نشریه بوم شناسی کشاورزی
سال یکم شماره 2 (زمستان 1388)

In order to investigate the effects of input intensity on species diversity, composition and density of weeds in corn (Zea mays L.), an experiment was conducted based on a randomized complete block design with three replications at the Agricultural Research Station, Ferdowsi University of Mashhad, Iran during the year 2009. Treatments included low input, medium input and high input systems. Low input received 30 tonha-1or 30 tonha-1 compost, zero tillage and hand weeding (twice). Medium input was based on 15 tonha-1 manure, 150 kgha-1 urea as chemical fertilizer, twice tillage operations and 2, 4-D (1.5 Lha-1, at five leaves emergence) as an herbicide and hand weeding (once). High input received 300 kgha-1 urea, four tillage operations and Paraquat (2 Lha-1, after planting) and 2, 4-D (1.5 Lha-1, at five leaves emergence). Manure and compost were applied in the planting time. Weed samplings were done in three stages (early, mid and late growing season). Results indicated that the highest and the lowest weed species diversity and density were observed in low input based on manure and high input systems, respectively. The highest range of weed relative density was obtained for black nightshade (Solanum nigrum) with 9.09-75.00%. The highest number of species was observed in low input based on manure. Also, management practices affected weed dry matter and diversity indices. The highest and the lowest amounts of weed dry matter were observed in low input based on manure and high input systems, respectively. In the first, second and the third stages of sampling, the maximum and the minimum amounts of Margalef index were observed in low input based on manure (with 5.3, 5.4 and 3.3, respectively) and high input systems (with 0.8, 2.3 and 2.6, respectively). In the first, second and the third stages of sampling, the highest and the lowest values of Shannon index were observed in low input based on manure (with 0.6, 0.7 and 0.5 respectively) and high input (with 0.1, 0.4 and 0.3 respectively) systems. Weed chemical control, intensive tillage operation and high corn density reduced weed number and dry matter in high input only.

In order to study the effects of corn density and planting pattern for reducing herbicide application, an experiment was carried out in 2007 at Varamin Research Station of Plant Protection Research Institute. The experimental design was a randomized complete block in a split plot arrangement with 4 replications. Experimental factors consisted of planting patterns at 4 levels included one row planting on each ridge with recommended density, two rows planting on each ridge with recommended density, 0.25 and 0.5 times more than recommended density in main plots and herbicide at 5 levels including Atrazin 1 L/ha plus EPTC 4, 5 and 6 L/ha, Atrazin 1 L/ha plus Allachlor 5 L/ha, EPTC 6 L/ha in subplots. Weed-free and weedy controls were added to treatments. Results indicated that altering planting pattern to two rows planting with 0.25 and 0.5 times more than recommended density significantly increased grain yield. Grain yield of herbicide treatments except weedy control had no significant difference in comparison with weed-free control. Therefore by using reduced rates of herbicides it is possible to decrease herbicide application. Herbicide application had significant effect on number of kernel rows per ear, 100-grain weight and ear diameter and grain yield was increased.

Production of beneficial halophytes such as kochia (Kochia scoparia) using saline waters and soils is one of the most sustainable methods of conservation in desert ecosystems. Kochia is one of the most common annual halophytes grown in Iran. Seed germination of four ecotypes of kochia in saline conditions was carried out using factorial based on Completely Randomized Design with four replicates of 25 seeds. The treatments were salinity in six levels (0, 7, 14, 21, 28 and 35 dS m-1 NaCl) and four ecotypes (Birjand, Sabzevar, Borojerd and Esfahan) of kochia seeds. Germination rate decreased as salinity increased. Up to 7 dS m-1 salinity had no significant effect on germination, but after that, the germination percentages and rate of germination reduced significantly. The Esfahan seed lot was the most sensitive ecotype to salinity with germination of %83 at 7 dSm-1. Sabzevar ecotype showed maximum germination percentages and the rate of germination. Birjand and Borojerd ecotypes had also desirable germination in saline conditions

Maize and mungbean rotational responses to sulfonylurea herbicides applied on wheat at the previous year were investigated in two separated experiments at Ahvaz in 2006 and 2007. In the first experiment, 10 treatments of herbicides applied to wheat at the year before planting, and after wheat harvesting, the maize crop was planted. Treatments consisted of Chevaliar (idosulfosulfuron + mesosulfuron) at 0.4L/ha, Apyrus (sulfosulfuron) at 28, 42, 56 and 68 g/ha, megaton (chlorsulfuron) at 20 g/ha, bromicide + topic ("bromoxynil + MCPA"+ clodinafop-propargyl) at 1.5+0.8 L/ha, Total (sulfosulfuron +mesosulfuron) at 45 g/ha, atlantis (idosulfuron + mesosulfuron) at 1.5 L/ha and non-treated control. The second experiment was the same as the first one, but the rotational crop following wheat was mungbean. Grain yield, biological yield and harvest index of rotational crops were analyzed. According to the result, when mungbean and maize were planted in rotation with wheat, residues of megaton and apyrus at 56 and 68 g/ha, had the most negative impacts on their yields. So that yield reduction were 37%, 24% and 21% in mungbean and 36%, 10% and 17% in maize, respectively. Therefore, it is needed to pay more attention to the response of rotational crops following wheat to residues of sulfonylurea herbicides in soil.

In order to study the effects of herbicide rates of metribuzin on nodulations and growth characteristics of chickpea, a series of experiments were carried out at research greenhouses of Ferdowsi University of Mashhad during 2009 in a randomized complete block design with four replications. Studied factors were: different doses of metribuzin herbicide (10- 25- 50- 75- 100- 125 percent of recommended dose) in autoclaved soil and two doses of 25 and 50 percent in un-autoclaved soil. The highest dry weight of root and shoot, height and leaf number was in no herbicide and inoculated control and lowest rate gained at 100 and 125 percent of herbicide doses. The highest root/shoot rate gained at herbicide doses of 100 and 125 percent. The changes trend of nodule number and dry weight per plant were significant (p

In acid soils, aluminium toxicity is the primary factor limiting crop and forage production. At soil pH < 5.0, Al solubility increases and Al appears to be rhizotoxic. The objectives of the present study were to compare Al tolerance among wild graminae of acid meadows and to evaluate the relation between a plant functional trait and the Al resistance, in nutrient solution. In addition, a sensitive Lolium perenne variety was included as a control. There was a great difference among the graminaceous species tested, when compared by relative root elongation and critical Al activity corresponding to 50% root elongation reduction. The {Al 3+}50 activities were 3, 13, 14 et 26 µM for Lolium perenne, Molinia coerulea, Holcus lanatus and Danthonia decumbens, respectively. No relation was found between the functional trait leaf dry matter content (LDMC) and Al resistance. Holcus lanatus, tolerant to Al toxicity, with a low LDMC, would deserve a further study of its nutritional qualities for cattle. The very tolerant D. decumbens, with a high LDMC, would present an interest for a later study of the mechanisms of tolerance to Al and possibly, for other applications like the protection of the very acid soils against erosion.

Wheat crop, considering its high planting area and consumption at national scale, demand a regular yield increase. Humic acid, as an organic acid obtained from humus and organic sources without any environmental destructive effects, improves wheat yield particularly in variable environment conditions. In order to evaluate the effects of different levels of humic acid on shoot and wheat yield, an experiment was conducted in 2008 at research greenhouse, Faculty of Agriculture, Ferdowsi university of Mashhad. A completely randomized block design with three replications was used with factorial combination of humic acid concentrations (0, 100, 200, 300 mg/l) and four foliar application times (tillering, stem elongation, flag leaf appearance and anthesis). The results showed that the effect of foliar application of humic acid at different times was significant for shoot dry and fresh weights, leaf area, shoot length and chlorophyll content. The highest shoot dry and fresh weights, leaf area and shoot height obtained from foliar application of 300 mg/l humic acid concentration at flag leaf appearance time; and maximum chlorophyll content was obtained at 200 mg/l humic acid at flag leaf. The highest biological and seed weight was obtained at 200 and 300 mg/l humic acid. The most effective time for foliar application to reach maximum spike length and weight, spiklet number, seed number and seed thousand weight was flag leaf emersion time. The lowest percentage of non-prolific spiklet obtained at 300 mg/l humic acid concentration at stem elongation time.

Potassium is an essential plant macronutrient. Various microorganisms including bacteria and fungi, algae, yeast and mosses are able to decompose silicate minerals and to dissolve nutrient such as K, Fe, Zn and Si. Aamong them bacteria are more important. The aim of this study was to determine the ability of microbial populations for releasing soil potassium. This study was carried out as a factorial experiment in completely randomized design including two factors, with three replications. To do so, 12 treatments including full combination of two bacterial geniuses (Azospirillum lipoferum and Azotobacter chrococoum) and two fungal geniuses (Asperigilus niger and Trichoderma hazarum) were inoculated into soil and the potassium was extracted by NH4oAc over four different times (0, 10, 20 and 30 days). Results indicated that the quantity of K released by soil inoculation with bacteria and bacteria plus fungi treatments, so that the treatment B1 (Azotobacter chrococoum) could covert about 6% of the soil potassium to available form by plants and released potassium content increased with elapsing of time. In all treatments, the most quantity of potassium was released 30 days after inoculation. Thus the biological potassium fertilizers can be a good substitute for chemical fertilizers

Today, due to the problems caused by herbicide application, there is a strong interest in developing alternative methods of weed control. To study the effects of soil solarization, barley straw mulch on weed flora, a field experiment was conducted at Research station of faculty of Agriculture, Ferdowsi University of Mashhad during the growing season of 2007-2008. This experiment was based on a randomized complete block design arranged as a split plot with three replications. Soil solarization treatment (Clear and black polyethylene and non-solarized control) and various straw mulch rates (0, 300 and 600 gm-2) were arranged on the main plots and sub plots, respectively. Seventeen weed species was identified by studying weed population which were mainly annual broad-leaves species. Results indicated that solarization with clear and black sheets reduced weed density and biomass after removing polyethylene sheets. Solarization with clear sheets reduced weed density and biomass, after application of straw mulch. Straw mulch had no significant effect on weed density, but in last sampling date it reduced biomass up to 44.15% and 52.90% in 300 and 600 gm-2, respectively. The interaction effects of solarization and straw mulch on weed biomass was significant but only at 90 days after application of straw mulch. The lowest weed biomass observed in solarized bared plots with applying clear sheets

An experiment conducted to study the effects of transplanting dates on rapeseed (Brassica napus L.) yield and its components as second crop after rice in Agriculture Faculty of Ghlilan University. This research was conducted in a Randomized Complete Block Design (RCBD) with 3 replications on the PF (sarigol) cultivar. Treatments consisted various dates of transplanting in cluding 1st November, 21st November, 11st December and 31st December. The results showed that the effect of different dates of transplanting were significant on the grain yield and oil yield

Salsola tomentosa is a permanent plant belonging to Chenopodiaceae family, Its type is formed in many areas and in some other areas it is seen sparsely with Artemisia species. Investigation and determination of ecological needs of the species S. tomentosa was begun in 1383 and lasted for 3 years. The aim of the experiment was to recognize the locus of this species growth in Razavi Khorasan province. In this research, factors such as: topography, pedology, climatic conditions, phonology, morphological characteristics, capability of seed germination, permanency and the mode of reproduction were studied. Geological and pedological studies of the stands with the use of the respective maps and field visitation and laboratory results were done. Growth chronology and morphological study was done by marking 30 plants in two habitats Gonabad and Bardskan within a fifteen-day interval. Also, plant vegetation was determined by using 3 transects with a length of 10 kms and with a distance of 3 kms away from one another. (in each site). A plotting of 1*2 was performed over each transect in every 1 km. the study result showed that S. tomentosa adapts itself to arid conditions. This species, due to having lots of hairs in shoots is not grazed in spring, summer and fall. For this reason, it is abundantly seen in the ranges of dry regions. Its importance is due to the fact that in winter when there is poor vegetative growth in the arid range regions, seeds and twigs are grazed by animals. And for this reason it is of great value to the ranchers. Also bioenvironmental factors and control of soil erosion. For this reason the development of species in arid areas is of great importance. This species grows in semi deep and deep soils with sandy and sandy loam textures with a large amount of gypsum in soil.

Carbon dioxide (CO2) concentration of the global atmosphere has increased during the last decades. Increasing global atmospheric CO2 concentrations are expected to influence crop production. In order to evolution of CO2 concentration effects on morphophysiologycal traits in Tagets, Ageratum and Gauilardia, a factorial experiment based on completely randomized design with 3 replications and 12 treatments was conducted at the greenhouses of Ferdowsi University of Mashhad at 2009. Treatments were 3 plant species (Tagets spp, Ageratum spp and Gauilardia spp) and 4 concentrations of CO2 (350, 700, 1050 and 1400 ppm). Plants were placed under increasing CO2 concentrations during of 30 days. Day and night temperatures were 25 and 18 °C in all treatments. The number of individual plant leaf, stomatal index, stomatal diameter, plant leaf area, SPAD number and plant dry weight were determined. Results indicated that increasing CO2 concentration from 350 to 1400 ppm leading to increase of 41.6, 3.35, 61.1, 17.1 and 73.9 percentage in number of individual plant leaf, stomatal index, individual leaf area, SPAD number and individual dry weight, respectively. Whilst increasing of CO2 concentration leaded to reduce of stomatal diameter (62 percent). Increasing of CO2 concentration affected individual dry weight accumulation and leaf area significantly. As there was a positive relation between increasing of leaf area and dry weight accumulation, increasing of CO2 concentration could have effect on production and beneficial of Tagets, Ageratum and Gauilardia by increase leaf area and dry weight accumulation.

Salinity is one of the environmental factors that have a critical influence on the plant emergence and plant growth and establishment. The determination of salinity tolerance threshold is a useful criterion to choose soil and irrigation water for cultivation of halophytes. In order to determine salinity tolerance threshold in Amaranthus retrofelexus, an experiment was performed in greenhouse based on a complete randomized block design with four replications in two stages. In first stage, the experiment was performed with salinity levels of 0, 10, 20, 30 and 40 dsm-1 and emergence percentage in salinity levels of 0 and 10 dsm-1 was 90 and 57%, respectively. In order to determine the full – scale of salinity tolerance threshold Amaranthus retrofelexus, the second experiment was conducted. At this second stages, treatment were different levels of salinity equal to 10, 12, 14, 16 and 18 dsm-1 NaCl. Amaranthus retrofelexus seedling were able to emerge up to the salinity of 14 dsm-1 NaCl. Generally, with increasing the levels of salinity, the seedling emergence percentage was decreased. According to result, salinity tolerance threshold for seedling emergence and performance of Amaranthus retrofelexus under controlled condition was 14 dsm-1

Recently organic agriculture as a most popular alternative production system has increasingly been considered by scientists, people and policymakers and governments in the world, and many research programs are directed to this sustainable production system. In organic agriculture it is hardly recommended to integrate plant with animal husbandry in agroecosystem. Various animal products such as meat, milk and even wool are interested by the consumers worldwide. Standards in organic agriculture are principles, regulations and criteria that must be considered from animal production up to packaging, processing and consumption. Many of animal husbandry systems in Iran have excellent potential to be easily converted to organic system, such as pastoral nomadism and even some industrial animal production units, but the main reason for the refusal of our products could be the absence of organic standards which are to be considered during the production of those products. Writing the basics and principles of animal organic standards and also organic food processing standards and regulations for Iran is the first significant and necessary step in order to develop organic food and animal production system. This paper recommends the principles and standards, considering IFOAM basic standards for organic animal products and food processing in Iran.