Sunflower Heads Research Articles

Precision, quantitative measurement of sunflower capitulum inclination: A trigonometry‐based approach

AbstractSunflower (Helianthus annuus) is a widely cultivated crop that exhibits a trait known as capitulum (or head) inclination at maturity. This trait is influenced by various structural factors, including head weight, stem traits, and plant height. A sunflower head should be at an angle at which the head faces the ground to avoid damage from the sun and birds. While this desired inclination range is known, current methods, including visual estimation and a model of measuring inclined length of the stem, fail to provide precise measurements of angle. This study introduces novel approaches to mathematically measure the head inclination angle. The research, which was conducted over the 2022 and 2023 growing seasons, involved an aluminum rod equipped with a ruler and a digital protractor to measure various height and angle components. Using the data collected, three methods were applied for measuring inclination: a previously published model as a control, a trigonometry‐based approach using angle and height measurements, and other model‐based approaches. A linear model resulted in a formula to calculate the head angle of any plant based solely on two height measurements, the highest point of the plant at both bloom (R5) and maturity (R9). Calculations of heritability and correlation suggest this method has created a precise alternative to existing estimation methods. The resulting formula has the potential to be paired with measurements from high‐throughput phenotyping methods, such as those facilitated with drones and ground robots, to fully automate the process of collecting head inclination data.

The all-day pollinator visits of sunflower inflorescences in Helianthus annuus plantations are independent of head orientation: Testing a widespread hypothesis.

Mature inflorescences of sunflowers (Helianthus annuus) orient constantly on average to the geographical east. According to one of the explanations of this phenomenon, the eastward orientation of sunflower inflorescences increases the number of attracted insect pollinators. We tested this hypothesis in three field experiments performed in flowering sunflower plantations. In experiments 1 and 2 we measured the number of insects trapped by the vertical walls of sticky sunflower models facing north, east, south, and west. In experiment 3 we counted the pollinators' landings on real sunflower inflorescences facing naturally east or turned artificially toward north, south, and west. We found that the all-day number of pollinators (predominantly bees) attracted to model and real sunflowers in H. annuus plantations is independent of the azimuth direction of sunflower heads, and after 10 h in the morning, the average number of pollinators counted every 20 min is practically constant in the rest of the day.

Phomopsis Head Rot caused by Diaporthe helianthi: A New Disease on Sunflower in Argentina

ABSTRACTDuring a survey conducted in the 2021, 2022 and 2023 seasons, sunflower heads showing symptoms of dry rot were collected from 80 fields in the semi‐arid Pampa region of Argentina. A total of 72% of the fields examined in 2021, 71% in 2022 and 63% in 2023 showed the presence of the disease. The highest incidence was recorded as 70% in 2021. Phomopsis head rot began as dry, brown spots on the back of the head, progressing to necrosis and twisting of adjacent leaves. Infected head tissue samples were surface sterilised, cultured on potato dextrose agar (PDA) and incubated at 25°C for 14 days. Diaporthe helianthi was identified based on cultural and morphological characteristics as well as molecular data. A phylogenetic analysis was performed. Internal transcribed spacer (ITS), translation elongation factor 1‐α (ef1‐α) and β‐tubulin sequences were deposited in GenBank, showing the identity with the ex‐type D. helianthi strain CBS 592.81. Pathogenicity experiments confirmed the presence of similar disease symptoms in inoculated sunflower heads, and D. helianthi was consistently reisolated from these organs. Our Koch's postulates testing results on heads constitute the first confirmed report that D. helianthi is the cause of Phomopsis head rot on sunflower in Argentina.

Seasonal Incidence of <i>Helicoverpa armigera</i> on Sunflower

Helicoverpa armigera (Hubner). the sunflower head borer, poses a significant threat as it can cause extensive damage by feeding on flower heads and seeds. Its presence can lead to yield losses. Effective IPM strategies are crucial to mitigate the impact of H. armigera infestations and ensure the profitability and sustainability. Monitoring pests is crucial for timely intervention and to minimize crop damage and optimize yields. The present field experiment was carried out during 2021 to study the seasonal incidence of H. armigera on sunflower. Result revealed that incidence of H. armigera was observed during 50th standard meteorological week which reached to peak during 7th SMW. However, it crossed the ETL during 4th SMW. In relation to weather parameters, H. armigera showed positive correlation with maximum temperature (r = 0.557*), while it was negative with evening relative humidity (r = - 0.605*). Further, multiple regression was carried out and it revealed that environmental factors influenced about 70.10% H. armigera incidence in sunflower.

Seasonal Incidence and Infestation Pattern of Sunflower Head Borer (Helicoverpa armigera) and Leaf Eating Caterpillar (Spodoptera litura) under the Influence of Climatic Factors

Field experiments were conducted at Regional Research and Technology Transfer Station (RRTTS), Ranital, Bhadrak, OUAT during the summer seasons of 2019-20 and 2020-21 to study the seasonal incidence of sunflower head borer and leaf-eating caterpillar in sunflower in relation to the abiotic factor. The seasonal incidence of the target insects, Spodoptera litura and Helicoverpa armigera, was investigated using pheromone traps installed in the unprotected sunflower plots (10 m x 5 m) at the research block. The trap catches of male adults were expressed as a number of males trapped per trap per week. In the observation plots, the sunflower hybrid Aruna was cultivated with the approved agronomic package of techniques without any plant protection measures. Weekwise larval populations of Spodoptera litura and Helicoverpa armigera were counted from 10 randomly selected tagged plants starting from the initiation of damage and expressed as larval intensity i.e. average larval population per plant. Besides, weekwise incidence of the pest (leaf damage by tobacco caterpillar and head damage by head borer) were also recorded. The findings of the investigation indicated that tobacco caterpillars' adult activity commenced from the 5th to 6th standard weeks (1st and 2nd week of February) and peak activity in the 11th standard week (3rd week of March). Similarly, the larval population began to appear in the 6th to 7th standard weeks in 2020 and 2021, respectively with a peak population build-up stage during the 12th standard week and their activity steadily decreased as the cropping season progressed. The peak infestation stage coincided with the period of maximum larval activity and the pest caused sizable damage from the early vegetative stage to the peak flowering stage of the crop. The sunflower head borer (Helicoverpa armigera) infested sunflower crops throughout the reproductive stage of the plant with adult activity beginning in the 9th to 10th standard weeks (last week of February-first week of March) and attaining the peak in the 12th to 13th standard weeks (3rd-4th week of March). Similarly, the larval population began to appear in the 10th to 11th standard week and reached the peak in the 13th to 14th standard week (last week of March to first week of April). Various environmental parameters viz. temperature, relative humidity and rainfall were collected from the automated weather station of Gramin Krishi Mausam Sewa (GKMS) located at RRTTS, Ranital., These abiotic factors were correlated with trap catch, larval intensity, leaf damage head damage to study the influence of ecological parameters on pest incidence and infestation. The findings of the investigation indicated that among the abiotic factors temperature had a positive influence and relative humidity exhibited a negative effect on the population and damage of Spodoptera litura. All the temperature variables and bright sunshine hour (BSH) exhibited a significant positive correlation and relative humidity (afternoon) had a significant negative correlation with the head damage Helicoverpa armigera.

НЕЙРОСЕТЕВАЯ СИСТЕМА РАСЧЕТА УРОЖАЙНОСТИ ПОДСОЛНЕЧНИКА

The article is devoted to the solution of the problem of developing a neural network system for calculating the yield of sunflower. The developed system is designed to simplify, automate and speed up the inspector's work on calculating the biological yield of sunflower. When assessing the biological yield, most of the time is taken by counting the seeds of a sunflower head. It is proposed to solve this problem using a trained convolutional neural network. The developed system allows you to add the name of a new calculation area, use phone cameras to obtain images of sunflowers (for mobile applications), add images to the system, search for and select the required subspecies of sunflower from the directory, obtain the values of the average weight of seeds of the selected subtype of sunflower, set the area of the determined sowing field, calculate the yield based on the added images, receive the result of calculating the biological yield of sunflower, and also receive previously calculated yield values by name from the device's memory and by the year of the assessment. The Python programming language was chosen to solve the problem of counting seeds in a sunflower head and developing a neural network system. The Roboflow system was used to create a sample with segmented images of sunflower heads. TenserFlow was used as a machine learning library. Keras and OpenCV libraries were used for segmentation and object recognition in the image. Google Colab was used as the development environment for the neural network system. The mobile application was implemented in Java using the Android Studio development environment. The desktop application was implemented in C# using the Visual Studio development environment on Windows Forms technology. The developed neural network system, based on the image transferred to the input of the neural network, detects a sunflower head, segments part of the image with the head, cutting out this area, then counts the seeds in the head and calculates the yield. The YOLOv8 convolutional neural network was used to segment the sunflower head. Using the Roboflow service, a data sample of 10,000 sunflower images was formed. Part of the data (70%) was used for training, and the rest of the data was used for testing the model. Testing of the neural network system showed its efficiency and the possibility of further practical use. Thus, the developed system allows accelerating the assessment of sunflower yield by automating this process.

Diversity Index and Phenotypic Character Analysis for Important Qualitative Traits of Sunflower [Helianthus annuus L] Genotypes in Central Highlands of Ethiopia

Sunflower (Helianthus annuus L.) is an important oilseed crop. It is grown for vegetable and industrial oils in the world. Sunflower oil is considered to be of supreme quality. The Production, productivity and area coverage of sunflower in Ethiopia is low and below the world average due to different reasons. Sunflower can contribute a big share in improving local edible oil production due to its short interval for maturity, high oil contents, better fitting in the cropping pattern, tolerance to drought and its high yield potential. Therefore, this study was conducted to quantify genetic variability of fourteen qualitative traits using Shannon-waver diversity index. A total of 220 genotypes including checks varieties were evaluated in 2020/21 main cropping season at Holeta, Ethiopia. Alpha lattice design was used with two replications and eleven blocks were nested within a replication. Based on fourteen qualitative traits significant variability or dissimilarity was observed among Sunflower genotypes. Analysis of Shannon-waver diversity index shows that H' values ranges from ~0.075 for leaf arrangement to ~0.99 for bract shape at the back of sunflower head. This shows that there is considerable diversity among the studied genotypes for the qualitative traits which can have good indications and amplification during selections of genotypes in sunflower improvement either ornamental type, confectionery or oil type sunflower.

Determining the Ruminal Degradability of Sunflower Head Residues and the Effect of its Different Levels on Digestibility, Blood Parameters and Chewing Activity of Fattening Afshari Lambs

Determining the Ruminal Degradability of Sunflower Head Residues and the Effect of its Different Levels on Digestibility, Blood Parameters and Chewing Activity of Fattening Afshari Lambs

Comparative Efficacy of Certain IPM Strategies Against Tobacco Caterpillar and Head Borer in Sunflower

The Experiments was conducted at Regional Research and Technology Transfer Station, Ranital, Bhadrak, OUAT(Odisha University of Agriculture and Technology), Odisha, India during the summer seasons(Jan-may) of 2019–20 and 2020–21 to evaluate the comparative efficacy some IPM modules against the head borer and leaf eating caterpillar in sunflower. Five IPM modules(three chemo-intensive and two bio-intensive modules) were evaluated against the existing pesticides application-based farmers’ practice. The results revealed that the IPM module (M2) comprising of installation of pheromone traps for pest monitoring @ 5 ha-1, poison baits (10 kg rice bran+2 kg jaggery+100 g Thiodicarb 70WP) for attracting and killing of tobacco caterpillar larvae and alternate spray of neem oil formulations (1500 ppm) @ 1.5 l ha-1 and the novel insecticide mixed formulation (Novaluron 5.25%+Emamectin benzoate 0.9% SC) @ 825 ml ha-1 at 15 days interval had significantly suppressed tobacco caterpillar (5.46% leaf damage i.e.. 67.59% reduction over FP) and sunflower head (2.93% head damage i.e. 75.32% deduction over FP). The IPM module ( M3) comprising of pheromone trap installation @ 5 each ha-1,poison baits (10 kg rice bran+2 kg jaggery+200 ml deltamethrin 5EC) and alternate spray of neem oil formulations (1500 ppm) @ 1.5 l ha-1 and Flubendiamide 480 SC @ 150 ml ha-1) also had statistically similar efficacy against the target pests with 6.40% leaf damage (62.02% reduction over FP) and 3.54% head damage(70.17% reduction over FP). Though, the BIPM module had moderate efficacy against the insect-pests under study, retained maximum population of predatory fauna like predatory bug (Eocanthecona furcellata) and lady bird beetles in the sunflower ecosystem.

Energy and emission properties of burley tobacco stalk briquettes and its combinations with other biomass as promising replacement for coal.

As a tobacco producer, Serbia has to deal with large amounts of leftover tobacco stalks after harvesting. One option for this type of biomass is to burn it, but burning is not encouraged in Serbia, since the levels of its combustion products have not been investigated yet. The aim of this study was therefore to determine the elemental composition, ash and nicotine content, heat values, and composition of gaseous combustion products of tobacco stalk briquettes and to see if their mixing with other types of biomass available in Serbia could improve their ecological profile. We made 11 different types of briquettes: six of pure raw materials, including burley tobacco stalks, sunflower head remains, wheat straw, corncob, soy straw, and beech sawdust and five by mixing tobacco stalks with these other raw materials in a 50:50 mass ratio. All briquettes meet the ecological criteria regarding the emission limits for nitrogen oxides (NOx), sulphur dioxide, carbon monoxide, and carbon dioxide. Nicotine content in flue gases (<10 mg/kg) is far below the maximum level allowed by the European Union. Heat values of all biomass samples are acceptable, although lower than those specified for solid biofuels (≥16.0 MJ/kg), save for corncob and beech sawdust and their mixtures with tobacco stalks. Our findings therefore encourage the use of tobacco stalks as a viable biofuel.

Modulating Surface Electron Density of Heterointerface with Bio-Inspired Light-Trapping Nano-Structure to Boost Kinetics of Overall Water Splitting.

Herein, inspired by natural sunflower heads' properties increasing the temperature of dish-shaped flowers by tracking the sun, a novel hybrid heterostructure (MoS2 /Ni3 S2 @CA, CA means carbon nanowire arrays) with the sunflower-like structure to boost the kinetics of water splitting is proposed. Density functional theory (DFT) reveals that it can modulate the active electronic states of NiMo atoms around the Fermi-level through the charge transfer between the metallic atoms of Ni3 S2 and MoMo bonds of MoS2 to boost overall water splitting. Most importantly, the finite difference time domain (FDTD) could find that its unique bio-inspired micro-nano light-trapping structure has high solar photothermal conversion efficiency. With the assistance of the photothermal field, the kinetics of water-splitting is improved, affording low overpotentials of 96 and 229mV at 10mAcm-2 for HER and OER, respectively. Moreover, the Sun-MoS2 /Ni3 S2 @CA enables the overall alkaline water splitting at a low cell voltage of 1.48 and 1.64V to achieve 10 and 100mAcm-2 with outstanding catalytic durability. This study may open up a new route for rationally constructing bionic sunflower micro-nano light-trapping structure to maximize their photothermal conversion and electrochemical performances, and accelerate the development of nonprecious electrocatalysts for overall water splitting.

Installing Flower Strips to Promote Pollinators in Simplified Agricultural Landscapes: Comprehensive Viability Assessment in Sunflower Fields

The installation of flower strips in simplified agricultural landscapes has been promoted as a tool to improve pollination services. While the effectiveness of flower strips in increasing pollinator visitation and yield is well-established, the social and economic feasibility of this measure remains unclear. Here, we evaluated the economic efficiency and social feasibility of installing flower strips to promote pollination under different scenarios of subsidy. A 2-year experiment was implemented by comparing sunflower fields with and without installed flower strips in central Spain, along with local farmer opinions obtained via a focus group. Flower strips significantly increased wild bee visitation to sunflower heads in the second year after implementation, with seed set being 11% higher on average in fields that had flower strips. Cost–benefit analysis revealed that investment in flower strips would be recovered by 4–5 years after installation, depending on the subsidy used. In the most favorable subsidy scenario, farmers could increase their annual benefits by 8.7% (29 €/ha) after recovering the initial investment. However, most local farmers did not perceive a significant increase in yield associated with the flower strip installation. The use of flower strips was negatively identified by farmers as a source of invasive weeds in adjacent fields, along with a lack of technical advice and economic incentives. Farmers fully agreed that direct economic subsidies were required for flower strips to be accepted as feasible approaches in the long-term.

Variety of Approaches for Generating Volume of Aquara-6 Sunflower Seeds

Sunflower is a major oilseed crop in the world. Its seeds are applied to extract oil which gives high nutritional value and can be kept longer than other vegetable oils. In this article, we focus on Aquara-6 sunflower in order to study the way for generating volume of seeds on each head. The distinctive features for this type of sunflower are high yield and large flowers. The aims of this study are to present five ways to calculate the volumes of Aquara-6 sunflower seeds for each head and to compare these methods to volume measurement by replacing them with water of all seeds. This is collected from the physical grain, including width, length, and thickness, of each sunflower head in order to prepare data for calculating volumes of five methods. After that they are estimated via five methods from three regions on sunflower heads and on the whole heads. Moreover, we analyze the comparison between the estimated volumes and the actual volumes of fifteen sunflower heads. The results show that the best way to approximate the volume of seeds on each head is the square pyramid's formular and the second way is the circular cylinder's formular. These methods can be alternative ways to generate the volume of sunflower seeds in the future. In addition, this can be helpful to study the moisture content, especially in the drying process.

Effect of Exogenous Fibrolytic Enzymes Supplementation or Functional Feed Additives on In Vitro Ruminal Fermentation of Chemically Pre-Treated Sunflower Heads

This study aims to provide possible utilization of sunflower head byproduct (SFH) as a feedstuff by implementing chemical pretreatments (4% sodium hydroxide (SFHNaOH) or 4% urea (SFHurea) and supplementation with either exogenous fibrolytic enzymes (EFE) or functional feed additive (FFA). The experimental EFE was a complex (1:1, v/v) of two enzyme products with high activity of β-1,3-1,4-glucanase and endo-1,4-β-D-xylanase and applied at 0 (SFHout), 1, 2, 5, and 10 µL/ gdry matter, while FFA was a fermentation byproduct rich in cellulase and xylanase activities, applied at 0 (SFHout), 0.5, 1, 2, and 4 mg/g DM. SFHurea had the highest (p &lt; 0.05) crude protein (CP) content compared to other SFH substrates. Linear enhancements (p &lt; 0.05) in kinetics of gas production (GP), metabolizable energy (ME), organic matter digestibility (OMD) and total short-chain fatty acids (SCFAs) concentrations were observed for all SFH substrates supplemented with EFE. The SFHout had the highest (p &lt; 0.05) potential GP, maximum rate (Rmax) of GP, ME, OMD and SCFAs. Supplementation of EFE was more pronounced than FFA in affecting the kinetic parameters of in vitro GP for all SFH substrates. SFHout supplemented with EFE seems to be the most promising substrate to enhance microbial fermentation in vitro.

Mature Sunflower Inflorescences Face Geographical East to Maximize Absorbed Light Energy: Orientation of Helianthus annuus Heads Studied by Drone Photography.

Mature sunflower (Helianthus annuus) inflorescences, which no longer follow the Sun, face the eastern celestial hemisphere. Whether they orient toward the azimuth of local sunrise or the geographical east? It was recently shown that they absorb maximum light energy if they face almost exactly the geographical east, and afternoons are usually cloudier than mornings. However, the exact average and standard deviation (SD) of the azimuth angle of the normal vector of mature sunflower inflorescences have never been measured on numerous individuals. It is imaginable that they prefer the direction of sunrise rather than that of the geographical east. To decide between these two photobiological possibilities, we photographed mature inflorescences of 14 sunflower plantations using a drone and determined the average and SD of the azimuth angle of the normal vector of 2,800 sunflower heads. We found that the average azimuth αinflorescence = 89.5° ± 42.8° (measured clockwise from the geographical north) of inflorescences practically coincided with the geographical eastern direction (αeast = 90°) instead of the azimuth of local sunrise αsunrise = 56.14° – 57.55°. Although the SD of the orientation of individual inflorescences was large (± 42.8°), our finding experimentally corroborated the earlier theoretical prediction that the energetically ideal azimuth of sunflower inflorescences is east, if mornings are usually less cloudy than afternoons, which is typical for the domestication region of H. annuus. However, the average orientation of inflorescences of two plantations in hilly landscapes more or less differed from that of the majority of plantations in plane landscapes. The reason for this deviation may be that the illumination conditions in hilly sites more or less differed from those in plane landscapes. Furthermore, in a plantation, we observed a group of south-facing inflorescences that were in shadow for about 5 h both after sunrise and before sunset. This southern orientation can be explained by the southern maximum of total light energy absorbed by the partly shadowed inflorescences during the day, as computed by our software integrating both the diffuse skylight and the direct sunlight received by sunflower inflorescences.

Importance of maternal resources in pollen limitation studies with pollinator gradients: A case study with sunflower

Pollen limitation studies are scarce in entomophilous crops, as it can be very tedious to supplement plants with hand pollination at the relevant plant scale. To overcome this, recent studies have used pollinator gradients over several fields to assess whether crops were pollen limited. But the plant maternal resources and thus the yield potential may vary between fields of the same crop. If these resources are not properly controlled, it may affect the conclusions of the study.We investigated the relationship between yield, measured as seed number, seed mass, and seed oil content per head, and pollinator density in sunflower (Helianthus annuus L.) by using a gradient of pollinator densities set both across and within fields. We analyzed the yield and the % of yield potential, the latter being assessed with pollen supplementations applied at the whole plant scale. We analyzed the data both with and without random effects including year, cultivar, field and sampling plot. We also compared the yields of open and pollen-supplemented sunflowers to sunflowers isolated under tulle bags to assess autonomous self-fertilization and self-production rates in each field.Without random effects included in models, yields increased with pollinator density but only up to 0.3 bees per head, implying pollen limitation only below this threshold, while with random effects included, the yields were marginally pollen limited across the whole range of pollinator densities observed (P = 0.072 and 0.037). Yet, on the other hand, there was no relationship between bee density and % of yield potential (assessed with pollen supplementation treatments), with or without random effects included, implying no pollen limitation across the complete range of bee densities observed in our study (0.1–1 bees per sunflower head). These last results are explained by variation in the yield potential between and within fields, and by the positive correlation found between yield potential and pollinator density. Insect pollination contributed on average to 53.7% and 42.8% of the seed number and mass per head, respectively, and also increased the seed oil content by 5.5% on average.Our study showed that plant maternal resources and random effects are crucial to consider when quantifying pollen limitation using pollinator gradients and yields. Pollinator gradients on a per flower basis are a useful tool to identify target pollinator densities to maximize yields, but should be combined with pollen supplementation treatments at the relevant scale in order to correctly assess pollen limitation.

Theoretical study of a sunflower harvester operation equipped with an auger reel

In Russia, the main oilseed crop is sunflower. Its crops occupy more than 95 % of the area under oilseeds, and annually account for 7.07 % of the area under grain crops. An urgent problem is the loss of oilseeds because of headers and harvesting attachments, which, according to agro technical requirements, should not exceed 2.5 % of the actual yield. The article describes the technological process of the sunflower harvester equipped with an auger-reel. The design of the auger- reel with stripper knives and winding is justified. A mathematical analysis of the capturing process a sunflower head by an auger- reel is proposed. Mathematical expressions are given for the forces acting on the stem during the auger- reel capture, equations for determining the reactions’ moments of the forces acting on the sunflower stem.

Design and Development of a Power Operated Sunflower Thresher

Sunflower production is increasing in Bangladesh, but farmers face problems separating the seeds from the sunflower heads. Sunflowers are traditionally threshed by beating the heads manually with a stick. The goal of this experiment is to design and develop a motor-driven machine that separates the seeds from the sunflower. An orthographic projection was drawn using SolidWorks 2016 software. The sunflower threshing machine was then fabricated according to the drawing in the FMPE Divisional workshop using locally available materials in 2017-18. The developed sunflower threshing machine was modified in 2018-19. The improved model was further modified to reduce the overall dimensions while maintaining the same capacity of the machine. The number of threshing rollers was reduced from 5 to 4. A threshing fan has been added to the improved version to separate the dust from the grains. The capacity of the motorized sunflower thresher was 115 and 304% higher than that of the pedal thresher and manual threshing, respectively. The capacity of the thresher was varied with moisture content. The capacity of the thresher varied from 89 to 125 kg/h at moisture content from 31 to 62% (wb).

Efficiency of Giberelonand Cytodef-100 phytohormones in the crop structure and productivity of sunflower in edaphoclimatic conditions of the Republic of Tatarstan

The studies were carried out to assess the effect of foliar dressing with Cytodef-100 and Giberelonphytohormones on fruit elements and gross yield of sunflower oil in edaphoclimatic conditions of the Republic of Tatarstan. The study was conducted in the sunflower crops of the Avenger hybrid in the Republic of Tatarstan in 2019–2021. The agrochemical indicators of typical gray-forest soil were as follows: humus content according to Tyurin – 3.0%, mobile phosphorus – 160 and exchange potassium – 145 mg/kg of soil according to Kirsanov. The soil medium response was close to neutral (pH 6.6). The results of the studies show that the total diameter of sunflower heads increases from 10.9 cm in the control sample to 13.3 cm in the joint use of 3 agrochemicals in the phase 4-8 of sunflower leaves: Euro-Lightningherbicide (1.2 kg/ha) + Cytodef-100 (150 g/ha) + Giberelon (50 g/ha). At the same time, the diameter of the empty part of the heads has a clear downward trend: from 2.2 cm to 1.7 cm in the latter version. The increase in marketable products due to the combined use of Cytodef-100 antistress drug and Giberelonphytohormone solution in combination with chemical weeding was 15.2% compared to the control sample (spraying of sunflower crops with Euro-Lightning (1.2 kg/ha) without Agrosintez LLC products.

The effect of hoeing time for weed management on yield and yield criteria of sunflowers (Helianthus annuus L.)

Hoeing time is important in weed management and is effective to reduce weed populations in sunflower cultivation. The study was conducted between 2018-2019 to determine the hoeing times for mechanical weed control in sunflower in Adana province of Turkey. To determine weed control time in experimental fields, weeds were allowed to germinate in natural conditions at intervals between 15 days for mechanical hoeing at the emergence of sunflower to the harvest time. The interactions between weeds and sunflower yield criteria were observed by periodic hoeing treatments. At the end of the experiments, the criteria for sunflower yield, seed yield, oil content, oil quality, head diameter, plant height, weed biomass, and coverages of hoeing time effects were determined. Combining the two-year data, it was observed that the sunflower yield and seed yield were the highest in plots of 75 and 90 days weed-free, while the lowest yield and seed yield were observed in 60, 75, and 90 days weedy. It was determined that the sunflower oil yield was higher in plots of long hoeing period time, but the oil quality did not change. It was found that sunflower height were statistically similar for each year in different hoeing period times, moreover, sunflower head diameter was not affected. In weedy plots with shorter hoeing times, higher weed biomass due to increased weed coverage was noted. As a result, it was determined that long-term hoeing in sunflower weed management increases the yield, and hoeing time is significant in sunflower weed management.