Nitrogen nutrition effects on triticale photosynthesis and assimilate translocation under late-season water stress conditions

In this study, photosynthesis and assimilate translocation and their contribution to improving grain yield and harvest index (HI) of triticale under different N sources and irrigation regimes in an arid climate were evaluated. There were two levels of water regimes: normal irrigation (IRN) and deficit irrigation (cutting irrigation after anthesis stage - IRD). Four N sources: Azospirillum brasilense (Bio), Azospirillum brasilense + 75 kg N ha−1 as urea (Bio + N75), 150 kg N ha−1 as urea (N150) and control unfertilized (N0) plots were used. Results showed the highest net photosynthesis rate (Pn) was observed in Bio + N75 (24 and 20 µmol CO2 m−2 s−1 at the milking and soft dough stages, respectively) under IRN. The IRD decreased Pn in all N sources, however, the highest reduction was observed in N150 and the lowest in Bio and Bio + N75 treatments. Similar trends were observed in other photosynthetic traits and assimilate remobilization, except for the instantaneous water use efficiency (IWUE), which increased by IRD when bio-fertilizer was applied. The highest grain yield was found by N150 under IRN, which was not significantly different from Bio + N75 treatment. In contrast, application of Bio + N75 resulted in the highest grain yield compared to the other N sources under IRD. Overall, since the lowest reduction in photosynthetic traits, assimilate remobilization, and grain yield of triticale under IRD conditions occurred when bio-fertilizer was applied, this N fertilizer regime could be recommended for the arid areas where water shortage occurs frequently.12 month embargo; published online: 28 June 2021This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu