In order to study the effects of INTERCROPPING on cucumber and tomato and determine the best plant density for these crops, an experiment was carried out for one year (1996) at Behbahan Agricultural Research Station. A randomized complete block design with fifteen treatments and four replications were used. In this experiment cucmber and tomato were grown as pure stads and intercrops in three plant densities: high, medium and low (4.2, 2.8 and 2.1 plants / m2 respectively). Cucumber was grown in combination with 75%, 50% and 25% of tomato. The replacement series technique was used to form the intercrops. According to the obtained results, the optimum plant density for cucumber and tomato were 2.8 plants / m2. Computation of LER (Land Equivalent Ratio) showed that C50T50 (50% cucumber + 50%tomato) and C25T75 (25% cucumber + 75% tomato) combinations in all planting densities were greatar than unity. So, the advantage of intecropping cucumber and tomato were confrimed. Medium planting density of C50T50 combination with mean yield of 40.71 tons/ha and yield advantage of 34% was the best treatments. The differences between qualitative characteristics (percent of dry matter in cucmber and tomato fruits as well as vitamin C content in tomato fruits) in all treatments were not significant.

To study the INTERCROPPING system of maize and sunflower an experiment was Conducted at Jiroft Agricultural Research Center In 1376 cropping. Experimental design was R, C. B. D. with five treatment and three replication. The Treatment were as fallows: M1: sole cropping of maize M2: 75 % maize + 25 % sunflower M3; 50 % maize + 50 % sunflower N4:25 % maize + 75 % sunflower M5: sole cropping of sunflower. The plants were planted as replacement method. calculation LER indicate that Ms treatment of INTERCROPPING system of 75% maize + 25 % sunflower had highest fresh matter, dry matter grain yield and total protein in the region. Also this treatment had higher efficiency in term of using of moisture as well. In general the Ms treatment could be recommended for high Yielding cropping system in this region.

INTERCROPPING of pearl millet and common vetch was studied at Research Station of Faculty of Agriculture, University of Tabriz in 1999. The experimental design was randomized complete block with 3 replications. The treatments consisted of constant density of pearl millet with 15 kg/ha and three density of common vetch with 50, 70, 90 kg/ha and their combinations with the total of seven treatments. INTERCROPPING system was additine. On the basis of standard LER, INTERCROPPING of pearl millet var. Nutrifeed with the third level of common vetch (90 kg/ha) was better than other the combinations. Its LER was 1.56. In some INTERCROPPING treatments, pearl millet yield in the second harvest was more than the first one. It seems that pearl millet exploited nitrogen remained prom vetch and decreased its interplant competition. Pure stand of common vetch was worthy of recommendation because of shorter growth period, optimum yield, better forage quality and improved soil fertility.

INTERCROPPING is defined as simultaneous planting of more than one species in a piece of land sufficiently close to each other so that interspecific competition occurs. In order to study the possibility of obtaining higher yields, INTERCROPPING of soybean cultivars was conducted during the 1999-2000 growing season at the agricultural experimental farm of Tehran University. In this study total yield and components yield in sole culture and INTERCROPPING were evaluated. The experimental design was a factorial with 3 replications in which the first factors were 3 different plant densities (20, 40 and 80 plant per 1 m2) and second factors were five different cropping ratios (100:0, 75:25, 50:50, 25:75 and 0:100 Hag and Clark 63 cultivars, respectively).The results showed that, the treatment of 50:50 (2 rows Hag +2 rows Clark) had the highest total yield. Calculated Land equivalent ratio (LER) showed that the seed yield of mixture of 50:50 Hag and Clark with 80 plant/m2 had highest LER i.e. 1.07. By increasing plant density number of pods per plant decreased. There was no significant difference between number of seed in pod and 1000 seed weight.

To study the effect of INTERCROPPING and nitrogen fertilizer treatments on the grain yield, a field experiment was conducted at the research farm of the Islamic Azad Uuiversity, Shooshtar, in 2005. The planting methods were laid out in a randomized complete block design in split-plot arrangements keeping different nitrogen rates, (50, 100 and 150 kg from urea resource) as main plots and various rates of INTERCROPPING corn-sunflower as sub plots with three replications. The INTERCROPPING treatments were S1 (100% sunflower), S2 (25% corn plus 75% sunflower), S3 (50% corn plus 50% sunflower), S4 (75% corn plus 25% sunflower) and S5 (100% corn). The results of the study indicated that seed yield of sunflower and grain yield of corn, total yield of sunflower and corn, 1000-seed weight and oil percentage of sunflower were significant. But 1000-grain weight and the grain number per pod wasn’t significant. The highest grain yield observed in N2S1 and N3S5 for sunflower and corn, was respectively (462 and 1319 per gr.m-2). In INTERCROPPING got the highest and the lowest seed yield of sunflower to pure stand and in S3, and at corn got to pure stand and in S4, respectively. An increase in nitrogen proportion raised the land equivalent ratio (LER). The highest and the lowest land equivalent ratio for grain yield were observed in hybrid levels of S4 and S3, respectively. The highest and the lowest land equivalent ratio (LER) were relevant to N1S2 and N3S4 (1.85 and 1.08, respectively). In addition, the highest and the lowest relative crowding coefficient (K) were relevant to N3S4 and N3S2 (0.2 and 7.2, respectively).

INTERCROPPING is a suitable method towards sustainable agriculture. On this basis an experiment was conducted in a field located in, km 5 of Mianeh-Tabriz road during 2009 growth season. The factorial of treatments was arranged with in Randomized Complete Block Design (RCBD) with two factors; cucumber cultivars (Emperor, Bingo, Superstar and Nefer) and intra row spacing of onion (8, 10 and 12 cm). Results showed that the yield of onion was significantly reduced only in INTERCROPPING with Emperor Cultivar. The highest yield of onion was obtained from 10 cm intra row spacing. Cultivars of Emperor and Superstar in comparison with two other cultivars produced more yield. The highest yield of cucumber obtained in sole culture and the yield reduced significantly in INTERCROPPING. The highest percentage of onion bulb dry matter obtained from 8 cm intra row spacing. The percentage of cucumber dry matter reduced significantly in INTERCROPPING with Nefer cultivar. The highest land equivalent ratio (LER) (1.56) was recorded in treatment of the combination of onion (with intra row spacing of 10 cm) with Superstar cultivar.

To evaluate beneficial effect of INTERCROPPING based on replacement and additive methods to sustainable agriculture, two experiments were conducted at the Agricultural Research Station of University of Tabriz in 2005 and 2006, to study the effect of INTERCROPPING potato and pinto bean by using these two methods. The experiments carried out using randomized complete block design with three replications and 16 treatments. The treatments, consisted of: eight treatments of replacement INTERCROPPING with 2:1 and 3:1 proportions of potato and pinto bean (with densities of 4.7 and 5.3 plants m-2 for potato and 45 and 55 plants m-2 for pinto bean), four treatments of additive INTERCROPPING (with densities of 4.7 and 5.3 plants m-2 for potato and 5.3 and 10.6 plants m-2 for pinto bean), two sole croppings of potato (4.7 and 5.3 plants m-2) and two sole croppings of pinto bean (45 and 55 plants m-2). Maximum tuber yield per plant, tuber yield of potato per unit area, tuber size, mean tuber weight, number of leaves and branches per plant were obtained from replacement INTERCROPPING treatments. Maximum grain yield of pinto bean per unit area was obtained from the replacement INTERCROPPING treatments; Maximum grain yield per plant, number of pods per plant, number of leaves and branches, plant height, dates of emergence, flowering, poding and ripening were obtained from the additive INTERCROPPING treatments. To evaluate the beneficial effect of INTERCROPPING, land equivalent ratio (LER) was more than one, and the maximum amounts for two years (1.25 and 1.27, respectively) belonged to replacement INTERCROPPING of 1:2 treatment (66% potato with 5.3 plants per m2 + 34%pinto bean with 55 plants per m2). This treatment, therefore, can be recommended to be the best INTERCROPPING pattern for sustainable agriculture.

Introduction Several factors affect the crop yield and weeds are among the most important factors reducing crop yields. There are high tendency to develop alternative methods of herbicides for natural control of weeds in organic products. One of the alternative methods to manage weeds is INTERCROPPING. INTERCROPPING is growing two or more crops simultaneously in a piece of land during a growing season. The objectives of the present study were to examine the effect of cereal-legume INTERCROPPING on weeds growth. Materials and Methods A field experiment was conducted in College of Agriculture of Darab, Shiraz University during 2014-2015. In the experiment 16 treatments (five weed free monocultures of wheat (M1), barley (M2), triticale (M3), pea (M4), faba bean (M5), 5 weedy monocultures of wheat (WM1), barley (WM2), triticale (WM3), pea (WM4), faba bean (WM5), and six replacement INTERCROPPING treatments of wheat + pea (I1), wheat + faba bean (I2), barley + pea (I3), barley + faba bean (I4), triticale + pea (I5) and triticale + faba bean (I6) without weed control) using a randomized complete block design (RCBD) with three replicates were studied. Cereals and legumes were planted simultaneously at 23 November 2014. Planting operation was conducted on both sides of the ridges. Weed diversity was calculated by Shannon diversity index: 1 ln s i H N i N i  N N    N=Total number of plants in each plot of one square meter, Ni= number of species i plants, S= total number of species, and H= Shannon diversity index. This index value ranging from zero to five, higher index value, greater diversity. Results and Discussion The results showed that the lowest density and biomass of weeds were obtained in both sole culture and INTERCROPPING of barley. For instance, the lowest weed biomass was observed in monoculture of weedy barley (1 g. m-2), INTERCROPPING of barley + faba bean (12. 67 g. m-2) and INTERCROPPING of barley + pea (56 g. m-2). The weed density at weed free sole culture of barley (30 plants. m-2) was lowest that followed by barley + faba bean INTERCROPPING (81 plants per m-2). The lowest species weed diversity was obtained in barley + pea (zero) and weedy barley (0. 007), respectively. The weed diversity of most INTERCROPPING treatments was similar or less than that of weedy sole culture. In General, pea or faba bean monoculture had greatest weeds density and biomass, because slow growth and late seedling establishment. However, cereals especially barley controlled weeds properly, due to greater growth rate, higher height and greater density than those of legumes. INTERCROPPING of pea and faba bean with cereals reduced weeds growth and had lower weeds density and biomass than those of pea and faba bean weedy monocultures. In order to increase of legume yields, more density of legume should be intercropped with cereals. Conclusion In general, INTERCROPPING treatments caused a significant decrease in weeds density and biomass compared to the legumes monoculture. In this experiment barley and triticale due to good properties such as fast growth, high plant height and more shading could considerably control weeds in both monoculture and INTERCROPPING treatments, reducing significantly weeds density and biomass in itself sole culture and INTERCROPPING treatments. To reduce the weeds growth in faba bean and pea, which have a poor competitive ability with weeds, INTERCROPPING with cereals, especially barley and triticale, in the south of Fars province is recommended. However, INTERCROPPING is one of the ways to reduce weeds in the long term and its effects on weeds in the long period will be much more. Acknowledgments The authors would like to acknowledge the College of Agriculture and Natural Resources of Darab, Shiraz University, to finance the project and all those who helped us in this project.

An experiment was carried out in the experimental field of Faculty of Agriculture, University of Tabriz in 1997 in order to study competition and yield of corn and soybean INTERCROPPING. The experiment was factorial based on randomized complete block design with three replications. Different combinations of corn and soybean densities constituted the treatments in the experiment. Assessing all intercropped treatments with LER index showed that the combination of 5.3 per m-2 corn x 42 per m-2 soybean, acquired the highest biological efficiency. We used ELER and SLER indices to choose the most efficient system. On the basis of other competition indices corn was a good competitor. However, in all intercropped treatments, competition of corn and soybean was complementary, because, land equivalent ratio in all INTERCROPPING treatments were greater than unity. This indicates the superiority of INTERCROPPING of these two species over their pure stands.

Background and objectives: One of the key strategies in sustainable agriculture is diversity restoration to agricultural environments and effective management it. INTERCROPPING, which is defined as growing two or more species simultaneously in the same field during a growing season, is considered one important strategy in developing sustainable production systems, particularly systems that aim to limit external inputs such as chemical fertilizer and herbicide etc. Compared to sole crops, INTERCROPPING system have higher utilization of resource i. e., nutrient use efficiency, water use efficiency, and land use efficiency. This research was done to evaluation advantageous of sunflower-legume INTERCROPPING systems, Materials and methods: The experiment was conducted as randomized complete block design with three replications at the Agricultural Research Station, Faculty of Agriculture, Bu-Ali Sina University, during 2013 and 2014 growing seasons. Experimental treatments were different planting patterns including sunflower, bean and soybean sole cropping, and additive INTERCROPPING of 30, 60 and 90% bean, as well as 30, 60 and 90% soybean with sunflower. INTERCROPPING systems were evaluated by using indices of land equivalent ratio (LER), system productivity index (SPI), total relative value (RTV), area-time equivalent ratio (ATER), aggressivity index (AI), competition index (CI) and relative crowding coefficient (RCC). Results: Results showed that crops grain yield and sunflower equivalent yield affected by planting patterns. The highest sunflower, bean and soybean grain yields were achieved at sole cropping and INTERCROPPING decreased grain yield of these crops. However, sunflower equivalent yield at INTERCROPPING patterns of 60 and 90% bean and soybean were more than sole cropping. At this treatments, indices of land equivalent ratio, total relative value, area-time equivalent ratio and relative crowding coefficient were more than 1 and competition index was less than 1 that showed INTERCROPPING is advantageous. In this study pay attention to aggressivity index, sunflower was aggressive in comparison to bean and soybean. Conclusion: The results of this present showed that, INTERCROPPING systems increased sunflower equal grain yield in comparison with sunflower sole cropping. In general, in the most of the treatments, sunflower-legume (bean and soybean) INTERCROPPING was better than their sole cropping and associated with improving economic yield and land use efficiency. The results of this present showed that, INTERCROPPING systems increased sunflower equal grain yield in comparison with sunflower sole cropping. In general, in the most of the treatments, sunflower-legume (bean and soybean) INTERCROPPING was better than their sole cropping and associated with improving economic yield and land use efficiency.