Nitrogen deposition enhanced productivity of sweet sorghum (Sorghum bicolor L.) in the arid region of China

Terrestrial ecosystems worldwide are experiencing increasing atmospheric nitrogen (N) deposition because of fossil-fuel combustion and fertilizer applications. As a C₄ feed crop, sweet sorghum (Sorghum bicolor L.) is widely used in the arid region of China since its high sugar content, good palatability and high yield. However, impacts of atmospheric N deposition on production of sweet sorghum are poorly understood in arid land ecosystems where soils are typically low in plant available N. At Hui Autonomous Region, Ningxia, China, a complete random block design was used to study the effects of four levels of N additions (45, 169, 197, and 224 kg ‍‌‌‍ha^-1 year^-1) on sorghum, node number, stem diameter, leaf number, plant height, yield per plant, dry matter, and sugar Brix of stem. Nitrogen application significantly affected the above parameters. When the amount of N applied was 224 kg ‍‌‌‍ha^-1 year^-1, the plant height (mean ± standard deviation, 256.9 cm ± 10.7, n=9), stem diameter (16.9 mm ± 1.1 ,n=9), number of leaf (10.8 ± 1.3, n=6) and node (4.9 ± 0.4, n=9), and dry matter per unit area (1.48 t ha^-1 ± 0.3, n=9) was highest. While N application did not affect sugar Brix of stem. Therefore, N deposition plays a linearly positive role in enhancing the productivity of sweet sorghum in the arid region of China.

Keywords: Agronomic traits, C₄ plant, Feed crop, Nitrogen addition