In order to isolate and to analyse the expression of developmentally regulated genes in sunflower, cDNA libraries were constructed using mRNA from 12 or 2O day-old seeds and then differentially hybridized with mRNA from dry seeds and leaves. cDNA encoding major storage proteins (helianthinin and albumin Met-rich), proteinase inhibitor and two other cDNA with unknown function were isolated. The steady state levels of the transcripts, detected with each cDNA, were determined in immature seeds and vegetative tissues at different stages. The accumulation of the five mRNAs was tissue-specific, limited to the mid-maturation stage of seed development. The albumin Met-rich nRNA accumulation occurred relatively later than t}re accumulation of both the helianthinin nRNA and the previously studied HaGS albumin mRNA in sunflower. This indicates that the mRNA synthesis of the two storage protein classes and of different precursors within one protein class is not synchronous. These observations were correlated to the deposit of the different storage protein precursors and are in agreement with a primary control of storage protein gene expression at the Ievel of mRNA transcription. The accumulation of helianthinin transcript was higher in the CANP3 normal variety in comparison with the HOC . high oil and oleic > line. The levels of the albumin Met-rich mRNA were in contrast similar in both lines. This could be in relation with the protein redistribution that is known to accompany the increase of seed dil content in sunflower and agrees with the fact that low oil varieties have higher helianthinin content than high oil varieties. We suggest that the albumin Met-rich fraction is not involved in this protein redistribution.

Anatomical differences were analyzed between the inbred line HA-89 of Helianthus onnuus, which is susceptible to the fungal pathogen Phornopsis/ Diaporthe helianthi Munt. Cvet. et al., and a resistant wild population of H. argophyllus. The anatomical structure of the interspecific hybrid was also studied and compared against the progenitors. Plant materials, especially leaves, were collected in the field in the period 1991-1993 at the anthesis stage of the plants. The results obtained after the analysis of the epidermal and vascular tissues were further processed using SYSTAT statistical package. The results showed that the characteristics of the interspecific hybrid were closer to the susceptible than the resistant parent component. Considering the initial assumption that differences in the dimension of the epidermal and vascular tissues could have significant influence on variability in resistance among genotypes, a negative conclusion can be drawn.

In the present study an attempt has been made to study the effect of Alternaria helianthi toxin on pollen germination and reaction of pollen of different genotypes to the toxin. The addition of toxin to pollen germination media led to a reduction in pollen germination. However, the inhibition of pollen germination was not uniform in all genotypes. The genotypes which are moderately tolerant to the disease at sporophytic level also produced pollen that germinated better in the presence of toxin than did pollen from highly susceptible genotypes suggesting the sporothytic gametophytic association. A strategy to utilise pollen assay to differentiate genotypes in resistanvsusceptible and pollen selection in developing disease resistant populations in sunflower is discussed.

Eleven naturally infected and four uninfected sunflower seed samples collected from different production areas of pakistan were tested for seed germination. Germination in all the infected sunflower seed samples was significantly lower as compared with healthy samples. The seed samples hav ing high infection of Alternaria alternata (Fr.) Kessler alone reduced the germination to the same extent when its infection was low but in combination of other pathogens especially with Fusarium spp. and Macrophomina phaseolina (Tassi) Goid. The number of abnormal seedlings and the recovery percentage of various seed borne fungi from the abnormal seedlings during germination was dependent on their infection level in the seed.

Field experiments were conducted in lggl and 1992 at Morden, Mani toba, on the efficacy of eight fungicides to control sunflower rust. Fungicides were applied either once at flowering or twice. at flowering plus 2 weeks later. Two applications of mancozeb resulted in the highest reduction in rust severity over the two years of this study followed by two applications of propiconazole.One application of mancozeb or propiconazole significanily reduced rust severity over the two-year period. One and two apprications of fluazinam, and two applications of chlorothalonil significantly reduced rust severity in 1991; while one and two applications of myclobutanil, and two applications of RH-7592 significantly reduced rust severity in 1992. Most fungicides increased yield over the control, however, significant increase in yield resulted only from one application of myclobutanil or benomyl in 1991.

Hybrid sunflower florets have been reported to contain two acetone soluble kauranoid compounds that conferred resistance, in the form of "larvicidal" effects, to the sunflower moth, Homeosoma erecteilum (Hulst). The objective of this study was to determine if the seed, florets, ray flowers or leaves from a hybrid sunflower contained acetone soluble kauranoid or other components that conferred resistance to larvae of the banded sunflower moth Cochylis hospes Walsingham. The mortality and development time of larvae reared on diets prepared with unexlracted seed (rearing diet), floret, ray flower or leaf material were compared with mortality and development of larvae fed complementary diets that contained acetone extracted seeà, floret, ray flower or leaf material as the test ingredient. Important findings of the study were as follows: l ) larval mortâIity decreased significanily when larvae were fêd diet prepared with ace tone-extracted seed compared with diet with unexrracted seed 2) substitution of florets into the diet was not Iarvicidal although substitution of florets into the diet resulted in a significant increase in rarval-development time, 3) the devel opment time on diet with ray flowers significanfly increased, 4) mortarity on the leafdietwas as high as on the rearing diet, and b) the effects offloretsl ray flowers, or leaves on mortality or development time of c. hospes were not related to acetone soluble components in sunflower because the resurts in each case were similar when either acetone extracted or intact floret, ray flower or Ieaf material were substituted in the diet. The difference in responce reported here for C. hospes and those reported for the sunflower moth H. eteitertum may reflect species differences in adaptation to the host plant or there may be significant differences in the chemical composition of different sunflower hybrids. Selection of sunflower for constituents that conferred resistance in the form of increased mortality and development time of C. hospes could be useful for greater control of this pest insect.

Sunflower stem canker caused by Diaporthe helianthi Munt.-Cvet.et al., is an important disease in the state of Tamaulipas, where more than 50% of infected plants have been observed. A field study was undertaken to determine the influence of stem canker on oil content and weight of seed and yield, at different stages of seed development. The lowest percentage of diseased plants was registered during flowering. Oil content, seed weight and yield were significanty reduced when stem canker occurred at any stage of seed development. These effects became progressively less pronounced with later disease appeaance.

In the capitulum of sunflower the process of generation of new floret primordia starts at the receptacle rim and continues towards its center. Then, each floret primordium differentiates gradually over space and time, in the centripetal direction. The florets appear in an annular generative zone first as a gentle dome and then become a two-part structure: the floret bract and the floret corolla.

This paper provides a detailed description of the beginning of the floret primordium differentiation during the floral morphogenetic process in the sunflower capitulum.

Three hundred and fifty sunflower genotypes were evaluated at the seedling stage for salt tolerance under control (non-saline) and a salinity level of ECe 12 dSm-1. Eighty-three of them were found sensitive to salinity at emegence and the remaining two hundred and sixty-seven which emerged were further evaluated for seedling growth parameters. Emergence percentage, shoot length, shoot fresh weiglt and root length exhibited greater variation. The genotgpic components of variance for these seedling traits were also greater in magnitude. The estimates of broad sense heritability for seedling parameters ranged from 78.9 to 96.5 percent. Genotypes were classified from highly tolerant to highly sensitive to salinity on the basis of their performance under salinity as compared with control. It is suggested that emergence percentage, emergence index, shoot length, and shoot fresh weight can be used as selection criteria for salt tolerance in sunflower at seedling stage.

Studies were conducted to determine the optimum number of testers required to rank lines according to their GCA and to understand the quantitative relationship between per se performance and combining abilitiy of the lines in sunflower. Forty-eight lines were crossed to 3 types of testers; an inbred, an open pollinated population and a single cross hybrid. The hybrids were evalu ated during summer 1994. Spearman's rank correlation coefficient indicated that the 3 testers as well as 2 tester combinations ranked the lines similarly for GCA. The correlatlons between per se performance and GCA were not significant for the studied characters except for days to 5O per cent flowering, days to maturity, plant height and oil content. Hence per se performance cannot be taken as a criterion for high GCA for yield and means of its components.

Two restorer lines of sunflower IVB3 (non-branching) and RLC-2 (branching) were irradiated with gamma rays at f O kR, l5 kR and 20 kR to induce variability for flowering, test weight and oil content. In the M2 populations of both genotypes, the mean value for oil content was increased but the test weight increase was observed only in IV83 genotype. Shift in mean values was accompanied with increase in range, variance and coefficient of variation for aII three traits in the M2 populations of both genotypes. Increased variation for flowering, test weight and oil content in irradiated population enabled effective selection for desirable genotypes. Early and late flowering lines identified in tite present study could be utilized for developing single cross hybrids with different maturity groups (early and late).

Interrelations of eight biomorpohological characteristics such as plant height, days to 50 percent flowering, days to maturity, stem girth, head diameter, seed set, 100-seed weight, oil content and their correlations with autogamy, self fertility and seed yield per plant were examined in a study that included 47 genotypes. The head diameter followed by 100-seed weight, plant height and stem girth showed significant positive âssociation with seed yield. The strongest associâtion was with head dianeter which was also revealed in the path coefficient analysis with the highest positive direct effect. Autogamy and self fertility showed significant negative correlation with seed yield. Days to 5O percent flowering also showed direct negative effects. The positive effect of plant height was through head diameter. Autogamy also showed highly negative association with important yiled-contributing characters such as head diameter, stern girth, plant height and 100-seed weight suggesting such negative associations are to be broken for achieving high yielding genotypes with high autogamy.

Successful cultivation of the sunflower in the UK depends heavily on the sowing of suitable varieties at ân âppropriate time. Data from 66 open pollinated half-sib families of sunflower were analysed to determine the impact of the normal and late sowing dates on the expression of six metrical traits namely, height at 6 weeks after sowing, flowering time, height at the time of flowering, head diameter, seed set and area of seed set. Comparisons of the rneans revealed that the Iate sowing grew significantly faster and taller and took 7 days less to mature. The normal sowing, on the other hand, set significantly more seed. The two sowing dates did not differ critically for the remaining traits. The performance of the families was observed to be consistent across the sowing dates and there was little coincidence of family x sowing date interaction or family x micro environmental interaction for any of the traits. These observations were further supported by the significant and positive correlations between the sowings while the associations between traits did not different uch either. Only one out of the 15 inter-trâit correlâtions was found to differ significantly. The important implications of these results are discussed and it is shown that early sown crop will be commercially more successful in the UK.

A study was conducted to evaluate the response of sunflower cultivars and plant densities grown in two different growing seasons of northern Tamaulipas. Two sunflower hybrids (De kalb G-l0O and G-f 0l) and two varieties (Rib-77 and Victoria) were evaluated under 3 plant densities: 27,5OO, 47.250 and 62,5O0 plants/ha. In 1994, the planting was in the "late" annual season (P-V) and in 1995 was in the "early" annual season (O-I). The highest yield was obtained during the "early" growing season, 2,170 kg/ha, while the lowest yield was 1,678 kg/ha during "late" season. In both seasons, the hybrids and variety Rib-77 had significantly higher yields than the variety Victoria. At Iow densities, increases in seed weight per head, stem and head diameter, and 100-seed weight were observed.

Sunflower seed storage needs particular care, due to its high fat content, easily cracking shell, exposing the kernel to various alterations, such as germination loss, colonization of fungi and attacks by insects and mites. Seed moisture content is critical mainly if long-term storage is intended. Proper management of equilibrium between relative air humidity and seed moisture is an essential element, dictating need for seed drying at storage start and frequent aeration during storage. The main fungi occurring in sunflower seed post-hârvest are listed and their involvement in spoilage of this produce is commented; likewise, a comprehensive list of insects and mites detected in Romania and elsewhere in stored sunflower is presented, some of these having definite role in enhancing spoilage. Measures intended to prevent or control the detrimental factors are briefly exposed, and some special attempts to eliminate these are mentioned.