Changes of photosynthesis and nitrogen metabolism in Cicer arietinum L. grown in the presence of foliar-applied proline

The leaf of Cicer arietinum L. was sprayed with different concentrations (0, 10, 20, 30, 40 or 50 mM) of proline at 30 days after sowing (DAS). A lower concentration (20 mM) proved to be the best, and significantly enhanced the growth characteristics of plants. This concentration of proline also enhanced the nodulation and nitrogen fixing efficiency of plants. A significant increase of 19.3, 33.3, 41.4, 27.2 and 46.5% in the activity of the enzymes glutamine synthetase, glutamate synthase, glutamate dehydrogenase, nitrate reductase and carbonic anhydrase, respectively, was observed. The treatment also enhanced gas exchange parameters by 21.4% (stomatal conductance), 25.3% (internal CO2 concentration), 76.3% (water use efficiency), 29.1% (transpiration rate) and 50.3% (net photosynthetic rate) over control.