ORIGINAL ARTICLE

Data source :  Google Scholar QueryDate : 2016-12-24 Cites : 1

Growth, Nitrogen Uptake and Carbon Isotope Discrimination in Barley Genotypes Grown under Saline Conditions

The effect of different salinity levels of irrigation water (ECw range 1-12 dS/m) on dry matter yield, nitrogen uptake, fertilizer nitrogen use efficiency (%NUE), stomatal conductance and carbon isotope discrimination (Δ¹³C‰) in three barley genotypes originating from different geographic areas (Arabi.Abiad, Syria; Pk-30-136, Pakistan and WI-2291, Australia) was investigated in a pot experiment. An increase in salinity resulted in a decrease in Δ13C in all the genotypes. Increasing salinity reduced leaf stomatal conductance which was less pronounced in WI-2291 comparing to other genotypes. At high salinity level, the reduction in Δ¹³C corresponded to a considerable decrease in the ratio (Ci/Ca) of intercellular (Ci) and atmospheric (Ca) partial pressures of CO₂ in all the genotypes indicating that such a decrease was mainly due to the stomatal closure. Moreover, since the reduction in dry matter yield in all the genotypes grown at 12 dS/m did not exceed 50% in comparison with their controls, the photosynthetic apparatus of all studied genotypes seemed to be quit tolerant to salinity. At the moderate salinity level (8 dS/m), the enhancement of leaf dry matter yield in the WI2291 genotype might have been due to positive nutritional effects of the salt as indicated by a significant increase in nitrogen uptake and NUE. Thus, the lower Ci/Ca ratio could result mainly from higher rates of photosynthetic capacity rather than stomatal closure. On the other hand, relationships between dry matter yield or NUE and Δ¹³C seemed to be depending on plant genotype, plant organ and salinity level. Based on growth, nutritional and Δ¹³C data, selection of barley genotypes for saline environments was affected by salinity level. Therefore, such a selection must be achieved for each salinity level under which the plants have been grown.