The effect of times of weeding on reducing herbicide dose in sugar beet was studied in 2011-2012 in Jovein. The experiment was conducted in split plot based on a randomized complete block design with three replications. The main factor was herbicide doses (0, 25, 50, 75 and 100% of recommended dose (Chloridazon 3.25 kg. a.i. ha-1 soil applied) and sub plot was times of hand weeding (0, one time hand hoeing, tow times hand hoeing, at 30 and 60 days after plant emergence). Traits like root yield and white sugar yields, impure sugar content, alkalinity coefficient, sodium, potassium, α-amino nitrogen and sugar content in molasses were evaluated. The result showed that the increased frequency of weeding reduced weed density, weed dry weight, α-amino nitrogen and percentage of impure and pure sugar contents, root yield and sugar yield. The least weed density and biomass of weeds were observed in recommended dose. Increasing the doses of herbicide increased impure sugar content (14.48%), α-amino nitrogen (57.86%), pure sugar (19.30%), root yield (77.67%) and sugar yield (111.17%) while it decreased potassium (18.77%), sodium (28.84%) contents and alkalinity coefficient (52.76%) as compared with that of control. For most of the traits, there were not statistically significant difference between the recommended dose and 75% of the recommended dose. Increasing the number of hand weedings reduced herbicide dosages. The, results finally showed that 25% dose reduction of herbicide in one time weeding and 50% dose reduction of it in twice weedings might produce desirable economic yield (root yield).

To study the effects of soil solarization, barley straw mulch and hand weeding on weed seedbank, a field experiment was conducted at Research Farm of College of Agriculture, Ferdowsi University of Mashhad during 2007-2008 growing season. This experiment was based on a randomized complete block arranged as a split-split plot design with three replications. Clear and black polyethylene, and non-solarized control were arranged on main plots. A different straw mulch rates (0, 300 and 600 gm-2), and weeding treatment were in the sub-plots and sub-sub plots, respectively. A total of 19 weed species was recorded in all treatments which were mainly annual broad leave species. Results indicated that solarization with clear sheets had 1.8 times less seed density than the control plots. Application of straw mulch decreased weed seed population. Also, hand weeding was effective in reducing weed seeds. Weed seedbank density in no-weeding plots was 3 times greater than weed control plots.The interaction between soil solarization, straw mulch and weeding on seedbank size was significant. The lowest number of weed seeds was observed in clear polyethylene, 300 gm-2 straw mulch and weeding.

Extended Abstract Introduction: Spinach (Spinacia Oleracea L.) belongs to Chenopodiaceae and is one of the most important leafy vegetables in the world. Spinach is a valuable human food source because its leaves are rich in minerals, vitamins, antioxidants, and phenolic compounds. Weeds are one of the significant challenges for spinach production. They can lead to a decrease in commercial biomass and spinach quality. The incidence of herbicide resistance in spinach fields has led to the use of environmentally friendly methods such as cover crops. These plants can cause physical suppression of the weeds by creating adequate biomass and developing a canopy. The aim of this study was to provide a quantitative study of the interactions of the cover crops (such as oat and daikon radish) and hand-weeding treatments on the suppression of the weeds and their effect on the vegetative growth and yield of spinach.Materials and Methods: The experiment was conducted in the crop years of 2020-2021 and 2021-2022 at the Research Farm of the Faculty of Agriculture and Natural Resources of the University of Mohaghegh Ardabili with 1350 meters above sea level and geographical coordinates 38˚ 19´ East and 48˚ 20´ North with cold and semi-arid climates. The experiment was performed as a randomized complete block design with three repetitions. Experimental treatments included the first factor of oat (Avena sativa L.), daikon radish (Raphanus sativus var. Longipinnatus), their intercropping (with 50 % seed ratio), and control treatment (without cover crops). The second factor consisted of hand-weeding and non- weeding. The seed rate of oat and daikon radish was 100 and 20 kg per ha, respectively, and were planted manually at a 3×4 meter plots. In this experiment, the seeds of Spinach Viroflay were used. Seeds were sowed manually among the residues of cover crops at 1.5 cm depth. Due to the amount of precipitation in two years, irrigation was performed if needed. The inter and intra-row spacing was 20 and 10 cm. Hand-weeding was done from the planting date to the final harvest of spinach. The investigated traits included dried biomass of cover crops, the density of dominant weeds, and Simpson, Shannon-Weaner, and Margalef indices.Results and Discussion: The biomass of cover crops was significantly affected by planting systems, seed density, and year (P ≤1 %). The results showed that the highest biomass of cover crops (538.83 gm-2) was obtained from oats. Also, the lowest biomass (325.83 g.m2) belonged to daikon radish. The dominant weeds were consisted of three species such as lamb's quarters (Chenopodium Album), italian bugloss (Anchusa Italica Retz), and common fumitory (Fumaria officinalis). The results showed that oat in two years had the lowest weed biomass (10.64 g.m2) and density of lamb's quarters, italian bugloss, and common fumitory (4.33, 5.00, and 4.25 number/m2). The maximum weed control efficiency index (57.67 %) was obtained from the oat monoculture. Also, the highest weed control efficiency index (51.47 %) was obtained from the hand-weeding. Margalef's index decreased in the first and second sampling times compared to 5.55 % and 9.85 % relative to the first year. The highest index of Shannon-Weaner's diversity belonged to control and daikon radish (0.47 and 0.47). The highest baby spinach yield and final yield in the first and second phases of sampling in two years were obtained from oats treatment (with 567.05 and 944 g.m2, respectively) and then from their intercropping (390.04 and 786.33 g.m2).Conclusion: The results showed that oat and its combination with daikon radish had the highest biomass compared to daikon monoculture. The effect of oat biomass on the decrease in density and biomass of the total weeds was significant, which was due to the amount of oat seeds consumed compared to daikon radish. In addition, hand-weeding reduced the density and biomass of the weeds more than non-weeding. Hand-weeding led to the lack of opportunity for weeds' growth. As such, the improvement of the baby spinach and the final yield was due to the hand-weeding of the weeds and the presence of the cover crops biomass in the experiment. The results of are inferred that oat monoculture is suitable both in terms of reducing physical competition of horticultural plants with weeds and improving spinach yield.

High quality standards in vegetables is one of the most important expectation of consumers presence of weeds would also reduce the quantity and quality of crops produced. Use of cover crops could be an environmentally friendly alternative to conventional chemical and mechanical methods. To this end for controlling weeds, a factorial experiment based on a randomized complete block was conducted at the Research Farm of Mohaghegh Ardabili University with three replications in 2017. Experimental treatments were the first factor, consisting of mono culture and intercropping of rye (Secale cereal L. ), hairy vetch (Vicia villosa Roth. ) and control treatment (no cover crop) and the second factor consisting of one time hand weeding and two times weeding, with 15 days intervals, and without hand weeding, as control. The results showed that the highest dry biomass of cover crops obtained from rye mono culture (530. 59 g. m-2) and the lowest biomass (47. 85 g. m-2) from hairy vetch mono culture. The highest reduction of total weed biomass (83. 24%) obtained from rye with hairy vetch without hand weeding. The highest yield of iceberg lettuce was obtained from hairy vetch mono culture with one-time hand weeding or from without hand weeding treatment (5025 and 4965 g. m-2, respectively). Also, the highest plant height, number of leaves and diameter of lettuce stem was not statistically significant difference from mono culture and intercropping of cover crops. The results showed that the combination of hand weeding and cover crop residues were more effective in controlling and reducing weed biomass, but the presence of cover crop residues in the shortron also increased the yield of iceberg lettuce through weed control.

To evaluate the yield loss of potato crop caused by weeds in the Ardebil potato fields and to compare the efficiency of the traditional hand weeding and chemical control, an experiment, using a randomized complete block, was conducted in two main potato producing regions of Ardebil (Niar and Agbilagh) in 1997. Three treatments that were included in the experiment were: no control (check), three time hand weeding during the growing season, and chemical control using Sencor (Metribuzin WP 70%) as pre-emergence herbicide. Analysis of variance indicated that there was a significant difference at I% level between the treatments in both regions. The tuber yield of chemical control treatment was 32% and 10% lower than hand weeding in Niar and Agbilagh, respectively. The tuber yield of no control (check) treatment was also 63% and 43% lower than hand weeding in Niar and Agbilagh, respectively. Combined analysis of variance revealed that there was a significant difference between two locations, treatments and the interaction of treatments locations. The mean tuber yield of hand weeding, chemical control and no control (check) were 29.8, 23.46 and 13.90t/ha, respectively. It was also found that the tuber yield of hand weeding and chemical control treatments were higher by 15.90 and 9.56 t/ha respectively in comparison with no control (check). The mean tuber yield in no control (check) was 53% lower than the hand weeding treatment.    

To survey the effects of hand weeding and different densities of dragoon’s head on weed population, yield and yield components, a field experiment was conducted in the 2015-2016, at the research station of the faculty of agriculture, university of Tabriz. The experiment was conducted as a factorial experiment in a randomized complete block design with three replications. The experimental factors included: Different planting densities (8, 16, and 24 plants m-2) and weed control (twice hand weeding and non-weeding). The interaction of experimental factors on all studied traits were significant. Chenopodium album (L.), Amaranthus retroflexus (L.), and Asperugo procumbens (L.), were the predominant weeds of dragon’s head and they had the highest number and dry weight in the density of eight plants m-2. In weeding conditions, with increasing the plant density to 24 plants m-2 reduced the number and dry weight of weeds and increased biological yield of dragon’s head (17.7%). Density of 16 plants m-2 in weed control condition, due to high grain and biological yields (290 and 534 Kg ha-1, respectively), number of capsules (47.7) and seeds (576.8) per plant and 1000-seeds weight (25.5 g), had a high harvest index (54.3%). Among the traits studied, the number of seeds per plant has the highest positive correlation with yield and the harvest index showed. The Dragoon’s Head produced significant yields even when weeds were not controlled; especially at densities of 8 and 16 plants m-2. Therefore, the density of 24 plant m-2 and hand weeding can be considered as agronomic and managerial strategies in control of weeds and the density of 16 and 24 plants m-2 as the optimal density to increasing the production of dragon’s head.

In order to the effect of mulch, hand weeding of weeds and plant density on yield and yield components of sweet corn (Sc403) an experiment in a factorial randomized complete block design with four replications was conducted in the farm of Shahid Salemi located in the Northeren of Ahvaz, during 2010. Experiment treatments included Mulch in three levels: control (m1), straw (m2) and bagasses (m3). Weeding in two levels: Non hand weeding (a1) and hand weeding weeds (a2) and density factor of two levels included: density of 60,000 plants per hectare (d1) and the density of 90,000 plants per hectare (d2). The results showed that the use of mulch had significant effect (5%) on biological yield, grain yield, grain number per row, 1000 grain weight, plant height, ear height of Earth's surface, stem diameter and harvest index, and mulch treatments didn't effect on other traits. Application of straw mulch had the highest effect on the meaningful traits. Also hand weeding weeds treatments had significant (5%) difference on grain yield, harvest index, seeds number per row, plant height, ear height of the Earth's surface and steam diameter and other traits didn't effected by factor of hand weeding weeds. The analysis of variance showed that the plant density on grain yield, biological yield, harvest index, seed number per row, 1000-grain weight, ear height Earth's surface and steam diameter had significant effect and it didn't have any effect on other traits. The highest grain yield (306.99 gr / m2) of the density of (90000 plant per hectare) was obtained in hand weeding conditions. At last the interaction of weeding in density and mulch on density had significant effect on biological yield, grain yield, and seeds number per row.