The effect of responses to vernalization, photoperiodism, and earliness per se of barley accessions from Dagestan on the duration of the period from shooting to heading

Background. Paratypic variability of the development rates of barley accessions from the Republic of Dagestan was analyzed for five years in the Northwe st of Russia (Pushkin, St. Petersburg) and in the North Caucasus (Derbent, Dagestan). Responses to vernalization, photoperiodism and earliness per se were tested in contrasting environments to assess their effect on barley development. Such studies make it possible to identify valuable adaptable plant forms in the barley germplasm collection for further use in breeding practice.Materials and methods. In Dagestan, the duration of the period from shooting to heading was measured for 12 samples of barley accessions in winter and spring sowing trials. Twenty samples sown in spring in both regions were compared. An empirical indicator of plant development rate was used for barley: the criterion “the number of days by which the period from shooting to heading of an accession exceeds the minimum across a sample” (DPSH).Results and conclusions. Early barley accessions with a low norm of responsiveness were identified: k-3772, k-15013, k-15034, k-15036, k-15186, k-15192, k-21803 and k-23785 – they combined weak sensitivity to a short photoperiod and vernalizing temperatures, so they are promising for breeding in regions where the length of the growing season is a limiting factor. The effect of the responses of barley accessions from Dagestan to vernalization and a short photoperiod on the duration of the period from shooting to heading was on average 8 (5.1–10.6) days and on their earliness per se 6 (4.8–8.2) days. Paratypic variability reflects the range of variation for these indicators. In Dagestan, vernalization temperatures and insensitivity to a short day are the main factors determining the earliness of local barleys in their native environment.

Genetic and Management Effects on Barley Yield and Phenology in the Mediterranean Basin

Heading time in barley is considered a key developmental stage controlling adaptation to the environment and it affects grain yield; with the combination of agronomy (planting dates) and genetics being some of the determinants of adaptation to environmental conditions in order to escape late frost, heat, and terminal drought stresses. The objectives of this study are (i) to apply a gene-based characterization of 118 barley doubled haploid recombinants for vernalization, photoperiod, and earliness per se; (ii) use such information to quantify the optimal combination of genotype/sowing date that escapes extreme weather events; and (iii) how water and nitrogen management impact on grain yield. The doubled haploid barley genotypes with different allelic combinations for vernalization, photoperiod, and earliness per se were grown in eight locations across the Mediterranean basin. This information was linked with the crop growth model parameters. The photoperiod and earliness per se alleles modify the length of the phenological cycle, and this is more evident in combination with the recessive allele of the vernalization gene VRN-H2. In hot environments such as Algeria, Syria, and Jordan, early sowing dates (October 30 and December15) would be chosen to minimize the risk of exposing barley to heat stress. To maintain higher yields in the Mediterranean basin, barley breeding activities should focus on allelic combinations that have recessive VRN-H2 and EPS2 genes, since the risk of cold stress is much lower than the one represented by heat stress.

Earliness per se×temperature interaction: consequences on leaf, spikelet, and floret development in wheat

Wheat adaptation can be fine-tuned by earliness per se (Eps) genes. Although the effects of Eps genes are often assumed to act independently of the environment, previous studies have shown that they exhibit temperature sensitivity. The number of leaves and phyllochron are considered determinants of flowering time and the numerical components of yield include spikelets per spike and fertile floret number within spikelets. We studied the dynamics of leaf, spikelet, and floret development in near isogenic lines with either late or early alleles of Eps-D1 under seven temperature regimes. Leaf appearance dynamics were modulated by temperature, and Eps alleles had a greater effect on the period from flag leaf to heading than phyllochron. In addition, the effects of the Eps alleles on spikelets per spike were minor, and more related to spikelet plastochron than the duration of the early reproductive phase. However, fertile floret number was affected by the interaction between Eps alleles and temperature. So, at 9 °C, Eps-early alleles had more fertile florets than Eps-late alleles, at intermediate temperatures there was no significant difference, and at 18 °C (the highest temperature) the effect was reversed, with lines carrying the late allele producing more fertile florets. These effects were mediated through changes in floret survival; there were no clear effects on the maximum number of floret primordia.