American-Eurasian J. Agric. & Environ. Sci., 10 (4): 675-683, 2011 ISSN 1818-6769 © IDOSI Publications, 2011

Evaluation of -legume and Cereal-Pseudocereal Intercropping Systems Through Forage Productivity and Competition Ability

A. Aynehband and M. Behrooz

Agronomy and Plant Breeding Department, Faculty, Shahid Chamran University, Ahwaz, Iran

Abstract: ( L.) and mungbean (Vigna radiata (L.) Wilczek) have been intercropped with (Zea mays L.) to evaluate the effects of mixture system and planting ratios on intercropping yield and competition indices. This field study was conducted during 2009 under Mediterranean region in Ahwaz, Iran. The experimental design was split plot with three replications. Two intercropping systems were in main plot and five planting ratios were in sub-plot. Various measures of the efficiency of intercropping system relative to sole cropping were employed. The results showed that regardless of planting ratios, maize:amaranth at the 75:25 mix-proportion had the highest intercropping forage yield but, maize:mungbean at this planting ratio was observed to be the most monitory advantages. Furthermore, mungbean intercropped with maize was more competitive than amaranth. Generally, maize was the dominant and non-dominant species in mixture with amaranth and mungbean, respectively. Although maize had lower yield in mixture than sole crop but, its means partial land equivalent ratio was not significantly differed between intercropped maize in amaranth or mungbean. The ratio of proportion also seemed to significantly affect the efficiency of intercropping. For example, different amaranth or mungbean planting ratios caused different in competitive ratio, crowding coefficients values, aggressivity values and actual yield loss indices on associated crop (maize). In other words, intra and inter competition were changed by change in planting ratios.

Abbreviations:A (Aggressivity), AYL (Actual yield loss), CR (Competitive ratio), IA (Intercropping advantages), K (Crowding coefficient), LER (Land equivalent ratio), SPI (System productivity index).

Key words: Amaranth % Competition % Intercropping % Maize % Mungbean

INTRODUCTION an appropriate intercrop having desirable plant type and growth pattern assumes greater importance. [3]. Intercropping system is becoming an integral part of Moreover, legumes when intercropped with cereal fix cropping system where sustainable agriculture is considerable amount of biologic nitrogen reduce external emphasized. This system can be seen as the practical input requirement and improve the quality and quantity of application of diversity, competition and facilitation in the forage yield. [4,5]. Therefore, one of the main goals of arable cropping systems [1]. this cropping system is to maximizing use of some Historically, intercropping of cereal with legumes is production resources such as space, light, water and commonly used for forage production in the nutrients [1,6]. This point require special attention to Mediterranean region and is likely to continue to be combining species with inherently different in some important, but cereal and non-legume mixtures are seldom characters such as morphologies, root system sown. [2]. Basically, its recognized practice for development in time and space and symmetric or economizing the use of growth resources and increasing asymmetric distribution of capture organs that induce the productivity and profitability per unit area and time. competition (or dominance) relationships between plants For instance, in maize intercropping system, selection of which may affect their performance. [7].

Corresponding Author: A. Aynehband, Agronomy and Plant Breeding Department, Agriculture Faculty, Shahid Chamran University, Ahwaz, Iran. Tel: +98-6113330011 Ext: 3042, Fax: +986113330079, E-mail: [email protected]. 675 Am-Euras. J. Agric. & Environ. Sci., 10 (4): 675-683, 2011

Competition among mixtures is thought to be the rainfall of 360 mm with 31º20× N latitude and 48º41× E major aspect affecting yield as compared cropping of each longitudes, average summer and winter temperature 39 crop. [8]. In fact, yield advantages occur when intercrop and 3°, respectively. The soil properties before planting components compete only partly for the same plant were sandy loam texture, pH, 7.7; organic C, 0.54%; total growth resources. Thus, when the intrspecific competition N, 0.49%; available P, 14 mg kg G1 and exchangeable K, is less than intraspecific competition. [9]. However, yield 160 mg kgG1. could be improved if best mixtures, optimum planting A randomized complete block design in a split-plot ratios, crop requirements and better adapted species were arrangement was used. Two intercropping systems (i.e. known. [10]. The challenge is therefore to identify crop Maize:Amaranth and Maize:Mungbean) constituted the species capable to sustaining their potential yield when main plots and five planting ratios (i.e. 0, 25, 50, 75 and grown in specific proportions with other crops. [2,8]. 100%) constituted the sub plots. Blocks were replicated Ideally, species suitable for intercropping should enhance three times. Sub plot dimensions were 6 by 4 m (24 m2). All the complementary effects of mixture. In this case, the crops in each intercropping system were planted in yield of one species surpasses the other and makes up for alternative rows and arranged in replacement series. The the inferior performance of the component crop. [11]. inter-row spacing was 75 cm and the intra-row plant In Iranian cropping systems, maize and mungbean are spacing for maize, amaranth and mungbean were 15, 15 among important crops, but amaranth is a new crop. and 7.5 cm, respectively. The same planting density of These crops mainly grown in sole systems, but 90,000 plant haG1 was maintained based on maize plant intercropping of maize with other legumes are common. density. Thus, the plant equivalent for maize:amaranth Maize is characterized by aggressivity in cereal-legume was 1:1 and for maize:mungbean was 1:2 in each mixtures and improved the quantity of cropping system intercropping system. The maize (cv. S.C. 704), amaranth [12]. While, legumes are thought to improve the yield (cv K 283) and mungbean (cv. Hendi) were planted at the quality of its associated crops. [13]. In addition, amaranth same day on 18 July at their appropriate planting ratios was selected because it has a complementary characters depending on the treatments. Seedbed preparation in compare with maize and would be an effective intercrop included ploughing, disk harrowing and cultivation. component in maize:amaranth mixture [14]. Nitrogen and P2O5 at 70-50-30 N-P-K were application as In recent years, several indices such as land urea and superphosphate. Crops in monocultures and in equivalent ratio (LER), relative crowding coefficient (K), mixtures were harvested in a randomly selected 4 m2 area competitive ratio (CR), aggressivity (A), actual yield loss of each plot by hand harvesting at the milk stage (R3 (AYL), system productivity index (SPI) and intercropping stage: 18-22 days after silking) of maize. Samples of each advantage (IA) have been developed to describe plot were separated for the determination of plant competition and economic advantage in intercropping. percentage in each mixture. Crop biomass then dried at 60° [5,13,15]. However, these indices have not been used in for 48 hours. Dry matter of each crop was measured as intercropping system of maize:amaranth and also economic forage yield. maize:mungbean to evaluate the competition among The advantage of mixed cropping compared to sole species. culture and the effect of competition between the two Therefore, this experiment was conducted to study: intercropping systems were calculated using different 1-The suitability of different cereal-legume and cereal- competition indices. Besides these, the economics of the pseudocereal intercropping systems in term of forage intercropping system were also worked out [3,5,15]. yield, biological productivity and economic advantages The functions are: and it’s compared to sole cultures and 2- To examine the C Land equivalent ratio (LER) was calculated as: different competition indices in these intercropping systems. LER = (LERa + LERb)

MATERIALS AND METHODS LERa = (Yab / Ya)

A field experiment was conducted at Agricultural LERb = (Yba / Yb) Faculty of Shahid Chamran University, Ahwaz, Iran, under Mediterranean condition during 2009. The experimental Where Y is the yield of each crop, a is maize and b is site is located at 20 m above sea level, had an average mungbean or amaranth crop, respectively.

676 Am-Euras. J. Agric. & Environ. Sci., 10 (4): 675-683, 2011

SC Crowding coefficient (K) was calculated as: RESULTS

K= (Ka × kb) Forage Yield: The greatest forage yield was obtained from maize planted as monoculture. Maize yield differed

Ka= Yab × Zba / ((Ya - Yab) × Zab) significantly from that of the two mixtures of maize with amaranth and mungbean intercropping. The highest intercropped maize forage yield was obtained from 75 Kb= Yba × Zab / ((Yb – Yba) × Zba) maize: 25 amaranth mixtures, while the lowest one was 25 Where Z is proportion of each plant in mixture. maize: 75 mungbean mixture. The highest intercropped C Aggressivity (A) was calculated as: amaranth and mungbean forage yield was from 25:75 planting ratio and the lowest one was from 75:25 mixture (Table 1). In addition, maize forage yield generally was Aa = (Yab / Ya × Zab) – (Yba / Yb × Zba) affected by the increase of maize ratio in mixture. However, forage yields of all mixtures were lower than Ab =(Yba / Yb × Zba) - (Yab / Ya × Zab) yields of maize in monoculture (Table 1). C Competitive ratio (CR) was calculated as: In Maize: Amaranth intercropping system, forage yield was higher by 10% than that in maize:mungbean Cra= (LERa / LERb)( Zba / Zab) intercropping system. All mixture of amaranth with maize (i.e. 25, 50 and 75% planting ratios), however, produced Crb =( LERb / LERa)( Zab / Zba) about 28, 36 and 39%, respectively, more forage yield than the monoculture amaranth, but about 20, 12 and 7%, C Actual yield loss (AYL) was calculated as: respectively, less than the monoculture maize (Table 1). A

similar trend also was observed for mungbean in AYL = AYLa+ AYLb maize:mungbean intercropping system. In particular, there

was an increase of 14% in amaranth forage yield when AYLa = ((Yab / Xab) / (Ya / Xa) - 1 ratio of amaranth increased from 25 to 75% in mixtures of

maize:amaranth intercropping systems. A similar trend AYL = ((Y / X ) / (Y / X ) - 1 b ba ba b b was observed for mungbean in mixtures of

maize:mungbean intercropping system as there was a Where X is sown proportion of each crop in intercrop. corresponding increase of about 22%. C Intercropping advantage (IA) was calculated as: The relative to monocropping of all crops exhibited an increasing trend as each proportion increased Ia = AYL × P a a a (Table 1). Moreover, the greatest maize relative to monocropping (79.17) was obtained in the maize:amaranth Ia = AYL × P b b b intercropping system at the 75:25 planting ratio.

Where P is the commercial value of plant (current price). Land Equivalent Ratio and Competitive Ratio: Difference C System productivity index (SPI) was calculated as: among intercropping systems and crops were significant (P < 0.05) for LERs Forage yield was lower but total LER SPI = (Sa / Sb) Yb + Ya was higher for the maize:mungbean than for the maize:amaranth intercropping systems (Table 1 and 2). Where S is the mean yield of each plant in sole culture Partial LER was higher for maize at 75:25 planting ratio in and Y is the mean yield of each plant in mixed culture. both intercropping systems than other proportions. Data were subjected to analysis of variance Moreover, partial LERs of maize were lower in (ANOVA) using the SAS statistical software program. maize:mungbean mixture as compared with that of The values in tables are means of the two consecutive maize:amaranth mixture at the all planting ratios. In growing seasons. Treatment means were compared with addition, the partial LERs of amaranth in mixture with Duncan’s multiple range test. maize at all ratios were lower than that of mungbean.

677 Am-Euras. J. Agric. & Environ. Sci., 10 (4): 675-683, 2011

Table 1: Forage yield and contribution each crop in monoculture for maize, amaranth and mungbean in different intercropping systems and planting ratios Forage yield (Mg hG1) Relative to monocropping (%) ------Planting ratio (%) Maize Amaranth Mungbean Total Maize Amaranth Mungbean Maize:Amaranth 0:100 --- 12.74 a --- 12.74 d --- 100 --- 25:75 8.90 c 9.05 b --- 17.96 c 39.4 71.07 --- 50:50 13.11 bc 6.75 c --- 19.87 abc 58.07 52.9 --- 75:25 17.88 b 2.93 d --- 20.81 ab 79.17 23.002 --- 100:0 22.78 a ------22.78 a 100 ------Maize:Mungbean 0:100 ------5.92 b 5.92 e ------100 25:75 6.91 d --- 8.26 a 15.17 d 30.61 --- 139.49 50:50 10.82 c --- 4.20 c 15.03 d 47.95 --- 71.04 75:25 15.91 b --- 3.50 c 19.42 bc 70.47 --- 59.23 100:0 22.58 a ------22.58 a 100 ------Means Maize:Amaranth 15.62 a 7.87 --- 18.79 a 69.16 a 61.743 --- Means Maize:Mungbean 14.06 b --- 5.47 15.62 b 62.26 b --- 92.44 Means in a column with the same letter are not significantly different at P=0.05

Table 2: Land equivalent ratio (LER) and competitive ratio (CR) for sole stands and mixtures of maize with amaranth and mungbean in different intercropping systems and planting ratios LER values CR ------Planting Ratio (%) Maize Amaranth Mungbean Total Maize Amaranth Mungbean Maize:Amaranth 0:100 --- 1 --- 1 c ------25:75 0.396 0.71 --- 1.10 bc 1.674 0.591 --- 50:50 0.58 0.53 --- 1.11 bc 1.094 0.914 --- 75:25 0.79 0.23 --- 1.02 c 1.03 0.87 --- 100:0 1 ------1c ------Maize:mungbean 0:100 ------1 1 c ------25:75 0.309 --- 1.39 1.69 a 0.657 --- 1.48 5050 0.48 --- 0.719 1.19 bc 0.667 --- 1.497 75-25 0.70 --- 0.6 1.3 b 0.385 --- 2.571 100-0 1 ------1c ------Means Maize:Amaranth 0.691 a 0.617 --- 1.047 b 1.266 a 0.791 --- Means Maize:mungbean 0.622 b --- 0.93 1.236 a 0.569 b --- 1.849 Means in a column with the same letter are not significantly different at P=0.05

This was probably because of the higher maize partial LER shows that in some mixtures, maize was more in maize:amaranth than maize:mungbean intercropping competitive than the associated crop and vice versa system. (Table 2). In maize:amaranth intercropping system, the Intercropped maize had higher competitive ratios CR of maize Significantly (P < 0.05) decreased as the (CR) in maize: Amaranth mixture than proportion of amaranth decreased in the mixture. maize:mungbean intercropping system at all planting Moreover, The mean value of CR for maize was ratios, indicating that maize is more competitive than greater in maize:amaranth intercropping system than amaranth in this intercropping System (Table 2). maize:mungbean mixture. The corresponding value of CR However, mungbean had higher CR values than for mungbean was also highest. This indicates that amaranth in mixture with maize, indicating the dominance mungbean was more competitive as amaranth in mixture of mungbean under this crop mixture. This clearly with maize.

678 Am-Euras. J. Agric. & Environ. Sci., 10 (4): 675-683, 2011

Table 3: Crowding coefficient (K), aggressivity (A) and system productivity index (SPI) of crops in different mixtures and planting ratios K values A values ------Planting ratio (%) Maize Amaranth Mungbean Total Maize Amaranth Mungbean SPI Maize:Amaranth 0-100 ------25-75 1.95 0.82 --- 1.599 a 0.0065 -0.0065 --- 2494 c 50-50 1.39 1.13 --- 1.57a 0.001 -0.001 --- 2507.28 c 75-25 1.27 0.896 --- 1.14 b 0.0018 -0.0018 --- 2306.99 d 100-0 ------Maize:mungbean 0-100 ------25-75 1.32 --- -1.18 -1.56 c -0.0065 --- 0.0065 3842.18 a 50-50 0.92 --- 2.45 2.25 b -0.0044 --- 0.0044 2686.036 c 75-25 0.795 --- 4.36 3.466 a -0.015 --- 0.015 2928.15 b 100-0 ------Means Maize:Amaranth 1.536 a 0.948 --- 1.436 a 0.0031b -0.0031 --- 2436.09 b Means Maize:mungbean 1.0116 b --- 1.876 1.385 b -0.0086a --- 0.0086 3152.122a Means in a column with the same letter are not significantly different at P=0.05

Table 4: Actual yield loss (AYL) and intercropping advantages (IA) of maize, amaranth and mungbean in different intercropping systems and planting ratios AYL IA* ------Planting ratio (%) Maize Amaranth Mungbean Total Maize Amaranth Mungbean Total Maize:Amaranth 0-100 ------25-75 0.58 -0.05 --- 0.53 b 26.1 -3.25 --- 22.85 c 50-50 0.16 0.059 --- 0.10 c 7.2 3.835 --- 11.035 d 75-25 0.055 -0.079 --- -0.024 d 2.475 -5.135 --- -2.66 e 100-0 ------Maize:mungbean 0-100 ------25-75 0.22 --- 0.86 1.08 a 9.9 --- 57.62 67.52 b 50-50 - 0.04 --- 0.419 0.379 b -1.8 --- 28.073 26.27 c 75-25 -0.06 --- 1.37 1.31 a -2.7 --- 91.79 89.09 a 100-0 ------Means Maize:Amaranth 0.265 a -0.023 --- 0.202 b 11.925 -1.52 --- 10.408 b Means Maize:mungbean 0.04 b --- 0.625 0.923 a 1.8 --- 59.161 60.96 a Means in a column with the same letter are not significantly different at P=0.05 *The current price ($ per Mg) of maize, amaranth and mungbean forage are 45, 65 and 67, respectively.

Crowding Coefficient, Aggressivity and System ratios. On the other hand, in the maize:amaranth mixture Productivity Index: The crowding coefficients (K) for (proportion of 75:25), total K values was close to one both amaranth and mungbean were the most at (Table 3). 75:25 planting ratio with maize. As expected, partial In all planting ratios, amaranth and mungbean LER of amaranth and mungbean was decreased as the aggressivity values were positive and negative, proportion of maize increased in mix-proportions respectively. The aggressivity (A) parameters indicated a (Table 3). Comparison among the partial K values different tendency for maize to dominant in mixtures showed that the intercropped mungbean had higher (Table 3). On the other hand, maize was the dominant

K than the intercropped amaranth in the mixture with species (Amaize positive) in the maize:amaranth mixtures at maize (Table 3). When the maize was lower than all planting ratios (Table 3). In the other mixture (i.e.

50%, the Kmaize had larger values (Table 3). Total maize maize:mungbean intercropping system), maize was the K were lower than one in the case of maize:mungbean non dominant species as measured by the negative value intercropping system at the 50:50 and 75:25 planting of aggressivity.

679 Am-Euras. J. Agric. & Environ. Sci., 10 (4): 675-683, 2011

The SPI for the 25:75 planting ratio of were intermediate or even lower than yields of maize:mungbean intercropping system was significantly monocultures due to competition between species [13]. (P < 0.05) greater than any of the other mixtures (table 3). Ghosh [14] reported that monoculture production of cereal The maize:amaranth intercropping ratios had a fairly the fodder or groundnut yielded higher than in the same SPI values. In addition, there were significant intercropped culture. This was partly the result of the differences between the two intercropping systems in higher plant population in the monocrops. In addition, the their means SPI values. However, the maize: mungbean crop did not experience inter-specific competition. Ghaley intercropping system generally had greater SPI than et al. [16] reported that legume-cereal intercrops reduce maize:amaranth intercropping. their advantage over sole crops in the case where N fertilizers are applied, reducing the inter-specific Actual Yield Loss and Intercropping Advantages: complementarity, often reported as reducing the

The maize AYL had positive values in the all proportion of legumes in the total harvested intercrop maize:amaranth intercropping system ratios and in the yield. Therefore, competition for nutrients and light in maize:mungbean intercropping system when the intercropping system is often interrelated, particularly for maize proportion was less than 50%. The highest AYLmaize legume/non-legume crop combinations [3]. In general, value was obtained from 75 maize:25 amaranth mixture, under growing conditions where cereal sole crops while the lowest was from 75 maize:25 mungbean (Table produce rather high yields, intercropping with legumes 4). Comparing two intercropped maize showed that maize has no advantages over cereal sole crops [10]. However, in maize:amaranth mixture had the higher partial AYL when evaluated over a number of years the intercrops are values than those in maize:mungbean intercropping expected to show more stable yields than the specific sole system (Table 4). There were a 58% )AYL = + 0.58), 16% crops [17]. (AYL = + 0.16) and 0.05% (AYL = + 0.05) increase in yield In this study, increasing maize proportion from 25 to of maize in the maize:amaranth intercropping system for 75% in maize:amaranth intercropping system increased 25:75, 50:50 and 75:25 planting ratios, respectively. In maize yield around 50%, but around 56% increased for contrast, in maize:mungbean mixture, the AYLmaize was same proportion in maize:mungbean intercropping system. positive just at 25:75 planting ratio. The mean AYL of the Total forage yield was highest in the proportion of 75:25 maize:amaranth intercropping system was higher than maize:amaranth (20.18 Mg hG1) which higher than maize:mungbean mixture (Table 4), indicating an amaranth sole yield (12.74 Mg hG1) but lower than maize advantage of this intercropping system. sole crop yield (22.58 Mg hG1) (Table 1). Hiebsch et al. [6], The IA, which is an indicator of the economic Banik et al. [8] and Lauk and Lauk [10] founded that when feasibility of intercropping systems, affirmed that all non legume crop was grown in associated with legumes, maize:mungbean intercropping ratios were advantageous irrespective of the specific combination, the Non legume mixture. Although, partials maize IA were negative in crop benefited with respect to the proportionate yield of 50:50 and 75:25 planting ratios. The highest and lowest its sole crop. This can be attributed to the complementary IA values were obtained by maize:mungbean and effect of legume association through nutrient transfer. maize:amaranth intercropping systems at 75:25 planting They results also showed that the pure stand of crops ratio, respectively. The lowest total IA value of – 2.66 maintained supremacy over the intercropping system with showed that this mixture lead to highest forage yield loss respect to economic yield, which may be due to limited than others. Also, mean total IA showed that the disturbance of the habitat and interactional competition in maize:mungbean intercropping had significantly higher IA the sole cropping environment. value than maize:amaranth mixture (Table 4). The land equivalent ratio indices were the greatest in maize:mungbean (1.69) in the 25:75 mix-proportion. Also, DISCUSSION this proportion had the highest maize:mungbean intercropping forage yield than others. This indicating The results showed that the sole cropping of maize that 69% more area would be required for solitary yielded higher than did all the maize:amaranth and cropping system compared to intercropping. Midya et al. maize:mungbean combinations. Although, such mixtures [18] reported that greater intercrop yield advantage from indeed increased the intercropping yield of amaranth and total intercropping system LER values higher than one mungbean than sole crop (Table 1). In some cases, it has were indicating the advantage of mixtures over sole been reported that yields of mixtures of legumes and stands in regard to the use of agro-environmental sources

680 Am-Euras. J. Agric. & Environ. Sci., 10 (4): 675-683, 2011 for plant growth. In this case, total LER was significantly relative dominance of components of an intercrop by different from 1.00, which shows an advantage from manipulating the initial advantage in competition. Many intercropping over pure stands in terms of the use of researchers have pointed out that an index of competition environmental resources for plant growth. On the other between two species could altered by the density of each hand, total LERs below 1.00 were not found in the cases component and by resource levels [5,13]. of all intercropping systems, which show an advantage of Considering all mix-proportions and intercropping these mixtures over each crop pure stands. Similar results systems, Amaize values were positive with amaranth and were reported for different proportion of plant in mixtures were all negative with mungbean, showing that maize was by [2,3,12,13,17]. the dominant and non dominant species in maize:amaranth In this study, partial LER values also showed that, and maize:mungbean intercropping systems, respectively. compared to amaranth, mungbean appears to have more The values of A and CR for mungbean were greater and beneficial land use efficiency in all mixtures. Hauggaard- for amaranth were lower than those of maize in each Nielsen and Jensen [11] reported that the LER values intercropping systems. Moreover, increasing the maize showed that in the intercrop plant growth resources were ratios in mixtures less changed the crowding efficiency of used on average 20% more efficient without N application amaranth than mungbean, which probably resulted in and 5-10% more efficient with N application. In addition, higher maize intra competition than associated crop, this effect was observed in term of the decreased partial thereby, lower maize CR and A values. Therefore, maize and total legumes LER values when N was applied. AYL values were negative when the maize ratio was the Because of application of N caused a dynamic change in highest. In this situation, mungbean became more the intercrop composition and thereby competitive ability aggressive (A) and competitive (CR) than maize crop. of each crop in mixtures for other resources [7,9,19]. Greater competitive ability of cereal to exploit resources in The crowding coefficient (K) values for maize was association with some legumes has been reported by much higher than 1, indicating an absolute yield other researchers [20]. Banik et al. [15] reported that The advantage of maize over the all amaranth planting ratios advantages accrued from intercropping systems, as (except at 25:75 mix-proportion of maize:mungbean evident from competitive functions, is due to better intercropping system). This result was appeared that utilization of growth resources under cereal-legume maize was more competitive than amaranth. In addition, K intercropping system. Hauggaard-Nielsen et al. [11] values for mungbean were higher compared to amaranth, revealed that legumes in intercrops are greatly affected indicating that mungbean was more competitive than and oppressed by the cereal component. This is amaranth in mixture with maize. In the present study, we especially evident with short-straw legume varieties. found that variation in k values was less in Moreover, when legume had a very strong negative effect maize:amaranth intercropping system. But, when the on the yield of cereals in intercrops, the negative effect density of mungbean was decreased in maize:mungbean was even greater at increased legume densities. The intercropping, competition among the plants to be against reason that intercrops in certain conditions have no maize, while it was in favor of mungbean (Table 3). It advantages over sole stands is the strong competition of seemed that mungbean more sensitive to intraspecific legumes with cereals. Doubling the density of cereal than interspecific competitions. Ghosh [4] reported that in increased the competitiveness of cereal intercropped with his study the k value was below one, which indicates that legume and the decrease in cereal yield was less intense, there was a yield disadvantage. Anderson et al. [9] compared with lower cereal densities. One of the reasons showed that had the competitive impact on both for decreased yields of cereals intercropped with legume pea and rape during the first half of the growing season. was the formation of considerably smaller grains in the They suggested that it is likely that size-related traits normal condition, when cereal was lower in height than resulting in an early growth advantage were the basis for intercrops. Hauggaard-Nielsen et al. [11] stated that this competitive dominance. Size asymmetric competition legumes exert strong pressure on cereals in the second between species tends to compound such as initial size half of the vegetation period, which is the time of grain advantage, so initial Differences in size may explain the formation. In a dry growing season, when legume was increasing competitive impact of barley towards its lower in height than intercrops with cereals, cereals were companion crops throughout most of the cropping remarkably more competitive than legume and there was season. This suggests the possibility of influencing the no considerable decrease in the 1000-seed weight of grain.

681 Am-Euras. J. Agric. & Environ. Sci., 10 (4): 675-683, 2011

On the other hand, assumptions that intercrop economics of production [8]. Therefore, when IA values components compete only partially for the same plant were positive, indicate that the intercropping system of growth resource. Varying density and relative frequency proportion mixtures had the economic advantage. when intercropping can be used as specific “regulators” Whereas, the mixture which had negative values, showed when specific intercrop objectives such as increased an economic disadvantage [5]. Also, founded that forage competitiveness towards weeds or specific grain yield legumes sole cropping gave the highest net income composition are desired [17]. Also, for aggressivity index followed by legume-cereal intercropping and cereal sole Banik et al. [8] and Ghosh [4] Reported that in cropping, respectively. But, cereal sole cropping, groundnut:maize intercropping system, the Aggressivity however, are less favored in cropping systems without of groundnut was negative; thus, it is considered as the use of chemical inputs. Legume-cereal intercropped less-dominant crop in the system. Associated maize was performance resulted in an intermediated net income and the dominant crop as measured by the positive value of is regarded as a better safeguard compared to sole aggrresivity. cropping [11]. Our results showed that about 37%

(AYLmungbean = + 1.37) increase in yield of mungbean but, CONCLUSIONS 0.06% (AYL = – 0.06) decrease in yield of maize in maize:mungbean intercropping system (75:25 ratio), when The present study concludes that intercropping of compared to their sole crop yields. The magnitude of maize with amaranth and mungbean in different planting mungbean AYL that is greater than amaranth AYL ratios had influenced on forage yield, competition indicated that mungbean was more resistant to yield loss between species and economics advantages as compared than amaranth in intercropped with maize. The maize AYL to sole cropping of the each crop. The maize:amaranth had positive values in maize:amaranth intercropping at all mixture and the maize:mungbean mixture had a best maize proportion (Table 4), indicating an advantage of intercropping total forage yield and economic intercropping over sole stands. In maize:mungbean advantageous, respectively. Furthermore, mungbean intercropping system, the yield loss of maize (AYL = – intercropped with maize was more competitive than 0.04 and – 0.06) compensated by the yield gain of the amaranth with maize. Therefore, maize was the dominant mungbean species when grown in mixture. In contrast, species in maize:amaranth mixture at all the planting ratios. although the partial AYL of maize, was positive in Yield of all maize intercropping were less than it was in maize:amaranth intercropping system (75:25), but this monocropping. However, results obtained from could not compensate the yield loss of the associated competition indices and LERs of the maize:amaranth and species (amaranth) in mixture, indicating a disadvantage maize:mungbean mixtures indicated a significant of intercropping (AYL negative). According to Banik et advantage from maize intercropping than the sole al. [8] and Banik et al. [15], the AYL index gave more cropping system. accurate information than the other indices on the inter- and intra-specific competition of the component REFERENCES crops and the behavior of each species involved in the intercropping systems. Thus, quantification of 1. Vandermeer, J., 1989. Ecology of intercropping. yield loss or grain due to association with other species Cambridge University Press, Cambridge UK., pp: 237. or the variation of the plant population could not be 2. Lithourgidis, A.S., I.B. Vasilakoglou, K.V. Dhima, obtained through partial LERs, whereas partial AYL C.A. Dordas and M.D. Yiakoulaki, 2006. Forage yield shows the yield loss or grain by its sign and as well as its and quality of common vetch mixtures with and value. in two seeding ratios. Field Crops Res., The intercropping advantage (IA) confirmed that all 99: 106-113. mixtures had positive values, except maize:amaranth in 3. Mucheru-Muna, M., P. Pypers, D. Mugendi, 75:25 ratio, which showed definite economic advantages J. Kungu, J. Mugwe, R. Merckx and B. Vanlauwe, compared to the sole cropping systems. The highest IA 2010. A staggered maize-legume intercrop values was obtained in maize:mungbean at 75:25 ratio (+ arrangement robustly increases crop yields and 89.09). In fact, the ultimate considerations for selection of economic returns in the highlands of Central Kenya. the best intercropping system are the advantages and Field Crops Res., 115: 132-139.

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4. Ghosh, P.K., 2004. Growth, yield, competition and 14. Clark, K.M. and R.L. Myers, 1994. economics of groundnut/cereal fodder intercropping Intercrop performance of pearl , Amaranth, systems in the semi-arid tropics of India. Field Crops Cowpea, Soybean and Guar in response to planting Res., 88: 227-237. pattern and Nitrogen Fertilization. Agron. J., 5. Dhima, K.V., A.S. Lithourgidis, I.B. Vasilakoglou and 86: 1097-1102. C.A. Dordas, 2007. Competition indices of common 15. Banik, P., A. Midya, B.K. Sarkar and S.S. Ghose, 2006. vetch and cereal intercrops in two seeding ratio. chickpea intercropping systems in an additive Field Crops Res., 100: 249-256. series experiment: Advantages and weed smothering. 6. Hiebsch, C.K., F. Tetio-Kagho, A.M. Chirembo and Eur. J. Agron., 24: 325-332. F.P. Gardner, 1995. Plant density and soybean 16. Ghaley, B.B., H. Hauggaard-Nielsen, H. Hogh-Jensen maturity in a soybean-maize intercrop. Agron. J., and E.S. Jensen, 2005. Intercropping of wheat and 87: 965-969. pea as influenced by nitrogen fertilization. Nutr. Cycl. 7. Mushagalusa, G.N., J.F. Ledent and X. Draye, 2008. Agroecosys., 73: 201-212. Shoot and root competition in potato/maize 17. Hauggaard-Nielsen, H., M. Gooding, P. Ambus, intercropping: Effects on growth and yield. Environ. G. Corre-Hellou, Y. Crozat, C. Dahlmann, A. Dibet, Exp. Bot., 64: 180-188. P. Fragstein, A. Pristeri, M. Monti and E.S. Jensen, 8. Banik, P., T. Sasmal, P.K. Ghosal and D.K. Bagchi, 2009. Pea-barley intercropping for efficient symbiotic

2000. Evaluation of mustard (Brassica compestris N2-fixation, soil N acquisition and use of other Var. Toria ) and legume intercropping under 1:1 and nutrients in European organic cropping systems. 2:1 Row-Replacement Series Systems. J. Agron. Crop Field Crops Res., 113: 64-71. Sci., 185: 9-14. 18. Midya, A., K. Bhattacharjee, S.S. Ghose and 9. Andersen, M.K., H. Hauggaard-Nielsen, J. Weiner P. Banik, 2005. Differed seeding of blackgram and E.S. Jensen, 2007. Competitive dynamics in (Phaseolus mungo L.) in (Oriza sativa L.) field on two- and three-component intercrops. J. Appl. Ecol., yield advantages and smothering of weeds. J. Agron. 44: 545-551. Crop Sci., 191: 195-201. 10. Lauk, R. And E. Lauk, 2009. Dual intercropping of 19. Hauggaard-Nielsen, H., M.K. Andersen, common vetch and wheat or , effects on yields B. Jornsgaard and E.S. Jensen, 2006. Density and and interspecific competition. Agron. Res., 7: 21-32. relative frequency effects on competitive 11. Hauggaard-Nielsen, H. And E.S. Jensen 2001. interactions and resource use in pea-barley Evaluation pea and barley cultivars for intercrops. Field Crops Res., 95: 256-267. complementarity in intercropping at different levels of 20. Li, L., C. Tang, Z. Rengel and F.S. Zhanf, 2004. soil N availability. Field Crops Res., 72: 185-196. Calcium, Magnesium and micro element uptake as 12. Banik, P. and D.K. Bagchi, 1996. A proposed index for affected by phosphorus sources and interspecific assessment of row-replacement intercropping root interaction between wheat and chickpea. system. J. Agron. Crop Sci., 177: 161-164. Plant Soil, 261: 29-37. 13. Agegnehu, G., A. Ghizaw and W. Sinebo, 2006. Yield performance and land-use efficiency of barley and faba bean mixed cropping in Ethiopian highlands. Eur. J. Agron., 25: 202-207.

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