The occurrence of fruits with absent or poorly developed embryo, also defined as seedless or incompletely developed fruits (IDF), significantly reduces the sunflower yield. Failures in pollination, fertilization and physiolog ical or morphological defects in the ovary and embryo, either post-pollination or post-fertilization genotype- and/or ambient-induced, are most common rea sons for the development of this type of fruits. A detailed study of the visit path pattern of diurnal pollinators in the crop, mainly honeybees (Apis mellifera L.), showed that there was a significant negative correlation (r2=-0.61; p < 0.05) between the areas covered by foraging paths (ACP), with the total IDF counted in the capitulum. Almost a complete limitation of insect visitation (0-30% ACP) resulted in poor seed set and IDF percentage ranging from 10 to 17%. Partial limitation of the insect visitation (60 to 90% ACP) diminished the number of IDF to 5 to 9%. Its is concluded that as much as 30% or more of the capitulum’s area must be covered by bee visits to minimize the development of IDF.

Hyperhydricity is a morphological and physiological disorder affecting plants regenerated in vitro. This malformation is associated with excessive hydration and abnormal shoot morphogenesis such as glassy water-soaked appearance of shoots. This undesirable phenomenon is a frequent problem in sunflower tissue culture systems and has been described by visual symptoms but there is no information on the anatomic structure of the affected shoots. In this paper we describe anatomic features of normal and hyperhydric sunflower shoots regenerated in vitro. The hyperhydric shoots were classified in four cat egories according to different abnormalities observed at the morphological level. The anatomic structure of leaves and stems of normal shoots did not dif fer from control seedlings. In contrast, hyperhydric shoots presented various anatomic defects, such as reduction of palisade parenchyma, an increase in cellular volume, hypolignification of vascular system and hypertrophy of corti cal and pith parenchyma. In addition, a crescent disorganization at the ana tomic level was observed among the different types of hyperhydric shoots. This study provides a characterization of the anatomic responses induced by hyper hydration in tissue culture regenerated sunflower plants.

Amounts of indole-3-acetic acid (IAA) and gibberellic acid (GA3) in vegeta tive and reproductive tissues of diverse sunflower genotypes have been investi gated using gas-liquid chromatography. Quantification of endogenous GA3 content in the homozygous line MB 514, characterized by cytoplasmic male sterility (cms), revealed a lower level of the hormone in contrast to the fertility restorer line RW 637 Rf. The highest amount of IAA was found in the hetero zygous F1 hybrid obtained by crossing these lines, regardless of tissues and ontogenetic phases analyzed. Similar features were found in leaves, apices, inflorescences and disk flowers in most of the investigated variants.

Quantitative ratio of IAA/GA3 has been studied during the growth and development of different sunflower genotypes that represent a cms-Rf system. It was shown that the IAA/GA3 ratio was variable and it depended on ontoge netic stage, plant organ and genotype. Thus, the IAA/GA3 ratio the maximal value in the male sterile line while the minimal ratio was found in the restorer line RW 637 Rf. The highest IAA/GA3 ratio was registered in cotyledon leaves, which decreased subsequently in the course of ontogenesis. During reproduc tive stages, the ratio was higher in inflorescences than in leaves. The exoge nously applied gibberellic acid (GA3) increased the ratio in the fertile line. Specificity of the IAA/GA3 balance in the male sterility-fertility phenotype expression and in GA-induced pollen sterility is discussed.

Maintenance of genetic uniformity of lines and hybrids is a prerequisite for successful production and placement of commercial hybrid seed on the market. Genetic purity of seed as specific seed trait is of great significance for seed science. Protein markers, seed storage proteins and isozymes, which are commonly used for the estimation of genetic purity, were used in this work to estimate genetic purity in sunflower hybrids. Analysis of helianthinin revealed tree zymogram patterns within and between sixteen sunflower hybrids. All of the 6 enzymatic systems analyzed, MDH, PGM, PHI, PGD, IDH and ACP, were polymorphic. A comparative analysis of genetic purity level of the sunflower hybrids was performed using electrophoretic methods. The methods of electro phoretic separation of isozymes and seed storage proteins were in agreement, with differences ranging from 1% to 5% in 81% of the samples. The level of pol ymorphism obtained by both methods was not distinct enough to be used in genotype identification.

Sunflower oil with increased levels of saturated fatty acids has important applications in food industry. The objective of this research was to develop novel variations with increased saturated fatty acid levels by chemical muta genesis. Seeds of four different accessions of Peredovik were treated with a solution of ethylmethane sulfonate. M2 seeds from a single M1 plant exhibited a large variation (5-29%) for palmitic acid content. The progenies of all selected M2 seeds showed again continuous ranges of variation (10-30%) for palmitic acid content. Similar continuous segregation was observed in some M3:4 and M4:5 families derived from high palmitic half seeds (>25%), although other families had uniformly high palmitic acid content. Previous genetic studies of CAS-5, a high palmitic acid mutant which showed clear bimodal distributions in the M2 generation, concluded that the trait was genetically controlled by alle les at three loci. The different segregation patterns observed in NP-40, the new high palmitic acid mutant, suggested that it was genetically different from CAS-5.

Immature zygotic embryos of sunflower fertility restorer line 147 R were treated with ultrasound before plating to embryo culture medium. Some mutant plants were isolated and self-pollinated for several generations. New sunflower forms with inherited morphological and biochemical changes were obtained through selection and self-pollination. Genetic changes that occurred during the regeneration procedure included fifteen morphological and bio chemical characters. In this study, negative genetic changes were registered for most of the indices. Positive changes were registered for leaf petiole length and number of leaves. Plant height was the least stable of all characters under study. Mutation for resistance to the local population of Orobanche cumana (race A-E) was obtained from the susceptible Bulgarian control line 147 R. All five investigated mutant restorer lines possessed 100% resistance to Orobanche and stable inheritance in subsequent generations. Our results showed that mutagenesis in sunflower can be successfully used to develop new lines useful for heterosis breeding.

Sunflower broomrape (Orobanche cumana Wallr.) is currently regarded as one of the most important constraints in sunflower (Helianthus annuus L.) production. In the last fifteen years, efforts to introduce genetic sources of resistance to this parasite in sunflower hybrids were followed by the occur rence of new virulent races that promptly overcame all known resistance genes. Due to this situation, most of the research efforts have focused on the develop ment and characterization of new sources of genetic resistance to the most vir ulent races and also on the genetic structure and variability of O. cumana populations and their evolution, in order to develop long-term strategies for sunflower broomrape management. Results of evaluation of sunflower germ plasm for resistance to different broomrape races have demonstrated that wild Helianthus species constitute the major reservoir of genes conferring resist ance to new virulent races. Cultivated germplasms are also valuable sources of resistance genes. Most of the resistant sources have been found to be control led by major genes, although quantitative resistance and epistatic effects have also been reported. Different dominance reactions, depending on the race of broomrape, the source of resistance and the susceptible parental line used for crossing have been observed. Molecular studies have shown that phenotypic variance for race E resistance was mainly explained by a major QTL associated to the resistance or susceptibility character, while race F resistance was explained by several QTL with a small to moderate effect, mainly associated with the number of broomrapes per plant, suggesting the existence of a quanti tative component in the resistance to race F. The relevance of these findings for sunflower breeding for resistance to broomrape is discussed.

The response of RIMI [imazethapyr-tolerant (T)] sunflower (Helianthus annuus L.) hybrid and the local imazethapyr-sensitive hybrid "Zoltan" (S) was investigated under controlled conditions. Hybrids grown in pots were treated post-emergence with imazethapyr at the two pairs of leaves stage. Visual injury evaluation and vegetative parameters were recorded. ALS (acetolactate syn thase) enzyme activity was estimated in vivo 24 h after imazethapyr applica tion. Tolerance level was determined based on the resistance ratio index (ED50- herbicide dose causing 50% growth inhibition of T hybrid/ ED50 of S hybrid). Significant differences were noted between the hybrids in the in vivo ALS activ ity and vegetative parameters. Indexes of resistance ranged between 5 and 452 for vegetative parameters, whereas the index for ALS activity was 210. The data confirmed the high level of tolerance of the hybrid Rimi as compared with the hybrid Zoltan.

In order to execute a breeding procedure efficiently, it becomes inevitable to examine the relationship between combining ability and heterosis. In the present investigation, diallel analysis of restorer lines (R lines) and their restorer × restorer (R × R) crosses was employed to identify and develop elite ‘R’ lines for subsequent use in sunflower hybrid development programs. Crosses with high SCA effects were arranged in order of their per se perform ance, general combining ability of the parents of these crosses and per cent heterosis over standard check hybrid LSFH-35 and KBSH-1. Best GCA effects and high mean performance characters were observed between high × high, low × high or low × low general combiners. The combinations J/6 × NDR-1, 6D-1R × DMLT-1Y, NDR-1 × LR-451 and 6D-1R × DMLT-1Y, which were best for seed yield/plant, oil content and 100-seed weight and head diameter, respectively, were between high × high combining parents, indicating additive × additive effects are fixable components, and single plant selection would be desirable in their segregating generations. The combination NDR 856 × 6D-1R, with high per se performance for pollen productivity, was between low × high combining parents, and the combination 6D-1R × NDR-1, for plant height, was between low × low combining parents, indicating better complementation between favorable alleles of the involved parents.

Two population improvement methods, mass selection (two cycles) and SI selection (one cycle) were imposed on a base population to study the response to selection by comparing their efficiency in improving autogamy, seed yield and oil content in sunflower. Mass selection was adopted for devel oping two distinct populations regarding maturity, one early (80-85 days) and one medium (95-100 days). The derived populations MSE -2 (early) and MSM 2 (medium) retained substantial variability for most of the characters even after two cycles of mass selection. As compared with the base population, these derived populations showed substantial improvements in seed yield, to an extent of 40 to 65%, oil content (38%) and oil yield (83 to 97%). However, the response to SI selection was effective only in improving oil content. For other characters including seed yield, the derived populations were inferior com pared with the base population.

Twenty-eight hybrids were generated by crossing seven male sterile lines with four restorers in the line × tester cross system. GCA and SCA effects of parental lines and heterosis effect of F1 hybrids have been evaluated for 4 characters. Two of the twenty-eight Byelorussian hybrids (Donskoy 22 and Signal) revealed higher values for oil yield with respect to standard checks. According to the data obtained it is quite possible to produce prospective Byelorussian hybrids under local soil-climatic conditions.

This paper reports the results of two experiments in which sunflower plants were grown from seed to seed in small pots to utilize greenhouse space efficiently. We used small plastic pots (9.0 × 8.6 × 9.0 cm) filled with approxi mately half a liter of potting soil in a temperature-controlled greenhouse with a light : dark cycle of 14 : 10 h. In the first experiment, 100 F2:5 plants were grown on a two-square-meter bench in the greenhouse during the winter of 2007. Ninety-eight of the 100 plants survived to maturity and produced an average of 62 viable seeds with a range of 36 to 102 seeds per plant. In com parison to the plants grown in six-liter pots, we observed that all the plants grown in the small pots had a significant decrease in plant size such as height, head diameter, and number of seeds per plant. The plants grown in the small pots flowered on average 9 days later than those in the large pots. No signifi cant difference was observed for germination rate between the seeds harvested from small and large pots. In the second experiment, two oilseed and two con fectionery sunflower inbred lines were grown during the summer of 2007 to confirm the observations from the first experiment. The results were essen tially the same as those observed in the first experiment. For number of seed produced per plant, an average of 13.0 to 42.2 seeds were obtained per head for each of the four lines grown in small pots, with no significant difference observed between oil and confectionery sunflower. Thus, our results suggest that it is possible to produce viable seeds from plants grown in small pots. This method should be useful for efficient line advancement in the greenhouse for breeding and genetic studies.

The present work was undertaken to evaluate volunteer corn control through the application of graminicides singly or combined with boron (B) sources as well as to assess the sunflower (Helianthus annuus L.) response to the application of this micronutrient. Experiments were arranged in a split-plot design with randomized complete blocks and five replications. The treatments applied were haloxyfop-methyl 0.048 kg a.i. ha-1 plus 0.5% (v/v) mineral oil, sethoxydim 0.22 kg a.i. ha-1 plus 0.5% (v/v) mineral oil, clethodim 0.12 kg a.i. ha-1 plus 0.5% (v/v) mineral oil, fluazifop-p-butyl 0.187 kg a.i. ha-1 and the hand-hoed control. The sub-plots consisted of the absence or presence of 400 g ha-1 of B from two sources (H3BO3–boric acid and Na2B8O13.4H2O–sodium borate), applied with the herbicides. All herbicides applied singly or combined with the two B sources were selective for the sunflower crop and efficient in controlling volunteer corn. The application of B in association with herbicides increased the content of this micronutrient in sunflower leaves.

Six field experiments were conducted on sunflower with treatments com prising of 4 dates of sowing (sown during different standard meteorological weeks viz., 28 (9-15 July), 30 (23-29 July), 32 (6-12 August) and 34 (21-26 August), 3 moisture conservation methods (ridge & furrow, skip row with fur row and flat bed) and 3 levels of fertilizer NP (40-20, 50-25 and 60-30 kg/ha) during kharif 1999 to 2004 at Solapur on semi-arid vertisols. Based on daily rainfall (RF), daily runoff (RO) and crop soil moisture stress index (MSI) were measured for each combination of date of sowing (DOS) and moisture conser vation (MC) method in each season. Correlation analysis indicated a positive relation of seed yield with rain fall in all 4 DOS. The relation was relatively higher for flat bed in 1st DOS, ridge & furrow in 2nd DOS, skip row with furrow in 3rd and 4th DOS. It was nega tively related with RO in 1st DOS, but positively related with the other 3 DOS. The relation was higher under ridge & furrow system in 1st DOS (negative) and 4th DOS (positive), while under flat bed in 2nd and 3rd DOS. Negative relation of MSI was found with yield under all the 12 combinations of DOS and MC indicating a higher relation under skip row with furrow in 1st, 2nd and 4th DOS, and flat bed in 3rd DOS. The relation between RF and RO was positive, while MSI had negative relation with both RF and RO. Regression models of seed yield through RF, RO, SMI, fertilizer N and P, along with fertilizer x MSI interaction were calibrated. The predictability ranged from 0.12 (ridge and furrow in 3rd DOS) to 0.91 (flat bed in 1st DOS). A ready reckon of optimal N and P doses at varying MSI levels (0.15 to 0.75) indi cated that ridge and furrow method is efficient in 1st DOS with an optimal N and P ranging from 51 to 53 kg/ha and 26 to 27 kg/ha, respectively. Skip row with furrow method was efficient when crop was sown in any of the other DOS with an optimal N ranging from 38 to 66 kg/ha (2nd DOS), 44 to 73 kg/ha (3rd DOS) and 47 to 74 kg/ha (4th DOS). The optimal P ranged from 19 to 33 kg/ha (2nd DOS), 22 to 36 kg/ha (3rd DOS) and 24 to 37 kg/ha (4th DOS) for attaining maximum productivity of sunflower on semi-arid vertisols.

Sunflower (Helianthus annuus L.) is an important oilseed crop. It was grown on more than 20 million ha in the world in 1997, of which over one mil lion ha were in West Asia-North Africa (WANA) countries, where Iran grew 60,000 ha and Syria 50,000. There is potential for substantial increase in sun flower area and production on dry land if optimum management practices are applied. An important management consideration is choosing a high yielding, good quality variety that will maximize seed yield and minimize seed costs. This study investigated the influence of hybrids and open pollinated varieties on yield and other agronomic traits of sunflower. Ten hybrids and eleven open pollinated varieties were compared, under rainfed conditions (Jindiress) and with minimum supplementary irrigation (Tel Hadya, ICARDA Aleppo, Syria) in 1993. Soil at Tel Hadya is red clay loam characterized as Calcixerollic Xero chrept (Inceptisol), Chromic Calcixeret (Vertisol); at Jindfiress, the soil is Cal cixerollic Xerochrept (Inceptisol). All of them are thermic and clayey to very fine clay. At both stations, equally good and statistically similar yields were obtained with hybrids and varieties. The average yield of the 21 cultivars was 2,207 kg/ha at Jindiress and 2,080 kg/ha at Tel Hadya. The average yield of the 11 OPVs was 2,073 kg/ha and that of the 10 hybrids was 2,220 kg/ha, which was similar. Thus, less costly OPVs can be used instead of costly hybrid seed. Farmer can also produce their own seed with little training; the cost will be one fourth of that of hybrids, which are imported and seldom available on time. In the absence of hybrids, F2 seed is resorted to by farmers which reduces the yields considerably. The rainfall during 1993 was lower than the long-term average; it was 277 mm (TH) and 417 mm (Jindiress). The information obtained are important to farmers, allowing them to maximize economic returns from rainfed areas by using limited supplementary irrigation in low rainfall locations and during dry years.