Effect of Salinity and Molybdenum Application on Photosynthesis, Nitrogenase Activity and Yield of Barley Inoculated with Azosprillium brasilense
In order to evaluate the effect of Azosprillium inoculation and molybdenum application on common barley grown in saline condition, a greenhouse experiment was conducted at Azad university, branch of Eghlid, Iran. The experimental design was factorial based on complete randomized design with four replications. The first factor comprised of four salinity treatments (1 as control, 5, 10 and 15 ds m−1), second factor comprised the levels of Mo application (1: treated and 2: untreated = control) and the third factor included two levels of Azosprillum inoculation (inoculated and uninoculated = control). The measured parameters were chlorophyll fluorescence, photosynthesis (Ps) rates, carbohydrates, nitrate, ammonium and protein content, nitrogenase activity, grain yield (GY) and yield components. The results showed that salinity decreased GY in all levels. GY reduction in inoculated treatment was lower (12.9%) than uninoculated treatment (29.7%). GY reduction was highly related to the reduction of grain number (GN) rather than reduction in ear mX2. Inoculation and application of Mo reduced harmful effects of salinity especially on mean kernel weight and grain number. Soluble saccharides and protein contents increased with increasing salinity. Inoculation and Mo application significantly increased the content of fructan and sucrose respectively. The mean values of Fv/Fm and photosynthesis rate reduced in the salinity treatments compared to the control. Inoculation and Mo application significantly increased photosynthesis rates at all salinity levels. The highest plant N content was obtained from inoculated, control salinity treatment by applying Mo. In inoculated barley roots with application of Mo, nitrogenase activity (NA) was not severely inhibited by salinity. Data also showed that Mo application positively affected nitrogenase activity. Inoculation, caused plant to cope on the stress, effectively by increasing fructan content and NO3 /NH4 ratio and lower decrease in whole plant N content and Fv/Fm ratio. Generally, Azosprillium inoculation helped plants perform better under salinity treatments and Mo application ameliorated plant nitrogen status.
KeywordsNaCl dry matter photosynthesis efficiency root inoculation potassium molybdate
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