Studies were carried out to (i) screen and select the barley germplasm for tolerance to increased levels of NaCI and Na2SO4 salinity and (ii) to understand the physiological mechanism of salinity tolerance at tillering, booting, and grain filling stages of growth in selected highly salt tolerant and highly salt sensitive genotypes. Results revealed that salinity tolerance ability of barley genotypes differed substantially at various growth stages. Highest tolerance was shown by B-90068 and lowest by jau-87 under both the salinities and the growth stage investigated. Rest of the genotypes indicated quite variable response to salinity at different stages.
Although NaCI salinity was more toxic than the Na2SO4, only a few genotypes showed differential behavior. Among the growth and yield parameters, increased number and area of green leaves, prolific root system, greater number of tillers per plant and grain yield per plant appeared to have positive correlation with tolerance to salinity. Increased number of tillers diluted the toxic effects of ions, so reducing their translocation to physiologically active parts. Similarly, increased photosynthetic area of salt tolerant genotype enabled it to display greater dry matter and grain yield production under salinity strees. Salinity applied as CI- and SO4 (on sio-osmotic basis) at germination stage indicated a reduced percentage of germination and subsequent growth. The growth and dry matter production of seedling was reduced in all the genotypes. Although SO4 salinity also showed the adverse effects but to a considerably lower extent than CI- For the study of physiological mechanisms at tillering, booting and grain filling stages, partitioning of elements and some photosynthetic parameters were determined under control, -0.60 and -0.75 MPa levels of NaCI level of NaCI and Na2So4. The tolerant genotype was able to partition the excess of toxic ions into physiologically less active parts while beneficial elements were preferentially transported to the active parts i.e leaves and roots. Rate of photosynthesis, stomatal conductance and rate of transpiration were also decreased under increased salinity. Elevated levels of salinity in either form caused a reduction in ear length, number of spikelets per ear, total grain yield and fertile tillers of all the genotypes but with quite differential behavior of the genotypes. Tolerant genotype displayed greater economic yield than the sensitive one. From the data, it appeared that osmotic rather than toxic component of salinity is a cripping factor in he reduced economic yield shown by the sensitive genotype. To conclude, B-90068 exhibited tolerance to salinity at all phonological growth stages and showed greater economic yield. This genotype is therefore suitable for growing in low to moderately saline areas, by enhancing seed rate by 20-25% to achieve optimum crop stand. It is expected that this study will be a baseline information for breeders to develop high yielding salts tolerant barley genotypes, and for botanists and plant physiologists to understand the physiological mechanisms of salt tolerance unsing advanced techniques.
Source: Ahmad, Abid Nisar (2002) COMPARATIVE RESPONSE OF BARLEY GENOTYPES TO CHLORIDE AND SULPHATE SALINITY. PhD thesis, University of Agriculture, Faisalabad