Callus cultures have been established from leaves and stem segments of perennial wild diploid species, namely H. giganteus L., H. trachclifolius Miller, H. nuttalli Torrey et A. Grey and H. maximiliani Schrad. The calli originated from leaves were weak and did not give rise to embryos. Callus growth in stem segments was intensive with 5x10-6-10-5 M 2,4-D and NAA. The calli were maintained in subcultures at 3x10-6 M level of NAA. Regular embyoid and shoot fornation was achieved with 10-6 and 3x10-6 M NAA in combination with BA. kinetin, zeatin and 2iP (10-6-10-5M). The highest number of embryoids and shoots has been obtained in all four spcrcies on solidified medium containing 3x10-6 M NAA+5x10-6 M BA. In agitated liquid medium containing 10-6 M NAA+5X10-6 M BA abundant mass of cell aggregates was produced which in turn, plated on solidified medium with 10-6 M NAA+ 10-6 M BA (or kinetin or zeatin) +40 mg/l adenine + 30g/l sucrose, gave rise to hundreds of embryoids and shoot like structures. Rooted plants were transformed to greenhouse.

Efttet of nitrogen and phosporus nutrition applied to leaves was studied in field experiments at differents stages of development of sunflower during 1987-1988. In 1987, 5, 10, 15 and 20 kg/ha N and 5+5, 10+10, 15+15, 20+20 kg/ha N was used as chemical leaf fertilizer at the stage of budding and budding+10% flowering, respectively. In the next year, at budding stage all the plots were sprayed with dose of 10 kg/ha N as a basic treatment with the aim to incrcase the achene yield. At full bloom, these plots have additionally been treatedwith 1, 3, 5 and 7 kg doses of P for increasing the oil content. The greatest head diameter, achene yield/head and oil yield/head heve been achicved with doses 10 kg/ha (at budding stage) and 10+10 kg/ha N (budding+10% flowering stage). Achene oil content was decreased by treatments with N, whereas doses of P applied at full bloom had no effect on it. Effect of increasing N-doses may be fitted to a quadratic equation.

The autogamy and self-incompatibility of four sunflower cultivars namely NK-262, NK-265, NK-281 and Sundak were investigated under six pollination treatments. The pollination treatments were natural self-pollination, manipulated self-pollination, assisted self-pollination, foreign pollination, cross-pollination.It appeared that sunflower cultivar NK-262 was self-compatible. Whereas, the efficacy of these pollination treatments in NK-265, NK-281 and Sundak were affected due to the ratio of seedset and autogamy exhibited by these sunflower cultivars. However, Sundak was self--incompatible. Maximum seedset (96.25%) was recorded in sunflower cultivar NK-262 under open-pollination. The minimum seed set of 12.14% resulted in Sundak when assisted self-pollination was adopted. Estimates for percent autogamy of NK-281 were higher (92.64%) under cross pollination. However, the autogamy for the other pollination treatments was minimum. There were significant differences among the sunflower cultivars for the percent modified autogamy. NK-262 and Sundak exhibited maximum and minimum modified autogamy of 101.45% and 28.70%, respectively.

The results of the trials carried out in the ČSFR for several years show that the yield potential of hybrids is under average growing conditions realized to 40-50%. The best growers reach the realization up to 70%. The maximum utilization represents 95% of the corresponding achene yield of 4.5 t/ha. By breeding for increase of the stand yield potential the achene yield up to 6.3 t/ha can be reached i.e., 3 t/ha of oil. This represents an increase of the present yield potential, of 140%. The optimum stand density varies according to the locality, soil texture, type of hybrid and sometimes according to the level of nutrition and management from 50 000 to 75 000 individuals per hectare, at the medium optimum 60-65 000 and yield per area (yield potential) up to 5.5 t/ha in experimental fields and 4.5 t/ha in production fields. Higher stand productivity is connected with the increase of individuals per area. However, plants toleranting increase of density have to posses progressive traits.

Crossings between 16 sunflower parent lines (8A, 4B and 4R) were carried out and as a result 16 single, 16 three-way and 16 doublecross hybrids were produced. After three years of testing it was found that the doublecross hybrids posses a higher oil content and are less influenced by the growing conditions in comparison with the simple and doublecross ones. The expression of the oil content trait is specific for the different parent ines in their participation as components of the various types of hybrids. An economic characteristic of some single, three-way and doublecross hybrids is presented.

The inheritance of fatty acid composition in F1 seed and of their progenies (F2) is studied.It is established that the oil quality of F1 seeds is determined by the joint action of the embryo genome and the female parent genome, but in different combinations a specific degree of expression of those factors is observed.In F2 progeny of F1 and RF1 seeds the accumulation of diffcrent fatty acids is determined by the sced genome and because of that the composition of the oil is identical.In some crosses a partial dominance is observed of the low and high content of linoleic, oleic and palmitic acids.In all crosses the stearic acid content super-dominates toward the parent with a higher value.

Results are presented in this report indicating studies of new sources of CMS and MS produced at IWS "Dobroudja". General Toshevo. Sterile analogues are developed through multiple crossing on the base of CMS ARG-1, ARG-3, AN-67 and MS AR G-2 of some fertile lines and varietics known as maintainers for CMS F.It is found also that some R lines for CMS F completely restore the fertility of sterile forms produced on the base of new CMS sources ARG-1, ARG-3 and AN-67 and MS ARG-2. Hybrid varieties are developed on the base of the sterile analogues with CMS ARG-1, ARG-3, AN-67 and MS ARG-2 and R lines determined for these CMS. These varieties are similar in qualities with those obtained by the participation of CMS F.'These results show that the new sources of CMS could have a practical utilization in sunflower production.

Three ncw CMS sources, ANT-1, Pet-2, ANN-1, are studied. B and R.lines for CMS of Pet-1 type are included in the investigation. The results show that the three new sources are different from the French type Pet-1. Differences are also present between the new CMS types. In ANT-1 and ANN-1 one and the same line appears as the maintainer of the two types. Restorers for CMS of ANT-1 and ANN-1 types from the lines used in the study are not found. In CMS of Pet-2 type the fertility is restored only by line RCMG-1. It is supposed that the complementary performance of two nonallelic genes controls the fertility restoring in CMS of Pet-2 type.

Mutagenic treatments were performed on F1 sunflower sceds with gamma rays (100 Gy, 200 Gy, 300Gy or 400 Gy dose) and with 0.2% ethyl methyl sulfonate. The screening for bifenox or glyphosate resistant progenies led to 18 M² homogeneous bifenox unaffected (resistant) progenies and 113 progenies segregating glyphosate partially resistant plants, respectively. The ratios of progeny numbers containing - bifenox homogeneous unaffected/segregant resistant plants,and -segregant partially resistant/homogeneously sensitive plants, suggested a mutational event towards a recessive allele.In the field, spraying with glyphosate appeared inefficient to study the mode of inheritance of the resistance. Therefore we developed an in vitro assay allowing us to investigate four progenies only segregating partially glyphosate resistant plants. About ten per cent of the individuals of these four progenies survived the in vitro assay while no control plant did. Glyphosate resistance was controlled for four generations of the progenies. The level of resistance against glyphosate was reproducible but low in vitro (10 ul Roundup/) or in field (360 g/ha) so that further work will be done to check a possible duplication of the EPSP synthase gene.

One of the most important pathogen of our field and culture plant production is Sclerotinia sclerotiorum (white mold). In case of its epidemic spreading it causes significant production losses in sunflower fields. For this reason we consider it important to know more about the generative reproduction cycle and the interaction of ecological conditions to this pathogen. To establish the above we have conducted laboratory and field studies during various phenophases of the sunflower. For our experiment we used various genotypes (NK-254, Remil, NS-H-26, GK-70 and SP-1) and have found that the development of Sclerotinia sclerotiorum infection very much depends on the phenological state of the host and the microclimatic conditions. From the infection point of view the dampness of the surroundings and the light conditious (1500-1600 lux is the optimum) were decisive. The sporulation of the fungus is found at 60-95% relative humidity of the air and the spores germinate in 4-5 hours at 18-25°C. According to our observation for the mycelial imbedding in the host's tissues the leaves must be wet up to 30-35 hours. On the other hand, regular interruptions of wet period can result in the failure of infection. From the development of epidemic point of view the most critical period is the state of the beginning of the generative phases of budding, blooming and yellow ripening. Presently, depending on the meteorological factors, the spraying of sunflower plants is justified. The dampness of suroundings is vital in this regard.

Comparison of artificial and natural basal stem rot infection tests showed significant correlations between the two traits, indicating that the toothpick method is suitable for developing genotype resistance. Since the results of the tests are reliable, the expression of inbred resistance in hybrids could also be followed.In the case of the material tested, no correlation could be found between inbred and hybrid reaction. Further research will be needed to find causes and develop new inbreds which transfer their resistance to the hybrids.

During the period 1984-86 the symptoms of an unusual, previously unknown disease were observed on sunflower hybrids and a variety in different parts of the country. Soft rot symptoms appeared on stalks, petioles and heads. The frequency and severity of the disease varied greatly on the different organs and areas It was presumed, that a bacterium is the causal agent of the disease. Isolations were performed and biochemical tests carried out. The identification procedure including artificial inoculation tests proved, that two Erwinia carotovora subspecies, namely E.c. subsp. carotovora and E.c. subsp. atroseptica are present which are able to infect sunflower causing a severe disease and loss of yield. Evaluating the behaviour of inbred materials and commercial hybrids under natural infection conditions, it can be stated that there are remarkable differences in resistance of the genotypes tested. This phenomenon can be a basis for breeding for resistance as an effective means of control ling this destructive disease.

Ecological factors have been studied to reveal the effect of the conditions of soil on the development of apothecia of Sclerotinia sclerotiorum. The different genotypes of the soils determined the sporogenesis. Most apothecia were developed on the surface of soddy alluvial and sandy soils. Strong correlations have been found between the physical, chemical and microbiologycal features of soil and the intensity ofapothecia development. The susceptibility of sunflower was studied in the field. NS-H-45, NS-11-43, S-2151 and U 55E, S-281, U 74E were tolerant to Sclerotinia sclerotiorum caused by spontaneus infection and inoculation in the field.

Eighty sunflower inbred, almost all registered in Crop Science, U.S.A, as parental lines, were tested at Agricultural Research Centre, Islamabad, during the autumn season of 1990 for charcoal rot resistance.The lines were artificially inoculated with Macrophomina phascolina prepared on PDA by toothpick method when plants started flowering. Infection was measured on pith by splitting the stalk, near maturity, 35 days after infection. None of the line showcd resistance, however, differencs in infection volume exhibited relative susceptibility. Inbred lines HA-89, HA--224, HA-232, 1 1^-288 and HARI had less than 20 cm pith infection.

In the paper results of trials with sunflower hybrids organized in sunflwer growing areas by the Research Institute for Plant Production Praha-Ruzyne in the vears 1984-1989 are summarized.In small--scalc trials 92 hybrids from 12 countries were tested, in mid-scale trials 59 hybrics from 5 countries. In small-scale trials vield differences between the years (always of a two-vear experimental cycle), between localities (when the assortment in the ČSFR and Austria was identical) and between hybrids themselves were compared. Hybrids were compared within the framework of each two-year cycle and in trans- formed yields also for the whole six-year period. In mid-scale trials yield analysis of the hybrids in the course of six years at three localities (at a various number of years at a locality) has been performed. As result, hybrids were assorted into yielding categories. Comparison of the success of single countries and firms according to the ranking in small scale trials prefers I ungary and GKI Szeged, in mid-scale trials the USA (firms Pionier and Northrup King), rumania and Yugoslavia were the most successfull ones.