مجله کشاورزی بوم شناختی
سال سوم شماره 2 (1392)

Understanding how a weed community is affected by ecological، agronomic and management factors is one of the most effective ways to control and establish management programs for each crop. In order to conduct weed mapping and study the weed population indices of weeds in corn fields of Kermanshah Province، 48 corn fields in different cities based on planting area were selected for sampling during 2010. After sampling the weeds based on standard methods، the weed population indices based on equations were calculated. Using geographic coordinates of field and weed data، a map for each weed species using GIS was produced. To evaluate the similarity of different cities of the province for weed species diversity and evenness، the cluster analysis method was used. The results showed that the dominant broadleaf weed species of Kermanshah Province were redroot pigweed (Amarunthus retroflexus)، common lambsquarters (Chenopodium album)، field bindweed (Convolvulus arvensis)، Chinese lantern (Physalis alkekengi) and common purslane (Portulaca oleracea)، respectively. The dominant grass weeds of Kermanshah Province were green foxtail (Setaria viridis)، Johnson grass (Sorghum halepens) and barnyardgrass (Echinochloa crus-galli)، respectively. Phytosociological studies on weeds in corn fields showed that، according to the Shannon-Wiener diversity index، Kermanshah’s cities were grouped into three clusters. Comparisons performed using the t-test showed that the diversity of cities of the province also have significant differences. The results of the Simpson similarity index showed that Ghasreshirin and Guilan-e-Gharb had the most common species (SQ=0. 82)، while Kerend City along with Ghasreshirin and Guilan-e-Gharb had no common weed species with the lowest similarity. Based on similarities and differences derived from weeds of corn fields in different cities، population parameters for the management of weeds in corn fields were developed and implemented using the same recipes.

In order to study weed density and dominance in irrigated wheat fields، 4126 fields were investigated in seven climatic zones (according to the Cilianinov method). 496 weed species from 42 families have been observed within these fields. Slightly semi-arid، humid، semi-humid، mean semi-arid، highly semi-arid، arid and absolutely arid climates had the highest density and mean، slightly and highly semi-arid، humid، semi-humid، arid and absolutely arid climates had the highest diversity (according to the Shannon-viener index)، respectively. Among 496 recorded species، 280 species belonged to five major families; Asteraceae، Poaceae، Fabaceae، Brassicaceae and Caryophyllaceae with 76، 69، 67، 44 and 24 species، respectively: These families had the highest diversity in irrigated wheat fields of Iran. Bindweed (Convolvulus arvensis) and wild oat (Avena ludoviciana) had the greatest abundance at 81. 9 and 59. 9 percent، respectively. In addition، these two weeds have been recognized as assertive and ascendant weeds، respectively. Mean، slightly and highly semi-arid، humid، semi- humid، arid، and absolutely arid climates had the first to sixth ranks on the weed species richness measurement. According to the results، mean semi-arid with highly and slightly semi-arid climates and mean semi-arid with arid climates had the highest and lowest species similarity on the base of the Sorenson index، respectively.

Accurate production planning is required for crop yield to be accurately estimated. Therefore we will be able to gain a forecast at the macro level by determining market demand for developing or mitigating products or other planning issues related to production systems. In order to study optimal cropping patterns in East Azerbaijan Province، potential productivity for wheat، barley، chickpea and safflower were studied based on an analysis of supply and demand sources. The AEZ model was used to estimate the potential of yield، as proposed by FAO. In this way، it is assumed that the cultivars enjoy high efficiency and that limitations of water and soil، pests and diseases do not exist. To form data layers، IDW and kriging methods were used. Zonation of potential production was conducted using the overlapping layers in the GIS. Model validation was conducted using RMSE and the Willmott index of agreement. The estimated values were more than the actual quantities for wheat and barley (r2=0. 71) but، for chickpea and safflower، they were slightly lower than the actual data (r2≅0. 50). The production capacity was acceptable for all four crops in the study region. Land in that province was relatively suitable for rain-fed cultivation of wheat and barley. Conditions for growing chickpea were detected as marginally suitable and unsuitable lands for safflower growing were in the maximum. In most regions، wheat and barley potential production showed a moderate to high capability. Potential for chickpea production was higher in the southern regions of the province and safflower enjoyed this situation in the Eastern. SPA for each crop and the GPA for all of them and for various scenarios were calculated then، based on results achieved، the cropping patterns were calculated. The GPA index suggested that cropping patterns that included barley-chickpeas-safflower had the highest value. After that، were wheat-chickpeas and barley-chickpeas compositions.

In order to study the effects of heavy metals stress and arbuscular mycorrhizal fungi (AMF) symbiosis on the growth and yield of pot marigold (Calendula officinalis L.) as a medicinal plant، a factorial experiment based on randomized complete block design with four replications was conducted at Research Greenhouse of Horticultural Sciences، College of Agriculture and Natural Resources، University of Tehran، in year of 2012. Experimental factors were two levels of mycorrhizal application (inoculated and non-inoculated with AMF) and five levels of heavy metals [0 (control)، 150 and 300 mg Pb، 40 and 80 mg Cd per kg of soil. Criteria such as time of early blooming and early flowering (days after transplanting)، herbal fresh and dry weight، plant height، number of lateral branches and total leaves per plant، leaf area، crown diameter، flower number per plant، flower diameter and flower fresh and dry weight were evaluated. The results showed that all the measured parameters improved in mycorrhizal plants compared to non-inoculated plants. Increasing heavy metal concentration had an adverse effect on all the measured criteria and only the plant height increased with an increase in Pb concentration; but this was not statistically significant. Application of Cd (80 mg per kg soil) showed a significantly negative effect on vegetative and generative growth of pot marigold and caused the lowest values of all the parameters in non-mycorrhizal plants. Additionally، using 80 mg/kg Cd، completely inhibited the generative growth in the non-mycorrhizal plants In conclusion، mycorrhizal inoculation of plants with no heavy metal pollution caused an improvement in growth and yield of C. officinalis.

Plant dry matter accumulation has a linear relationship with accumulative Photosynthetically Active Radiation (PAR). Intercropping could be an ecological strategy for increasing light interception in agronomic systems which may improve Radiation Use Efficiency (RUE). In order to evaluate the radiation interception and use efficiency of intercropped bean (Phaseolus vulgaris L.) with borage (Borago officinalis L.)، the present field study was conducted at the farm of the Faculty of Agriculture، Ferdowsi University of Mashhad during the 2009-2010 growing season. Treatments included one row of bean + one row of borage (1:1)، two rows of bean + two rows of borage (2:2)، three rows of bean + three rows of borage (3:3)، four rows of bean + four rows of borage (4:4) with pure bean and borage as controls. Results indicated that leaf area index (LAI)، radiation interception، total dry matter and RUE of bean and borage increased in all intercropping treatments compared with sole cropping. Intercropping benefited bean more than borage in all measured traits. Season-long mean RUE in bean varied between 0. 77 g MJ-1 in 4:4 and 1. 50 g MJ-1 in two rows of bean + two rows of borage. Also، season-long mean RUE of borage ranged from 0. 63 g MJ-1 in 4:4 to 1. 37 g MJ-1 in two rows of bean + two rows of borage. The highest LAI for bean (4. 3) was obtained in two rows of bean + two rows of borage. In general، row and strip intercropping of bean with borage increased radiation use efficiency and combination of two rows of bean + two rows of borage was the most promising one.

In recent years، concern over the health of food products، particularly of legumes which are a leading source of protein throughout the world، has increased significantly. To study the effect of different levels of super absorbent water application in soil and humic acid foliar application on some agroecological characteristics of bean، (Phaseolus vulgaris L.)، a split strip plot arrangement based on RCBD with three replications was conducted in the 2010-11 growing season at the Research Field of Agriculture Faculty of Ferdowsi University of Mashhad. The main plot factor was application of super absorbent water polymer in 3 levels (0، 40 and 80 kg ha-1) and the sub-plot factor was foliar application of humic acid in 2 levels (0 and 3 kg ha-1). Two irrigation intervals (7 and 14 days) were assigned to the strip plots. The results showed that the interaction of super absorbent application and humic acid foliar application on seed yield was significant، as the highest and the lowest seed yield resulted from 80 kg ha1- super absorbent، with and without humic acid application (3475. 9 and 1710. 6 kg ha-1، respectively). Dry matter accumulation was significantly affected by interaction of super absorbent application and irrigation interval، as the seven-day irrigation interval in all super absorbent levels was superior compared to the 14 days of irrigation interval، as dry matter accumulation at 0، 40 and 80 kg ha-1 of super absorbent application were increased by 15، 9 and 11 percent، respectively. The interaction of humic acid and irrigation interval revealed that humic acid application at 7 and 14 days of irrigation intervals increased LAI 11 and 14 percent، respectively. The triple interaction effect of experimental factors showed that CGR increased as a result of application with no application of humic acid plus seven and 14 days of irrigation intervals when the super absorbent application was increased. In general، these results suggest that it could be possible to reduce chemical fertilizer use as a result of using of ecological inputs، meanwhile reducing environmental hazards and conserving of long term sustainability.

In order to evaluate the use of cover crops to control weeds in forage corn، an experiment with a factorial arrangement based on a randomized complete block design with three replications was conducted in 2012at the Agricultural Research Station (Samian) in Ardabil. The first factor included different cover crops comprising rye، hairy vetch، clover and no cover crop، plus a plot without weed control. The second factor consisted of nitrogen splits of 225 kg urea per hectare with two levels، the first level (1/2 at sowing + 1/2 in the 8 to 10 leaf stage of corn)، the second level (1/3 at planting + 1/3 in the 8 to 10 leaf +1/3 a week before tasseling of corn) to the desired split in two، and three corn growth stages were used. The third factor consisted of two levels of weed sampling frequency at 60 days and 90 days after planting corn. Combined analysis of variance showed that the rye cover crop، hairy vetch and clover reduced the biomass of annual weeds of Chenopodium album L. and Amaranthus retroflexus L. at about 95، 88 and 70 percent and 81، 77 and 60 percent compared to the control، respectively. Also decreased weed densities of about 67، 52 and 32 and 68، 55 and 26 percent، respectively، were identified. In addition، these cover crops reduced biomass of perennial weeds of Convolvulus arvensis and Cynodon dactylon compared to control، at about 82، 79 and 62 and 77، 73 and 57 percent، and density of about 57، 53 and 32، and 65، 55 and 31 percent، respectively. Cover plants and split nitrogen interactions have significant effects on fresh corn forage. The highest fresh yield of forage corn (51307 kgr per hectare) was obtained from full weeding. After weeding treatments، forage yield in hairy vetch treatment significantly was more competent than the other cover crops. In general، taking into account the interests of more effective control of weeds and forage production، treatment of hairy vetch cover crop and the second split of nitrogen fertilizer level was found to be appropriate.