Sunflower Cultivars Research Articles

ITRAQ-based proteomics of sunflower cultivars differing in resistance to parasitic weed Orobanche cumana.

Orobanche cumana is an obligate root parasite causing severe damage to many economically important crops, including sunflowers worldwide. For efficient control measures, it is necessary to understand the resistant mechanism during interaction at molecular level. The present study emphasizes on comparative proteomics to investigate the mechanistic basis of compatible and incompatible interaction of O. cumana with resistant (JY207) and susceptible (TK0409) sunflowers. More than 3500 proteins were identified from two cultivars by iTRAQ analysis. Identified proteins associated with general functions, posttranslational modification, energy production and conversion, carbohydrate transport and metabolism, and signal transduction mechanisms were the most represented category of induced proteins in both cultivars. The resistant interaction was characterized by alteration of defense-related proteins involved in recognition of parasites, accumulation of pathogenesis-related proteins, biosynthesis of lignin, and detoxification of toxic metabolites in JY207 after inoculation. The susceptible interaction was characterized by decreased abundance of proteins involved in biosynthesis and signaling of plant growth regulators including auxin, gibberellin, brassinosteroid, and ethylene in TK0409 after inoculation. The present study provides comprehensive details of proteins and differential modulation of pathways regulated under compatible and incompatible interaction, allowing the identification of important molecular components for development of sustainable resistance against this parasite.

Circulatory Management of Nutritional Substance Growing Sunflower and Extracting Nutrition by Hot-compressed Water Treatment

Sunflowers are grown as an ornamental plant and a catch crop beside an oilseed crop in Japan. Seed residues after oil milling are recycled as a feed for livestock and a fertilizer. After harvesting, crop residue such as stem and leaves are returned to the soil by the tillage in conventional cultivation. This report discusses the appropriate circulatory management of crop residues and plant nutrition considering them as a new commodity and plant nutrients resource for activating small agriculture. To study the characteristics of the nitrogen uptake from soil, sunflower cultivar named Hybrid Sunflower was grown with fixed row distance of 70 cm and varying hill distance of 10, 20, 30, 40 and 50 cm in a 5 m * 5m plot at a university farm, Tokyo, Japan. Growth survey was carried out every week. Sunflower whole crops sampled at each plot were dried in the oven at 70 °C for 1 day soon after the blanching treatment and stored until the extraction experiment. Sunflower sample at the growth stage of after flowering had the largest mass compared with the stage of before flowering and seed harvesting. Total dried matter of whole crop in 10cm-plot was the largest among the planting density conditions for each growth stage. The dried matter of crop residue at the growth stage of seed harvesting was 613, 408, 323, 281 and 279 g/m2 for the plot of 10, 20, 30, 40 and 50 cm, respectively. Nitrogen contained in sunflower stem was 2.5 to 5.5 g-N/m2 and that in seed was almost double, 5.9 to 7.5 g- N/m2. Sunflowers were processed to extract nitrogen by the hot-compressed water (HCW) treatment. Ground sample of sunflower stem mixed with water was heated at temperature of 180, 200 and 220 °C with gas pressure of 2 MPa in a pressure tight reactor for 5 and 30 min to release nitrogen from the solid fibre. Sample was separated into the solid matter fraction and the liquid matter fraction after the treatment. Extracted nitrogen as liquid matter was 37.9, 45.5 and 49.4 % at temperature of 180, 200 and 220 °C, respectively. Approximately 40 to 50 % of nitrogen contained in sunflower stem was recovered as the liquid matter. The liquid matter can be returned to the soil as a fertilizer while the solid matter containing cellulose and hemi- cellulose can be used as a raw material for bioethanol production.

Stearic sunflower oil as a sustainable and healthy alternative to palm oil. A review

Palm oil is widely used in the food industry because of its lower cost, high oxidative stability index, long shelf-life, and a reasonable replacement of trans fats. However, increased palm oil production reduces biodiversity, damages the ecosystem, and poses health risks to humans. Unsustainable development of palm plantations has caused deforestation and loss of natural habitat, rendering many species (Sumatran orangutans, elephants, and tigers) critically endangered. Similarly, decomposition and burning of carbon-rich soil in vast and deep peatlands is increasing carbon emissions. Furthermore, excessive consumption of palmitic acid (and other saturated fats except stearic acid) increases bad cholesterol and the risk of cardiovascular diseases. Therefore, we need healthier, stable, and solid/semi-solid oils at room temperature with longer shelf-life and without trans fats. Here, we review the advancements in the development of sunflower oil varieties containing high stearic (∼18%) and high oleic (∼70%) acids which makes them healthy and sustainable alternatives to palm oil. First, the high-stearic-high-oleic sunflower crops can have grain and oil yield as high as 4036 and 1685 kg/ha and oleic and stearic acid yield up to ∼73 and ∼21%. Second, high-stearic-high-oleic oils obtained from mutant and hybrid sunflower cultivars have higher oxidative stability index and therefore have better stability, quality, and functionality than regular sunflower oil. For example, the oxidative stability index of commercially available Nutrisun at 110 °C is six times greater than that of regular sunflower oil. Finally, recent advances have made several mutant and hybrid cultivars with high grain and oil yield and high levels of stearic and oleic acids available. Given this progress, natural healthy high-stearic-high-oleic sunflower oil can now be grown in both the hemispheres in a sustainable manner with the currently available advanced technology and without damaging the ecosystem as is currently happening with palm oil cultivation.

THE EFFECT OF SOWING DATE AND NITROGEN FERTILIZER FORM ON GROWTH, YIELD AND YIELD COMPONENTS IN SUNFLOWER

The purpose of this study was to investigate the effects of sowing date and nitrogen fertilizer forms on the yield and agronomic characteristics of two cultivars of oil sunflower (early, Sirena and late, Teknosol) in Erzurum, Eastern Anatolia of Turkey, in 2013 and 2015. Three sowing dates were established at about 10-day intervals from late-April to early and mid-May (22 April, 2 May and 12 May 2013; and 28 April, 8 May and 18 May 2015). Three nitrogen fertilizer forms ammonium sulfate, ammonium nitrate, and urea were used. The results of this study showed that sunflower seeding from 28 April to 8 May gives more assurance for higher yields. The present results highlighted the practical importance of fertilization with appropriate nitrogen fertilizer forms in seed and oil yield formation in sunflower, and the urea form can be suggested to meet its N requirements. The yield differences measured for three sowing dates and nitrogen fertilizer forms were primarily related to the changes in head diameter and 1000 seed weights. According to the results of this study, early sunflower cultivars, having the highest yield and agronomic characteristics can be recommended for the similar ecological condition of our study region a short growing season and high altitude.

Emergence response of sunflower (Helianthus annuus) cultivars to supra-optimal soil temperatures

Seedling emergence is a sensitive stage during sunflower (Helianthus annuus L.) establishment. Abiotic stresses, such as high soil temperatures (above 40 °C), can cause delayed emergence resulting in uneven stand and ultimately poor yields. Therefore, the emergence and early growth responses of seven sunflower cultivars to four daily supra-optimal soil temperatures (DSST) of 35, 40, 45 and 50 °C were evaluated. The experiment was laid out as a randomised complete block design with four replications repeated twice in a glasshouse. Results clearly indicated that emergence index (EI) declined with an increase in soil temperature. A moderate decline was observed from DSST 35 °C to 45 °C, but from DSST 45 °C to 50 °C the decline was extreme. Root length of seedlings 24 h after planting were inconsistent between plantings. Root length at surface cracking and 48 h after surface cracking indicated that seedling root length at DSST 35 °C was longer than at DSST 45 °C and 50 °C. The lowest dry mass for both plantings was recorded at DSST 50 °C. Morphological differences were also visible for sunflower seedlings at the selected temperatures, but there were no definite visible differences between cultivars. Generally, deformed seedlings were observed at temperatures above DSST 40 °C.

The tortoise beetle Physonota maculiventris (Chrysomelidae: Cassidinae) is suitable for release against the weedy Mexican sunflower Tithonia diversifolia (Asteraceae) in South Africa

ABSTRACTThe biology and host range of the defoliating beetle Physonota maculiventris Boheman (Chrysomelidae: Cassidinae) were studied in quarantine to determine its suitability for release as a biological control agent against Mexican sunflower, Tithonia diversifolia (Hemsl.) A. Gray (Asteraceae), in South Africa. Females laid 5.25 ± 0.25 (mean ± SE) egg batches during their lifetimes, with each batch consisting of approximately 33 eggs. Larvae were highly gregarious as early instars and both larvae and adults fed voraciously, often defoliating the plants completely. The life cycle of the beetle was completed in 67.5 ± 7.5 days under quarantine conditions. Among the 58 test plant species subjected to no-choice tests, P. maculiventris developed successfully on T. diversifolia and some sunflower (Helianthus annuus L.) cultivars. However, only minor damage was recorded on non-target species, notably the exotic weed Xanthium strumarium L. and some H. annuus cultivars. Also, survival to adulthood was considerably lower on sunflower cultivars than on the target weed during these tests. During choice tests, P. maculiventris oviposited and developed successfully on T. diversifolia only, with only minor feeding damage on some H. annuus cultivars, suggesting that the beetle’s field host range will be confined to the target weed. Risk analysis also showed that P. maculiventris presents an extremely low risk to non-target plant species (e.g. within the tribe Heliantheae and other close relatives). The study concluded that P. maculiventris is safe for release in South Africa and an application for its release is being considered by the relevant South African regulatory authorities.

Response of Branching and Nonbranching Cut Flower Cultivars of Sunflower to Pinching and Planting Density

Pinching sunflower (Helianthus annuus) grown for cut flowers in the vegetative stage increases stem yield at least 3-fold. Four experiments were conducted to further investigate the cultivar response differences to pinching, to explore the response to planting density, and to examine the effect of the time of pinching. In the first two experiments, two branching and one nonbranching cultivar in 2011, and three branching cultivars in 2012, were grown at 6 × 6-, 9 × 9-, and 12 × 12-inch spacing and pinched at the six-leaf stage. Pinching led to stem yield increases, but reduced flower size and stem length. Combining closer spacing with pinching further decreased flower size, increased the number of stems, and the gross value of stems per unit area. At highest densities flowers were too small to be saleable. The inverse relationship of flower size to stem numbers per unit area held true across all cultivars in both years. The branching cultivar Starburst Lemon Aura was the most productive of the cultivars tested when pinched, yielding 15,744 stems/1000 ft2 at the closest spacing. In 2013 and 2015, delaying the time of pinching from the 6-leaf to the 10-leaf stage reduced stem production among three nonbranching cultivars from 2.8 to 1.8 stems/plant, compared with an increase from 4.2 to 5.1 stems/plant for the branching cultivar Goldrush. The difference in pinching response among cultivars in 2013 and 2015 may have been related to relative severity of septoria leaf blight (Septoria helianthi) that infected the lower leaves. The results of the four experiments confirmed the efficacy of pinching on productivity and value of sunflowers, with best results obtained when pinching was done at the six-leaf stage.

Effects of foliar spray of nano-particles of FeSO4 on the growth and ion content of sunflower under saline condition

ABSTRACTThis study investigated the effects of foliar spray of normal and nano-particles of iron sulfate (FeSO4) on the response of sunflower cultivars to salinity. Treatments included five cultivars (Alstar, Olsion, Yourflor, Hysun36 and Hysun33), two salinity levels (0 and 100 mM sodium chloride (NaCl)), and three levels of fertilizer application. Fertilizer treatments were the foliar application of normal and nano-particles of FeSO4. Foliar application of FeSO4 in either form increased leaf area, shoot dry weight, net carbon dioxide (CO2) assimilation rate (A), sub-stomatal CO2 concentration (Ci), chlorophyll content, Fv/Fm and iron (Fe) content and decreased sodium (Na) content in leaves. The extent of increase in chlorophyll a content by foliar spray of FeSO4 nano-particles was significantly greater than normal form. The results showed that the FeSO4 nano-particles increased biomass production of sunflower plants greater in comparison with normal form, although no significant difference was found between two forms.

Molecular diversity of sunflower populations maintained as genetic resources is affected by multiplication processes and breeding for major traits.

SNP genotyping of 114 cultivated sunflower populations showed that the multiplication process and the main traits selected during breeding of sunflower cultivars drove molecular diversity of the populations. The molecular diversity in a set of 114 cultivated sunflower populations was studied by single-nucleotide polymorphism genotyping. These populations were chosen as representative of the 400 entries in the INRA collection received or developed between 1962 and 2011 and made up of land races, open-pollinated varieties, and breeding pools. Mean allele number varied from 1.07 to 1.90. Intra-population variability was slightly reduced according to the number of multiplications since entry but some entries were probably largely homozygous when received. A principal component analysis was used to study inter-population variability. The first 3 axes accounted for 17% of total intra-population variability. The first axis was significantly correlated with seed oil content, more closely than just the distinction between oil and confectionary types. The second axis was related to the presence or absence of restorer genes and the third axis to flowering date and possibly to adaptation to different climates. Our results provide arguments highlighting the effect of the maintenance process on the within population genetic variability as well as on the impact of breeding for major agronomic traits on the between population variability of the collection. Propositions are made to improve sunflower population maintenance procedures to keep maximum genetic variability for future breeding.

Effect of Auxin Treatment on Growth and Physiological Traits in Two Sunflower Cultivars Under Saline Conditions.

Salinity considered one of abiotic stress affected to crop productivity. The present investigation aimed to give insights about the effect of NaCl saline on two cultivars sunflower plants (Helianthus annuus. L) and determine the usefulness of increasing relative salt tolerance by auxin treatment. Different responses of two sunflower cultivars Sakha 53 and China and differently susceptible to salinity stress levels by NaCl treatment in hydroponic culture experiment were investigated. The cultivar more tolerant (Sakha 53) showed less reduction in height , fresh and dry weight of the different plant organs, membrane stability, plastid pigments contents and more expression of antioxidant enzymes under high salinity level (175 mM NaCl) compared with China cultivar. Also the growth parameters were significantly increased due to IAA treatments. The physiological mechanisms of tolerance to salinity are descussed at the cellular, organ was studied. The use of plant hormones in two sunflowers under NaCl stress, improved plants salt tolerance through an improvement of relative water content, membrane stability, enhancement of chlorophyll and carotenoids biosynthesis, some antioxidant enzymes, which reflect an increase the most growth parameters of sunflower. Thus, our tested phytohormones prevent the harmful effects of NaCl in two sunflowers.

Performance of sunflower cultivars at different seeding periods in central Brazil

ABSTRACT Sunflower (Helianthus annuus L.) is a very important crop for Brazil, and especially for Chapada do Parecis which is the largest domestic producer, because of its climate and soil conditions are adequate to the development of the specie. The performance of cultivars and sunflower seed sowing periods were evaluated in Central Brazil. Experimental design comprised an 8 x 5 factorial randomized complete block, with eight sunflower cultivars (Aguará 06, Aguará 04, MG 305, CF 101, SYN 3950HO, SYN 045, GNZ NEON and HELIO 251) and five decennial seeding periods, with three replicates. Analysis of variance and Scott-Knott´s test (p<0.05) were applied. Cultivars GNZ NEON and SYN 045 provide the highest production rates in achenes, with higher value in favor of GNZ NEON. SYN 3950HO (this with higher value), CF101, MG 305, SYN 045 and Aguará 04 gets the highest oil rates in the achenes, with SYN 045, GNZ NEON, Aguará 04, CF101 and SYN 3950HO with the highest oil production. The first seed sowing period is the most productive and the first and fifth periods have the best results for oil productivity. Cultivar GNZ NEON and the first period exceede the others with regard to vegetative and reproductive variables.

<b>Different nitrogen and boron levels influence the grain production and oil content of a sunflower cultivar

Nitrogen is essential for plant growth and development and directly influences both grain production and oil content. Boron has been studied in sunflower cultivation due to high demand of this culture for this nutrient. This study aimed to evaluate the N and B differential supply effect on the grain and oil production of sunflower plants. The experiment was conducted in a greenhouse and used two sunflower hybrids: BRS 321 and Neon. N and B were applied via nutritive solution according to the following treatments: B + 50 N (2.49 kg ha -1 B and 10 kg ha -1 N at planting and 40 kg ha -1 B as additional fertilization); B + 10 N (2.49 kg ha -1 B and 10 kg ha -1 N at planting); 50 N (0 B and 10 kg ha -1 N at planting and 40 kg ha -1 N as additional fertilization) and 10 N (0 B and 10 kg ha -1 N at planting). Analyses of total N and B in all collected plant parts were performed, as well as measurements of grain production for each chapter and oil extraction at the end of the cycle. The association between B fertilization and a greater amount of N fertilization was essential to BRS 321 oil production. Regarding grain production at lower levels of N fertilization, Neon presented the best response to B application.

Genetic progress in sunflower crop in Rio Grande do Sul State, Brazil.

The sunflower has adaptability to growing regions with different climatic and soil characteristics, showing drought tolerance and high-quality oil production. The State of Rio Grande do Sul is the third largest sunflower producer in Brazil, with research related to the sunflower breeding initiated after the decade of 1950. The aim of this study was to evaluate the genetic progress for grain yield, oil content, and oil yield of sunflower (Helianthus annuus L.) in the State of Rio Grande do Sul. Data of grain yield, oil content, and oil yield obtained from 58 sunflower cultivar yield trials in 19 municipalities in Rio Grande do Sul during the period from 2005 to 2014 were used. Genetic progress was studied according to the methodology proposed by Vencovsky and data from sunflower cultivar yield trials were used. Annual genetic progress of sunflower during the period of 10 years (2005-2014) was 132.46 kg⋅ha-1⋅year-1 for grain yield, -0.17%/year for oil content, and 48.11 kg⋅ha-1⋅year-1 for oil yield. The sunflower-breeding programs in the State of Rio Grande do Sul were efficient for the traits grain yield and oil yield and presented no efficiency for oil content.

Evaluation growth analysis and grain yield of sunflower cultivars under sowing date in dry condition

Sunflower is one of the most important edible oil that growth of annual crops, it is grown over a widely area and is considered a crop adapted to an every environmental conditions, in order to study growth analysis of sunflower under sowing date and cultivars in dry condition a farm experiment was conducted a split plot arranged in a complete randomized block design with three replications in the Dry Research Station. Main plots consist of four level sowing dates with ten-day intervals from (March 30 - April 30) and subplots consist of three cultivars: Record, Zarya and Azargol. In different sowing dates observed that sunflower plants had slow growth in the primary stage afterwards had a quick growth, so in second sowing date sunflower plants had a quick growth with received 1220 growing degree days. Among different cultivars, Record, cultivar had highest crop growth rates and relative growth rate. Record cultivar with 125 days had highest growth duration and Zarya with 122 days had lowest growth duration so sowing date and cultivar had a significant effect on grain yield, grain yield reduced with delayed in sowing date and Record had a highest grain yield. Results of evaluation total dry matter (TDM) showed that Record cultivar had highest total dry matter also, among different cultivars statistical significant different was observed thus delay in sowing date reduced oil yield and highest oil yield was obtained from Record cultivar.

Pinching Ornamental Sunflowers Increases Cut Stem Yield and Reduces Flower Size

Most sunflower cultivars (Helianthus annuus) grown as cut flowers produce single stems and do not form branches. If pinched (i.e., apical meristem removed) in the seedling stage, plants form branches from basal nodes. In four experiments conducted under field conditions, pinching seedlings increased the number of marketable sunflower stems per plant 2.6 to 4.6 times, but the flowers formed were reduced in diameter by 43%, and flowering was delayed by 1 week to 10 days. Leaving six instead of four basal nodes after pinching only increased stem yield slightly in 2005 but not in 2006. Increasing the space available per plant from 9 × 9 to 12 × 12 inches increased flower diameter of pinched and control plants from 7 to 7.9 cm, but the resulting lower yield per unit area reduced overall value. In three out of four experiments, ‘Procut Orange’ produced more stems after pinching than ‘Sunrich Orange’. Pinching nonbranching sunflowers is a promising technique, increasing yield by a factor of three, and the value of the harvested flowers by 82%.

Structural changes in leaves and roots are anatomical markers of aluminum sensitivity in sunflower1

ABSTRACT Aluminum (Al) toxicity in plants evidences the importance of genotype evaluation to the identification of tolerance markers. This study aimed at evaluating the effects of aluminum stress on the relative water content, membrane damages and anatomical changes, in Al-tolerant and Al-sensitive sunflower cultivars. Sunflower plants [Catissol (Al-tolerant) and IAC-Uruguai (Al-sensitive)] were grown in nutrient solution (control) or nutrient solution containing 0.15 mM of AlCl3 (Al-stress treatment), in a greenhouse. The experimental design was completely randomized, in a factorial arrangement consisting of four harvest times x two sunflower cultivars x two Al levels, with four replications. The results showed that Al negatively affected the absolute integrity percentage and relative water content only for the IAC-Uruguay cultivar. These results in the stressed leaves of the Al-sensitive cultivar may be due to damage in the xylem structure. In addition, the increase in leaf blade thickness and parenchyma layers, as well as lignification of root tissues, are important traits of IAC-Uruguay plants and may be used as anatomical markers of Al sensitivity in sunflower.

Sources of resistance to Alternariaster leaf blight in sunflower pre-breeding lines derived from interspecific crosses and wild Helianthus species

Leaf blight caused by Alternariaster helianthi (Hansf.) Tubaki and Nishihara is one of the important diseases of sunflower that causes considerable yield loss. Resistance against leaf blight in the germplasm, parental lines and released sunflower cultivars is rather limited. Hence, screening of sunflower accessions comprised interspecific derivatives, core germplasm, pre-breeding lines, exotic lines and wild Helianthus species was carried out under natural field conditions over five years viz., 2003 to 2009. Sunflower lines which showed resistance under field conditions were further confirmed under controlled conditions by artificial inoculation with A. helianthi. Among interspecific crosses evaluated, pre-breeding lines derived from crosses of cultivated sunflower with wild H. annuus (ANN-SF) followed by trispecific crosses of cultivated sunflower with H. argophyllus, wild H. annuus (ARG-ANN-SF) and cultivated sunflower with H. argophyllus (ARG-SF) showed less leaf blight disease under field conditions. The disease severity was greater during 2004–05, 2006–07, 2007–08 and 2009–10 which was favoured by high rainfall, many rainy days and high relative humidity. Six sunflower accessions showed less leaf blight severity. Of three A. helianthi isolates tested, Ah-112 was found to be highly aggressive causing more than 30% leaf blight severity on all tested cultivars. Among different wild Helianthus species tested against leaf blight by detached leaf and whole plant assay techniques, H. tuberosus Acc 03, 1705, 08, 07, 15, 2729, H. maximiliani Acc 007 and H. strumosus Acc 15 recorded <20% leaf blight severity in the whole plant assay method indicating some resistance. Appropriate strategies are being devised to utilize the interspecific accessions and wild Helianthus species identified to be moderately resistant to Alternariaster leaf blight in the sunflower breeding programmes.

Exploring Spatiotemporal Patterns of Phoma Black Stem in Sunflower

AbstractField experiments were conducted over two growing seasons with three sunflower cultivars to explore the spatiotemporal dynamics of phoma black stem epidemics and to test hypotheses pertaining to (i) disease spread from a known inoculum source; (ii) spatial patterns of the disease; (iii) disease spatiotemporal association; and (iv) association between disease intensity and sunflower defoliation. The spatial patterns of disease were random in most of epidemics, and disease gradients were not detected. Our results suggest absence of secondary infections, that is, that the studied phoma black stem epidemics were monocyclic under the experimental conditions reported here. Significant associations between the number of dead leaves per plant and the number of phoma black stem lesions per plant were detected towards the end of epidemics.

Integration of competitive cultivars and living mulch in sunflower (Helianthus annuus L.): a tool for organic weed control

Selection of highly competitive cultivars (Cvs) of sunflower might limit weed growth. However, competitive ability alone may not be sufficient in suppressing weeds in sunflower. Competitive cultivars may have to be combined with other complementary management strategies such as selection of appropriate living mulch species. Two experiments were conducted to evaluate the combined effects of crop cultivar and living mulch on weed growth and sunflower yield. Three sunflower cultivars (Allstar, Azargol, and Farokh) and three living mulch treatments (intercropping of buckwheat, snail medic, and hairy vetch as living mulch) were evaluated in a factorial design. For each cultivar, a plot without living mulch (sole sunflower) was considered as weedy check. The sunflower cultivars significantly differed in their competitive ability against weeds. The Cv. Azargol has a superior competitive ability than Allstar and Farokh, on the basis of its impact on crop grain yield and weed infestation level. The highest grain yield (7126 kg ha−1) was obtained in Cv. Azargol. All living mulch species also reduced weed biomass and density compared to weedy check. This research revealed that use of buckwheat as living mulch caused the most inhibition effect on weed biomass and density. Overall, selection of Azargol as a competitive cultivar and buckwheat as living mulch which provided 96 % control was the best combination method for broadleaf weed control, while Farokh-buckwheat, which provided 77 % weed suppression was more effective combination for grass weeds. Our findings suggest that combining highly competitive sunflower cultivars with proper living mulch species is a feasible weed management strategy; however, selection of both crop cultivar and living mulch species should be adapted based on dominant weed spectrum.

Effects of biochar and fertilizer management on sunflower (Helianthus annuus L.) feedstock and soil properties

ABSTRACTThe need for bioenergy is increasing with increase in global energy demand, and sustainable soil and fertilizer management practices for bioenergy feedstock production are gaining importance. In this greenhouse study, we evaluated the effects of biochar and fertilizer nitrogen on soil and energy crop sunflower (Helianthus annuus L. var. Giganteus). Sunflower plants were treated with three rates of biochar, control (0 Mg ha−1), low (25 Mg ha−1) and high (50 Mg ha−1), and three rates of fertilizers, 0% (control), 50% (low) and 100% (high) of the recommended nitrogen dose. Plant height, quality (chlorophyll content), biomass yield, feedstock energy, ash content and tissue nutrients were measured along with soil moisture and pH. Results showed an 11% increase in mean plant height under low biochar compared to control biochar-treated plants. High nitrogen treatment produced 26% and 18% more stalk and total above-ground plant (whole plant) biomass, respectively, compared to the control nitrogen treatment. High biochar treatment resulted in higher soil moisture holding, but lower soil pH than the control biochar treatment. Plant quality, energy and ash contents were not affected by either biochar or nitrogen. The plant tissue analysis provides a complete tissue macro- and micronutrient information on sunflower cultivar Giganteus, which was not done previously.