Volume 38, Issue 63 -

The obligate biotrophic Oomycete, Plasmopara halstedii , causal agent of sunflower downy mildew, is capable of producing new pathogenic races over time. Although changes in the P. halstedii race composition were reviewed for the first time in 2007, since then the pathogen has continued to change its virulence character dramatically. There was a need, therefore, to update information on pathogenic diversity of P. halstedii by making accounts of the temporal and spacial changes in the pathogen populations in North and South America and Europe. This paper, based on current publications and personal communications, attempts to present an accurate overview of races in Europe and Americas for the last 7 years.

Sunflower is a crop of world interest that is acquiring economic importance in Mexico. The aim of this study was to determine the effect of nitrogen (N) and phosphorus (P) on the growth of the root system and its relationship with the canopy dry matter and yield and its components of sunflower ( Helianthus annuus L.). The planting of cv. Victoria was conducted in Montecillo Mex., of temperate climate in a vertisol under conditions of seasonal rainfall on 16 May, with population density of 5 plants per m 2 . Treatments consisted in supply 0–200 kg ha −1 of N and P. The time to phenological stages was similar between treatment. The N and in minor degree the P increased grain yield (GY) and oil yield (OY) by increases in the grains number (GN), capitulum area (CA), canopy dry matter (CDM) and radical area (RA). In contrast, the P increase RDM but decrease the CDM/RDM relation. The effect of the interaction N * P on GY, OY indicates it is necessary to seek the best combination of N and P for increased the production of sunflower. The size grain and oil content in the grain did not change with N and P. The growth cycle was 122 days, with a seasonal ETc of 207 mm and 1,369°C d (Heat unit, HU).

Evaluation and characterization of sunflower hybrids using morphological, physiological and biochemical data are necessary and essential in sunflower breeding programs. The aim of this paper was to evaluate the productive possibilities of some sunflower hybrids grown in Macedonian environmental conditions. The experiment was carried out during the period 2013 and 2014 on the research field of the Faculty of Agriculture, “Goce Delchev” University – Shtip, in Ovche Pole locality, Republic of Macedonia. Total 20 sunflower hybrids were used as an experimental material. The trial was arranged as randomized complete block design (RCBD) with three replications. The average content of oil and oleic acid were 45.6 and 65.2%, respectively. The highest seed yield from all sunflower hybrids was obtained for the hybrid NLK12M144 (3,344 kg ha –1 ) and the lowest for hybrid NLK12S126 (2,244 kg ha –1 ). Cluster analysis classified the sunflower hybrids into four groups based on agronomic traits and seed yield. Most of the hybrids were included in cluster I and III (7 hybrids) followed by cluster IV. Using principal component analysis two main components have been extracted, with eigenvalue greater than one. They account for 72.99% of the variability in the original data. Only four hybrids had positive values for both main components (NLK12M144, NLK12S070, NLK12S125 and NLN12N011 DMR). The results from this study can be used to identify the best sunflower hybrids grown under Macedonian environmental conditions and to select the superior hybrids for future exploitation.

In breeding process it is important to know the extent of association between the traits that affect the yield. Objective of this study was to determine genotypic and phenotypic correlation and path coefficients in 50 sunflower hybrid combinations in order to identify research priorities in sunflower breeding. Relationships between seed yield and five bio-morphological traits in sunflower (oil content, protein content, 1,000-seed weight, head diameter and plant height) were studied. Head diameter had the highest correlation coefficient with seed yield, at phenotypic and genotypic level. Path analysis revealed that all evaluated traits had positive influence on seed yield at both, genotypic and phenotypic, levels. The highest direct effect on seed yield was found for head diameter, while protein content had the lowest direct effect on seed yield. Study has shown that the greatest improvement in sunflower seed yield can be achieved through selection on head diameter.

This study was carried out to determine the correlation between agronomic traits and seed yield of sunflower hybrids and also to determine the direct and indirect effects of analyzed traits on seed yield. The primary task in sunflower breeding programs is to increase the seed yield, as well as create new hybrids with high potential for seed and oil yield. The experiment was set up according to randomized block design during two growing seasons (2013 and 2014), on research area of the Faculty of Agriculture, “Goce Delchev” University – Shtip, in Ovche Pole locality, Republic of Macedonia. As an experimental material 20 sunflower hybrids were used. 1,000 seed weight, seed length and width, oil content, oleic acid content and seed yield were analyzed. 1,000 seed weight showed positive and significant correlation with seed width, seed length and seed yield. On the other hand, negative and significant correlation was obtained between 1,000 seed weight and oil content. 1,000 seed weight expressed the highest positive direct effect on seed yield. The results obtained from correlation and path analysis showed that the efficiency in the selection of seed yield in sunflower hybrids should increased through the selection of 1,000 seed weight.

The drought resistance and genetic structure of F 2 sporophytic populations for some morphological marker traits after pollen selection for water stress tolerance in F 1 sunflower hybrids has been studied. The emasculated inflorescences were moistened with 10% and 20% of PEG 6000 solution in the experiments and with distilled water in the control. Freshly collected pollen was used for pollination after drying up the PEG solution on stigmas. F 2 resulted seeds were germinated in 20% solution of PEG 6000 for a period of 3 days, and then the percentage of seed germination was counted. Germinated and not germinated seeds were separately planted. Segregation ratios in F 2 populations for leaf venation and leaf chlorophyll deficiency marker traits were analyzed at early stage of development. Pollen treatment significantly increased the drought resistance of F 2 populations and changed the monogenic ratios for leaf chlorophyll deficiency marker trait.

Even though the sunflower is the second most widespread oil plant in the Czech Republic, there is a lack of information about the effects of climate, nitrogen and micronutrients application on sunflower oiliness and fatty acid composition of sunflower achenes. To obtain such information, we established five year experiment (2008–2012) to study the effect of climate, nitrogen (C-control, N 60–60 kg N ha −1 , N 90–90 kg N ha −1 , N 120–120 kg N ha −1 ) and of foliar application of boron (N 90 + B), zinc (N 90 + Zn) and molybdenum (N 90 + Mo) on sunflower oiliness and composition of fatty acids (palmitic, palmitoleic, stearic, oleic and linoleic acids). According to our results, oiliness and fatty acid composition was significantly influenced by climate and fertilizer treatment. Oiliness was influenced mainly by climate (96.4%), the effect of fertilizer treatment was minor (2.5%). Within the frame of climate, the effect of precipitation was slightly higher than of temperature. A strong and negative relationship between the dose of nitrogen and oiliness was revealed ( r = –0.79), the difference between C and N 120 treatment was 2.1% on behalf of C treatment. The highest oiliness was recorded in 2011 (50.72%) and in C treatment (48.48%). The fatty acid composition was not significantly influenced by fertilizer treatment, but was significantly influenced by the climate conditions of the year. Application of micronutrients was not connected with any significant increase in oiliness or in the fatty acid composition due to a high initial content of those micronutrients in top soil.

The present paper shows results obtained on effects of priming of sunflower seeds, subjected to accelerated ageing and the cold test, on seed vigour. Seeds were primed with distilled water, the potassium nitrate solution (0.2%) and the gibberellic acid solution (0.04%). The following parameters were tested: energy of germination, germination, proportion of abnormal seedlings, lengths of roots and shoots of normal seedlings. Accelerated ageing in the course of 3 and 5 days resulted in a statistically significant reduction in energy of germination and germination; it adversely affected the length of roots and shoots and it increased the proportion of abnormal seedlings. Seed priming with all three solutions mitigated adverse effects of 3-day accelerated ageing on energy of germination. Furthermore, seed priming with gibberellic acid prior to 3-day accelerated ageing positively affected seed germination and neutralized a negative effect of accelerated ageing on the number of abnormal seedlings, as well as on lengths of shoots and roots of normal seedlings. The cold test (at 5°C for 7 days) negatively affected energy of germination and the root length, increased the proportion of abnormal seedlings and did not affect seed germination. Priming of seeds with distilled water prior to the cold test completely neutralized the adverse effect of low temperatures on energy of germination. Finally, priming of seeds with all three solutions completely neutralized the adverse effect of cold test on the root length.

Sunflower is an important oilseed crop grown throughout the year due to its short duration, day neutral, low photoperiod sensitivity and wider adoptability to agroclimatic conditions and soil types in Asian countries. Lower yields of sunflower in rainfed vertisols are attributed to lower soil moisture and nutrients availability. In this situation, we conducted field studies at research farm and farmers’ fields to know the response of sunflower to rainwater conservation and nutrient management in vertisols of India. Compartmental bunding and ridges and furrows conserved more rainwater in profile, thus producing greater sunflower seed yields varying from 22% to 28% compared to farmers’ practice of flat-bed sowing. Greater seed yield with resource conservation is attributed to higher head diameter with greater head weight and seed weight per plant over flat-bed sowing. Nutrient management as farmers practice INM 1 (15 kg N ha −1 + 15 kg P 2 O 5 ha −1 + 1.0 t farmyard manure ha −1 ) with Azospirillum seed treatment (INM 2 ) produced 5–6% higher seed yield, whereas recommended rate of nutrients (40 kg N ha −1 + 40 kg P 2 O 5 ha −1 + 2.0 t farmyard manure ha −1 ) with Azospirillum seed treatment (INM 3 ) produced 13–16% greater seed yield both at research farm and farmers’ fields over INM 1 .