Leaf disks may be difficult to wet. Seven surfactants tested in whole seedling immersion (WSI) inoculations all permitted good infection and sporulation; all but Tween 20 and 80 induced stunting. All treatments improved wetting of disks in LDI; sporulation was best with Tween 20. Sometimes in LDI inoculations sporulation is less than expected in incompatible cultivar-race combinations, or more than expected in incompatible combinations. Decreased sporulation is often associated with profuse bacterial growth. Of eleven readily available antibiotics tested rifampicin appeared best at reducing bacterial contamination without ad verse effects on downy mildew. Mold growth was often profuse on disks when bacterial competition was reduced by rifampicin treatment. In spite of these difficulties, the LDI method is proving useful in various studies, and efforts are being made to resolve the problems.

In the recent years, at least three sunflower downy mildew races other than race t have been reporled from several European countries. To cope with this new situation, race iden tification on an international base is required.

Methods of determining races of sunflower downy mildew (Plasmopara halstedii (Farl.) Berl. & deToni) vary in both minor and majordetails, which may result in different interpretations. We propose the use of standardized methods and conditions of inoculation, incubation, and evaluation, which should make it possible to obtain essentially uniform results at any laboratory. We also suggest methods of surveying and collecting mildew samples to determine race distribution and prevalence. Sunflower lines which can be used to differentiâte eight currently distinguishable mildew races, and the known or postulated resistance genes they carry, are listed.

Broomrape (Orobanche clonana Wallr.) is an obligate parasitic plant which feeds on sunflower roots and causes very high yietd losses in sunflower. Due to broomrape problem, production area dropped down by as much as 50% in Turkey during 1956-62. This problem was solved with planting resistant varieties. Flowever, broomrape became a problem again in 1980. This study was conducted at the Thrace Agricultural Research Institute to determine the existing broomrape races in Thrace during 1983-90. Broomrape seeds collected from sunt-lower fields in the region and differentials obtained from Romania were used in this study. It was concluded that broomrape recently seen in the Thrace region was race "E".

An interegeneric hybridization is conducted with species from the genera Tithonia and Helianthus. Hybrid plants F1 - F4 between H. annuus and T. rotundifolia are produced. The inheritance of characters in F1 is intermediary and specific depending on the forms used. Plants are produced in next generations witlr valuable characters which could be useful in breeding. A presence of restoring genes of fertility is fund in T. rotundifolia for the cytoplasms of H. petiolaris and H. argophyllus. On the basis of these genes new restorers are developed for these two cytoplasms.

Results of hybridization between cultivated sunflower and 30 species of the genus Helianthus are presented in the paper. It was conducted by conventional methods. Some problems of the methodological and practical nature are clarified and also possibilities for producing interspecific hybrids using wild species of Helianthus from the collection of the Wheat and Sunflower Institute "Dobroudja", General Toshevo, Bulgaria, are investigated..

Taking into consideration fact that the genetic diversity for concentration of individual elements of mineral nutrition is an important problem both theoretically and practicâlly, we undertook an investigation with sunflower plants. Sunflower specificity in N, P, K, Ca and Mg concentration was examined with 20 inbred lines. Collections of inbreds belong to the Institute of Field and Vegetable Crops, Faculty of Agriculture, Novi Sad. The inbreds were grown in nutrient solution by the method of water culture, in greenhouse for 25 days. The plants were examined for the content of N, P, K, Ca, and Mg. Also, dry mass of root, stem and leaf as well as leaf area were measured. On the basis of the results obtained one can draw the following conclusions. Concentration of the elements depended on plant organ analyzed (root, stem, leaf. In all inbreds examined, the highest concentration of N and Ca was found in leaf, then in stem and root, and the highesl Mg concentration was recorded in stem, then in leafand root. In a great number of lines, the highest P concentration was found in root. The highest chemical heterogeneity in different plant organs was recorded with K. The results show that the genetic specificity for mineral nutrition is manifested not only through different contents of mineral elements but also in their distribution into individual plant organs.

Helianthus species are native from North America. Cultivated sunflower H. annuus L. has reduced genetic variability and therefore breeding programs lack significant advances. Wild species from this genus may provide the genetic pool that will allow genetic advancement. The objective of the present study is to collect germplasm lrom 72 species of Helianthus, reported as native to Mexico, for preservation and breeding purposes. During 1988 and 1990 seasons 3-5 populations from the species annuus, petiolaris, niveus and smilis were explored and herbarized. Seed was collected from 21 of these populations and is now available for use in breeding programs with cultivated sunflower. It is necessary to continue the exploration to collect plants from all the reported species and others that may exist.

A principal factor analysis was performed on 25 traits of eight varieties and strains of sunflower (Hellanthus annuus L.) grown in replicated field plots at one location in the State of Tamaulipas, Mexico in 1990. Drought was created by terminating irrigation through vegetative to seed filling stage. Factors representing patterns ofvariables interpreted as yield, harvest index, escape and storage were extracted. These factors were identified with the source and sink conslructs ofcrop physiologists. lt is suggested that the development of higheryielding sunflowers underwaterstress must be based upon rapid phenological development combined with â long reproductive pcriod, heavy stems at anthesis and the ability to translocate those assimilates to seed dcvelopment; this could be achieved by producing a heavy biomass at maturity and a high plant and head growing rates.

Under rainfed conditions in Northern Mexico, the main cause of low yield in sunflower is drought. The objective of this work was to determine tlre water use and consumption patterns of 3 sunflower genotypes, evaluated in two sowing dates under irrigation-drought conditions. The mid and long season genotypes had more watcr consumption under drought, produced more dry matter, had a greater water use efficiency, better response to drought and more grain production than the short season control, which escaped drought.

A set of experimental hybrids obtained following the "Nested" mating design (Hallower and Miranda, 1981) was used to analyze genetic variability, in the source population, for drouglrt resistance, calculated as the relative yield reduction underdrought with respect to the irrigated control and drought susccptibility index "S" (Fisher and MAurer, 1978). The results indicatc that the major part of genetic variability for this character was accounted for by the additive variance with a high heritability expressed in narrow sense. Of great interest is the inbred line HAS whose two hybrids (7 and 8) have reduced their yield under drought by only 14 and 9% in relation to the âverage field red uct ion of 42%. The escape effect of this result is insignificant and for this reason physiological studies are planned to detect the responsible resistance mechanisms. Selection for high seed yield and drought resistance seems to be possible for the environment of Central Italy because the correlation between yield potential and the "S" index is non-significant, but in very arid areas this possibility might not be valid.

Sunflower is rapidly becoming an important oilseed crop in India with major area under rainfed conditions. Increasing emphasis is being laid to develàp genotypes resistant to intermittent moisture stress. This study reports results of a field screening at two growth stages of 24 sunflower genotypes for performance under imposed moisture stress. Late genotypes, on average, performed better than carly types. This was due to their intrinsicâlly higher recovery growth rates on alleviation of moisture stress. Pot culture experimenti on contrasting genotypes indicated that the rate of leaf area recovery on alleviation of stress formed an important parameter in determining the resistance to moisture stress. We dicuss the stratesies for improving sunflower productivity under rainfed conditions in peninsular India.

Trials were conducted in the three-year period 1987-89 at the Experiment Centre of the Department of Agronomy and Agro-Ecosystem Managment, Pisa University, situated at Torretta, San Piero a Grado (P1). In an experimental randomized block design with 5 replications, 15 treatments of chemical weedkilling made up of active compunds singly or in mixtures, intended for distribution at crop pre-cmcrgence, with the exception of lmazametabenz applied at post-emergence, were compared each year with the control. At the site on which the experiments took place, the tested pre-emergence compounds showed in general a good herbicide efficacy; Fluorchloridone, the mixure Oxyfluorfen + Alachlor, which appeared however slightly phytotoxic, and those obtained by adding Metha-benzthiazuron or Metobromuron or Linuron to Pendimethalin, were seen to be particualrly actlve. Concerning the achene yield, in the first two experiment years the treatments which gave the best results were Fluorchloridone and Methabenzthiazuron + Pendimethalin: Whereas in 1989 the best results were given by the mixtures Alachlor + Linuron, Oxadiazon + Metolachlor and Pendimethalin * Linuron.

In 1989, 11 inbred lines, randomly selected from the ND-02 bulk population characterized by a high oleic acid content, were mated following a factorial design. The obtained hybrids were sown in 1990 and were analyzed for fatty acid composition of the oil and quantitative yield (seed and oil). The gcnetic variability is consistent for a ll the characters analyzed and the non-additive variance component (S.C.A.) was more important than the additivevariance (G.C.A.) for oleic acid, linoleic acid and seed yield characters. The absence of correlation between seed yield and oleic acid content does not seem to prevent breeders from obtaining hybrids with a high level of both characters and a positive correlation between stearic acid oil content and seed yield, if confirmed in the subsequent studies, could indicate interesting new research lines.

Achenes oIeight high oleic content lines of Helianthus annuus were germinated in Petri dishes at four osmotic potentials of sodium chloride. Germination behaviour is analyzed. Seedling growth proved to be more sensitive than germination to salinity stress, cms lines are more affected. Newly germinated plants show a decrease in size and weight with salinity increment.

In the Asian continent, after China, India is the second largest sunflower growing country. In India, edible oilseeds are cultivated over an area of 19 million hectares with 17 million tonnes production. Peanut, rapesced mustard, sunflower, sesame and safflower are the major ediblc oilseed crops. However, about 75 per cent of the total oilseed production is contributed by pcanut and rapcseed mustard. Next only to these crops, in recent years sunflower has emcrged as a potential oilseed crop in both rainfed and irrigated farming.

Sunflower grown in the UK produces a high quality oil but few commercially available varieties are sufficiently early maturing for our northern climate. Varieties maturing within 140 days are requiref as harvest after the end of September increases the risk of disease and an unacceptably high seed moisture content. Many aspects of agronomic practice and methods of disease control were examined in order to select those most suited to UK conditions. More than 200 varicties and breeding lines were grown during thc period 1985-1990. Data are given on the phenology and yield of seected varietics, as affected by sowing dates, row spacing, seed rates and fungucids. If a wide range of early maturing varietics, which meet specified phenological and yield critcria, were available, it would enhance the potential for sunflower as an alternative oil crop in thc UK and elswhere in northern Europe.