the initial phase of stress, the shoot Na(+) accumulation independent phase termed the 'osmotic stress' phase. However, after 20 d of treatment, the shoot area of salt stressed plants was reduced compared with non-stressed plants. This was accompanied by a significant increase in the concentration of Na(+) in the shoot. Variation in the senescent area of the cultivars IR64 and Fatmawati in response to a high concentration of Na(+) in the shoot indicates variation in tissue tolerance mechanisms between the cultivars. Image analysis has the potential to be used for high-throughput screening procedures in the development of salt-tolerant rice. The ability of image analysis to discriminate between the different aspects of salt stress (shoot ion-independent stress and shoot ion dependent stress) makes it a useful tool for genetic and physiological studies to elucidate processes that contribute to salinity tolerance in rice. The technique has the potential for identifying the genetic basis of these mechanisms and assisting in pyramiding different tolerance mechanisms into breeding lines.
    Rice 08/2014; 7(1):16. DOI:10.1186/s12284-014-0016-3 · 3.92 Impact Factor
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    • "Previous studies reported that Na + transporters, such as AtHKT1, are involved in xylem loading by controlling the retrieval of Na + from the xylem to alter the root/shoot Na + distribution (Mäser et al. 2002, Davenport et al. 2007). In shoots, Na + is preferentially accumulated in the leaf sheath to protect the leaf blade from damage, especially in young expanding tissues (Wei et al. 2003, Rahnama et al. 2011). In the present study, the sharp increase in Na + in the petiole, leaf main vein and leaf blade in both canola cultivars was responsible for an obvious decline in shoot dry weight. "
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