Effects of Nitrogen Application Amount on Soil Selenium Speciations, Physiological Characteristics and Yield of Triticales in Selenium-Enriched Area

Selenium (Se) biofortified wheat could enhance human health by providing essential Selenium. Different nitrogen application rates (0, 60, 120, 180, 240 and 300 kg N ha(-1)) on soil Se speciations and contents, the differences of Se accumulation and yield of triticales were investigated. The concerntration of total Se, water-soluble Se (SOLSe), and exchangeable Se (EXCSe) in 0-20 cm and 20-40 cm soil layers showed an increasing trend from anthesis to maturity, and decreasing tendency as nitrogen application increasing. TZ-8293 compared to TH-3 exhibited the highest grain Se content and accumulation at the maturity, measured 77.00 mu g kg(-1) and 73.11%, respectively. Compared to the control, the concentration of flour Se in TH-3, and TZ-8293 under the 240 kg N ha(-1) treatment significantly increased by 90.97 and 91.67%, respectively, and the yield of TH-3 under 240 kg N ha(-1) treatment was significantly the highest, measuring 7889.84 kg ha(-1). Following anthesis, net photosynthetic rate (P-n) showed an significantly increasing tendency with the application of nitrogen increased, however, transpiration rate (T-r), intercellular CO2 and stomatal conductance (C-i), and gs in flag leaf decreased significantly with the increase of nitrogen application rate. The correlation analysis showed that there were (extremely) significant negative correlations among Se content, yield and yield components (-0.30 <= R-2 <= -0.89), excessive nitrogen application may hinder the formation of soil available Se, which can have a negative impact on the absorption of Se, finally impede the biofortification of Se in triticale. In conclusion for locally Se-enriched triticale cultivation, it was recommended to apply nitrogen fertilizer rate of 120-240 kg N ha(-1) on TH-3.