Variation for carbon isotope ratio in a set of emmer (Triticum dicoccum Schrank) and bread wheat (Triticum aestivum L.) accessions

A high level of drought tolerance is an important objective in breeding new generation wheat varieties. A group of six landraces of the emmer wheat (Triticum diccocum Schrank), as well as two landraces, two old cultivars and two modern varieties of bread wheat (Triticum aestivum L.) were evaluated for their ability to discriminate 13C, a trait related to stomatal closure and consequently, an important component tolerance to drought. Three emmer wheat landraces and one of the bread wheat landraces has the lowest. Therefore, emmer wheat may play the role of a donor of the tolerance to drought in wheat breeding programs targetting drought prone conditions.Key words: Emmer wheat, bread wheat, drought tolerance, carbon isotope ratio, discrimination

Agronomic characteristics of the spring forms of the wheat landraces (einkorn, emmer, spelt, intermediate bread wheat) grown in organic farming

Organic farmers look to the possibilities of growing neglected crops, such as the spring forms of hulled wheat – einkorn, emmer and spelt – for support in developing the organic farming system. In 2008, 169 landraces from the gene bank at the Crop Research Institute in Prague were tested on certifi ed organic plots. The experiment was aimed at fi nding suitable varieties for the organic farming system. In summary, our fi ndings show that einkorn (Triticum monococcum L.) and emmer wheat [Triticum dicoccum Schrank (Schuebl)] are resistant to powdery mildew and brown rust, spelt wheat (Triticum spelta L.) is less resistant to these two diseases, and the intermediate forms of bread wheat are very sensitive to such infestation. The varieties evaluated incline to lodging, as they have long and weak stems. Einkorn and emmer wheat have short and dense spikes and a low thousand grains weight, whereas spelt wheat has long and lax spikes. The level of the harvest index is low. Potentially useful varieties were found during the fi eld experiment and evaluation, and our future efforts will therefore focus on improving resistance to lodging and increasing the productivity of the spike

Habitats as predictors in species distribution models: Shall we use continuous or binary data?

The representation of a land cover type (i.e. habitat) within an area is often used as an explanatory variable in species distribution models. However, it is possible that a simple binary presence/absence of the suitable habitat might be the most important determinant of the presence/absence of some species and, thus, be a better predictor of species occurrence than the continuous parameter (area). We hypothesize that the binary predictor is more suitable for relatively rare habitats (e.g. wetlands) while for common habitats (e.g. forests) the amount of the focal habitat is a better predictor. We used the Third Atlas of Breeding Birds in the Czech Republic as the source of species distribution data and CORINE Land Cover inventory as the source of the landcover information. To test our hypothesis, we fitted generalized linear models of 32 water and 32 forest bird species. Our results show that for water bird species, models using binary predictors (presence/absence of the habitat) performed better than models with continuous predictors (i.e. the amount of the habitat); for forest species, however, we observed the opposite. Thus, future studies using habitats as predictors of species occurrences should consider the prevalence of the habitat in the landscape, and the biological role of the habitat type in the particular species' life history. In addition, performing a preliminary comparison of the performance of the binary and continuous versions of habitat predictors (e.g. using information criteria) prior to modelling, during variable selection, can be beneficial. These are simple steps that will improve explanatory and predictive performance of models of species distributions in biogeography, community ecology, macroecology and ecological conservation

Drought tolerance of land races of emmer wheat in comparison to soft wheat

As water deficiency becomes a more frequent cause of the reduction in wheat yield levels, the search for donors of drought tolerance to be bred into adapted land races becomes urgent. Drought tolerance has been evaluated by the 13 C discrimination method in six land races of emmer wheat ( Triticum dicoccum SCHRANK), compared with land races, obsolete cultivars and modern varieties of soft wheat ( Triticum aestivum L.). The results of a two-year trial show that most of the genetic resources of emmer wheat, and intermediate land races of wheat are predisposed to drought tolerance. These varieties respond to dry conditions more sensitively, as they close their pores earlier (a lower value of the discrimination of 13 C isotope). As for other land races and the top modern varieties of soft wheat, they are not thought to be predisposed to drought tolerance and their crop stands are liable to serious damage

Diversity of carbon isotope discrimination in genetic resources of wheat

Strong drought tolerance is an important objective in breeding new wheat varieties. We compared the drought tolerance of land races and modern varieties of various spring wheat forms. 13C discrimination (CID) indicated how significantly the tested wheat varieties were inclined to drought tolerance. CID is a trait related to stomatal closure and consequently an important component of the tolerance to drought. Samples were grown in České Budĕjovice (CZ), from 2009 to 2012. Twenty-three varieties, comprising einkorn, emmer, spelt, land races and control variety of bread wheat were grown and tested. Results have shown some varieties achieved low CID values (which meant they were more inclined to the drought tolerance). There were emmer and spelt varieties among them in particular. The spelt varieties which were inclined to the drought tolerance most significantly were — Triticum spelta No. 8930, Tabor 23 and Tabor 22. The emmer varieties called May-Emmer and Weisser Sommer were also inclined to drought tolerance significantly. By contrast, the intermediate forms, the modern (control) varieties of bread wheat, and einkorn varieties, were expected to be less tolerant to drought as well. Some of the wheat land races (the spelt and the emmer in particular) reached low values of CID. Therefore, they can play the role of drought tolerance donors in the wheat breeding programmes

Unmanned aerial systems-based monitoring of the eco-geomorphology of coastal dunes through spectral Rao's Q

International audienceQuestion: Does spectral diversity captured by unmanned aerial systems (UAS) provide reliable information for monitoring the eco-geomorphological integrity of Mediterranean coastal dune ecosystems? Can this information discriminate between two coastal areas with low (LP) and high (HP) human pressure? Location: Tyrrhenian coast, Central Italy. Methods: By processing UAS images, we derived the normalized difference vegetation index (NDVI) and topographic variables at high spatial resolution (0.5 m) for 150 m wide strips starting from the coastline inland on two representative coastal tracts under low and high human pressure. We mapped the sea–inland heterogeneity applying Rao's Q index to the plant biomass (NDVI) and geomorphology variables (elevation and slope). Since Rao's Q index can be calculated in a multidimensional space, we summarized the variability of these three variables into a single eco-geomorphological layer. We then inspected and compared how the Rao's Q index values for plant biomass, geomorphology and eco-geomorphology change as a func-tion of the distance from the sea between the two coastal sites. Results: Rao's Q heterogeneity values vary along the sea–inland gradient of well-preserved sites (LP). The maximum eco-geomorphological heterogeneity was found at intermediate distances from the sea and decreased toward the inner sector where the dune geomorphology was more stable and vegetation more homogeneously dis-tributed. Instead, Rao's Q heterogeneity values featured constant low values along the gradient on the HP site, highlighting a simplified eco-geomorphological gradient related to the high human pressure. Conclusions: Using UAS, the eco-geomorphological gradient of coastal dunes can be quantified at a very fine spatial resolution over management-relevant extents. Rao's Q index applied to sensing imagery successfully captured the differences in the eco-geomorphological heterogeneity along the sea–inland dune gradient and among sites with different levels of anthropic pressure. This approach supports frequent surveys and is particularly suitable for spatial monitoring of key coastal functions and services. © 2021 International Association for Vegetation Science