Volume 39, Issue 64 -

Water availability is a major factor limiting plant productivity in both natural and agronomic systems. Identifying putative drought resistance traits in crops and their wild relatives may be useful for improving crops grown under water-limiting conditions. Here, we tested the expectation that a desert-dwelling sunflower species, Helianthus niveus ssp. tephrodes (TEPH) would exhibit root and leaf traits consistent with greater ability to avoid drought than cultivated sunflower H. annuus (ANN) in a common garden environment. We compared TEPH and ANN at both the seedling and mature stages under well-watered greenhouse conditions. For traits assessed at the seedling stage, TEPH required a longer time to reach a rooting depth of 30 cm than ANN, and the two species did not differ in root:total biomass ratio at 30 cm rooting depth, contrary to expectations. For traits assessed at the mature stage, TEPH had a higher instantaneous water use efficiency and photosynthetic rate on a leaf area basis, but a lower photosynthetic rate on a mass basis than ANN, likely due to TEPH having thicker, denser leaves. Contrary to expectations, ANN and TEPH did not differ in leaf instantaneous stomatal conductance, integrated water-use efficiency estimated from carbon isotope ratio, or nitrogen concentration. However, at both the seedling and mature stages, TEPH exhibited a lower normalized difference vegetative index than ANN, likely due to the presence of dense leaf pubescence that could reduce heat load and transpirational water loss under drought conditions. Thus, although TEPH root growth and biomass allocation traits under well-watered conditions do not appear to be promising for improvement of cultivated sunflower, TEPH leaf pubescence may be promising for breeding for drought-prone, high radiation environments.

In the last 10 years the sunflower crop area of Argentina has shifted towards the Southwest as a result of the expansion of soybean cultivation. Early sowings require greater tolerance to low temperatures in order to optimize the use of water resources by the crop, especially in the seedling stage, when cold stress limits growth and productivity. Helianthus petiolaris is a wild genetic resource that has contributed to the production of sunflower cultivars. The goal of this study was to evaluate the tolerance to low temperatures in H. petiolaris plants. Morphological traits (plant height, leaf width and leaf length) and physiological traits (electrolyte leakage, chlorophyll content, and glucose content) were compared in eight accessions having an early germination in the field and one with normal life cycle. Acclimated and non-acclimated plants were subjected to cold stress followed by a recovery period. Physiological traits during early growth stages showed differences in cold tolerance and for acclimation ability between accessions, suggesting the existence of heritable components. Four accessions were the most cold-tolerant among the studied populations, suggesting a natural adaptation related to the geographical site. Results point out that H. petiolaris is a useful genetic resource to contribute to sunflower breeding in the search of cold tolerant cultivars.

Delayed planting is recommended to reduce damage from sunflower insect pests in the United States, including the sunflower moth, Homoeosoma electellum (Hulst) and banded sunflower moth, Cochylis hospes Walsingham. However, in some locations, planting earlier or growing later-maturing hybrids could improve yield or oil content of sunflowers which would partially offset any added costs from insect pests or their management. Because the abundance and distribution of some sunflower insects have changed since recommendations for delayed planting were developed, experimental plots were grown in 2012 and 2013 at sites in North Dakota, Nebraska, Iowa, and Illinois. Sunflowers were planted two to four weeks earlier than normal, including hybrids that flower two to three weeks later than elite commercial hybrids. The sum of seed damaged by sunflower moth, banded sunflower moth, and red sunflower seed weevil, Smicronyx fulvus LeConte, (i. e., total percentage) was influenced by location, but not the relative maturity of tested entries. However, when damage attributed solely to the red sunflower seed weevil was analyzed, more damaged seed were found for late-maturing entries in North Dakota and Nebraska. In addition to the trial data, current pest populations are lower than when delayed planting was first recommended and insecticide use during sunflower bloom is both common and effective. Together, these observations suggest factoring insect pests into planting time decisions may be unnecessary, except for areas with a history of problems with severe pests that cannot be managed using insecticides (e. g., sunflower midge, Contarinia schulzi Gagné).

During two growing seasons there were studied 11 sunflower breeding lines and their 30 analogues obtained via backcrossing, chemical mutagenesis and selected as natural mutants. The variability of such agronomic traits as crop yield, seed oil content, 1,000 seed weight, plant height, leaf and petiole size, number of leaves and branches, and head diameter was investigated. The traits of crop yield, leaf size, number of branches were the most variable, whereas the most stable were 1,000 seed weight, seed oil content, plant height, and the number of leaves. The influence of mutant genes which control ray flower color and shape, leaf color and shape, dwarfness, number of leaves and ray flowers, and shape of bracts on the manifestation of important agronomic traits was estimated. No negative impact of the genes of ray flower color and shape and leaf color was noticed. The gene of fringed leaf margin reduced plant height while the gene of erect petiole increased development of that trait. The genes of dwarfness can negatively influence seed oil content and 1,000 seed weight.

The experiment involved 7 different cms analogues as a female parent and 6 restores lines as male parent to synthesis of a set of these 42 hybrids. The experiment was conducted during spring season 2012 in Line×Tester breeding design and evaluated for combining ability of 7 morphological, physiological and important sunflower yield components traits. The results based on GCA effects of parents for different characters revealed that among the lines DV-10A and among testers P93R, P143R and RHA83R6 were found to be the good general combiners for seed yield and oil content with early maturing except P143R, which is good combiner for flowering and late maturity. The crosses CMS-XA×RHA83R6 and PRUN-29A×RHA83R6 were found to be superior and exhibited highest SCA effects with highest mean values for oil content but for seed yield having negative SCA effects with average for seed yield. The hybrids PKU-2A×RHA83R6 and E002-91A×P93R having high mean seed yield with high SCA effects.

Article describes inheritance of pigmentation traits in seed pericarp of cultivated sunflower. Study took into account presence of anthocyanins in seed pericarp as well as throughout the plant. Segregation was analyzed based on anthocyanin coloration in pericarp and hypodermis seed coloration. Nature of inheritance was determined for anthocyanin synthesis in hypodermis as well as gene control for yellow shade coloration in white hypodermis. Two nonallelic genes with complementary type of interaction were confirmed for formation of anthocyanins in achene. Yellow shade of white hypodermis was confirmed to be inherited monogenically dominant in relation to white hypodermis. It was established that presence of anthocyanin pigmentation can mask main hypodermis pigmentation.

The sunflower is a newly planted crop in the Czech Republic, which represents the northern edge of the species’ range, and there is a lack of information about the effect of nutrient application on yield components. To fill this gap, we performed a fertilizer experiment on Greyic Phaeozem over the years 2008–2012 to evaluate the effects of N, B, Zn and Mo application on achenes yield. We compared the control (C) without any N fertilizer, N treatments (N 60, N 90, N120 kg N ha −1 ) and N treatments accompanied with micronutrients (N 90+B – 0.3 kg B ha −1 , N 90+Zn – 0.35 kg Zn ha −1 , N 90+Mo – 0.125 kg Mo ha −1 ). The mean achenes yield over all years ranged from 3.9 in C to 4.34 t ha −1 in N 60. Achenes yield over all treatments ranged from 3.04 in 2008 to 4.91 t ha −1 in 2010. We concluded that sunflower can be produced with application rate up to 60 kg N ha −1 on highly productive soils in the Czech Republic and for similar other soils in the region. The increase in N application above 60 kg N ha −1 can decrease achenes yield. Application of B and Zn achieved slightly higher, while the addition of Mo slightly lower achenes yields when compared to the treatment with the same level of N and without micronutrients addition. We concluded that the application of micronutrients at the sites with sufficient content of those micronutrients in soil has almost no effect on achenes and biomass yield. Achenes and biomass yield was primarily affected by weather conditions in particular years, affecting plant growth, disease and predatory occurrence. Fertilizer treatments did not significantly affect the weight of achenes per head, weight of thousand achenes, the number of achenes per head, the number of heads per ha and number of achenes per ha during the experiment. The significant effect of the year was recorded, showing major effect of weather conditions on above mentioned parameters.

The population of oomycete Plasmopara halstedii (Farl.) Berl. et de Toni (sunflower downy mildew pathogen) has been monitored in Krasnodar and Rostov regions and the Republic of Adygea for more than 15 years. Prior to the beginning of the 2000s there were races 100, 300, 310 and 330 in the regions. In the period from 2004 to 2007 races 100, 300, 310 and 700 were recorded sporadically. The race 330 was the most common; in a number of agrocoenoses it was 100 % of samples. In some fields races 710 and 730 prevailed. In 2008–2011 only races 330, 710 and 730 were found; the race 330 have been still prevailed and was also found on Ambrosia artemisiifolia L. Since 2012, in the majority of fields races 710 and 730 prevailed, and the race 330 wasn’t allocated in many of them; for the first time in Russia pathotype 334, that able to overcome Pl 6 , was found in Krasnodar region. In the period of 2013–2015 increased distribution of the race 334 in the Krasnodar region and the Republic of Adygea was observed. At the same time, in 2014 in one field in the Rostov region only races 310 and 330 (prevailed) were identified. The virulence of the pathogen population is closely connected with the cultivated assortment of sunflower. Further spread and accumulation of P . halstedii race 334 and the emergence of new pathogen pathotypes in the said regions are predicted.

Sunflower ( Helianthus annuus L.) is used as “seed snacks”, so called “pipas”, in the Mediterranean countries which may offer an interesting opportunity for agricultural diversification of this crop. The morpho-phenological variability already demonstrated in the Tunisian local populations can be a basis for the creation of new varieties well adapted to climate and soil conditions in that region. The molecular characterization of 59 accessions and reference lines generated 194 alleles from 30 SSR loci (3–10 alleles per locus) and 54 haplotypes, built from 117 SNP detected by NGS sequencing of 7 genes (4–16 haplotypes per gene). These data highlight some uniqueness of the Tunisian material compared to 7 control lines but a low genetic dispersion between accessions. However, a core collection of 8 populations, capturing 88 % of the Tunisian genetic diversity, could be proposed for a future sunflower breeding program.