Temperature, water and fertilizer influence the timing of key events during grain development in a US spring wheat

Controlled environments were used to define the manner in which temperature, water and fertilizer affect the timing of key transition points during grain development and to investigate the effects of combined environmental factors in a US spring wheat (Triticum aestivum (L.)). When plants were subjected to very high temperature regimens (37/17 or 37/28degreesC day/night) during grain development, the times to maximum kernel water content, maximum dry weight and hay-vest maturity were shorter than in plants maintained under a 24/17 degreesC day/night regimen. Starch accumulated at similar rates, but the onset and cessation of starch accumulation occurred earlier. Apoptosis in endosperm tissue also occurred earlier under high temperatures and coincided with physiological maturity. The addition of drought to the 37/17 degreesC regimen further shortened the time to maximum water content and dry weight and reduced the duration of starch accumulation, but did not influence the timing of protein accumulation or kernel desiccation. Post-anthesis fertilizer had little effect on time to maximum water content, dry weight, apoptosis, or harvest maturity under any of the temperature regimens and did not influence the timing of starch accumulation. However, both the rate and duration of protein accumulation were reduced when post-anthesis fertilizer was omitted. (C) 2003 Published by Elsevier Science Ltd.