Plant regeneration potential of two F1 sunflower interspecific hybrids was evaluated. Immature embryos (8-10 days old) were harvested. Basal MS medium supplemented with 2 mg/ml zeatin proved to be better than other variants tested for callus initiation and regeneration. Regenerable calli were obtained from both hybrids. Complete plantlets were formed within 20-30 days. Part of the regenerated plants showed no major alterations in morphology as compared with the original ones.

Six CMS (CMS-342, CMS-343, CMS-349, CMS-351, CMS-352 and CMS-353) and five testers (RHA -344, RHA-345, RHA-346, RHA-348 and RHA-354) with high oleic acid were crossed for combining ability analysis. It was carried out at GKVK, University of Agricultural Sciences, Bangalore, India. Non-additive gene action was observed for days to 50 percent flowering, plant height, head diameter, stem girth, seed yield per plant, oil content and oleic acid whereas additive gene action was noticed for 100 seed weight. Among females HA-351 was the best general combiner for oleic acid, HA-342 for seed yield per plant and HA-349 for earliness and oil content. The male tester RHA-344 was the best combiner for seed yield per plant and RHA-348 for oleic acid, oil content and plant height. The crosses CMS-349 x RHA-346, CMS-353 x RHA-348 and CMS-343 x RHA-346 were the best cross combinations for oleic acid, oil content and seed yield plant respectively.

Reciprocal interspecific crosses were made between sunflower (H. annuus L., 2n=34) and the annual species H. praecox sap. hirsute Engleman & Gray (2n=34) using conventional breeding methods. F1, F2 and F3 hybrids and one backcross generation were obtained. The cross compatibility between H.annuus and H. praecox ssp. hirtus showed differences, depending on the direction of the cross. The manifestation of the parental characters in the hybrid material was studied, as well as the resistance of the F1, F2 and BC1 generations to Plasmopara helianthi, Phomopsis helianthi and Orobanche cumana. The seed oil content and fatty-acid composition of the oil in the hybrid progenies were also evaluated. Initial sunflower hybrid material with linoleic type of the seed oil and resistance to downy mildew and broomrape was produced for future breeding programs.

Seven broomrape resistance incorporated HA-89-derived female lines were evaluated to assess their combining ability effects in this study. Combining ability effects of 8 CMS lines (seven broomrape resistance introduced backcross derivatives of HA-89 plus HA-89 itself) in combination with 2 restorer lines were assessed by using the line x tester analysis technique. General and specific combining ability effects were estimated on 6 traits. Most of them were found to be improved for the GCA effects in hybrid combinations compared with the background line HA-89.

Seven sunflower female lines, obtained from HA-89 after incorporating broomrape resistance with 3-4 backcrosses using different broomrape resistant sources, were evaluated for development of broomrape resistant hybrids.

Eight female lines (CMS of the maintainer HA-89 and 7 new females), 2 restorers, and their 16 F1 hybrid combinations were used in the study. Female lines, restorers and their F1 hybrids were tested against Orobanche. Agronomic and quality characterization of the parental lines were also carried out in this study.

Although 7 backcross derivatives of HA-89 were found to be resistant to broomrape, only six of them gave resistant hybrid combinations after crossing with broomrape susceptible restorers. When compared with HA-89, some of the backcross derived female lines were found to be similar or improved for several characters, such as oil content.

Six sunflowers inbreds were crossed in partial diallel fashion to evaluate their general and specific combining ability for yield, yield components and oil content under saline conditions. Specific combining ability (SCA) variances were higher than general combining ability (GCA) variances for all the plant traits studied which manifested non-additive genetic control. However, substantial amount of additive variance was contributing for plant height and oil content. GIMSUN-459 and GIMSUN-318 were high general combiner while GIMSUN-459 x GIMSUN-477 was a good specific combination for production under saline soil conditions.

The trial was carried out in two years (1992 and 1993) at two different locations in the centre of Italy (Pisa and Grosseto) and the main aim was to evaluate the influence of four different environmental conditions (Pisa, 1992; Grosseto, 1992; Pisa, 1993 and Grosseto, 1993) and the effects of two different water availabilities (without and with irrigation) on six sunflower hybrids: Ares, Cisa, Granada and Oleica, with high oleic acid content, and Gloriasol and Select, conventional hybrids (high linoleic), used as controls. The experimental scheme adopted was a split-block experimental design with five replications. The following characteristics were observed: duration of main phenological periods, plant height, leaf area index at flowering, aboveground biomass and seed yield per plant, harvest index, growing degree-days, water use and water use efficiency.

The water use efficiency for seed yield per plant was highest at Pisa, 1993 under rainfed conditions (1.02 g/l) and at Grosseto, 1993 under both water treatments (1.00 g/l). The irrigation treatments led to an increase of the harvest index in all environments except for the wettest environment (Pisa, 1992). In the four environments examined, the growing degree-days ranged from 789 to 1108℃ and from 1612 to 2036℃ for the sowing-flowering and sowing-maturity periods, respectively. Seed yield per plant in all high oleic hybrids, with the exception of Ares, were not significantly different from those of Select and Gloriasol in all environments, with the exception of Pisa 1993, which was characterized by a limited water availability during flowering-maturity period, where all high oleic hybrids showed a significant decrease of seed yield per plant.

Trials were carried out in two years (1992 and 1993) and two different locations in the centre of Italy (Pisa and Grosseto) and the main objective was to evaluate the influence of four different environmental conditions (Pisa, 1992; Grosseto, 1992; Pisa, 1993 and Grosseto, 1993) and the effects of two different water availabilities (without and with irrigation) on six sunflower hybrids: Ares, Cisa, Granada and Oleica, with high oleic content and Gloriasol and Select, conventional hybrids (high linoleic), used as controls. The experimental scheme adopted was a split-block experimental scheme with 5 replications. The main yield characteristics, seed and oil yield, mechanical hull extraction and oil fatty acid profile were analyzed.

No significant difference in achene yield potential was observed among the hybrids analyzed in all environments, except at Pisa 1993, where, under high temperature during flowering period and limited water availability, the conventional hybrids showed higher yield potential than the high oleic hybrids. The high oleic hybrids showed a significant lower achene oil content than the Select. Of the high oleic hybrids present in the Italian national varieties register an influence of the different environments on fatty acid composition was found only in Ares, which presented an oleic acid content lower and more unstable than the other genotypes, with an elevated range of variability (about 14%) by its oleic content mean (72.3 %) calculated across environments and water managements. This confirms that the genetic control of the high oleic could be different among the genotypes analyzed. Achene mechanical dehullability was affected both by genetic characteristics and environmental conditions.

In sunflowers, the incorporation of resistance to the fungus Plasmopara halstedii generally involves the use of methodologies that are not very accessible due to their high cost. The use of simple techniques would permit easier access to cultivars resistant to this parasite. This paper describes an approach combining two techniques for an early screening test for downy mildew resistance in sunflower. The whole-seedling immersion technique was applied to immature germinated seeds of different sunflower cultivars in a suspension of Plasmopara halstedii zoosporangia. This methodology did not produce any negative or modifying effect on resistance to the mildew, it was capable of producing similar disease reactions when the genotypes under evaluation were naturally infected by this pathogen in other experiments. It is concluded that this new and innovating technique allows resistant sunflower genotypes to be identified at very low cost in breeding programs.

Epidemics of Alternaria blight (Alternaria helianthi (Hansf.) Tubaki and Nishihara: A. alternata (Fr.) Keissler) simulated at different plant growth stages showed yield losses as high as 57 and 48 percent in "Morden" and "APSH11" varieties of sunflower respectively. Other yield attributes like test weight of seed and number of seeds per head were also significantly reduced. Regression equations developed on percent disease severity and yield losses gave a coefficient of determination between 0.88 and 0.96.

Seedlings of four different experimental hybrids H1, H12, H37, H44, at the age of 28 days after sowing, were subjected to two different concentrations of culture filtrate (oxalic acid) from Sclerotinia sclerotiorum Lib. De Bary. while control plants were grown in the absence of toxins. Forty-eight hours after the treatment, the following characters were observed: plant height difference PHD, plant dry weight difference (PWD), basal stalk diameter difference (BSDD), oxalic acid content (OAC) in plants and shikimate dehydrogenase (SKDH) activity. Among the hybrids considered, genotype H1 appeared to be the most tolerant to Sclerotinia sclerotiorum culture filtrate, as confirmed by its genetic background. PWD and BSDD were unaffected by oxalic acid treatments and a significant increase in OAC and SKDH activity was observed with respect to the control.

The results of this study indicated a positive relation between oxalic acid content of fungal culture filtrate and the enzymatic activity of SKDH in sunflower plants subjected to the treatment. The oxalic acid content in plants attacked by the pathogen increases, reaching a threshold limit beyond which damage becomes visible or defense mechanisms are triggered, which implies an increase of SKDH activity, presumably related to the resistance mechanism.

The proteic structure of SKDH was also investigated and the hypothesis that SKDH alloenzyme is a monomer encoded by a single gene in a biallelic codominant locus was confirmed.

Second dimension SDS-PAGE, using a 3% ß-mercaptoethanol solution, revealed that SKDH is an isozyme characterized by two allelic forms: SkDH-a (64 kDa) and SkDH-b (57 kDa). When a 6 % ß-mercaptoethanol solution was used in correspondence of the SkDH-b band, two bands (40 and 34 kDa) were observed in the treated and control genotypes

A field experiment was conducted to study the performance of sunflower as a better alternative crop under late sown rainfed conditions. Six sunflower genotypes of different durations were evaluated and their suitability in relation to rainfall distribution was assessed. Almost all cultivars sown late have faced moisture stress at grain filling with varied stress durations. Medium duration cultivars eventhough faced with terminal drought, performed better over other maturing groups. However, short-duration cultivars were also preferred due to their early maturing character. But long-duration cultivars which experienced moisture stress at almost all crucial periods like flowering, pollination and grain filling stages were sidelined.

This two-years study was conducted to determine the effects of planting date and plant population on seed yield, oil content and certain plant characteristics of sunflower under dryland conditions in the Marmara Region of Turkey. Three planting dates (March, April, May) were established with two hybrids (Sunbred-265 and H-1) and open pollinated cultivar (VNIIMK-8931) at three plant populations (30,000, 47.500 and 95.000 plants/ha).

Seed yield and yield components decreased significantly with later planting dates. The highest seed yield, 1000-seed weight, seed weight per head. oil content and oil yield were obtained when sunflowers were sown in mid-March or mid-April. Compared with mid-May, the plantings in mid-March and mid-April increased seed yield by about 41% and 34%, respectively. Number of days from planting to flowering (50%) decreased as planting dates were delayed. Plant population significantly affected seed and oil yields and other plant characteristics measured. As plant population increased, head diameter. 1000-seed weight, and seed weight per head decreased, but plant height increased. The highest seed yield, oil content and oil yield were obtained at 95.000 plants per ha.

This research was carried out to determine the effects of six phosphorus (P205) rates and two application time on sunflower (Helianthus annuus L.) seed yield and yield components. The sunflower hybrid used in the experiments was Edirne-87. The research lasted for two years, 1991 and 1992, and it was conducted at the Thrace Agricultural Research Institute in Edirne, Turkey.

The experiments were established in a split plot arrangement in randomized complete block design in three replicates. Phosphorus application times were used as main plots. These were autumn and spring time applications. Six rates of phosphorus were used as sub-plots: 0, 20. 40, 60, 80, and 100 kg/ha P2O5.

Mean values of time to flowering, time to physiological maturity, plant height, head diameter, seed yield/ha, 1000 seed weight, oil content, and oil yield were determined in each plot and analyzed using ANOVA.

According to the two-year results of this research, relationship between sunflower grain yield and phosphorus rates was found significant (R=0.922 ** ) in Edirne conditions. Phosphorus rates can be expressed by following regression equation Y: 1321 + 10.39 X - 0.066 X2. Based on 1996 phosphorus fertilizer and sunflower crop prices for optimum economical sunflower production it was recommended that the application rate of phosphorus should be 70 kg/ha in Edirne conditions.

Experiments carried out with ethanol plant extract 1 (Asclepias syriaca L.). 2 (Astragalus onobrychis L.) and 3 (Chenopodium ambrosiodes L.) applied to lard and bleached sunflower oil as substrates showed their antioxidative activity. The increase of extract concentration and the addition of citric acid or lecithin as synergists increase the inductive period. The comparison of oxidative stability of sample with 0.01% BHA, control sample and samples with the investigated extracts showed that the extract effect, even at significantly high concentration (0.2%), is several times lower than those of commercial antioxidants. The addition of synergists improves the effect of extract, but it does not change the pattern of antioxidative activity. The use of highly unsaturated substrate, completely bleached sunflower oil, indicates for plant extract 3 practically the same order of inductive periods. The mentioned decrease in differences is not caused by significant increase of antioxidative activity of the extract itself, but by lower activity of BHA in the substrate which indicates the importance of careful selection of antioxidative materials for different substrates.