A total of 245 test cross progenies obtained by crossing cytoplasmic male sterile (CMS) lines and restorer (RHA) lines were evaluated in replicated trials in 1995 and 1997. Experiments were carried out in two locations (Osimo, East Central Italy and Budrio, Northern Italy) in 1995, whereas in 1997 trials were conducted only in Osimo. General combining ability (GCA) and specific combining ability (SCA) of the parents was evaluated to identify genotypes suitable to be used as testers for breeding programs and to verify the performance of hybrids. The results obtained in 1995 were used to make test crosses in 1996 to be evaluated in 1997. The GCA and SCA of RHA and CMS lines were nearly always significant for all the studied traits when lines were randomly taken in 1995. When selected testers were used on the basis of the results of the first year, the SCA of new RHA lines and GCA of new CMS lines were not significant for achene yield, but they were for the other traits. The best GCA estimates for RHA were often higher than those of CMS, indicating that selection for RHA could be more useful than for CMS. As expected, GCA was always lower than SCA. CMS and RHA, with high variance among their test crosses for yield and many other traits, could be used as testers. The lack of a tester with high variance in all traits requires more than one tester in evaluating lines. The GCA of a line can change in function of the germplasm with which it is combined.

Genetic diversity was assessed in 46 non-oilseed sunflower genotypes for 14 characters by adopting D2 analysis. Oil content and plant height exhibited maximum contributions towards genetic divergence. The genotypes were grouped into 11 clusters. The inter-cluster D2 values ranged from 288.17 to 3972.34. The contribution of oil content towards genetic divergence in the 46 genotypes was confirmed when D2 analysis was performed for seed characteristics such as test weight, volume weight, hull content, kernel recovery, oil and protein content.

Standard heterosis was estimated for eight quantitative traits in top-cross hybrids of three diverse cytoplasmic male sterile (CMS) sources of sunflower viz., Helianthus petiolaris (CMS-PET1), Helianthus petiolaris ssp. fallax (CMS-PEF1) and Helianthus annuus ssp. lenticularis (CMS-ANL2) maintained under different nuclear backgrounds. The top-cross hybrids were derived by crossing the above three CMS sources with 12 male parents in a line x tester design. Significant heterosis over two standard checks in the desirable direction was observed for all traits. All three sources under study advanced the maturity in most of the hybrids. CMS-PET1 was found to be the best compared with the other sources as far as oil content was concerned. Mean performance of the hybrids for achene yield and other economically important characteris tics indicated that the hybrids derived in the cytoplasmic background of CMS ANL2 were the best followed by CMS-PET1 and CMS-PEF1 suggesting that CMS diversification in heterosis breeding programs would be rewarding in sunflower.

Yield performance, heritability and trait correlation were studied in 20 sunflower genotypes. Hybrid SF-100 produced the highest seed yield of 3669 kg ha-1 followed by NK-265 and Gloriasol with 3289 and 3264 kg ha-1, respectively. Heritability (broad sense) values ranged from -5.58% in seed per capitulum to 98.72 for 50% flower. 100-achene weight, 1st flower, complete flowering, maturity, and oil content showed high heritability values of 98.65%, 98.56%, 98.38%, 96.03% and 95.72%, respectively. Seed yield was positively correlated with all traits studied. Path coefficient analysis revealed that first flower had the highest positive direct effect on seed yield followed by seed per capitulum, 100-achene weight complete flower, and head diameter, while 50% flower had the greatest negative direct effect on seed yield.

The aim of this work was to develop a simple method for calculating disk flower number and their density in sunflower head. The formula developed on the basis of the Golden section includes initial data of the number of small-short rows and the number of florets in a row. It takes no more than a minute to gain initial data for calculating the formula for one head.

Regression analysis is explored for the multivariate data of two field experiments conducted with 7 sunflower genotypes, GUJ-SUN-1, MSFH-8, MSFH-17, KBSH-1, JWALA, PAC-36 and MORDEN, grown during kharif 1997 and 1998 in a dryland alfisol. Observations on 8 physiological traits, stomatal conductance, photosynthesis, leaf nitrogen, stem nitrogen, leaf weight, stem weight, leaf number and leaf area, as observed on 30, 45 and 60 days after sowing were used in the analysis for selecting the best genotype which is consistent in plant growth and has an efficient performance apart from identifying the dominant traits. Regression functions for predicting physiological traits have been calibrated by regressing the observations of a trait on 60 days after sowing through its observations on 30 and 45 days after sowing. The genotypes have been assessed based on the significance of traits, predictability and estimate of error derived for each trait. The analysis indicated the dominance of photosynthesis, stomatal conductance and stem nitrogen in kharif 1997 and stomatal conductance, photosynthesis and leaf nitrogen in kharif 1998 for the growth of sunflower. The analysis also indicated the superiority of PAC-36 in kharif 1997 and JWALA in kharif 1998 having 8 and 7 significant regression coefficients of traits, respectively.

H.maximiliani was micropropagated using culture of shoot apices on modified Murashige and Skoog medium (DV). Further propagation of in vitro grown plants was done by culture of their nodal segments and shoot tips on the same medium supplemented with phloridzin, silver nitrate and casein hydrolysate (DV'). Rooting was induced by dipping the explants into IBA solution prior culture. Viable protoplasts (90%) were isolated from leaf mesophyll. These protoplasts divided (18%) in culture in agarose droplets.

Various reports state that the sunflower disease, primarily caused by Diaporthe/Phomopsis helianthi Munt.-Cvet. et al., has a wide geographic distribution in Europe, USA, Argentina and Australia. Various Phomopsis isolates obtained during this investigation of the sunflower disease differed in conidial type (α, β, α and β). Phomopsis helianthi was the only isolate producing exclu sively β-conidia and perithecia on debris (Diaporthe helianthi). The other Phomopsis isolates were saprobes on sunflower plants.

All four seed diffusates used for treatment of sunflower seeds, Aza dirachta indica, Capsicum annuum, Coriandrum sativum and Eugenia jam bulana, reduced the populations of seed-borne fungi: Alternaria alternata, Drechslera tetramera, Emericellopsis terricola, Fusarium moniliforme, F. semitectum, Macrophomina phaseolina and Phoma oleracea. Of four seed diffusates, those from A.indica and C.sativum controlled the fungal populations almost 100%. Seed germination was increased in seed samples of both sunflower cultivars under study, HO-1 and NK-212. The obtained results indicate that seed diffusates could substitute costly chemicals for safe control of seed-borne diseases, protecting at the same time the environment from chemical pollution.

We investigated possibilities for the formation of reproductive structures of important sunflower pathogens, Phomopsis helianthi and Phomamac donaldii, on the husk and kernels of naturally infected and inoculated seeds. Pycnidia were typically formed at the wider part of the husk in all sunflower lines and hybrids infected by P.helianthi and/or P.macdonaldii, partly immersed in the epidermis. The pycnidia of P.macdonaldii were larger than the pycnidia of P.helianthi. The kernels infected by P.helianthi showed slight structural changes in comparison with the non-infected achenes. An exception were the seeds of a line which, on infection by P.helianthi, showed a complete disintegration of the central part of the cotyledon while numerous pycnidia formed in the outer layers of the parenchyma. Seeds of lines infected by P.macdonaldii were consid erably damaged. The cotyledonary tissue was disintegrated and pycnidia arranged in rows formed in the outer layers of the parenchyma.

Chemical desiccation with Reglone Forte has been tried in production fields under four sunflower hybrids. Reglone Forte (2 l/ha) was applied at 7-day intervals from the end of pollination till maturity. Seed moisture was determined prior to each treatment. Seed oil content was determined at maturity, using the method of nuclear magnetic resonance. The highest oil content was found in the control, the lowest in the treatment 7 days after flower (DAF). The absence of significant differences among treatments 21 DAF, 28 DAF and the control was an indication that there was no large increment in oil content in the period after the average seed moisture reached 44.34% and maturity. Considering individual hybrids, there was no large oil content increase already from treatment 14 DAF, with the exception of hybrid NS-H-43 which evidently required a later treatment. Considering the time of treatment in relation to seed moisture, this hybrid achieved maximum oil content when treated at 31% seed moisture. In hybrid NS-H-26 RM, however, maximum oil content was achieved with treatment at 25% seed moisture.

A field study was conducted on four desiccants; Dimethipine, Metoxuron (Dosanex), Drop-leaf and Diaquat, during 1990 and 1991. Two rates of each desiccant were sprayed on sunflower (Helianthus annuus L.) hybrid NK-212 15 days after flower completion. Two harvesting dates (10 and 20 days) after desiccant application were superimposed on each desiccant treatment. The objective of this specific study was to determine the relative efficacy of different desiccants at two different rates, harvested on two different dates after application and their consequent effect on seed yield, oil quality and other agronomic characters of sunflower. As an average of the two years, desiccant treatment means were significantly different for all the traits studied. The lowest seed yields (1667 and 1674 kg/ha) were obtained from lower and higher doses of Diaquat, respectively. Conversely, higher yields were obtained by both rates of either Drop-leaf (2222 and 2342 kg/ha) or Metoxuron (2121 and 2168 kg/ha) as compared with the other treatments. Application of Diaquat and Dimethipine reduced the yield significantly as compared with the control, Drop-leaf and Metoxuron (Dosanex). Similarly, low and high oil contents were attributed to Diaquat and Drop treatments, respectively. This study concluded that Drop-leaf and Metoxuron (Dosanex) can be safely used as desiccants on sunflower at the rates of 0.225 and 0.750 kg ai/ha, respectively. The sunflower crop should be harvested 35 days after flower initiation or 25 days after flower completion to get higher seed yield, oil content and low seed moisture contents to mini mize the post harvest losses and simultaneously vacate the field 5 to 10 days earlier for the subsequent crop.

Field experiments have been conducted to study the effect of organic and inorganic sources of nutrients applied alone or in combination on the growth and yield of sunflower. Application of a recommended dose of fertilizer (62.5:75:62.5 kg NPK ha-1) coupled with 10 t ha-1 of farmyard manure has recorded highest seed and stalk yields of sunflower. Growth and yield parameters were also favorably influenced by the application of the recommended dose of fertilizer coupled with farmyard manure. Seed oil content was not influenced by the application of organic or inorganic sources of nutrients.

A hydroponic study was conducted to investigate the influence of Ca sup ply on K+/Na+ selectivity of sunflower at 0, 75 and 150 mM NaCl in root medium. Sunflower (Helianthus annuus L. cv. Hysun-33) seeds were germinated in moist quartz sand and twelve-day old seedlings were foam-plugged in lids of plastic pots each containing 2.5 l of continuously aerated half strength Hoagland's nutrient solution without calcium salts. The solution pH was adjusted to 5.9 by adding HCl and NaOH. There were three salinity levels (0, 75 and 150 mM NaCl) and two calcium levels (5 and 10 mM CaCl2). The exper iment was organized in a randomized complete block design (RCBD) in three replicates. At low concentration of calcium (5 mM), sunflower growth decreased drastically with increasing concentration of NaCl in nutrient solu tion. On the other hand, plants grown in high concentration of NaCl experienced less damage with relatively higher concentration of calcium. At relatively higher concentration of calcium (10 mM Ca), sunflower plants absorbed and translocated relatively more potassium and less sodium, than at low concentration of calcium (5 mM Ca), demonstrating the positive role of calcium in alleviating the hazardous effects of salinity on sunflower growth.

Investigations conducted during last years showed serious violations of ecological equilibrium in many agricultural regions. Crops produced in these regions are commonly used as food and feed. It has been established that the content of heavy metals in the soils and agricultural crops grown nearby the metallurgical factories is much above the admis sible concentration. Micro-particles of Pb, Cu, Zn and Cd separated in the atmosphere by aerosols, accumulate in the soil, plants and water areas. From the studied heavy metals the coarse particles of Zn commonly pile in soil nearby the contaminator, and the heavier particles of Pb are distributed by the prevailing winds. These elements accumulate shallow in the upper layer and confined to quantity move down. The irregular contamination of soil around certain factory is in great part dependent on turbulent movement of air, wind lessness and the condition of fluctuating atmosphere - inversion. Contamination with heavy metals is most oftenly in according with areas. Maximum accumulation is found out on boundary areas in a distance at about 1000 m from the factory called the area of accumulation, and 15 000 m away from the factory called area of distraction. Commonly, on this area is grown one of the specific for Bulgaria culture - the sunflower. This needs solving of many prob lems connected with studying the accumulation and depous of localization of heavy metals in sunflower grown on contaminated soil, as well as their influence upon soil fertility.

Effect of different row directions on yield and yield components of sunflower (Helianthus annuus L.) was studied in a field experiment at National Agricultural Research Center, Islamabad, Pakistan, during spring 1991 and 1992. Four row directions, i.e., north-south (NS), east-west (EW), north-east south west (NESW) and north west-south east (NWSE) had very little effect on seed yield and other agronomic characters of sunflower. The differences in the mean plant height, head diameter, seed yield, 100-achene weight and fatty acid profile were statistically non-significant. Trends were similar in both years. As an average of the two years, although statistically non-significant, the highest seed yield of 3065 kg/ha was obtained from north east-south west (NESW) row direction and the lowest yield of 2624 kg/ha from east-west (EW) row direction. The most pronounced effect of row direction was noted on seed moisture con tent. As an average of the two years, the maximum seed moisture content at harvest (21.4%) was obtained from east-west (EW) row direction and the mini mum (14.6%) from north-south (NS) row direction. NESW row direction also gave significantly lower moisture content (15.1%) than EW (21.4%) and NWSE (18.1%) row directions. Therefore, using north-south and NESW row directions would help the crop to dry more quickly before harvest and reduce post harvest costs and losses. Seed production fields that require examination of sunflower heads to detect pollen production should be planted in NS rows for efficient roguing to maintain genetic purity. For research plots, EW rows with plot labels on the east end are often preferred, because it is easier to evaluate most plots when all heads face the viewer.

Sunflower (Helianthus annuus L.) hybrid NK-212 was planted at National Agricultural Research Center, Islamabad, during 1992 and 1993 to assess the impact of various levels of simulated leaf damage, commonly caused by insects, hail or foliar diseases, on source and sink relationship. Insect attack, hail and foliar diseases often partially defoliate sunflowers and may become important factors limiting the production. Reduction in leaf area may also occur in the field as a consequence of pathogens or atmospheric conditions. Artificial defoliation was chosen as an experimental means to assess its effect on seed yield and plant behavior. It had also made possible to evaluate the effect of such a reduction at different phenological stages and to identify the leaves that contribute greatly to the seed yield. The leaves were clipped in vari ous proportions from different parts of the plant, i.e., lower, middle and upper. The removal of upper 2/3 and 1/2 leaves caused a yield reduction of 29 and 55.8%, in 1992 and 37 and 44.8%, in 1993, respectively. In 1992, about 1% yield decline was recorded when the lower 1/3 leaves were removed and 6% yield decline with the removal of the lower 1/2 leaves. In 1993, the yield reduction was 26.7 and 39.2% due to removal of lower 1/3 and 1/2 leaves, respectively. This indicated that the upper leaves (source) contribute more towards seed yield (sink) than the lower ones. Correspondingly, the results indicated that insects and pests feeding on the upper portion of the sunflower plant can cause larger reduction in seed yield than those feeding on the lower leaves.