Abstract

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 (IR_N) and deficit irrigation (cutting irrigation after anthesis stage - IR_D). 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 (P_n) was observed in Bio + N₇₅ (24 and 20 µmol CO₂ m⁻² s⁻¹ at the milking and soft dough stages, respectively) under IR_N. The IR_D decreased P_n 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 IR_D when bio-fertilizer was applied. The highest grain yield was found by N₁₅₀ under IR_N, 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 IR_D. Overall, since the lowest reduction in photosynthetic traits, assimilate remobilization, and grain yield of triticale under IR_D conditions occurred when bio-fertilizer was applied, this N fertilizer regime could be recommended for the arid areas where water shortage occurs frequently.

摘要

本研究评估了干旱气候下不同氮源和灌溉制度下小黑麦的光合作用和同化物易位及其对提高小麦产量和收获指数（HI）的贡献。有两个水平的水情：正常灌溉（IR _N）和亏缺灌溉（花期后切割灌溉 - IR _D）。四种氮源：巴西固氮螺菌(Bio)、巴西固氮螺菌 + 75 kg N ha ^-1作为尿素 (Bio + N ₇₅ )、150 kg N ha ^-1作为尿素 (N ₁₅₀ ) 和对照未施肥 (N ₀ ) 地块. 结果显示净光合速率最高（P_n )在 IR _N下在 Bio + N ₇₅（在挤奶和软面团阶段分别为24 和 20 µmol CO ₂ m ^-2 s ^-1）中观察到。IR _D在所有 N 源中都降低了P _n，然而，在 N ₁₅₀中观察到的降低幅度最大，在 Bio 和 Bio + N ₇₅处理中观察到的最低。除了瞬时水分利用效率 (IWUE) 外，其他光合特性和同化物再动员也观察到了类似的趋势，当施用生物肥料时，瞬时水分利用效率 (IWUE) 会因 IR _D增加。IR _N下的 N ₁₅₀粮食产量最高，这与 Bio + N ₇₅处理没有显着差异。相比之下，在 IR _D下，与其他氮源相比，Bio + N _{75 的应用}导致最高的谷物产量。总体而言，由于施用生物肥料时，IR _D条件下小黑麦的光合性状、同化物再动员和谷物产量降低最少，因此可以推荐这种氮肥方案用于经常缺水的干旱地区。