Sunflower Cultivars Research Articles

Dissimilaridade genética de girassol por meio de caracteres quantitativos

Objetivou-se com este estudo avaliar, por meio de caracteres quantitativos, a dissimilaridade genética entre cultivares de girassol em diferentes localidades, além da concordância entre os métodos, visando à extração de linhagens para possíveis cruzamentos. Foram cultivados oito híbridos de girassol em duas localidades no noroeste do Rio Grande do Sul, com solo predominantemente do tipo Latossolo Vermelho distrófico. Foram utilizados métodos multivariados para determinar a divergência genética, utilizando a distância generalizada de Mahalanobis. Apesar dos rendimentos distintos entre locais e cultivares, os métodos de agrupamento tiveram concordância entre si. Para obtenção de populações segregantes, a cultivar 'Olisun 5', independente da localidade, demonstrou-se com maior potencial de hibridação, tendo as maiores contribuições por meio do número de aquênios por capítulo e altura de inserção do capítulo.

Influence of Row Spacing and Planting Dates on some characters (field and quality) of Sunflower cultivars (Helianthus annuus L.).

Influence of Row Spacing and Planting Dates on some characters (field and quality) of Sunflower cultivars (Helianthus annuus L.).

Seed priming with Trichoderma harzianum isolates enhances plant growth and induces resistance against Plasmopara halstedii, an incitant of sunflower downy mildew disease

Three rhizosphere fungal isolates viz., PGPFYCM-2, PGPFYCM-8 and PGPFYCM-14 of Trichoderma harzianum, applied as seed treatment to a highly susceptible sunflower cultivar were evaluated for their ability to promote growth and induce resistance in sunflower against downy mildew disease caused by Plasmopara halstedii. Treatment of sunflower seeds with both conidial suspension (1 × 108 spores ml−1) and talc formulations (2.1 × 107 spores g−1) at 8 g kg−1 seeds and 10 g kg−1 seeds, significantly promoted growth and reduced disease incidence under both greenhouse and field conditions. Among the treatments, PGPFYCM-14 (1 × 108 spores ml−1) was highly significant (P = 0.05) in inducing resistance of 63 and 69 %, followed by PGPFYCM-2 which offered 41 and 42 % disease protection under greenhouse and field conditions respectively. Formulation treatments of PGPFYCM-14 also protected the plants significantly (P = 0.05) when compared to the untreated control. There was a significant increase in NPK macronutrients uptake in all the treated plants compared to the untreated control and maximum NPK uptake was observed with PGPFYCM-14 (1 × 108 spores ml−1). Under in vitro conditions, all the tested isolates expressed increase in seed germination and vigour index over the control. Tested plant growth promoting fungal (PGPF) isolates remain significant in enhancing vegetative and reproductive growth parameters, including plant height, early flowering, reduced crop duration, ear head size and crop yield under field conditions when compared to the untreated control.

The role of antioxidants in improving sunflower cultivars' performance grown under saline conditions

The role of antioxidants in improving sunflower cultivars' performance grown under saline conditions

Produção do girassol e teor de óleo nos aquênios em função da temperatura do ar, precipitação pluvial e radiação solar

O presente estudo teve o objetivo de avaliar o efeito da temperatura do ar, precipitação pluvial e radiação solar, ocorridos em cada fase fenológica da cultura do girassol, na produção de aquênios, no teor de óleo dos aquênios e na produção de óleo do girassol. Foram conduzidos dez experimentos em intervalos de 20 dias, com início em 30/07/2007 e término em 28/01/2008. Cada experimento constituiu uma época de semeadura. Para verificar a normalidade dos erros e homogeneidade das variâncias, inicialmente, realizou-se uma análise individual por experimento para, em seguida, realizar análise conjunta. O delineamento experimental utilizado foi o de blocos ao acaso com quatro tratamentos (cultivares) e quatro repetições, em cada época de semeadura. Houve interação entre épocas de semeadura e cultivares para todas as variáveis estudadas. Foram feitas análises de correlação entre as variáveis meteorológicas e as de produção do girassol. A produção de aquênios, teor de óleo e produção de óleo nas cultivares de girassol foram mais elevados quando ocorreram temperaturas mais baixas na fase vegetativa, maiores precipitações pluviais na floração e maiores índices de radiação solar na fase vegetativa e de enchimento de aquênios.

REDUCED DROUGHT TOLERANCE DURING DOMESTICATION AND THE EVOLUTION OF WEEDINESS RESULTS FROM TOLERANCE-GROWTH TRADE-OFFS

The increased reproductive potential, size, shoot allocation, and growth rate of weedy plants may result from reduced resource allocation to other aspects of plant growth and defense. To investigate whether changes in resource allocation occurred during domestication or the evolution of weediness, we compared the mycorrhizal responsiveness, growth, and drought tolerance of nine native ruderal, nine agriculturally weedy (four U.S. weedy and five Australian weedy), and 14 domesticated populations (eight ancient landraces and six improved cultivars) of the common sunflower (Helianthus annuus). Domesticated sunflower cultivars were less drought tolerant, but had higher plant growth and fecundity and coarser roots than wild populations. There were no changes in level of drought tolerance between improved cultivars and ancient landrace plants, but there was an increase in allocation to flowers with recent selection. Weedy populations were intermediate between domesticated cultivars and native ruderal populations for plant growth rate, root architecture, and drought tolerance. Weedy populations benefited most from mycorrhizal inoculation by having fewer wilted leaves and wetter soil. Overall, we found that trade-offs between drought tolerance and several aspects of plant growth, including growth rate, allocation to flowering, and root architecture, govern evolution during sunflower domestication and the invasion of disturbed habitat.

Tocopherols and phytosterols in sunflower seeds for the human food market

Sunflower seeds for the human food market are derived from both oilseed-type cultivars, with black achenes and low hull proportion, and confectionery-type cultivars, with striped achenes and high hull proportion. The objective of this research was to evaluate tocopherol and phytosterol contents in the seeds of both types of cultivars. Five oilseed-type and seven confectionery-type cultivars were evaluated in replicated field trials in two locations of Morocco and Spain. Large variations were found in hundred-kernel weight (2.6 to 5.5 g), kernel oil content (42.7 to 67.5%), tocopherol content (203 to 397 mg kg –1 kernel), and phytosterol content (2179 to 3555 mg kg –1 kernel). Both types of cultivars did not differ for kernel weight, kernel oil content, or tocopherol and phytosterol profiles. However, oilseed-type cultivars had significantly greater average tocopherol and phytosterol contents, though confectionery-type cultivars with levels of tocopherols and phytosterols similar to the best oilseed-type cultivars were identified. The large variations in kernel tocopherol and phytosterol contents found in this research suggest that there is room for breeding for increased levels of these compounds in order to develop healthier sunflower cultivars for the human food market.

Spatial distribution of sunflower cultivars and the relationship between growth features

This work aimed to evaluate the performance of six genotypes of sunflower under two spatial distributions between plant rows, and verify the cause effect relation between growth features. The experiment was carried at experimental area of Federal Technological University of Paraná (Campus Dois Vizinhos), evaluating six sunflower cultivars and two spatial distributions (40 and 80 cm between rows), remaining the total plant population similar, 55.000 plants by hectare. It was performed a path analysis, identifying the features that have most influence on sunflower grain yield and one hundred grain weight, also multiple regression analysis was used to estimate the equation for grain yield and one hundred grain weight. It was verified that sunflower genotypes do not present different performances under the evaluated spatial distributions, however, the genotypes showed to be significantly different for most of the features evaluated. Direct effect under grain yield was observed for the features number of plants and stem diameter at 15 days, while the indirect effects were observed for plant stature via stem diameter, both at 15 days. For the feature one hundred grain weight it was verified that only plant stature at 90 days promoted a direct effect, but negative.

Interaction Between Cadmium and Lead and the Effects of These on the Concentration of Zinc and Manganese in Sunflower

The pollution of soil by heavy metals is considered to be quite a big problem in many areas ofthe world. To limit the accumulation of lead and cadmium from soil in the products, a correct understanding ofthe characteristics and specifications of the translocation of cadmium and lead is necessary. In order to evaluatethe effects of cadmium and lead interaction on zinc and manganese concentration, three levels of cadmium (0,100 and 200 mg/kg), and three levels of lead (0, 200 and 400mg/kg) were tested on a sunflower cultivar SHF81-85 in a factorial experimental design with three replications. The results showed that cadmium has increasedthe cadmium and lead concentration in the shoot and root, while the effects of lead, were only significant on theconcentration of lead in the shoot, and the concentration of both cadmium and lead in the root (p<0.05).Cadmium and lead revealed a preventing effect on zinc and manganese concentration in the root and shoot ofthe plant. More investigations at field conditions are recommended.

Girassol ornamental: caracterização, pós-colheita e escala de senescência

The ornamental sunflower widen the market of ornamental plants in Brazil. Thus, this study aimed to present a characterization of post-harvest management and to propose a range of senescence stage of sunflower as an ornamental in relation to senescence, flower longevity and benchmark values of trade. The production of flowers is a high risk activity for the fragility of the product, aesthetic qualities and conditions of production as well as lower post-harvest durability of the product. This study proposes a range of senescence stages for ornamental sunflower cultivars as the aging of different chapters to assign salaries and marketability of the crop.

Nitrogen application rate, leaf position and age affect leaf nutrient status of five specialty cut flowers

This study was conducted to determine the effect of nitrogen fertilizer levels on growth and yield of specialty cut flowers, ‘Chief’ celosia, ‘Sensation’ cosmos, ‘Sunbright’ and ‘Sunrich Orange’ sunflowers and ‘Benary Giant Mix’ zinnia, as well as record influence of leaf position and age on leaf nutrient concentrations. Plants grown in open field were supplied with five different N levels beginning five days after transplanting: no added N (control); one, two or three applications of N at 112kgha−1 at 40 day intervals; and a single application of 336kgha−1. Plants fertilized with two or three applications of 112kgha−1 produced the most flowers in celosia and all fertilizer applications increased yield equally in zinnia, but had no effect on cosmos and both cultivars of sunflower. Nitrogen fertilization produced the longest flower stems for cosmos and both sunflower cultivars, but had no effect on celosia and zinnia stem length. Nitrogen fertilization rate did not significantly affect days to harvest of all species tested. For leaf nutrient analysis, the upper one-third of the plant proved to be a reliable tissue source in all species. Generally, young leaf samples collected early in the season had higher nutrient concentrations as compared with the same leaf position at mid or late season. Increasing N fertilization increased N content of foliage for all species. Our recommended tissue nutrient levels were generally lower than those previously recommended for greenhouse-grown bedding plant cultivars of the same species.

Evidence of selection on fatty acid biosynthetic genes during the evolution of cultivated sunflower

The identification of genes underlying the phenotypic transitions that took place during crop evolution, as well as the genomic extent of resultant selective sweeps, is of great interest to both evolutionary biologists and applied plant scientists. In this study, we report the results of a molecular evolutionary analysis of 11 genes that underlie fatty acid biosynthesis and metabolism in wild and cultivated sunflower (Helianthus annuus). Seven of these 11 genes showed evidence of selection at the nucleotide level, with 1 (FAD7) having experienced selection prior to domestication, 2 (FAD2-3 and FAD3) having experienced selection during domestication, and 4 (FAB1, FAD2-1, FAD6, and FATB) having experienced selection during the subsequent period of improvement. Sequencing of a subset of these genes from an extended panel of sunflower cultivars revealed little additional variation, and an analysis of the genomic region surrounding one of these genes (FAD2-1) revealed the occurrence of an extensive selective sweep affecting a region spanning at least ca. 100 kb. Given that previous population genetic analyses have revealed a relatively rapid decay of linkage disequilibrium in sunflower, this finding indicates the occurrence of strong selection and a rapid sweep.

Analysing and modeling the relationship between yield and yield components in sunflower under different planting dates

The relationships between planting dates and yield and it's components in sunflower was evaluated through orthogonal polynomial regression analysis. Five field experiments were conducted during the summer season of 2011 to study the effect of five planting dates and three oilseed sunflower genotypes and their interactions on yield and yield components of sunflower. The highest seed yield, oil yield, plant height, head diameter, 1000-seed weight, seed yield plant-1 and oil content were obtained at the earliest planting date (1st May). The evaluated genotypes differed significantly for all the studied traits. Sakha 53 cultivar was the best cultivar in seed yield, oil yield, plant height, head diameter, thousand seed weight and seed yield plant plant-1 followed by Giza 102 and Pioneer hybrid 63M02, respectively. Orthogonal polynomial regression analysis revealed that, yield and yield components were significantly affected by planting date in linear responses. Multiple linear regression analysis indicated that seed yield plant-1, head diameter and thousand seed weight were the most important variables contributing toward higher seed yield (kg ha-1). Finally, it can be concluded that planting sunflower cultivar Sakha 53 on 1st May was recommended for maximizing seed and oil yields per unit area under the environmental conditions of this study. Key words: Sunflower, planting date, genotype, regression analysis, yield, yield components.

Biochemical and Molecular Characterization of High Population Density Bacteria Isolated from Sunflower

Natural and beneficial associations between plants and bacteria have demonstrated potential commercial application for several agricultural crops. The sunflower has acquired increasing importance in Brazilian agribusiness owing to its agronomic characteristics such as the tolerance to edaphoclimatic variations, resistance to pests and diseases, and adaptation to the implements commonly used for maize and soybean, as well as the versatility of the products and by-products obtained from its cultivation. A study of the cultivable bacteria associated with two sunflower cultivars, using classical microbiological methods, successfully obtained isolates from different plant tissues (roots, stems, florets, and rhizosphere). Out of 57 plantgrowth- promoting isolates obtained, 45 were identified at the genus level and phylogenetically positioned based on 16S rRNA gene sequencing: 42 Bacillus (B. subtilis, B. cereus, B. thuringiensis, B. pumilus, B. megaterium, and Bacillus sp.) and 3 Methylobacterium komagatae. Random amplified polymorphic DNA (RAPD) analysis showed a broad diversity among the Bacillus isolates, which clustered into 2 groups with 75% similarity and 13 subgroups with 85% similarity, suggesting that the genetic distance correlated with the source of isolation. The isolates were also analyzed for certain growth-promoting activities. Auxin synthesis was widely distributed among the isolates, with values ranging from 93.34 to 1653.37 microM auxin per microng of protein. The phosphate solubilization index ranged from 1.25 to 3.89, and siderophore index varied from 1.15 to 5.25. From a total of 57 isolates, 3 showed an ability to biologically fix atmospheric nitrogen, and 7 showed antagonism against the pathogen Sclerotinia sclerotiorum. The results of biochemical characterization allowed identification of potential candidates for the development of biofertilizers targeted to the sunflower crop.

Effects of time and duration of short-day treatments under long-day conditions on flowering of a quantitative short-day sunflower (Helianthus annuus L.) ‘Sunrich Orange’

The effects of short-day (SD) treatment on differentiation, development and anthesis of flower buds, and on cut flower quality were investigated in a leading cut sunflower (Helianthus annuus L.) cultivar, Sunrich Orange, a quantitative SD plant. Plants were cultivated under long-day (LD) conditions with night interruption lighting from 2200 to 200h. SD treatment (11.5h photoperiod) for 1, 2, or 3 weeks was commenced at the cotyledon, two true leaves, or four true leaves stage. The control plants were grown under LD conditions throughout the experimental period. SD treatment for 1 or 2 weeks promoted flower bud initiation even when delivered at the cotyledon stage (9 days after sowing), indicating that the juvenile phase is very short in this cultivar. Flower differentiation and development were also accelerated by the SD treatment, and resulted in 19–39 days earlier anthesis. The quality of cut flowers was improved by SD treatment to desirable characteristics such as decreased weight, shortened stem and reduced stem diameter. The present study suggests that under LD conditions such as found in summer, SD treatment for 2 weeks from the cotyledon or two true leaves stage can promote LD-delayed flowering of quantitative SD sunflower plants without reducing cut flower quality.

Efeito de épocas de semeadura sobre cultivares de girassol, no Sul do Estado do Tocantins

This study had as its objective, evaluating the agronomic performance of sunflower (Helianthus annuus L.) cultivars when sown at different times, under the environmental conditions in the south of the State of Tocantins. The experiment was carried out during the 2008/2009 agricultural year, in randomized blocks in a 4 x 5 factorial design (four sowing dates and five sunflower cultivars) with three replications. Each plot consisted of four rows 5.0m in length, spaced 0.80 m apart with 0.20 m between plants. For all sowing dates, the characteristics evaluated were: flowering, plant height, stem diameter, head diameter, normal achenes, grain weight per thousand and grain yield. There was significant correlation of sowing dates with the evaluated cultivars for the traits of flowering, plant height and grain yield. In relation to periods of sowing, there was generally a negative influence on all evaluated traits for the later dates, due to an Indian summer causing moisture stress during the critical period of plant development and the occurrence of disease, especially alternaria leaf-spot. The first sowing period (November) showed higher productivity with an average of more than 3,000 kg ha-1. Irrespective of sowing dates, the more productive cultivars were the hybrids Helio 360 and Helio 884, with an average of 1,709 and 1,697 kg ha-1 respectively.

Seed yield and associated trait improvements in sunflower cultivars over four decades of breeding in South Africa

Genetic improvement for seed yield and oil-content in sunflower cultivars was initiated in the early 1970s in South Africa. Since then no study has been carried out to assess the progress and contribution of new cultivars to seed yield improvement to justify continued investment into breeding new cultivars. The aim of this study was therefore to quantify the contribution of new cultivars to seed yield and associated traits in sunflower over four decades of breeding in South Africa. Two data-sets were used in this study: (1) side-by-side evaluation of historical and current sets of popular cultivars in the same environment under one set of trial management practices; and (2) yield trends in commercial farmers’ fields based on annual production estimates. The absolute genetic gain (yield increase per year) for seed yield in the side-by-side trials ranged from 18 to 32kgha−1year−1 with a mean of 24kgha−1year−1. In contrast, the absolute seed yield increase under commercial production was 12kgha−1year−1. The estimated relative genetic gain for seed yield based on side-by-side trials was 1.5% year−1 and the relative gain in seed yield per year under commercial production was 1.9% year−1. The contribution of new cultivars to total seed yield progress in sunflower were 56.3% for the period 1970–1989; 23.9% from 1990 to 2009 and the mean over the four decades under consideration 1970–2009 was 41.6%. Positive increases in genetic gains for oil yield, oil content and number of seeds per head were also obtained although the gain in oil content was relatively low.

Produção do girassol e teor de óleo nas sementes em diferentes épocas de semeadura no Centro-Sul do Paraná

O presente estudo teve o objetivo de avaliar o efeito de dez épocas de semeadura na produção de aquênios, no teor de óleo dos aquênios e, como consequência, na produção de óleo em quatro cultivares de girassol em Ponta Grossa, PR. Dessa forma, foram conduzidos dez experimentos em intervalos de 20 dias, com início em 30/07/2007 e término em 28/01/2008. Cada experimento constituía uma época de semeadura e, para verificar a normalidade dos erros e homogeneidade das variâncias, inicialmente, realizou-se uma análise individual por experimento para, em seguida, realizar análise conjunta. O delineamento experimental utilizado foi o de blocos ao acaso com quatro tratamentos e quatro repetições, em cada época de semeadura. Entre épocas de semeadura e cultivares, houve interação para todas as variáveis estudadas, sendo que as maiores produções de aquênios e de óleo ocorreram nas semeaduras do final de julho, mês de agosto e de setembro. O teor de óleo dos aquênios foi maior nas primeiras épocas de semeadura, diminuindo nas épocas mais tardias, enquanto as maiores produções de aquênios foram obtidas com as cultivares 'M734' e 'Aguará 4'.

Antioxidative and physiological responses of two sunflower (Helianthus annuus) cultivars under PEG-mediated drought stress

Drought stress is one of the most important yield-reducing factors in crop production. Sunflower, an oilseed crop, is severely affected by abiotic stress. In this study, 2 sunflower cultivars (Musala and Aydın) were evaluated in terms of various biochemical and physiological responses under 2 different polyethylene glycol-mediated drought stress conditions. Stress-determining parameters such as malondialdehyde (MDA), hydrogen peroxide (H_{2}O_{2}), and proline contents were determined. Both cultivars showed similar responses at osmotic potentials of both -0.4 and -0.8 MPa. Aydın was less affected than Musala under these stress conditions. MDA, H_{2}O_{2}, and proline levels were similar at both -0.4 and -0.8 MPa osmotic potentials in the 2 different cultivars. The 2 cultivars differed significantly in ascorbate peroxidase and catalase enzyme activities, which were more prominent in Aydın for both stress levels. However, glutathione reductase activity did not appear to be an essential part of the antioxidative system in either of the cultivars. Engineering antioxidative enzyme levels might provide a potential mechanism to cope with drought stress in sunflower.

Contribution of interspecific hybridization to sunflower breeding

SUMMARY This investigation is directed at improving sunflower using hybrid forms resulted from interspecific hybridization. The aim is to create new B/A and R lines from interspecific hybrid forms that are resistant to diseases, the parasite broomrape, herbicides, and other stress factors and are characterized with high combining ability and to obtain on this basis highly productive oilseed sunflower hybrids with varied fatty acid composition of oil. The investigation was carried out during the period 1983-2010. It involved 16 cultivars and 18 B lines with their analogues as well hybrid material originated from 38 Helianthus species - 9 annuals and 29 perennials. Intraspecific hybridization and purposeful selection were the methods used. Crossing between interspecific hybrids and crossing of interspecific hybrids with sunflower cultivars or lines were applied. Self-pollination, sib-pollination, backcross with pollen from cultivated sunflower and pollination with pollen from different interspecific hybrids were carried out. Phytopathological and biochemical evaluation of seeds and plants and morphological characterization of sunflower forms, lines and hybrids were performed. New sunflower forms and lines were created as a result of this investigation. A greater part of them possess resistance to downy mildew, phomopsis, phoma and alternaria, tolerance to sclerotinia and full resistance to the different races of the parasite broomrape. The new forms were distinguished by new plant architecture, different vegetation period and seeds with different size and coloration. New B/A and R lines having high combining ability and seed oil and fatty acid contents were obtained. Fifteen sources of cytoplasmic male sterility ( cms) were obtained from interspecific hybrid forms, as were 251 sources of genes for restoration of fertility ( Rf genes). Five new hybrid cultivars of the oilseed type that were obtained on the basis of these lines were created and registered. The obtained results from the investigations showed that by interspecific hybridization new genetic material was transferred to the cultivated sunflower. These results have augmented the contribution of interspecific hybridization to sunflower breeding.