The influence of a spring habit gene, Vrn-D1, on heading time in wheat

The adaptability of wheat cultivars to environmental conditions is known to be associated with a vernalization requirement, that is, spring/winter habit. To clarify the genetic effect of the spring habit gene, Vrn‐D1, on heading time in the field, recombinant inbred lines (RILs) with or without the Vrn‐D1 gene were produced from F₂ plants of the cross between ‘Nanbukomugi’ and ‘Nishikazekomugi’, non‐carrier and carrier cultivars of this gene, respectively. Using growth chambers with a controlled temperature and photoperiod, three components of heading time, i.e. vernalization requirement, photoperiodic sensitivity and narrow‐sense earliness (earliness per se), were evaluated in each RIL. RILs with the Vrn‐D1 gene (E lines) showed greatly reduced vernalization requirements and slightly shorter narrow‐sense earliness than RILs without Vrn‐D1 (L lines), although no difference in photoperiodic sensitivity was observed between the two groups. RILs were planted at four different sites in Japan and examined for their heading time in the field. E lines headed significantly earlier than L lines at all locations, indicating that the earliness of E lines is stable in various environmental conditions. These results indicated that spring habit caused by Vrn‐D1 gene, as well as narrow‐sense earliness, was responsible for heading time in the field.