Effect of salinity on the cotton cultivation and introduction of Amaranthaceae halophytes in the Yellow River Delta, China.

Abstract Cotton is a main cash crop in the Yellow River Delta in China. Although cotton is known for its high salt tolerance, cotton yield is severely affected by excessive salt accumulation in soil. A large amount of the Yellow River water is introduced annually to leach surface salts; however, it has limited effects due to poor soil physical quality. In this study, we aimed to investigate the impact of soil salinity on cotton growth and the viability of Amaranthaceae halophytes as alternative crops. Cotton and Amaranthaceae plants, including Suaeda salsa, Kochia scoparia, swiss chard, table beets and spinach, were planted in a large field in the Yellow River Delta that had spatial differentiation in terms of soil electrical conductivity (EC). Our analysis on soil revealed that Na+ was the major cause of high EC; however, soil alkalization was not observed in highly salinized areas. Cotton biomass showed a strong negative correlation with soil EC. Although all tested Amaranthaceae plants also decreased biomass in high EC areas, this effect was clearly less pronounced in S. salsa and K. scoparia. To our surprise, levels of major (K+, Ca2+ and Mg2+) or minor (Fe2+, Mn2+, Zn2+ and Cu2+) essential elements were not significantly affected by soil EC in all plant species, suggesting that ion imbalance was not the main factor of growth reduction. All Amaranthaceae halophytes absorbed more Na+ but less Ca2+ than cotton, thus it would be possible that Amaranthaceae plants function better than cotton in terms of maintaining soil quality.