Responses of Barley to High Ambient Temperature Are Modulated by Vernalization

Abstract

Ambient temperatures are increasing due to climate change. Cereal crops development and production will be affected consequently. Flowering time is a key factor for adaptation of small grain cereals and, therefore, exploring developmental responses of barley to rising temperatures is required. In this work, we studied phasic growth, and inflorescence traits related to yield, in eight near isogenic lines of barley (<i>Hordeum vulgare</i> L.) differing at the <i>VRN-H1</i>, <i>VRN-H2</i> and <i>PPD-H1</i> genes, representing different growth habits. The lines were grown in contrasting vernalization treatments, under two temperature regimes (18 and 25°C), in long days. Lines with recessive <i>ppd-H1</i> presented delayed development compared to lines with the sensitive <i>PPD-H1</i> allele, across the two growth phases considered. High temperature delayed flowering in all unvernalized plants, and in vernalized spring barleys carrying the insensitive <i>ppd-H1</i> allele, whilst it accelerated flowering in spring barleys with the sensitive <i>PPD-H1</i> allele. This finding evidenced an interaction between <i>PPD-H1</i>, temperature and vernalization. At the high temperature, <i>PPD-H1</i> lines in spring backgrounds (<i>VRN-H1-7</i>) yielded more, whereas lines with <i>ppd-H1</i> were best in <i>vrn-H1</i> background. Our study revealed new information that will support breeding high-yielding cultivars with specific combinations of major adaptation genes tailored to future climatic conditions.