To investigate the effect of organic fertilizer applications on yield and competition indices of basil (Ocimum basilicum L.) in different combinations of intercropping with sesame (Sesamum indicum L.), an experiment was carried out in split plot based on randomized complete block design with three replicates in 2011. The main plots were six fertilizer treatments consisted of 20 and 40 Mg ha-1 of vermicompost and sewage sludge plus 50% recommended chemical fertilizer, chemical fertilizer alone (100 kg ha-1 of urea, triple super phosphate and potassium sulfate) and control (no fertilizer application). Subplots were different planting ratios (sole cropping of basil and sesame, 75% + 25%, 50% + 50 %, 25% + 75% of basil+sesame). In this experiment, the 25% basil+75% sesame and 50% basil + 50%sesame under40 Mg. ha-1 of enriched sewage sludge application had the highest economical yield (up to 3097.47 kg ha-1) with a land equivalent ratio (up to 1.24). According to the AGGRESSIVITY coefficient estimates of two plant species basil incombination of 25% basil + 75% sesame and sesame in 50% basil + 50% sesame and 75% basil + 25% sesame under organic fertilizer application would be dominant species competitave in ranges of 0.12 to 0.30 and 0.11 to 0.57, respectively.

Interference interaction of two rice cultivars (Hashemi and Khazar) with Bolboschoenus planiculmis in planting ratios of 4: 0, 3: 1, 2: 2, 1: 3 and 0: 4, rice seedling: weed tuber were investigated in a replacement series studies. The results showed higher height for Hashemi cultivar than Khazar and B. planiculmis and less tiller number and total dry weight for both rice cultivars comparing to B. planiculmis. Stem multiplication and dry matter production of B. planiculmis decreased more in competition with Hashemi than that with Khazar. Total production of rice tillers and weed stems per pot increased with raising the ratio of weed at the planting proportion. Multiplication of one tuber of weed comparing to three plant of rice was four times more and produced equal dry weight. Relative yield, rice AGGRESSIVITY index and relative crowding coefficient showed more competitive ability for weed against both rice varieties. As the ratio of rice at the planting proportion raised, biological yield, grain yield, panicle number, and total, filled and unfilled seed number increased. At the competition condition, lower biological yield and panicle length, while higher harvest index, panicle number and 100-seeds weight for Hashemi than khazar. In general, this experiment indicated greater competitiveness for B. planiculmis than the rice cultivars, and Hashemi cultivar showed more interference interactions on the weed than Khazar.

Competitive relationships of watergrass (Echinochloa oryzoides) and barnyardgrass (Echinochloa crusgalli) with rice in different plant proportions of 0:4, 1:3, 2:2, 3:1, and 4:0, weed:rice in each hill were investigated in a field experiment. Weed biological and grain yield (both Echinochloa species) were higher than rice; however, the harvest index was higher for rice compared to weed species. Relative yields (based on number of tillers, biological yield, and grain yield), replacement series diagrams, rice AGGRESSIVITY index, and relative crowding coefficient exhibited higher competitiveness for weed than rice. Rising in the ratio of each species at the planting proportion increased the biological, grain and relative yield and harvest index in both rice and weed. Furthermore, it caused an increase in rice AGGRESSIVITY index. In all tested plant proportions, weeds were superior to rice regarding biological and grain yield, except for 1:3 weed:crop in which both species were similar for grain yield. Comparing two Echinochloa species, watergrass, had lower biological yield, but higher harvest index. Grain and relative yields, and relative crowding coefficient were not significantly different for two weed species; however watergrass led to more reduction in grain yield, harvest index, relative yield and AGGRESSIVITY index of rice.

To evaluate agronomic performance of two soybean cultivars in different planting patterns a field experiment was conducted with complete randomized block design with four replications at Agricultural Research Station of Qaemshahr in Mazandran province in 2008. Two cultivars (032; Nekador and Sari) in 50: 50 planting ratio were row intercropped in different planting patterns including; one, two and three rows of each cultivar. Different intercropped planting patterns showed significant effect on grain yield and yield components. However planting patterns did not have significant effect on100 grain weight. Results indicated that the highest canopy height and pod number per plant were obtained from three and one row planting patterns, respectively. Calculation of LER revealed that the maximum intercropping efficiency (LER=1.39) in one row planting pattern was higher than the sole crop stand. The evaluation of pod distribution in different part of main stem showed that higher grain yield of intercropped planting patterns was due to greater number of pods in upper part of the canopy. Comparison of actual: expected grain yield ratio indicated that the higher grain yield (%) in different planting patterns was obtained from 032 variety. In conclusion, the higher AGGRESSIVITY of 032 over Sari was the main reason for its higher grain yield in different intercropped planting patterns.

Introduction: With the continuous growth of world population, degradation and ecological imbalance throughout the world, there is a need to increase agricultural production and environmental protection measures. In this respect, efforts to supply nutrients to the environment are at the head of the programs. One of the ways to approach this goal is the use of intercropping systems (Najafi & Mohammadi, 2005). Suitable performance in intercropping systems may be achieved by selecting genotypes possessing traits consistent with and appropriate for establishing minimum and maximum synergy and competition employing proper agronomic practices such as density and planting pattern (Mutungamiri et al., 2001). In this context, selected plants should be less competitive in terms of environmental impact. The purpose of this study was to investigate the effect of different planting patterns on the competition between the two species of calendula and soybean and to evaluate the yield and quality of an intercropping system compared with a mono-cropping system.Materials and Methods: In order to evaluate the competition between soybean and calendula, a field experiment was conducted based on randomized complete block design with 7 treatments and 3 replications in the research farm of the Faculty of Agriculture, the University of Tabriz in 2009. The treatments included pure stands for both species, 1: 1, 2: 2, 4: 2, 4: 4 and 6: 4 for soybean and calendula number of rows per strip, respectively. Before planting, soybean seeds were inoculated with Bradyrhyzobium japonicum. Before harvesting, the number of pods per plant, seeds per plant, 1000- grain weight, grain yield, percentage of oil and protein of soybean grain were measured in 10 randomly selected plants. The number of flowers per plant, dry inflorescence weight and dry petal weight of Calendula were recorded. The harvest of flowers of calendula began on July 30 and harvesting was done every 15 days in six steps. It was continued to mid-October. Total dry petals and sepals of 6 withdrawals flower per plot were considered as inflorescence dry weight. The land equivalent ratio (LER), actual yield loss (AYL), relative crowding coefficient (RCC), AGGRESSIVITY (A) and competitive ratio (CR) were determined at the end of the growing season. For statistical analysis, analysis of variance (ANOVA) and Duncan’s multiple range test (DMRT) were performed using MSTAT-C.Results and Discussion: The results showed that the effect of planting pattern on the number of pods per plant, seeds per plant, 1000-grain weight, grain yield of soybean, percentage of oil and protein contents of soybean was not significant. The effect of planting pattern on inflorescence dry weight and dry petal weight of calendula was significant. Row and strip intercropping 6: 4 produced greater dry inflorescence weight and dry petal weight than calendula monoculture. The highest petal and inflorescence yield was achieved by 1: 1 (87.63, 30.75) and 6: 4 (41.75, 22.68) intercrops, respectively. The effect of planting pattern on the number of flowers per plant was significant at 1% level. The number of flowers per plant for row intercropping and strip intercropping of 1: 1 and 6: 4 were greater than calendula monoculture. The highest flowers per plant was achieved by 1: 1 and 6: 4 intercrops, respectively. The land equivalent ratio was greatest for 6: 4 and 1: 1 intercrops equal 1.34 and 1.13, respectively and the lowest land equivalent ratio was achieved by 2: 2 intercrops. The actual yield loss value of all treatments were positive that indicated increased yield. In row intercropping and strip intercropping 4: 4 and 2: 2 competitive ratio of calendula (1.13, 1.25, 2.06) was>0 and the competitive ratio of soybean (1.07, 1.2) was>1 that show that yield advantage was greater than mono-cropping system. The relative crowding coefficient (RCC) of calendula (0.46, 0.46, 0.76) was greater than that of soybean that proves the competitive advantage of calendula against soybean. In strip intercropping, 6: 4 and 4: 2 AGGRESSIVITY of soybean (0.98, 1.43) was>0, that indicates the relative yield of soybean is greater than calendula. The negative AGGRESSIVITY of calendula (0.93, 1.19) in this treatment shows that the relative yield of calendula is less than soybean. In row intercropping and strip intercropping 4: 4 and 2: 2 competitive ratio of calendula (1.13, 1.25, 2.06) was>0 and competitive ratio of soybean (1.07, 1.2) was> 1 that shows that yield advantage was greater than mono-cropping system.

Relative competitive ability of3 soybean cultivars (Willims, Clarck and Hobit) and redroot pigweed were assessed during entire growing season by using replacement series experiments .Decreasing the proportion of plant density resulted in increasing relative yield (RY) of soybean cultivars. Competition within species was higher than competition among" species. Relative yield of redroot pigweed was less than soybean cultivars due to higher inter- specific competition rather than intra- specific competition. Relative yield total more than 1 indicates niche differentiation between soybean and redroot pigweed. Also relative crowding coefficients (RCC) for soybean cultivars higher than unit, indicates higher inter specific competitive cultivars than potential redroot pigweed. AGGRESSIVITY (A) index in soybean cultivars were higher than redroot pigweed. However, in Hobit AGGRESSIVITY was less than other cultivars.

Introduction: Intercropping, the agricultural practice of cultivating two or more crops in the same space at the same time, is an old and commonly used cropping practice which aims to match efficiently crop demands to the available growth resources (Agegnehu et al., 2006; Dhima et al., 2007). Intercropping of chickpea with linseed reduced the chickpea yield by 60.3%, although linseed occupied only 33% of the total area. The loss of chickpea yield was compensated by the additional yield of linseed, and thus the system productivity of chickpea+linseed intercropping was increased by 43.4% compared with sole chickpea (Ahlawat & Gangaiah, 2010).The objectives of the present study were to study the competition indices of barley and pea intercropping and effects of nitrogen and different intercropping arrangements on forage yield.Materials and methods: In order to evaluate effects of nitrogen and different intercropping arrangements of barley and pea on yield and competitive indices, an experiment was conducted as factorial based on Randomized Complete Block Design with three replications on farm research on Gonbad Kavous University (37o26’N, 55o21’E, and 45m above sea level) in 2011-2012. Different intercropping arrangement levels were a sole crop of barley, intercropping of one line barley and one line pea, intercropping of two lines of barley and two lines of pea, intercropping of three lines of barley and three lines of pea and sole crop of pea and nitrogen consumption was in four levels of none application of nitrogen and application of 25, 50 and 75 kg.ha-1.Seed planting was done during the first week of December 2011. Sowing was performed manually by planting twice more seeds of pea than the expected plant density. Sole barley (cv. Sahra) planted at the rate of 160 kg.ha-1 and sole pea (cv. Sungro) planted at the rate of 500000 plants.ha-1. Row spacing was 20 cm. The experimental plots for a sole crop of barley, a sole crop of pea and one row of barley+one row of pea were 4 rows and for two rows of barley+two rows of pea and three rows of barley+three rows of pea were 6 and 8 rows, respectively.50% of urea was applied during sowing. The other 50% of urea was side banded when the barley plants were at flowering stage. Weed control was performed manually. Forage yield was determined by harvesting each crop from 2, 4 and 6 rows. Barley was harvested at soft drought and the pea was harvested at seed filling stage in 3 May 2012. Data were analyzed using SAS software. Analysis of variance was performed for the forage yield and Equal Yield of barley.Results and discussion: The results showed the effects of different intercropping arrangements, nitrogen application and interaction of different intercropping arrangements × nitrogen application on forage yield and Equivalent Yield of barley was significant (a=1%). The high forage yield and Equivalent Yield of barley belonged to a sole crop of barley with application of 75 and 50 kg Nha-1 with 14.51 and 14.3 tonha-1, respectively. The minimum dry weight and Equivalent Yield of barley was obtained from the sole crop of pea without consumption of nitrogen with 3.76 and 4.7 tha-1, respectively. Increasing the pea and barley rows in intercropping treatments decreased forage yield because of lower yield of pea. Land Equivalent Ratio in intercropping treatments was less than 1. This index in barley was greater than pea (0.643, 0.588 and 0.543 for barley and 0.198, 0.247 and 0.362 for pea in 1, 2 and 3 rows, respectively). Other indices (Relative Crowding Coefficient, AGGRESSIVITY, Competitive Ratio, Actual Yield addition, Intercropping Advantage and Equivalent Yield of barley) in barley were also greater than pea in intercropping. Barley was the dominant crop in this study.Conclusion: Forage dry weight and Equivalent Yield of barley in a sole crop of barley with consumption of 75 and 50 kgN.ha-1 was the maximum and in sole crop of pea with non-consumption of N was minimum. All indices in barley in this study were greater than pea. This indicated that barley was the dominant crop.

Introduction: Intercropping of legumes with cereals is one of the old practical multi-cropping techniques to increase crop yields and to improve land use efficiency (Thobatsi, 2009; Poggio, 2005). Hence, competition among mixtures is thought to be the major aspect affecting yield as compared with solitary cropping. Species selection, seeding ratios and competition capability within mixtures can affect the growth and yield of the species used in intercropping systems (Agegnehu et al., 2006; Banik et al., 2006). Some competition indices such as land equivalent ratio, AGGRESSIVITY, relative crowding coefficient and competitive ratio have been proposed to describe competition and economic advantages of intercropping systems (Dhima et al., 2007). Therefore, the objective of this study was to compare the productivity of corn intercropped with different bean cultivars compared with sole cultures and to examine the competitive relationships of corn and bean cultivars in intercrops.Materials and Methods: A field experiment was carried out in randomized complete block design with three replicates at the Sari Agricultural Sciences and Natural Resources University (latitude 36oN, longitude 53oE and altitude of 25m below sea level, GARMIN, GPSmap) during 2010. The experimental treatments were mono-cropping of corn, white bean, bush bean, red bean, pinto bean, and intercropping of corn with bean types in 50: 50 planting ratio. The plot size was 3.0 m×6.0 m (providing 5.3 plants/ m2 for solitary treatment). Experimental plots of pure corn and mixed crops received the 300 kg/ha of urea, 100 kg/ha of potassium sulfate and triple super phosphate and the pure bean cultivars plots received 100 kg/ha of urea, potassium sulfate and triple super phosphate all applied at planting. The experiment was planted on May 1 in 2010 and was harvested on September 20 in 2010. Grain yield was determined by harvesting each crop separately from the mixtures in the two middle rows. The land equivalent ratio (LER), AGGRESSIVITY (A), relative crowding coefficient (K) and competitive ratio (CR) were calculated by using the following formula:LER=Yc/Ycc+Yb/Ybb where Ycc and Ybb are the yields of corn and bean cultivars as sole crops, respectively and Yc and Yb are the yields of corn and bean cultivars as intercrops, respectively;“formula” where Zc and Zb are the proportions of corn and bean cultivars in the mixture, respectively; “formula” For statistical analysis, analysis of variance (ANOVA) and least significant difference (LSD) were performed using SAS version 9.1 (SAS Institute Inc., Cary, NC, USA).Results and Discussion: In the present experiment, intercropping the corn-bush bean and corn-pinto bean had the highest economical yields (5718.4 and 5687.1 kg/ha, respectively) and land equivalent ratios (LER=1.13 and 1.21, respectively).Among different crops, the highest relative crowding coefficients were related to red bean (K=1.85), pinto bean (K=2.41) and sword bean (K=2.80). The most AGGRESSIVITY value, however, belonged to pinto bean intercropped with corn (A=-0.02). Also, both the red bean and pinto bean (CR=0.75 and CR=0.98, respectively) had the maximum competitive ratios. Furthermore, the most corn relative crowding coefficient (K=1.15) belonged to corn and sword bean intercropping. The maximum corn AGGRESSIVITY value was observed in corn intercropped with white bean (A=+0.60) and bush bean (A=+0.69). In conclusion, according to competition indices, intercropping of 50% corn+50 % red bean and pinto bean plants were superior as compared with other combinations.Acknowledgments: The authors wish to thank the Sari Agricultural Sciences and Natural Resources University for supporting this study.

Introduction: The practice of growing two or more crops simultaneously in the same field is called intercropping and it is a common feature in traditional farming of small landholders. It provides farmers with a variety of returns from land and labour, often increases the efficiency with which scarce resources are used and reduces the failure risk of a single crop that is susceptible to environmental and economic fluctuation. The most common advantage of intercropping is the production of greater yield on a given piece of land by making more efficient use of the available growth resources using a mixture of crops of different rooting ability, canopy structure, height, and nutrient requirements based on the complementary utilization of growth resources by the component crops.Moreover, intercropping improves soil fertility through biological nitrogen fixation with the use of legumes, increases soil conservation through greater ground cover than sole cropping, and provides better lodging resistance for crops susceptible to lodging than when grown in monoculture. Careful planning is required when selecting the component crops of a mixture, taking into account the environmental conditions of an area and the available crops or varieties. A number of indices such as land equivalent ratio (LER), relative crowding coefficient (RCC), AGGRESSIVITY (A), competitive ratio (CR), actual yield loss (AYL), and intercropping advantage (IA) have been proposed to describe competition within, economic advantages and equivalent yield of intercropping systems (Agegnehu et al., 2006; Banik et al., 2006; Dhima et al., 2007). The objective of this study was to determine the best treatment of sole or intercropping of wheat and chickpea and evaluation of competition indices in intercropping under nitrogen consumption.Materials and methods: In order to investigate the competition indices of intercropping of wheat and chickpea under nitrogen effect, an experiment was arranged as factorial based on Randomized Complete Block Design with three replications during 2009-2010 in Gonbad Kavous University farm. Planting patterns factor included four levels of sole cropping of wheat (W), two rows of wheat with one row of chickpea (W2C1), one row of wheat with two rows of chickpea (W1C2) and sole cropping of chickpea (C) and nitrogen application consisted of four levels of 0, 25, 50, 75 and 100 kgN ha-1. Each plot had 5 rows and the rows distance was kept 25 cm in all the treatments. Sowing date was 19th December 2009 and plants harvested at 25th May 2010. Eventually, seed yield and indices of land equivalent ratio, relative crowding coefficient, AGGRESSIVITY, competitive ratio, actual yield loss, intercropping advantage and barley equivalent yield were computed. Analysis of variance was performed using SAS Software (Ver.9.1.3) and treatment mean differences were separated by the least significant difference (LSD) test at the 0.05 probability level.Results and discussion: The results showed that the highest grain yield and wheat equivalent yield was obtained from sole cropping of wheat. In the intercropping of two rows of wheat with one row of chickpea and one row of wheat with two rows of chickpea land equivalent ratio was 0.87 and 0.71, respectively, that was less than sole cropping of wheat and chickpea. This means that intercropping requires 13% to 29% more land than the sole crop to produce equal yields which indicating greater land-use efficiency of sole crops than intercrops. relative crowding coefficient of wheat in two rows of wheat with one row of chickpea and one row of wheat with two rows of chickpea was 1.93 and 1.73 and of chickpea was 0.15 and 0.17, respectively. The AGGRESSIVITY parameter indicated a tendency for wheat to dominate chickpea in both intercropping. Competitive Ratio in two rows of wheat with one row of chickpea was greater than one row of wheat with two rows of chickpea. Actual yield loss and intercropping advantage in wheat was positive and in chickpea was negative. Intercropping of wheat and chickpea decreased actual yield loss and intercropping advantage. The present study concludes that intercropping of wheat with chickpea in different planting patterns affected seed yield, competition between the two species and economics of the planting patterns as compared to solitary cropping of the same species.Conclusion: Results of this study illustrated that intercropping of wheat and chickpea was not suitable system.Intercropping indices such as Land Equivalent Ratio, AGGRESSIVITY, Competitive Ratio and Intercropping Advantage indicated that wheat crop was the dominant species in two intercropping treatments.

This experiment was conducted under pot conditions to investigate competitiveness of spring wheat (Triticum aestium, Chamran cultivar) subject to various plant populations of wild oat Avena fatua, using completely randomized design with three replications in 2006 in the greenhouse of Ramin Agricultural and Natural Resources University, Mollasani Khouzestan. The treatments included pure stands of wheat and wild oat at one level (ratios 4: 0 and 0:4), and density difference ratios wheat and wild oat at seven levels (4:1, 4:2, 4:3, 4:4, 1:4, 2:4 and 3:4). The results showed that relative crowding coefficient (RCC) of wheat to wild oat and wild oat RCC to the wheat were equal. This indicated that competitive ability of the two plants were similar. While relative grain yield of wheat decreased by increasing relative leaf area of wild oat. Ability AGGRESSIVITY of wild oat showed that wild oat was more successful in using environmental sources, observed clearly in ratio the 4:4. Moreover mean stem height, mean spikelet number per spike, mean grain number per spike, mean 1000-grain weight, final biomass and grain yield of wheat plant decreased with increasing wild out density.