The steady state levels of sunflower transcripts, detected with heterologous probes to either the Â9, the Al2 or the Àlb desaturase, were determined in embryos and vegetative tissues at different stages. The presence of Â15 gene transcript was limited to the leaves. Transcripts of À9 and the Â12 genes were detected in embryos between 12 and 20 DAp, and as few as traces in the other tissues examined. The accumulation of Â9 gene transcript precedes that of the À12 gene. The levels of mRNA accumulation in CANpS, a line with normal levels of oleic acid, and a high oleic acid line (Hoc) were compared after standardization of signal intensities. Âg mRNA accumulation was slightly higher in HOC than in CANpS. In contrast, Â12 mRNA accumulation wâs significantly reduced in HOC than in CANP3. The HOC mutation is correlated with a reduction in the steady state level of a putative seed-specific ^12 gene. We also observed that the Â9 and Â12 nRNA accumulate to higher levels in developing seeds maintained at 26.C dav/22"C night than at 2O'C dayl18"C night. From a genomic library, 2 arld, 4 clones carrying homologous sequences to the a9 and the a12 desaturases, respectively, were used for amplification with primers unique to each desaturase. This allowed us to have a clear identification for each desaturase. Moreover, such an ag desaturase fragment was amplified in 12 different wild species covering most of the Helianthus genus. sequence variability revealed a mixture of two À9 sequences in all the species of He&anthus

Isozyme variation was studied in a Helianthus argophgllus population, two inbred lines of sunflower, H. annuus, an interspecific line, and within progenies of crosses between those materials. Nine isozyme systems were resolved on starch gels. Fifteen loci were studied, I I of them being poly,rnor phic. Both species shared alleles at a_ll loci; four alleles were present only in H. argophylltts. Intrapopulation variability in the wild species was analyzed, and genetic distance among materials resembled their origin and genetic relationships. Isozj,'rne markers allowed evaluation of uniformity within inbred lines and identification of hybrid seed among progenies of all crosses.

The present study was conducted to genetically characterize a pigment-deficient mutant of sunflower induced by h uitro tissue culture. There's a mutant designed as chlorina-apicarûs. shows pale yellow cotyledons: the first true leaves are initially green, then they become yellow starting from the apex. This phenomenon of photobleaching causes the plantlets to die rn the first stage of development. segregation data from heteràzygous progenies indicate that the trait is controlled by one recessive gene. The symbol ch-ap is proposed for the gene that controls this trait.

Tender bracts were used for callus induction and shoot bud formation in "KBSH- 1", "BSH- 1 " and "Morden" genotypes of sunflower. High-frequency callus induction was observed on MS medium supplemented with NAA or 2, 4-D alone or in combination with BA. Such callus-reeenerated shoot buds after four weeks of incubation on MS medium with 0.1 mg/l BA in "KBSH- 1 " only. Further studies with other genotypes. Different cell lines and culture conditions are needed to obtain a high frequency of regeneration.

Cold pretreated anthers with uninucleate microspores of KBSH_1, "BSH-l", and "Modern" genotypes of sunflower, under dark incubation. resulted in maximum callus induction (>85%). The callus frequency from anthers of "KBSH- l " (92.8Oo/o) and "BSH- I " (92.7jo/o) was almost similar in MS medium with 2 mg/ I 2, 4-D and 1 mg/l BA, while in "Modern, it was the highest on medium with I mg/l each of NAA and BA. Uninucleate microspores of anthers are divided symmetrically to give rise to multicellular proembryo-like bodies. Occasional shoot bud formation from cultured anthers of "BSH-1" and "KBSH-I" was observed on medium with 0.5 or 1.0 mg/l NAA and 1.0 mg/l BA. Calli of "BSH-I" subcultured on plain MS medium resulted in the formation of meristematic centres.

The objective of this investigation was to evaluate the effects of different crop management practices during three years of experimentation on sunflower cultivars characterised by different hull anatomy, in order to study the 'environment x genotype' interaction on hullability. The experiments were conducted from l99l to Ig93 at the Pisa University Experimental farm (latitude 43° and 41' North, Longitude 10 ° and 23, East), adopting three different combinations of water level and nitrogen availability and three different cultivars, Oscar, Viki, and Euroflor of Helianthus annuus L. The cv, Euroflor, characterised by thin hulls and high achene oil content, showed an unusual, positive relationship between seed oil content and hullability, thus offering breeders the possibility of overcoming the barrier of simultaneously improving these two characteristics. However, at the same time, considerable attention must be given to the pedo-climatic environmental conditions. In fact, this cultivar significantly improved its hullability with crop management practices that favoured light water and nitrogen deficits during the grain-filling period, while, in contrast, the other two earlier cultivars had better hullability characteristics with good water and nitrogen supplies.

Experiments were carried out on a slightly leached chernozem during l99I-1994. Four nitrogen rates in sunflower and five nitrogen rates in the coming winter wheat were investigated. The aim of the study was to find out relationships between nitrogen fertilization in the predecessor and in the coming winter wheat, as well as their effect on the yield formation of the cereal culture. It was established that the nitrogen fertilization in sunflowers had a significant influence on the grain yield of the coming winter wheat. The total nitrogen rates (previous + direct) correlated positively with the wheat grain yield. The highest coefficient of correlation was calculated when the theoretical total nitrogen rate contained l/3 of the previous and the direct rates.

Competition and yield advantage of sunflower-summer legumes intercropping systems were studied at University of Arid Agriculture, Rawalpindi, Paki star, during surrùner 1994 to determine their feasibility for increased yield from the same resources. Sunflower-soybean and sunÏlower-mungbean intercrop ping systems gave the highest (I.38) land equivalent ratio, followed by sunflower-mashbean intercropping system (1.34). The three intercropping systems gave a higher combined yield than single cropping of component crops. Among the component crops, sunflower appeared to be the dominant with higher values for relative crowding coefficient, positive aggressivity, and higher competitive ratio. Sunflowers in the three intercropping systems showed similar behaviour for aggressiveness and competitive ratio. Also, the degree of competition offered by sllmmer legumes was very similar.

Lysine content in sunflower seed storage protein is not sufficient to meet the requirements of FAO. As far as the storage protein amino acid composition of Helianthus annuus is concerned, the lysine content of the species from the IWS "Dobroudja" collection investigated in our laboratory is not substantially different from that of cultivated Helianthus annuus varieties and hybrids. In a previous study, we have reported data about Bidens tripartita's high lysine content in the storage protein of seeds (3.4%for Hetianthtts o.nrtuu.s and 5.8 g/lbr Brdens tripartita). In 1994, we collected 14 new Bidens tripartita accessions from different parts of Bulgaria. A biochemical characterization of these genotypes, including fatty acid composition, storage protein electrophoretic subunits, and amino acid composition, is presented in this study. It was established that linoleic acid varied from 64.0 % to 73.8% and oleic acid from 18.3% to 23.4%. Seven different storage protein electrophoretic patterns were found in the 14 investigated genotypes. Lysine content varied from 4.83% to 5.45%.

Several populations of wild sunflower species have been tested for resistance to stem canker by inoculating with the mycelium of the fungus. The highest degree of resistance was exhibited in Helianthus tuberosus L. By isolation of S-day-old embryos, we obtained 21 hybrid plants out of more than 200 embryos isolated. All F1 plants were found resistant. A modified 85 medium gave good results in the production of healthy, enlarged embryos from excised young hybrid embryos. The F1 hybrids had a lower pollen viability. Meiotic irregularities occurred in all F1 interspecific hybrids.

The objective of this work was to estimate yield losses in sunflowers caused by sclerotinia head rot. Subplots with different levels of disease intensity (percentage of plants with head rot) were generated by inoculations utilizing different environmental conditions and genetic materials (five commercial hybrids). Seed yield, seed oil content, weight per 1,000 seeds, dockage percentage, and oil acidity were recorded in the inoculated subplots and in the healthy ones, which were used as controls. Highly posiûve correla tions between percentage of diseased plants and reduction in seed yield (1=Q.76***), increase in dockage (r=0.67***), and oil acidity levels (r=O.58***) were found. Yield reduction estimates varied among hybrids; this indicates that they are genetically different for their tolerance to head rot. The obtained results permit to state that head rot causes direct (seed yield reduction) and indirect (increase in dockage and oil acidity levels) damages to the sunflower crop. An inverse relation would exist between the magnitude of both types of damage. That is, when capitula are completely disintegrated, there would be no indirect damages, whereas if the development of the disease is slow (high genotypic tolerance, unfitted environmental conditions for the pathogen or both), indirect damages would be greater since more heads can be harvested. It is concluded that sunflower breeding for head rot control must be oriented to select those genot5æes with better resistance levels (in terms of lower percentage of diseased plants) rather than to select genot5æes with better tolerance levels (in terms of yield losses).

Study was conducted at the Thrace Agricultural Research Institute during 1990-91 for the purpose of finding answers to the question of what the effect of orobanclrc is on sunflowers planted at different dates. Sunflower varieties Türk-Ay-1, Vniimk-8931, sundak, and TR-259 were planted at 5 different dates with fields infested with Orobanche. The first appearance of Orobanche shoots on the soil surface was earlier at late planting dates compared to early planting dates. It was also observed that the number of Orobanche shoots per plant was fewer when sunflower planting was made late.

A comparative study on heterosis was conducted on nine single, eighteen double, and eighteen three-way cross hybrids for six characters, viz., maturity (days), head diameter (cm), 100-seed weight (g), number of seeds per head, seed yield per plant (g), and oil content (%). The results of the study revealed that single cross hybrids were best for head diameter, number of seeds per head, and seed yield per plant. The double cross hybrids were superior for earliness and 100-seed weight. The three-way cross hybrids were inferior to single and double-cross hybrids in exploiting heterosis.

Two independent experiments were conducted under normal and saline soil conditions with an aggregate ECe of 15.50 dSm and pH of 8.23. Phenotypic and genotypic correlation coefficients were computed between various morphological and physiological parameters in both oçeriments independently. Phenotypic and genotypic correlation coefficients under nor ma-l and saline conditions for all the traits agreed very closely. This similarity was due to the control of experimental error. Under normal and saline conditions, almost all the parameters in the study showed positive correlation to achene yield, except days to flower, which was negative, and oil content and Na-concentration, which were non-significant under normal soil conditions, and days to flower and K- concentration in leaves were negative under saline soil conditions. All achene yield components showed positive association with each other under both soil conditions. The association of physiological parameters under saline soil is rather confusing. It is suggested that selection for high achene-yielding lines under normal soil conditions can be based on head diameter, achene setting percentage, 100-achene weight, and leaf area, and under saline soil conditions, selection should be practiced on the basis of yield components in early flowering lines.

Achenes germination of sunflower lines (Helranthus annuris L.) treated with ethephon is presented. Four different maintainer lines were treated with five concentrations of ethephon (2.0ml.l-1, 3.0ml.l-1, 4.0rnt.l-1, 5.0mt. l-1, 6.0 ml.l-1 ). Plants were treated before flowering and open-pollinated. The percentage of viable, abnormal, and non-viable germs was determined, with a strong genotypical reaction being observed. It was possible to rank the lines by sensitivity to ethephon. The optimal achene number per plot can be determined based on characters of germination of genotypes.

Four sulphur sources, i.e., ammonium sulphate, potassium sulphate, calcium sulphate, and ferrous sulphate, each at 0.5 mM of SO4 in the root medium, were used to grow sunflowers under controlled conditions. Five harvests with the time intervals of 0, 6, 24, 48, and 16g hours were taken. Root and shoot growth was proportional to the time irrespectively of the sources. significant relationships (r=o.99) were shown by fresh weight and dry matter yield (DMY) with respect to the harvest time, irrespective of the sources. Ammonium sulphate and ferrous sulphate shared a positive relationship with SO4 uptake (r=0.85) in the root. After 48 hours, the various sources showed distinct contributions for root DMY.

Recurrent selection of sunflower hypocotyl calluses maintained at different levels of salinity improved the tolerance capacity. At loth sub-culture, the selected Ussues of cvs - EC 68415 and Modern, showed better growth at the highest (- I.368 MPa) salinity. Growth, turgor, and accumulation of solutes and ions were greater in these tissues. However, the involvement of turgor and proline in salt tolerance seems to be doubtful. The increase in sodium chloride rn the medium enhanced the uptake of sodium and potassium, leading to maintenance of a greater K/Na raûo in selected tissues, thereby suggesting a role for ionic equilibrium between potassium and sodium.