Stunting in 'Gigas' Wheat as Influenced by Temperature and Daylength

Abstract

When plants of the uniculm 'gigas' wheat line 492 were grown at 15/ 10°C, all plants were severely stunted in long days (LD) but normal in short days (SD). The results of reciprocal transfers between SD and LD indicate that line 492 plants pass through a stage which is very sensitive to LD at 15/ 10°C, between about 14 and 27 days after sowing, just before double ridge formation at the shoot apex. LD during that interval caused stunting in most plants whereas SD at that stage allowed all plants to develop normally. Transfers between temperature regimes of 15/10°C and 24/19°C under LD also indicated that the period just prior to double ridge formation was critical for stunting. In the uniculm line 492 stunting in LD was caused by temperature regimes cooler than 21 /16°C;, whereas in the oligoculm line 380 the main shoots of most plants were normal even at 15/ 10°C.