Leaf area index (LAI), light interception (LI, %), and frequency of two stem diseases (Phomopsis helianthi, Phoma macdonaldii) were assessed for sunflower over two years (1994 and 1995) at Auzeville (southwestern France). The field experiments compared different crop management methods varying in genotype, crop density, N fertilization, fungicide application, and irrigation. A relationship between LI and LAI was proposed and discussed in regard to crop density and growth stages. A close relationship was found between the rate of infection by Phomopsis and LI at anthesis in unsprayed plots. This relationship could be used to predict the potential infection as a function of foliar development. The relationship was less obvious with Phoma.

Leaf area development and stomatal resistance of field-grown sunflower plants (hybrid Mimosa) were studied in response to irrigation with saline water. Salt-treated plants were irrigated with 1olo commercial sea salt water solution. Irrigation started on the 3oth day after sowing when plants had 10 primordia and 2 fully expanded bases.l leaves. Midday leaf water potential decreased during the season in both salt-treated [I1) and control plants (10), with lower values for 11. At anthesis, 65 days after sowing, the difference was 0.12 MPa and LAI of I0 was 3.3I whereas for 11 it was 20% lower. Il plants showed a remarkable morphological adjustment to salt stress by modulating leaf area through leaf expansion rate, whereas the role of leaf senescence was negligible. There was no physiological adjustment in terms of stomata-l resistance. In conclusion, I)eld-grown salt-treated sunflower plants showed avoidance mechanisms which are similar to those observed elsewhere in water stress conditions.

The effect of source-sink relationships on yield and its components was studied in two Tield trials. Sunflower plants (confection type, cv. DY-3) with small and large heads were treated as follows: seed from the peripheral area of the head was removed at the end of flowering, or leaves were removed soon after appearance (early leaf removal) or at the end of flowering (late leaf removal). Floret number was significantly lower in small vs. large heads, but was not affected by the source-sink manipulations. The percentage of filled seeds in the peripheral and intermediate head zones was 75-80, whereas in the central head zone it was 50-55. Neither head size nor source-sink manipulations had any effect on the percentage of filled seeds. With respect to the applied treatments, seed weight was the most responsive yield component studied. Seed weight was higher in large vs. small sunflower heads; it increased as a result of seed removal and decreased as a result of leaf removal.

Dry dormant seeds of sunflower cultivar VNIIMK - 8931 were irradiated with 15O Gy gamma rays (Co60). The influence of the mutagen was determined in the M1 generation. In the M2, Ma, and M5 generations, there were plants with lightly yellow cotyledons that died. Some mutated plants were isolated and self-pollinated for several generations. New sunflower forms with inherited changes were obtained through selection and self-pollination. One of the new forms was characterized by modified leaf and leaf petiole characters. The leaves were light green, lustrous, with a well-expressed vein. The leaf edges were serrated and runcinated with sharp points. The petioles had a joint near the leaf blade. The plant form was similar to an ornamental cabbage type. These plants had other important characteristics that were of interest for selection. This mutant has been noted as M 95-674. It can be used as an ornamental form as well as for heterosis breeding.

Crosses between six sunflower (Helianthus annuus) lnbred lines were produced utilizing a partial diallel experimental design. After three years of testing, it was found that the highest general combining ability (GCA) for seed weight per plant was produced by lines 3230 and 30O4. For oil content, the highest GCA was shown by lines 3230 and 3o64. The environmental conditions influenced to a great degree the evaluations of specific combining ability (scA), while general combining ability was determined to be more stable. The nonadditive gene effects for the seed weight per plant and oil content are more unstable in variable environments in comparison with the additive gene effects.

Interspecific hybridization was made between the cultivated sunflower Helianthus annuus L. and two perennial diploid species, Helianthus diuarica tus L. and Helttnthtts mollûs Lambert. Reciprocal crosses were made. Conventional breeding methods were used. Six inbred lines and one variety, Peredovik, were included in the hybridization. Hybrid plants were produced in both directions. The hybrid plants originating from crosses between the perennial species and cultivated sunflower had a perennial habit. Such plants were also produced from reciprocal crosses: line I234 A x Helianthus mollis and line 3064 A x Helianthus diuaricatus. The second hybrid and BCI generations were produced from the F1 material, showing great diversity of phenotypes.

Hybrid material obtained from reciprocal hybridization between the cultivated sunflower and 29 wild Helianthus species was used for the production of new sunflower fertility restorer lines. Single and double back crossing, sib-pollination, and self-pollination were applied. New R-lines were developed from the hybrid material, obtained by repeated individual selection and self-pollination, and combining useful agronomic traits from the wild Helinnthus species and cultivated sunflower - Rf-genes, coming from. different species, high seed oil content, resistance to some diseases and broomrape, and very good combining ability. Good hybrid varieties with commercial value were produced with the participation of these new R-lines.

The main goal of these investigations \Mas to study the changes in oxidative stability of oil after periods of seed storage (12 and 2+ months after harvesting) held in room conditions (temperatures between 15- 20 °C). Investigations were carried out with samples of sunflower seed with high and nor mal linoleic acid contents. Samples were obtained from an ongoing search at the Institute of Field and Vegetable Crops, Oil Crop Department, University of Novi Sad. Oil samples from high linoleic acid seed inàicate a significantly shorter induction period (by Rancimat 617 apparatus at 100 °C) as compared with oil samples with oleic acid content.

The possibility for application of hyphal interference as an additional method for confirmation of the specificity of the Phomopsis heltrnthi isolated from Helianthus annuus has been examined. With this aim, inter-relations of 13 fungal isolates, members of the Diaporthe/Phomopsis complex, have been studied. Microscopic investigations of the demarcation zones between colonies of the same and different isolates of Phomapsis/DiaporÛLe, revealed the phenomenon of the hyphal interference between different isolates. The results obtained suggest that hyphal interference could serve as an additional parameter for a more reliable determination of fungal specificity.

Twenty sunflower (Helianthus annuus L.) hybrids+OPV were evaluated for their resistance to leafblight and stem spot disease caused by Alternarirt helinnthi in the field under epiphytotic conditions at the National Agricultural Research Centre, Islamabad, during the autumn season, 1984. Only one hybrid, Suncross 25-3, was found significantly (P=0.05) highly resistant, 5 were moderately susceptible with non-significant differences in their reactions, and the remaining hybrids were either susceptible or highly susceptible to the disease.

A total of twenty experimental hybrids of sunflower were tested for their resistance to three pathogenic races of Plasmopara hrrlstedi. The experiments were conducted in a plastic house where WSl-inoculated seedlings were grown and evaluated for disease reactions twice in a 4-week period. As control, a universal susceptible (cv. GK-70) and a few (both compatible and incompatible) differential lines were used to ascertain that the reaction to the races was correct. All the sunflowers tested under the plastic tunnel were resistant to race I, with only two entries showing some infection. As for race 3 resistance, they varied greatly. Three entries exhibited good resistance (7o infection <20), two others were moderately resistant (20- 50% infection), and fifteen showed susceptibility. A similar segregation was found with race 4 resistance, where, besides three resistant entries and I I susceptible ones, there were six hybrids with intermediate reaction (7o infection 20-50). The results obtained suggest that sunflowers with resistance to downy mildew races 3 and 4 are available and mav be released soon.

Cytoplasmic male sterility (CMS) in sunflower has been correlated with the expression of orf522, a chimeric mitochondria-l gene, generated by the insertion of exogenous genetic material, at the 3' side of the atpA locus. In order to investigate the role of the orf522 in CMS, we constructed a recombinant plasmid, suitable for transforming tobacco plants by particle gun methodol oS/. Several transformation events were obtained. Molecular analysis revealed that the orft22 gene is integrated into the nucleus. No integration events were observed in the mitochondrial (mt) genome. All the transgenic plants were fertile, suggesting that the orfr22 from sunflower does not confer male sterility in trânsgenic tobacco when expressed at the nuclear level.

The regeneration of whole fertile sunflower plants is highly variable and depends mainly on the genotype, though the nature of the explant and the hormone content of the culture medium are also important. Ten Helirtnthus annuus L. genotypes were evaluated ur uitro for their morphogenic response: the inbred lines HA 3004, HA 89A, cp 762A, Gp 7628, RHA 274, Rf BS-SO, and the hybrids HpS-4, Morgan 733, ACA 984, and Contiflor 3. Cotyledons of mature seeds were used as explants. The basa-l medium was MS, to which different concentrations of growth regulators were added: Mr, KIN 2 mg/l + IAA 1 mg,rl i MII, BA0.5 mg/t + IAA0.5 mg/t: MIII, MI + O.I mgll cAg; and MM MII + 0.1 mg/l GA3. All media contained 200 mgll of glutamine. Callus (C), regeneration (R), and hypertrophy (H) percentages were evaluated on the 30th day after initiation of the culture. The statistical analysis showed significant differences among genot5æes and non-significant differences. "-orig media for R. Lack of independence for genotype-regeneration was also detected by the G-test.

Genetic variability in 22 self-pollinated sunflower lines resulting from NS selection was studied on the level of isozymes. Isozymes as genetic markers were used for the estimation of breeding material, genetic identification, and potential for its usage for hybrid development. On the basis of seven en4l mic systems and seven loci from which certain isoqrmes were obtained, the homozygous lines and their variability were found. Seven polymorphous iso4/micloci: Estl, Mdh2, Pgdl, Phil, Pgm4, Gdhl, and ArrdApcl, and 2-3 alleles of each locus were used for genetic identification. Genetic distance between the analyzed genotypes was determined on the level of a group of genetic markers, and it provided proof of their efficiency and reliability.