Seasonal variation in natural abundance of δ<sup>13</sup>C and <sup>15</sup>N in <i>Salicornia brachiata</i> Roxb. populations from a coastal area of India

<p>High and fluctuating salinity is characteristic for coastal salt marshes, which strongly affect the physiology of halophytes consequently resulting in changes in stable isotope distribution. The natural abundance of stable isotopes (δ<sup>13</sup>C and δ<sup>15</sup>N) of the halophyte plant <i>Salicornia brachiata</i> and physico-chemical characteristics of soils were analysed in order to investigate the relationship of stable isotope distribution in different populations in a growing period in the coastal area of Gujarat, India. Aboveground and belowground biomass of <i>S. brachiata</i> was collected from six different populations at five times (September 2014, November 2014, January 2015, March 2015 and May 2015). The δ<sup>13</sup>C values in aboveground (−30.8 to −23.6 ‰, average: −26.6 ± 0.4 ‰) and belowground biomass (−30.0 to −23.1 ‰, average: −26.3 ± 0.4 ‰) were similar. The δ<sup>13</sup>C values were positively correlated with soil salinity and Na concentration, and negatively correlated with soil mineral nitrogen. The δ<sup>15</sup>N values of aboveground (6.7–16.1 ‰, average: 9.6 ± 0.4 ‰) were comparatively higher than belowground biomass (5.4–13.2 ‰, average: 7.8 ± 0.3 ‰). The δ<sup>15</sup>N values were negatively correlated with soil available P. We conclude that the variation in δ<sup>13</sup>C values of <i>S. brachiata</i> was possibly caused by soil salinity (associated Na content) and N limitation which demonstrates the potential of δ<sup>13</sup>C as an indicator of stress in plants.</p>