REACTION OF SUNFLOWER GENOTYPES TO THERMAL STRESS CONDITIONS IN THE SANDY SOILS AREA OF SOUTHERN OLTENIA

The researches carried out during 2016-2017 at RDCSPS Dabuleni aimed at the behavior of biological sunflower material, created at NARDI Fundulea, under conditions of thermal water stress from the sandy soils in southern Oltenia. The results obtained at 109 sunflower genotypes underline the favorability of Romania's southern area for sunflower culture. It showed significantly distinct positive correlation between the rate of  photosynthesis in the plant, and photosynthetic active radiation (r = 0.282 **) as well as between foliar sweating rate and leaf surface temperature (0.412 **). The production was differentiated according to the genotype and the climatic conditions of the agricultural year, ranging from 2299-5180 kg / ha, with an average of 4307 kg / ha

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

Broomrape, caused by Orobanche cumana, has affected sunflowers since the early 20th 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 Orobanche spp. and/or particular to O. cumana 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 – O. cumana system as a case study

Characterization of post‐haustorial resistance to sunflower broomrape

The development of durable resistance to broomrape (Orobanche cumana Wallr.) in sunflower (Helianthus annuus L.) requires detailed characterization of the genetic and physiological bases of resistance. The objective of the present study was to map the resistance gene accurately, and to characterize the mechanism of resistance to broomrape observed in a sunflower inbred line (PHSC1102). PHSC1102, which was consistently resistant against race F and race G populations of broomrape, was crossed with PHSC1201, which was susceptible to races F and G. A mapping population of 150 F2 genotypes was phenotyped by evaluating F2:3 families for resistance to broomrape races FGV and GTK. The use of single nucleotide polymorphism (SNP) markers mapped the OrSII gene to Linkage Group 4 (LG4) of the sunflower genome. Mini‐rhizotron and histological studies of the resistant line revealed that the attachment of broomrape to host roots was similar in both the resistant and susceptible lines and that the resistance was observed at a late stage (i.e., after tubercle development). Interestingly, the resistance of the PHSC1102 line was associated with the production of phenolic compounds, which were hypothesized to restrict the parasite's growth. This research provides novel and valuable information about the host–parasite interactions between sunflower and broomrape