Warmer Nights During Early Stages Affect Wheat Development Without Grain Yield Penalty

This study analyses the impact of higher night temperature during the tillering phase on grain yield, focusing on crop development and tiller production dynamics in wheat (Triticum aestivum L.). Field experiments were carried out at the School of Agriculture, Buenos Aires, Argentina during the 2015 and 2016 growing seasons and combined: (1) two nitrogen availability levels (60 and 200 kg N ha(-1)) and (2) two night temperature conditions (control unheated and night temperature increase (NTI) during the tillering phase). The heating treatment increased night temperature similar to 2.3 degrees C above the ambient night temperature. Across growing seasons, average minimum temperature during the tillering phase ranged from 8.5 degrees C to 12.4 degrees C. Warmer nights reduced time to anthesis (similar to 4 days) due to a shortening in the duration of the tillering phase. NTI did not modify the maximum tiller number at plant level or per unit area. Higher N availabilities increased maximum tiller number similar to 30% compared with low N levels. Increased night temperature did not modify (P = 0.3418) grain yield in high and low N availabilities. Although development during the tillering phase was accelerated, the NTI during this stage would have a minor impact on both tillering and yield and its numerical components.