Introduction: An adjuvant has been defined as ‘a material that when added to a spray solution improves or modifies the performance of an herbicide’. There are five categories of adjuvants including drift retardants, extenders, stickers, wetters, and penetrants. The latter can chemically be divided into mineral or vegetable groups. Although some reports have found that vegetable oils are less effective than mineral oils, in view of the environmental concerns, the use of vegetable oils seem to be a suitable alternative to mineral oils because they offer a series of advantages such as being biodegradable and renewable resources. The plants essential oils are extracted from the medicinal plants not only have an adjuvancy activity at low concentrations but also have an herbicidal activity at high concentrations. It is believed that the benefit of vegetable oils as adjuvant can be related to their ability (i) to increase the drying period of the spray droplets during their fly time before impacting the leaves, (ii) to prevent bouncing off after impacting the leaves, (iii) to decrease contact angle of the droplet on the leaf surface and improve the spreading of them on the leaf surface, (iv) to delay crystallization of the active ingredient on the leaf surface, (v) to reduce the volatizing and photo-decomposing period of the herbicide active ingredient, (vi) to act as a penetrant agent on the leaf epicuticular wax in order to enhance the penetrability of the herbicide active ingredient into the plants. A fundamental part of all agrochemical researches is search to detect the natural chemicals offering adjuvancy properties to enhance the biological activity of agrochemicals.Therefore, we conducted a dose-response experiment to determine the potential influence of Blackseed, Fennel, Olibanum, and Rose oils as oily based-adjuvants in enhancing the imazethapyr activity against jimsonweed.Materials and Methods: The jimsonweed seeds were collected from plants in the fields of Qazvin and were stored in the dark at room temperature until further use. Bioassays were conducted in a greenhouse located on the Ferdowsi University of Mashhad, Iran. The seeds were washed every 1 h for 7 days for a total of 168 washings to remove seed germination inhibitors according to Andersen. They were sterilized with 5% (v/v) sodium hypochlorite solution for 10 min and rinsed with distillated water twice. Then, 25 jimsonweed seeds were sown in 2 L plastic pots filled with a mixture of sand, clay loam soil, and peat (1: 1: 1). The pots were irrigated three times a week. At the 1- and 2-leaf stage, the seedlings were thinned to 4 plants pot-1 and fertilized twice with 20 mL of a N: P: K (20: 20: 20) fertilizer with a concentration of 3% (w/v). The pots were irrigated every three days with tap water. Treatments were sprayed at the 4-leaf stage. Experimental design was a factorial arrangement with the 5 doses of imazethapyr (Pursuit® 10% SL) and the four essential oils at concentrations of 0.5 and 1% (v/v) in a completely randomized design with four replications. The emulsifier alkylarylpolyglycol ether was used to emulsify the substances in spray solution (95% oil+5% emulsifier). Treatments were applied at 180 L ha-1 at 200 kPa using a calibrated moving boom sprayer with an 8002 flat-fan nozzle. Three weeks after spraying, biomass from each pot was collected and then weighted after oven-drying at 75°C for 48 h. The data were subjected to a non-linear regression analysis using the following logarithmic logistic dose-response model described. The relative potency that is the horizontal displacement between the two curves was calculated by the ratio of doses producing the same response.Results and Discussion: The slope of dose-response curves for jimsonweed to imazethapyr without or with each adjuvant were significantly similar as indicated by the same slope (b), so that they could be considered to be parallel. This indicates that the adjuvants were biologically inactive if they are used alone (without herbicide) at the tested concentration. Based on shoot fresh and dry weights of jimsonweed, the values of ED10 (6.47 and 7.50 g a.i. ha-1), ED50 (18.08 and 19.01 g a.i. ha-1), and ED90 (50.48 and 43.54 g a.i. ha-1) were obtained. All these values decreased in the presence of all the adjuvants. The relative potency values were significantly different from 1, indicating a significant enhancement in the imazethapyr activity when the adjuvants were added to the spray solution. Based on fresh weight of jimsonweed, the imazethapyr activity was improved up to 4.61-fold with addition of Fennel oil at 1% (v/v). Nonetheless, based on fresh weight of jimsonweed, it was improved up to 4.50-fold with addition of Olibanum at 1% (v/v). Based on dry weight of jimsonweed, the adjuvants were ranked according to their performance in improving imazethapyr activity as follows: Fennel>Olibanum>Blackseed> Rose when they were applied at 0.5% (v/v). But, at 1% (v/v), they were ranked as follows: Olibanum>Blackseed>Rose>Fennel. There are no reports available about the effect of the tested adjuvants as an adjuvant for herbicide, but similar studies were reported by Cabanne who found that the clodinafop-propargyl activity was enhanced up to 5- to 6-fold with adding pine essential oil (Pinus pinaster Ait.) to spray solution at 0.5% (v/v).Vegetable oils have also been found to be effective adjuvants for several post-emergence herbicides. Only in case of Blackseed oil, increasing the concentration had a significant effect to enhance the imazethapyr activity as compared to others. The benefit of concentration effect has formerly observed by researchers who reported that there was a strong concentration effect for rapeseed oil since their influence on phenmedipham and glyphosate uptake and activity was lower at 0.1% than at 1% (v/v).Conclusion: Since the main barrier for diffusing a hydrophilic herbicide such as imazethapyr into the leaf tissue is hydrophobic cuticle, thus oil based-adjuvants have been known to work best with them. On the other hand, a shift from non-environmentally friendly adjuvants to environmentally friendly (namely from mineral oilbased adjuvants to vegetable oil-based adjuvants) in adjuvant trend has been occurred due to being biodegradable and renewable. Thus, it is necessary to look for new essential oils offering adjuvancy properties to improve the efficacy of such foliar-applied herbicides because it is a straightforward approach to reduce the risk of adverse side-effects of herbicide via reducing herbicide dose needed to control suitable weeds. From the present study, it could be concluded that the oils Blackseed, Fennel, Olibanum, and Rose showed a strong adjuvancy properties for imazethapyr against jimsonweed and hence they could be suitable for developing and testing as an oily based-adjuvant. Though it is questioned whether crop selectivity could be threatened when these adjuvants are applied, further work is required under field conditions to answer this question.

Stigma of DATURA STRAMONIUM L. is bilobed, papillate and at maturity covered with a sticky exudates (wet papillate type).There is a little information on the stigmatic excretion of the mature stigma of DATURA STRAMONIUM. In the present study, the ontogenetic and ultrastructural aspects of papillae were investigated in four stages of stigma development, using transmission electron microscopy. After gathering 5-75mm buds and in order to perform histological studies, different stages of fixation, blockage, and section were done by ultra-microtome. Fine sections stained with uranil acetate and citrate lead. In the course of development, papillae as well as underlying stigmatic cells showed secretory activity. Remarkable expansion of the endoplasmic reticulum and great modification of vacuolar contents during the ontogenesis of papillae suggested their effective role in the secretion process. Secretion began very early in 20-25 mm long buds. In this stage, electron dense droplets appeared in the cytoplasm and vacuoles. Furthermore, dense black aggregates were observed at the surface of the endoplasmic reticulum. These structures represented stigmatic secretion material. High electron density of secretory components gets recognizable following the post fixation with OsO4 by means of transmission electron microscopy. In the mature stigma, droplets increased in number, coalesced and formed large lipid bodies under the cuticle and on the stigma surface. This procedure caused the cuticle to ruptures and become distance from the cell wall.

Xanthium strumarium and DATURA STRAMONIUM are two of the most important weeds of maize in Iran. Their growth was compared in a field study conducted over 2 years. Relationships were derived between weed density and crop yield, yield components and various growth parameters. Yield, grain number ear-1 and grain weight were affected more by X. strumarium than by D. STRAMONIUM. Xanthium strumarium followed a pattern of growth resembling that of the maize, whereas D. STRAMONIUM continued growing for a longer period, mainly affecting maize during the grain-filling period. A large portion of the loss in maize yield caused by X. strumarium could be explained by a reduction in grain number ear-1, whereas a greater portion of the maize yield loss from D. STRAMONIUM was explained by a reduction in grain weight. Weed biomass was greater for X. strumarium than for D. STRAMONIUM, whereas seed production was higher for D. STRAMONIUM. It is concluded that although X. strumarium should be given the highest priority for control in maize on the basis of its superior competitive ability, control of D. STRAMONIUM is also essential because of both its considerable competitiveness in the current crop and its long-term effects resulting from its greater seed production.

DATURA is an important medicinal plant for production of various alkaloids. Seed dormancy and the problem of germination is the most important barrier to produce this plant. In order to solve the germination problem in this important medicinal plant, the present study was carried out as a factorial experiment with three factors based on completely randomized design with three replications. The first factor consisted of two DATURA ecotypes (Hamadan and Esfahan), the second factor included three levels of physical treatments of breaking dormancy (no scratching; scratch with sandpaper and wet bathing of bain marie bath for 7 days at 60 ° C; scratch with sandpaper and dry chilling for 7 days at 4 ° C), and the third factor included five levels of chemical treatments of breaking dormancy (no application of chemical treatments [putting the seeds on distil water from the beginning of the experiment to the end of the experiment]; NaOH 20% for 90 minutes; NaOH 20% for 90 minutes + gibberellin 500 ppm for 48 hours; NaOH 20% for 90 minutes + potassium nitrate 300 ppm [putting the seeds in potassium nitrate solution from the beginning of the experiment to the end of the experiment]; NaOH 20% for 90 minutes + gibberellin 500 ppm for 48 hours + potassium nitrate 300 ppm). Interaction of ecotypes and seed dormancy breaking treatments was significant for most traits except; number of leaves per plant, root fresh weight, shoot length and stem fresh weight. The results showed that the chemical treatment of NaOH 20% + gibberellin 500 ppm, was the best dormancy braking treatment for the fresh harvested seeds of DATURA. Therefore, using this treatment is recommended to break seed dormancy more than 70 percent, without significant damage on the seeds. In general, it was found that the chemical treatments were more effective than physical treatment on breaking the dormancy of DATURA seed and the main cause of breaking seed dormancy and stimulation of vegetative growth of seedlings obtained was the combination of NaOH with gibberellin.

DATURA STRAMONIUM L., of the family Solanaceae, is a toxic and medical annual that grows as a wasteland weed in Iran.Its flowers are white with a pentamerous trumpet shaped corolla, five stamen and two fused carpels. The stigma is of the wet and papillate type. In the present study, the ontogenetic and structural aspects of papillae were investigated using light microscopy. The papillae were unicellular and originated from the epidermis at the apex of very young style (within buds £10 mm in length).In the course of development, they progressively covered the stigma, then lysed and detached from its surface. This was an early - began in ³15 mm long buds -and continuous process and caused almost lack of the papillae in pollinated opened flowers. Papillae as well as underlying stigmatic cells showed secretory activity during their development. Secretion began very early in 20-25 mm long buds. These structures represented stigmatic secretion material. Electron density of secretory components after post-fixation with Auramine O revealed their lipoid nature. With further development a large number of lipoid droplets were observed just below the cuticle. In the mature stigma (in 40-60 mm long buds) droplets increased in number, coalesced and formed large lipid bodies under the cuticle and on the stigma surface. This procedure caused the cuticle to rupture and become distanced from the cell wall. It seemed that lipoid exudates passed through the ruptures and reached the stigma surface. Otherwise, the existence of these ruptures may facilitate the passage of the lipoid material that occurs through the thin cuticle.

Heavy metals are emitted into the atmosphere by various anthropogenic sources. In the present study, the effects of different concentrations of cadmium (0, 75, 150 and 225 mg. l-1) were examined on certain morphological and physiological parameters in DATURA STRAMONIUM L. The results showed that in the group treated with 225 mg. l-1 of Cd, fresh and dry weight of shoot, shoot length, leaf area, net assimilation rate, cell membrane stability index, relative water content of tissue decreased 36. 5, 11. 75, 11. 95, 63. 75, 4. 28, 25 and 11. 29 percent respectively. The number of photosynthetic pigments and soluble carbohydrate content in the Cd-treated plants were decreased in comparison to the control ones, while a significant increase was observed in the total protein content and activity of the polyphenol oxidase enzyme. The seed protein profiles showed the formation of new bands and increase in the density of some bands in Cd-treated plants could be related to the synthesis of cell detoxification proteins. A decrease in total protein and number of protein bands was observed in the group treated with 225 mg. l-1 of Cd in comparison to the other Cd treatments, which was probably caused by the toxication of the translation machinery. The results of this study indicated that, although the plant did not need this heavy element, Cd had detrimental effects on D. STRAMONIUM and Cd uptake leading to negative effects on their function. It seemed that D. STRAMONIUM was able to resist the damages caused by Cd toxicity, via altering some physiological parameters and changing the protein pattern.