نشریه بوم شناسی علف های هرز
سال یکم شماره 1 (پاییز 1389)

Berteroa incamora (hoary alyssum) is one of the noxious and poisonous weed in south Canada. Due to high seed production and toxic vegetative organs, it is a threat in range land, pastures and fields. The aim of this study was to investigate the Thermo ecophysiological characteristics and the relationship between germination capacities and growth and development of seedling due to different temperatures. This experiment consisted of 9 different levels of temperatures in 5 degrees intervals, from 5 to 450c. The effects of temperature on imbibition's seeds were evaluated by placing the seeds in water for l and 2 hours. To study the effects of temperature on growth and development, the seeds were placed primarily in darkness under constant humidity at 220c for 23 to 48 hours reached the radicle to 6mm. Then 100 similar seeds were maintained in 4 replications of 25 in darkness for 10 days in temperature from 5 to 450c to evaluate the growth and development criterions of epicotyl and radicle. The result indicated the range of biological temperature for germination was between 10 and 350c. The trend of germination at optimum temperature between 200c and 300c increased linearly. By changing the temperature to 350c, germination decreased from 91% to 56%. The highest length of epicotyls to 19mm was obtained at 150c. The growth of radicle and plumule was inhibited completely at 350c.

In order to achieve a non-chemical way based on ecological approach for controlling of C. arvense and the possibility of using insects as biological control agents, a series of tasks including collecting, identification and basic evaluation of herbivore insects is being used to control Canada thistle were conducted in North Khorasan province. Three different climatic sites of C. arvense with 6 km. distance from each other were chosen in the province. Each site was regularly visited during spring and summer. In each screen, parasites on host plants were collected by using umbrella and aspirator. Then 10 sample plants – each of which from one site – and their roots were taken to laboratory. In the lab, all parts of the host plants were inspected for any possible insect. Then the insects were collected and identified. The result of the study was to identify 12 species of herbivor insects on Canada thistle plants which Cleonis pigra and Lixus scolopax caused 22% mortality in the stalk of C. arvense. Among the collected phytophagous insects, an species belong to order coleopteran (Cassida rubiginosa) caused a biomass reduction up to 76%. It was found that a curculionid species (Larinus planus) reduced the seed production of Canada thistle to 17%.

This survey was done to study the allelopathic effects of methanolic extract of Eucalyptus camaldulensis leaf on germination criteria of two weeds called Mountain Rye (Secale montanum) and Mallow (Malva sylvestris). It was done in a completely randomized design with three replications and six levels (0, 1. 5, 3, 6, 9, 18 gr/liter). The means data comparisons was Duncan's method at p<0. 05. Results showed that Eucalyptus extracts had inhibitory effect on both species of weeds, but Mallow affected more than Mountain Rye. The measured parameters were germination percentage, germination rate, germination index, vigour index, plumule and radicle length, and their wet and dry weights. In both species the highest quantity belonged to control; the lowest quantity, to 18 gr/liter treatment. In Mallow the results of 1. 5 gr/liter and 3 gr/liter concentrations didn’t have clear difference to each other and to control, but 18 gr/liter concentration had significant effect on seed germination so that there was a main difference to control. In Mountain Rye, 1. 5 gr/liter concentration had little effects on seed germination but 18 gr/liter concentration had the most strong effect so that there was a significant difference to control.

In order to control weeds in onion (Allium cepa), a factorial experiment with completely randomized block design was conducted in 2009-2010 in Behbahan. The experiment included 12 treatments with 3 replications in each. The treatments were onion cultivars in 3 levels namely Behbahan, Ramhormoz and Primavera and weed control in 4 levels including hand cultivation during the whole period of growth and herbicides like Oxyflorofen (Goal) in 480g. per hectare, Oxadiazon (Ronestara) in 360g. per hectare and mixture of Ioxynil (Totril) and Sethoxydim(Nabu-s) in 675g. and 250g. per hectare, respectively. Characters such as weeds numbers 15 and 30 days after herbicide application and weed dry weights 30 days after spraying were investigated. Based on the results among control methods, mechanical procedure caused the highest weed control, dry weight loss and yield increase percentage. Among herbicides, the highest yield was achieved by Oxyflorofen treatment. Among cultivars, Behbahan had the highest yield.

In order to investigate the effects of different integrated weed management methods on potato, an experiment was conducted on research filed in Najaf Abad, Bardsir, in 2009. This examination was designed in a randomized complete block (RCB) design with 4 replications and 9 treatments including 1- Metribuzin Herbicide (H), 2- Hand Weeding (HW), 3- Cultivation (C), 4- Metribuzin Herbicide + Hand Weeding (H+HW), 5- Metribuzin Herbicide + Cultivation (H+C), 6- Hand Weeding + Cultivation (HW+C), 7- Reduced Herbicide+ Hand Weeding (RH+HW), 8- Reduced Herbicide+ Cultivation (RH+C), and 9- weed free. The results indicated that (H+HW) and (H+C) treatments showed the lowest weed biomass. The experiment treatments had a significant effect (p≤0/01) on potato tuber yield. Mean yield comparison showed that the highest potato tuber yield occurred in (H+C) and (RH+C) treatments; then in (H), (H+HW) and (RH+HW), respectively. ANOVA results showed that small, medium and large tuber numbers were significantly affected (p≤0/01) by the treatments.

This study was conducted to determine the efficacy of sulfosulfuron WG 75% (at doses of 13. 25, 26. 5, 53 and 106 g/ha), rimsulfuron DF 25% (at doses of 10, 20, 40 and 80 g/ha) and nicosulfuron SC 4% (at doses of 0. 25, 0. 5, 1 and 2 l/ha) to control broomrape in tomato in Chenaran, Khorasan Razavi province, Iran, in 2009. The layout was a completely randomized block design with 12 treatments plus hand weeding control, weedy check and broomrape check with four replications. The tomato cultivar was "Mobil majar. "Three weeks after transplanting tomatoes (by 25 cm intervals in row), herbicides were sprayed by a "Matabi" sprayer calibrated to spray 400 l/ha. Plot size was 3. 75m×8 m. Results showed all herbicide treatments decreased significantly the dry matter of broomrape compare to the weedy check. Sulfosulfuron at doses of 26. 5, 53 and 106 g/ha and rimsulfuron at doses of 20, 40 and 80 g/ha had the maximum tomato biomass and fruit weight. Nicosulfuron, although decreased dry matter of broomrape significantly, however caused severe damage on tomato leading to remarkable yield loss.

In order to control weed in corn farms (single cross 704) by using integrated methods of mechanical, cultivation and chemical, an experiment (split plot in RCBD) – including three replications – was carried out in 2009 at Khozestan province, Ramhormoz city. Main factors including non- chemical treatments (irrigation, cultivation and no tillage) and tributary factors such as herbicides Equip 2lit/ha, Cruise 1. 5 lit/ha, Alachlor 5 lit/ha in addition to Atrazine 1 kg/ha and non- treatment (with and without weeds) were done. The results showed that the irrigation operation can control a high percentage of corn weed. Among used herbicide, Cruise and Equip had the maximum effects on Echinocloa Crusgalli, Amarantus Retroflexus and Convolvulus Convolvulus, respectively. The minimum effects on amount and weight of dry weeds was seen in treatment of Equip and Lasso. Non chemical methods (irrigation and cultivator) improved corn grain yield to 57-60 %. Among used herbicides, Cruise had maximum effects on the corn grain yield.