Influence of sulfur supply, ammonium nitrate ratio, and arbuscular mycorrhizal colonization on growth and composition of Chinese chive

Tissue concentrations of phytochemicals formed by Allium species may be influenced by plant nutrient supply or rhizosphere microorganism activity. To test these relations, three plant nutritional factors were varied in two experiments with Chinese chive [Allium tuberosum]: (a) increasing sulfur concentrations in the substrate, (b) two ratios of ammonium to nitrate in supply, and (c) inoculation with arbuscular mycorrhizal (AM) fungi. Shoot dry weight, nutrient composition (nitrate, N, P, S), and organosulfur compounds (measured indirectly as pyruvic acid) were determined.In the first experiment, the supply of intermediate sulfur compared to low sulfur supply resulted in increased shoot dry weight and pyruvic acid concentrations. A further increase in sulfur supply increased plant pyruvic acid production in the absence of effects on dry weight.In the second experiment, AM fungi hardly increased shoot dry weight, nutrient, or pyruvic acid concentrations significantly. Pyruvic acid concentration was increased at an ammonium:nitrate ratio of 50:50 compared to a ratio of 5:95, whereas shoot dry weight was not significantly different. We conclude that both, supply of surplus sulfur or supply of equal amounts of ammonium and nitrate, can contribute to the production of high amounts of health related organosulfur compounds in Chinese chive.

► Three S levels, two NH4+:NO3− ratios, and AM fungi were tested on Chinese chive.
► Intermediate S was sufficient for optimal growth of Allium tuberosum.
► Increasing S concentration in the substrate increased organosulfur compounds.
► AM fungi decreased organosulfur compounds.
► Highest yield of organosulfur compounds was produced at NH4+:NO3− ratio of 50:50.