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 (SOL Se ), and exchangeable Se (EXC Se ) 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 μg 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 CO 2 and stomatal conductance ( C i ), and g s 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.