Sunflower Culture Research Articles

RESEARCH ON THE TOLERANCE OF SUNFLOWER HYBRIDS TO THE HERBICIDES CHALLENGE 600 SC AND VIBALLA

In order to deal with the weeding specific to the area, we have located at the Livada Research and Development Station a technological experience in sunflower culture. The major objective of this research was the tolerance of Chearfield, Express SUN and Conventional sunflower hybrids to Challenge 600 SC and Viballa herbicides in the pedoclimatic conditions of Livada, Satu Mare county, and implicitly the effectiveness of treatments with the aforementioned herbicides. The reserve of weeds on the soil types from the "luvosol albic" orchard being much higher as a result of the preservation of the seeds in the soil for a longer period of time determines a high level of weeding compared to which the herbicide Challenge 600 SC (aclonifen 600g/l ) 4l/ha pre-emergence applied to the sunflower crop, regardless of the type of hybrid, proved to be effective and selective throughout the vegetation period. The effectiveness of the new herbicides was determined by the climatic conditions and the floristic composition of the weeds.

Анализ взаимодействий между внекорневыми удобрениями и химическим составом листового аппарата подсолнечника

The purpose of the work is to use the analysis of sunflower foliage as a diagnostic tool for the accumulation of trace elements from the use of foliar top dressing "Revitaplant Sunflower". These studies were conducted in 2021-2022 at the experimental field of I. A. Bunin YSU in the Lipetsk region. Sowing was carried out on plots with three repetitions and two variants:control (without micro-fertilization treatment) and Revitaplant Sunflower 2 l/ha. The treatment was carried out in the vegetation phase of 6-8 leaves of the culture. The use of "Revitaplant Sunflower" on sunflower culture positively affected the chemical composition in the leaves of sunflower plants. The analysis showed a high response of sunflower to the assimilation of iron and manganese and optimal for copper and zinc. Keywords: SUNFLOWER, MICRONUTRIENTS; THE CONTENT OF TRACE ELEMENTS IN SUNFLOWER LEAVES

The Study of the Impact of Complex Foliar Fertilization on the Yield and Quality of Sunflower Seeds (Helianhtus annuus L.) by Principal Component Analysis

The aim of the paper is to assess the impact of Foliar Fertilizations (FF) on the yield and quality of sunflower seeds. This research was carried out in the agricultural years of 2019–2021 in the experimental field of the university. The method of planting in the field was carried out in subdivided plots with three repetitions and six fertilization options. The experimental variants were as follows: Control (Mt), V1—FF 10:10:10+ME (microelements), V2—FF 8:10:0+8B (Boron)+ME, V3—FF 15:0:0+2S (Sulfur)+1B+ME, V4—FF 15:0:0+4B+ME, and V5—FF 8:8:8+ME. FF treatments were carried out in the vegetation phases specific to the sunflower crop. These varied from 2–6 L ha−1, depending on the chemical composition of the product. The application of treatments with FF to the sunflower culture positively influenced both production and its quality expressed by specific quality indices, namely the content of proteins, lipids, carbohydrates, fibers, and minerals. The results were discussed not only in view of classical statistics but also using the Principal Components Analysis (PCA), which allows a more complex evaluation of the effects of foliar treatments on the production and quality of sunflower seeds.

The effects of cytokinin and plating density on protoplast culture of sunflower

The effects of cytokinin and plating density on protoplast culture of sunflower

The species composition of weeds in sunflower crops in the steppe zone of the Krasnodar Territory

In sunflower crops cultivated in the steppe zone of the Krasnodar Territory, 92 species of weeds were identified. The core of the weed component of agrocenoses consists of 2 especially active species - Amaranthus retrof-lexus L. and Chenopodium album L., 5 highly active species - Ambrosia artemisiifolia L., Convolvulus arvensis L., Abu-tilon theophrasti Medik., Echinochloa crusgalli (L.) Beauv., Persicaria maculosa S.F. Gray, 2 medium-active species Cir-sium setosum (Willd .) Bess. and Vicia cracca L. and 2 fairly active species Sinapis arvensis L. and Lathyrus tuberosus L. These are the types that should be paid special attention to while developing protective measures. In addition, 22 inactive species and 59 inactive species were identified, the presence of which in sunflower crops is due to a decrease in the level of technology of this crop cultivation. The territorial totality of weeds of the ecotope of segetal habitats is a segetal flora, one of the subdivisions of which is the partial flora of the ecotope under the cultivation of sunflower culture. The species composition of the segetal flora is characterized by stability, therefore it can be predicted for a certain time perspective. The activity of species changes with the change of crops in the crop rotation scheme, which significantly increases the role of phytosanitary monitoring.

Acúmulo de biomassa e produtividade do girassol cultivado sob adubação orgânica e mineral

O acúmulo de matéria seca no girassol é extremamente importante para a produção de grãos, no qual, quando possui uma adubação inadequada a produção é prejudicada. Objetivou-se avaliar o acúmulo de biomassa e a produtividade de grãos do girassol adubado com formulados de NPK (mineral e organomineral). O experimento foi realizado em uma casa de vegetação, localizada em área experimental do IFGoiano – Campus Rio Verde – GO, no município de Rio Verde, Goiás. O delineamento experimental utilizado foi em blocos ao acaso, analisado em esquema fatorial 4×2 com três repetições. Os tratamentos consistiram em quatro doses do formulado 04-14-08 NPK: 50, 100, 150 e 200% da recomendação que correspondem, 90 kg ha-1 de N, 180 kg ha-1 de P e 40 kg ha-1 de K para a cultura do girassol e duas fontes mineral e organomineral. A aplicação dos formulados nas respectivas fontes e dosagens foi realizado na semeadura. Foram efetuadas as análises de acúmulo de matéria seca, massa de água e produtividade de grãos. A fonte NPK mineral proporciona maior massa fresca das folhas, massa seca do caule, massa de água e massa seca da parte aérea do girassol do que a fonte orgnomineral. As doses de 162 e 138% da recomendação de NPK, via fonte mineral e organomineral proporcionam a maior produtividade de grãos para a cultura do girassol, respectivamente.

Crescimento e desenvolvimento do girassol irrigado e adubado com organomineral

O cultivo do girassol (Helianthus annuus L.) na segunda safrinha, na região Centro-Oeste brasileira é uma importante estratégia econômica e ecológica para o sistema de produção, cujo conhecimento de suas necessidades hídricas e nutricionais são indispensáveis, devido às condições do clima nesta época do ano. Objetivou-se no presente estudo, avaliar o crescimento e desenvolvimento da cultura do girassol cultivada sob diferentes condições de déficit hídrico e, níveis de adubações com NPK de origem mineral e organomineral. O experimento foi conduzido em vasos plásticos preenchidos com Latossolo Vermelho distroférrico, localizado em área experimental do Instituto Federal Goiano, no município de Rio Verde, Goiás. O delineamento experimental utilizado foi o de blocos ao acaso analisado em esquema fatorial 4×4×2, com três repetições. Os tratamentos foram as combinações de quatro reposições hídricas iguais a 50, 75, 100 e 125% da capacidade de água disponível no solo; quatro doses do formulado de NPK referentes a 50, 100, 150 e 200% da recomendação e duas fontes do formulado NPK, mineral e organomineral. As reposições hídricas foram determinadas através de lisímetros de pesagem eletrônica e a água aplicada via sistema de gotejamento superficial. O aumento na reposição hídrica proporciona a maior altura de planta e diâmetro de caule. As reposições hídricas de 125 e 103% proporcionaram os maiores acúmulos de matéria seca das folhas e do caule, da cultura do girassol. Na dosagem de 50% da recomendação de NPK, a fonte organomineral mostrou-se superior a mineral, para a massa seca das folhas e massa fresca do caule.

Sunflower biometrics and chemical salinity attributes of soil irrigated with waters of different qualities

Poor quality water, such as sewage, has become an alternative to reduce the consumption of good quality water by irrigation, especially in arid and semi-arid regions; however, water rich in salts can be harmful to agricultural systems. This research evaluated the impacts of salinity of waters of different qualities on the development of the sunflower culture and on the soil. The research was developed in the area of the Environmental Studies Team (EEA/UEFS), and the experimental design used was completely randomized, consisting of four treatments: rain water (0.20 dS m-1), well water (1.50 dS m-1), cesspool effluent (3.50 dS m-1) and brackish water (5.00 dS m-1), with the irrigation manually done and the blade calculated based on daily evapotranspiration. Irrigation with effluent promoted a better development of the sunflower crop, and the increase in the salinity of the irrigation water in the other treatments promoted a decrease in the total fresh and dry phytomasses, plant height, stem diameter, number of leaves, leaf area, internal and external diameters of the capitula and in the consumption and efficiency of water use. The use of rainwater, well water and cesspool effluent proved to be suitable for irrigation of the sunflower crop; however, the latter sodified the soil, which would already be recommended for the application of treatments for soil recovery.

Apera spica-venti (L.) P. Beauv. resistance to herbicides in Lithuania and Ukraine

Goal. Check the resistance of populations of Apera spica-venti (L.) P. Beauv. to herbicides from the class of inhibitors acetolactate that are used in crops of winter wheat.
 Methods. Field and laboratory studies. Visually evaluated the treatment efficacy 4 weeks after application (WAT4). Visible symptoms on the surviving plants were considered in percentage (0% — no survival, 100% plants without visible damage) to the raw options of the same population.
 Results. Among the tested populations of A. spica-venti resistant to herbicides from the class of inhibitors acetolactate not detected. In all regions of Ukraine, where selected seed samples, there were repeated crops of winter wheat, and was the precursor of the culture of sunflower, soybean, lupin, etc., for control of weeds in crops which were applied the herbicides with a different mechanism of action. The reason for the low efficiency of herbicides in crops of winter wheat could be low rates of application, weather conditions, other factors associated with the technology application of herbicides.
 Conclusions. Ukraine has not confirmed the resistance of Apera spica-venti (L.) P. Beauv. to the action of herbicides from the class of inhibitors acetolactate, which takes place in Lithuania. Primarily due to differences in the technologies of cultivation of winter wheat, particularly in rotations. In Ukraine, information about the presence in crops of resistant biotypes of weeds are quite limited. To prevent resistance it is necessary to conduct herbological monitoring of major crops considering the experience of countries where this problem is becoming more acute, to develop measures to prevent it.

Direct seeding associated with a mixture of winter cover crops decreases weed abundance while increasing cash-crop yields

In this study, we aim to evaluate the respective and combined effect of soil tillage reduction and winter cover crops (CCs) on both weed species recruitment and sunflower (Helianthus annuus) yields. By controlling the species composition and propagule pressure of weeds, we tested four soil cover rotation treatments with winter CCs (either Camelina sativa or a winter CC-mix of Leguminosae-Brassicaceae) or nothing (control) followed by a sunflower culture or nothing (control) in combination with two soil preparation treatments (reduced tillage vs. direct seeding) in a randomized complete block design with three replicates per treatment. Our experiment thus comprised 24 experimental units (4 m × 1 m). In each experimental unit, seeds of 40 weed species were sown in May 2017 and seedling emergence was subsequently monitored in mid-July, August and September 2017. We used generalized linear models to analyze the effect of soil cover rotation, soil preparation and the two-way interaction term on species richness, abundance (i.e. number of individuals) and sunflower yield. We additionally used generalized linear mixed-effects models to analyze species relative abundance changes throughout the monitoring period and relative to an exhaustive vegetation survey performed at the beginning of the experiment. Our results show that reduced tillage may increase weed species richness under some circumstances, as well as the abundance of two annual species (i.e. Viola arvensis and Fumaria officinalis). Winter CC-mix reduces the abundance of the most dominant weed species (i.e. the grass Echinochloa crus-galli) while increasing the average weight of sunflower seeds per stem. Irrespective of the tillage treatment, we found that C. sativa favors the presence of patrimonial weed species at the expense of noxious species. We conclude that direct seeding associated with winter CC-mix allows controlling weed abundance while increasing cash-crop yields, and thus meets criteria for a sustainable agriculture.

Rain Use Efficiency in Southern Romania after Using the Device for Soil Modelling in Interrupted Furrows for Weeding Crops -DMBC-5

The global impact of climate change, with the potential to affect agriculture through changes in temperature, rainwater distribution and amount, leads to the need to develop integrated technologies that increase rain use efficiency and support soil and environmental quality, ensuring higher agricultural outputs with lower costs. Soil modeling in interrupted furrows is a very efficient rainwater harvesting system, but has not yet been scientifically assessed for the conditions in Southern Romania as the other soil working systems have been. For this purpose, a soil modeling device consisting of a frame with triangle for coupling to the tractor, wheels for adjusting and limiting the working depth, soil loosening knives, ridge ploughs and furrow compartmenting equipment was compared with the conventional technology for sunflower culture in two localities in Southern Romania: Crânguri in Giurgiu County and Mărculeşti in Calarasi County. The device for soil modeling in interrupted furrows for weeding crops provides a viable option that has positive effects on soil properties and ensures increased crop yields compared to conventional works as well as the opportunity to increase the efficiency of water recovery in agriculture by harvesting rainwater.

Sewage sludge used as organic manure in Moroccan sunflower culture: Effects on certain soil properties, growth and yield components

The wastewater treatment and sludge production sectors in Morocco are recent. Considered as waste, no management strategy for sewage sludge (SS) has been implemented. Thus, its disposal definitely represents a major environmental problem since sludge is either incinerated, used as landfill or simply deposited near wastewater treatment plants. The objective of this study was to determine the effects of dehydrated SS on certain soil properties (pH, electrical conductivity (EC), Mineral nitrogen, available phosphate P2O5, and soluble potassium K2O), and also on growth and yield components of the sunflower (Helianthus annuus L.). An experiment was conducted using six treatment rates (0; 0 + NPK; 15; 30; 60 and 120 t ha−1). The results showed that soil pH was significantly affected by SS, becoming less alkaline compared to the control, while electrical conductivity increased significantly when the applied doses were above 30 t ha−1. Also, a significant enrichment in mineral N and available phosphorus was detected in amended soil. However, no differences were found between pots having received the mineral fertilization and the SS at 15 t ha−1. Stem height growth of the sunflower seedlings receiving SS increased significantly compared to the two controls. For both the aerial and root parts, significant increases in dry biomass accumulation were observed compared to the unamended plants. Net CO2 assimilation (An) increased, while stomatal conductance (gsw) and transpiration rates (Tr) decreased with increasing SS rates. SS application at 15 t ha−1 presented similar values of the yield components compared to plants fertilized chemically. However, grain yield (in quintals ha−1) was noted to be 2.4, 5 and 8 times higher in treatments receiving SS respectively at the rate of 30, 60 and 120 t ha−1.

Effect of Co-planted Purslane (Portulaca Oleracea L.) on Cd Accumulation by Sunflower in Different Levels of Cd Contamination and Salinity: A Pot Study

Heavy metal bioaccumulation can be affected by various crop-weed interactions that potentially exist in agroecosystems. A pot experiment was conducted to evaluate the role of rhizosphere interaction of sunflower and purslane (Portulaca oleracea L.) weed on cadmium (Cd) uptake and its allocation to sunflower grains. The experimental treatments consisted of two cropping systems (mono and mixed culture), two adjusted salinity levels (0 and 0.5% NaCl) and three artificial levels of Cd in soil (Control, 3 and 6 mg kg−1). The results showed that the growth of sunflower in the presence of purslane in comparison to mono culture of sunflower led to change of total Cd content and Cd allocated to grains only in saline conditions. Promoting effects of salinity on Cd concentration of grain were alleviated where sunflower was co-planted with purslane. Besides, supply of Zn in grains of co-planted sunflower was strongly affected by salinity. Results of this study revealed that although co-planted purslane could alter conditions in the shared rhizosphere, it had no effect on enhancing Cd uptake by neighboring sunflower directly.

SSR-MARKERS OF GENES FOR RESISTANCE TO DOWNY MILDEW IN SUNFLOWER

One of economically valuable traits of sunflower culture is resistance to the pathogenic fungus – downy mildew ( Plasmopara helianthi Novot.). Stability to the most aggressive pathogen races is controlled by a number of Pl genes, which are groups into several clusters. At present intensive research of marking Pl loci is being carried out. In order to create the system of DNA-markers for selection of sunflower genotypes with certain allele composition of Pl genes molecular-genetic polymorphism of lines-carriers of Pl genes and lines, which do not have resistance genes, by alleles of microsattelite loci, localised on 1, 8, 13 groups of linkage of sunflower genetic map, was studied in the work. 13 lines-differentiators HA-288, RHA-265, RHA-274, DM-2, PM-13, PM-17, 803-I, QHP-1, FT-226 (QHP-1 analogue), HA-R4, HA-R5, HA-335, RHA-419 and lines of Ukrainian selection 108 А and ОС 1029 В were used as the research material. Genotyping of the studied lines by 34 microsattelite loci, localised on 1, 8 and 13 groups of linkage of sunflower genetic map at the distance not more than 10 cM from Pl gene clusters. Marker alleles of microsattelite ORS 328 , which make it possible to identify samples, carrying genetic material, characteristic of the line Pl 6 НА-335 carrier, were detected. Characteristic of the line-donor of gene Pl 8 QHP-1 allele of the size 410 bp of locus ORS 781 , which can be useful in marker selection of recombinants, was detected. Marker alleles by loci ORS 509 , ORS 610 , ORS 1182 , ORS 605 , ORS 675 , ORS 1039, which make it possible to distinguish line RHA-419, the genotype of which has the gene of universal resistance Pl ARG .were determined. Detected were alleles, characteristic of the genotypes of lines-donors of Pl 13 HA-R4 and QHP-1 by loci ORS 1008 and ORS 965-1 . Application of the identified markers of certain Pl genes in marker selection was proposed in order to accelerate targeted selection of samples in the process of creation of new sunflower lines and hybrids.

Coeficientes de sensibilidade ao déficit hídrico para a cultura do girassol nas condições do semiárido cearense

Aiming at determining the sunflower culture water stress (KY) sensitivity coefficients in individual stages and at the entire crop cycle for the conditions of the Ceara semiarid, Brazil, a field experiment was conducted in the municipality of Pentecoste, Ceara (Brazil). The experimental design was that of randomized blocks with four replications and eight treatments, defined as a function of the time of induction of water deficit in the three sunflower phenological stages (vegetative, flowering and production formation), corresponding to the occurrence of water deficit in one, two or three stages. The water deficit irrigation dose was half the applied water dose corresponding to full irrigation. KY values were obtained through the relationship between the fall of relative income and the relative evapotranspiration deficit, according to the method of Doorenbos and Kassam. The evapotranspirations (potential and culture) were calculated using the soil water balance method. The results showed that the water stress sensitivity varied in the following order: production formation, vegetative and flowering, for water deficit applied to only one developmental stage. For the deficit conditions in two stages, the coefficient KY showed that the lack of water has the greatest impact on sunflower achene yield when it occurs in the stages vegetative and production formation. Since the values of KY were all lower than 1, it is concluded that the sunflower culture showed a low sensitivity to the water deficits studied in this research.

Adventitious bud regeneration from cotyledonary node, hypocotyl, cotyledon and euphylla of various genotypes of sunflower (Helianthus annuusL.)

Isolated culture of sunflower is significantly important in seeking new species of sunflowers with plenty of essential oil by modern biotechnologies. Thus, the callus development and adventitious bud regeneration from various explants of sunflower were studied by in vitro tissue cultures. It was found that the callus were readily formed on six genotype explants cultured in media with IAA and 6-BA, but adventitious bud regeneration from these callus was relatively weak. The adventitious bud regeneration inductivities of four tissue explants from different genotype sunflowers were ordered as followed: cotyledonary nodes > hypocotyls > cotyledons > euphyllas. The desired concentrations of 6-BA inducing adventitious bud regeneration were at 1.2–1.8 mg/l for cotyledonary nodes, 1.8 mg/l for hypocotyls and 0.6 mg/l for cotyledons, respectively. But no adventitious buds were differentiated from euphyllas only by 6-BA. The best medium for organogenesis was composed of MS+0.03 mg/l IAA+1.2–1.5 mg/6-BA by which euphyllas also were induced to regenerate adventitious buds with an averagely 20.83% inductivity. Among several genotype sunflowers, PR29 had the highest regeneration frequency and the regenerated plantlet has been successfully cultured.

Chelate-assisted phytoextraction of cadmium from a mine soil by negatively charged sunflower

The effects of some chelating agents and electricity on cadmium phytoextraction from a mine soil were examined in pot culture of sunflower to achieve more remediation efficiency. At the beginning of the flowering stage, ethylene-diamine-tetra-acetic acid (EDTA) as a chemical chelator, cow manure extract (CME) and poultry manure extract (PME) as organic chelators were applied (2 g kg−1 soil) during irrigation. Seven days later, Helianthus annuus was negatively charged by inserting a stainless steel needle in the lowest part of the stem with 10 and 30 V direct current electricity for 1 h each day for 14 days. Afterward, concentration of cadmium in roots and shoots, cadmium translocation factor (TF), cadmium uptake index (UI) and soil available (diethylene-triamine-penta-acetic acid extractable) cadmium were measured. Results indicated that EDTA reduced roots dry weight while none of the roots and shoots was affected by other chelating agents and by electrical treatment as well. Highest concentration of cadmium in shoots was measured in 10 V-control with no significant differences with 30 V-PME and 30 V-EDTA. Utilization of chelating agents did not increase the cadmium TF and cadmium UI while highest values for cadmium TF and cadmium UI were observed in 10 and 30 V treatments, respectively. Available cadmium in the soil near root system treated with 10 and 30 V was relatively lower compared with the soil far from root system. Results of this experiment indicated that charging the plant with direct current electricity ameliorated the efficiency of cadmium phytoremediation.

Determinação dos períodos de interferência de plantas daninhas na cultura do girassol

O objetivo deste estudo foi determinar o período anterior à interferência e o período total de prevenção à interferência da comunidade infestante sobre a cultura do girassol (híbrido M 734). O delineamento experimental utilizado foi o de blocos casualizados, com quatro repetições. Os tratamentos foram compostos por parcelas constituídas por períodos de controle e de presença de plantas daninhas. Para os períodos de controle, o girassol foi mantido livre das plantas daninhas pelos períodos crescentes de 7, 14, 21, 28, 35, 42, 49 e 125 dias após a sua emergência (DAE). Quanto a convivência, a cultura foi mantida na presença da comunidade infestante pelos mesmos períodos. Foram avaliados a densidade e o peso da matéria seca das plantas daninhas e, no girassol, a altura de plantas, o diâmetro de capítulos e a produtividade de aquênios e de óleo. Para a produtividade de aquênios, o período anterior à interferência foi de 15 DAE da cultura, e o período total de prevenção à interferência, de 39 DAE. O período crítico de prevenção à interferência abrangeu 24 dias do ciclo da cultura. Quanto à produtividade de óleo, o período anterior à interferência foi de 32 DAE, e o período total de prevenção à interferência, de 28 DAE.

THE SHORT BREEDING CYCLE PROTOCOL EFFECTIVE ON DIVERSE GENOTYPES OF SUNFLOWER (Helianthus annuus L.)

Immature embryo culture of sunflower (Helianthus annuus L.) was studied for shortening the generation time in breeding programs. The seed development from pollination to maturity in sunflower takes 50-60% (60 days) of the life cycle duration (120-150 days). This technique allows the production of fertile plants from immature embryos of 11 sunflower genotypes. Immature embryos of 10-12 days after pollination were dissected from seed grown plants (SGP), were transferred into MS medium allowing shoot and root development for 5-10 days. Young plantlets were transferred to soil, developed to maturity and were then self pollinated and set seed. The first cycle of immature embryo raised plants (IERP) was obtained. The four cycles of IERP were obtained from immature embryo culture technique in contrast to one generation per year with conventional breeding. The majority of cultured embryos developed into vigorous plantlets with 3-6 leaves. Out of 1320 immature embryos, the average response of the explants were 92.1% (1216). The 75% of the developed plantlets had vigorous roots and were transplanted into viol containing 1:1:2 peat: perlite: soil mixture (v/v) at 24 ± 2 o C in 16h/8 h (light/dark) in the growth chamber. The only 70.3% of them was grown to maturity, self-pollinated and set seed. The overall result was average 40-45 regenerated and matured plants per 100 immature zygotic embryos. The regenerated plants also showed no morphological changes. The analysis of variance for all agronomic characters (plant height, head diameter, number of leaves, stem diameter, number of branches and seed number per head) taken from the mean of four generations in vitro grown plants resulted in significant differences among genotypes at 5% level. All the agronomic characters examined at in vitro regenerated plants decreased compared to field grown plants.

The herbicide aclonifen: The complex theoretical bases of sunflower tolerance

Aclonifen is a diphenylether herbicide in which one ring is unsubstituted and the other is NH 2-1, Cl-2, NO 2-6 substituted. This substitution, especially NH 2-1, is a particular feature in the diphenylether herbicidal family. In contrast with other herbicides of the same family (acifluorfen, oxyfluorfen, bifenox) this compound is not only acting through a phytotoxic protoporphyrin IX accumulation but also through an inhibition of carotenoid biosynthesis. Both biochemical targets are associated to chloroplast structuration in young seedlings under light and the pre-emergence or preplant treatment is consequently an appropriate agronomic strategy. Numerous weeds such as Alopecurus sp., Sinapis sp., Brassica sp., Chenopodium sp. are very sensitive to this herbicide but sunflower culture appears very tolerant. Our results suggest that this tolerance has a complex origin including (1) low root uptake, (2) conjugation in the roots probably with glutathione and (3) low xylem transfer from root to shoot. The low root uptake is associated to aclonifen crystallization on the root surface at high concentrations. The combination of this physico-chemical effect with a sufficient root conjugation rate can explain both the very low amounts of aclonifen or derivatives found in the aerial parts and the strong sunflower tolerance.