The Resistance of Sunflower to the Attack of Some Pathogenic Agents in the Climate Conditions of the Northeast Baragan

Due to its national economic importance, the sunflower crop has established itself as the main oleaginous crop cultivated in Romania. It faces several diseases that are difficult to fight chemically. The creation of hybrids resistant to the attack of pathogens has proven to be an effective, safe, and environmentally friendly solution. This paper aims to examine the resistance of some biological sunflower creations created in Romania, to the attack of Phomopsis helianthi and Phoma macdonaldi fungi, in 2021. The experiment was placed in field conditions with a natural infestation, at A.R.D.S. Braila. The used biological material was represented by nine new sunflower hybrids. Two problem pathogens were studied: Phomopsis helianthi (perfect stage Diaporthe helianthi) and Phoma macdonaldi (perfect stage Leptosphaeria lindquistii). The climatic conditions of 2021 were favorable for the growth of the pathogens. Phoma macdonaldi had an average attack frequency of 38.8% and an average attack intensity of 1.71%, while Phomopsis helianthi recorded average values of 67.8% and 3.08%, respectively. The lowest attack degree of the Phoma macdonaldi pathogen was found in H3 (0.35%). Regarding the pathogen Phomopsis helianthi, the hybrid H3 showed good resistance, with an attack degree of 1.64%

Water-yield relations of maize (Zea mays L) in temperate climatic conditions

A field study was carried out from 2001 to 2007 in order to determine the water-yield relationship of maize in the Vojvodina region, a northern part of the Serbia Republic. The yield response factor (K-y) was calculated to express the response of maize to water stress both for the growing season and specific growth stages. To assess the effectiveness of irrigation on maize yield, an irrigation water use efficiency (I-WUE) and evapotranspiration water use efficiency (ETWUE) were determined. The study indicated that in the climatic conditions of Vojvodina maize is most sensitive to water stress in the flowering and pollination stage (K-y = 0.52), but less sensitive in the stages of vegetative gowth (K-y = 0.37), grain filling and maturity (K-y = 0.41). Values of yield response factor in the growing period (K-y = 0.54) indicated that maize is moderately sensitive to soil water stress in the temperate climatic conditions of Vojvodina. The I-WUE and ETWUE were in intervals of 0.47 to 3.00 kg m(-3) and 0.67 to 2.34 kg m(-3) respectively, mostly depending on the extent of favorable conditions of the season for maize production and irrigation water applied. The parameters K-y, I-WUE and ETWUE could be used by maize growers as a guide in the study region in terms of optimum utilization of irrigation water for the planning, design and operation of irrigation projects and for improving the production technology of the crop

Gene banks for wild and cultivated sunflower genetic resources

Modern breeding of sunflower (Helianthus annuus L.), which started 100 years ago, increased the number and the diversity of cultivated forms. In addition, for more than 50 years, wild sunflower and other Helianthus species have been collected in North America where they all originated. Collections of both cultivated and wild forms are maintained in gene banks in many countries where sunflower is an important crop, with some specificity according to the availability of germplasm and to local research and breeding programmes. Cultivated material includes land races, open pollinated varieties, synthetics and inbred lines. The majority of wild accessions are ecotypes of wild Helianthus annuus, but also 52 other species of Helianthus and a few related genera. The activities of three gene banks, in USA, France and Serbia, are described in detail, supplemented by data from seven other countries. Past and future uses of the genetic resources for environmental adaptation and breeding are discussed in relation to genomic and improved phenotypic knowledge of the cultivated and wild accessions available in the gene banks.L’amélioration moderne du tournesol (Helianthus annuus L.) a débuté il y a un siècle, diversifiant et augmentant le nombre des formes cultivées du tournesol. De plus, des collectes de tournesols sauvages et d’espèces du genre Helianthus ont lieu depuis 50 ans en Amérique du Nord d’où ils sont tous originaires. Ainsi, des collections de tournesols cultivés et sauvages sont conservées par des centres de ressources génétiques dans de nombreux pays où le tournesol est une culture importante. Chacun d’eux présente des spécificités par rapport aux ressources génétiques maintenues, en fonction des programmes de recherche ou de sélection variétale locales. Le matériel génétique cultivé comprend des écotypes, des populations et des lignées tandis que les accessions sauvages correspondent eux écotypes d’Helianthus annuus sauvages et des 52 autres espèces apparentées du genre Helianthus. Les activités de trois centres de ressources génétiques des États-Unis, de la France et de la Serbie sont décrites en détail, complétées par des données provenant des centres de sept autres pays. L’historique de l’utilisation des ressources génétiques et les perspectives futures pour l’adaptation des variétés à l’environnement sont discutés ainsi que leur caractérisation au niveau génomique et phénotypique.The Supplementary Material is available at [https://www.ocljournal.org/10.1051/ocl/2020004/olm]

Genetic resistance to sunflower broomrape (Orobanche cumana Wallr.)

Trabajo presentado en el Third Internacional Symposium on broomrape (Orobanche spp.) in Sunflower, celebrado en Córdoba (España) del 3 al 6 de junio de 2014.Orobanche cumana Wallr causes important economic damage in sunflower production in a number of countries around the world. Historically, breeders have been successful in developing cultivars resistant to this parasite, but the introduction of new resistance sources has been followed by the appearance of new pathogenic races overcoming resistance. Sunflower selection for broomrape resistance makes use of different methods for testing breeding materials, looks for resistance sources, and has so far produced significant results. Dominant genes for resistance to races A, B, C, D, E, and F have been found and incorporated into cultivated sunflower genotypes. However, in the last fifteen years, new broomrape populations are being discovered for which very limited or none of the existing commercial hybrids have proven to be resistant. In this review, we will focus on recent contributions on breeding for broomrape resistance, including the identification and characterization of new sources and mechanisms of resistance, their the genetic and molecular characterization, and also recent research about important aspects on the parasite side. Additionally, we will discuss the need of long term strategies involving (i) the complete host-parasite system and the integration of classical and molecular approaches, (ii) international cooperation to establish a common designation of the new races of the parasite and genes for resistance in different countries, and (iii) a greater level of collaboration between breeders from public institutions and private companies, which will all contribute to the development of more durable sources of resistance.N

Broomrape (Orobanche cumana Wallr.), the most important parasite in sunflower crop in Romania

Broomrape (Orobanche cumana Wallr.) is a parasitic angiosperm that has been causing a great deal of damage to sunflower production for more than a century. There has been a constant tug-of-war between sunflower breeders and Orobanche cumana, with frequent changes in which side has the upper hand. Almost as soon as the breeders find a source of resistance to the latest race of the parasite, broomrape responds by evolving another virulent race. Russian researchers identified the first two races of this parasite (A and B), after that, being identified other four races (C, D, E and F) as well as the sunflower differentials carrying the dominant genes for resistance, by the researchers in Romania and Spain. In the last years, some authors have communicated the appearance of the new, very virulent populations of broomrape, in different regions cultivated with sunflower, over the world. Sunflower selection for broomrape resistance makes use of different methods for testing breeding materials (in the field or in greenhouse), looks for resistance sources and has so far produced significant results. Dominant genes for resistance to races A, B, C, D, E and F have been found and incorporated into cultivated sunflower genotypes. The resistant hybrids having resistance to the broomrape populations more virulent than race F have been produced by incorporating genes of resistance, coming specially from wild Helianthus species. The aim of our investigation was to compare the virulence of broomrape samples collected in different areas cultivated with sunflower and infested with broomrape, from Romania. The same, we studied the dissemination of these populations in time and territory, in relation with different sunflower resistant genotypes. It was evaluated the influence of the parasite populations on the sunflower hybrids seed yield. Ten populations of broomrape collected from different locations in Romania have been used in the artificial infestation conditions, for establishing the presence of different broomrape (Orobanche cumana Wallr.) races in these areas. The broomrape samples were stored in saved conditions and used for artificial infestation in the green house and phytotron. There have been tested sunflower differentials for the broomrape races until the sixth one and, different hybrids with different resistance to the newest virulent populations of the parasite. Results of evaluation of sunflower differentials for different races or populations of the parasite Orobanche cumana have demonstrated that in Romania, the three more spread broomrape populations in the largest area cultivated with sunflower, are very different regarding the virulence and dissemination of the parasite. The influence of the parasite on sunflower seed yield was very high, depending by the hybrid type of resistance

Agroecology of broomrape Orobanche cumana distribution in five continents

Trabajo presentado en el Third Internacional Symposium on broomrape (Orobanche spp.) in Sunflower, celebrado en Córdoba (España) del 3 al 6 de junio de 2014.The factors associated with the distribution of parasitic weed Orobanche cumana Wallr. (Broomrape), limiting sunflower production in Europe and the surrounding continents of Asia and Africa, have not been adequately investigated. The goals of this study were to broaden the understanding of environmental factors associated with broomrape’ distribution in Europe, and to predict suitable habitats based on environmental factors which would be vulnerable to invasion and establishment of broomrape in North and South America. A robust agroecological database included 35 quantitative parameters associated with trials conducted by ten public research organizations from five continents. The database consisted of 117 sites (habitats), Europe (79), Africa (3), Asia (6), and Americas (29), equally distributed between invaded and non- invaded habitats. Environmental parameters analyzed using an ANOVA and PCA showed that all sunflower areas from Europe were vulnerable to broomrape attack. The parasitic weed develops in soil and climate environmental conditions similar to non-invaded areas. Its expansion to nearby areas of the Africa and Asia continents seems to indicate a broadening of the environmental conditions to which the parasitic weed can tolerate. Habitat conditions of sunflower crop areas in South America showed more similarity to invaded habitats than North America. The absence of the ability to predict actual broomrape distribution based on environmental factors enforces the need to use cultural practices of crop rotation and genetic resistance in infected areas. Strict phytosanitary controls need to be enforced to prevent the inadvertent introduction into non-infected areas and its spread in infected areas.This work is a part of the projects TR31025, Ministry of Education, Science and Technological Development of Republic of Serbia, and PNCyO 112745, Instituto Nacional de Tecnología Agropecuaria, Argentina.N

History of the race structure of Orobanche cumana and the breeding of sunflower for resistance to this parasitic weed: A review

<p class="Default">Broomrape, caused by <em>Orobanche cumana</em>, has affected sunflowers since the early 20^th century in Eastern Europe. Currently, it limits sunflower oil production in Southern and Eastern Europe and in some areas of Asia, causing around 50% seed losses when susceptible hybrids are grown. Covered in this review are aspects such as: biological processes that are common to <em>Orobanche</em> spp. and/or particular to <em>O. cumana</em> in sunflower, genetic resistance and its mechanisms, races of the parasite identified in different countries throughout the time and their increasing virulence, and breeding for resistance to some herbicides as a novel control option. The main purpose is to present an updated and, as far as possible, complete picture of the way both the parasitic weed and its host crop have evolved in time, and how they co-exist in the current agriculture. Additionally, we propose a system for determining the races of the parasite that can be internationally adopted from now. In the context of minimal harmful effects on the environment, changing patterns of land use in farming systems, and global environment changes, the final goal of this work is to provide all those interested in parasites from field crops and their integrated management compiled information on the sunflower – <em>O. cumana</em> system as a case study.</p