Tropentag 2006. University of Bonn, October 11-13, 2006. Conference on ... and 2006 in the Soconusco Region of Chiapas, Mexico, with special attention to: i).
Tropentag 2006 University of Bonn, October 11-13, 2006
Conference on International Agricultural Research for Development
Effects of Legumes Intercropped in Mango Orchards in the Soconusco, Chiapas, Mexico FRANCISCO MARROQUÍN AGREDA1, JÜRGEN POHLAN2, MARC J. J. JANSSENS3 1University
of Bonn, Institute of Horticulture, Germany Colegio de la Frontera Sur (ECOSUR), Manejo Integrado de Plagas, México 3University of Bonn, Institute of Horticulture, Germany 2El
Abstract Fruit orchards are the principal agricultural crops that generate sustainable economic income to the farmers of the Soconusco Coast, Chiapas. These areas integrate 23000 ha of mango crops cultivated with high chemical inputs, open soil management and flowering stimulation. Outcome of this management is agro-ecological unbalance causing high costs, irregularly yields and requiring quarantine measures for commercial mango orchards in order to prevent infestation with fruit flies. In order to alleviate these problems, the principal objectives of this research work were centred around the integration of soil cover with Cajanus cajan, Phaseolus vulgaris Genotype “Frijol de Vara” and Phaseolus acutifolius Genotype “Frijol Escumite” and their effects on fruit development, yield and quality. Since 2005, the effects of different intercropping systems with leguminous crops were integrated in two typical mango fruit regions of the Soconusco. Three leguminous crops i.e. Cajanus cajan, Phaseolus acutifolius and Phaseolus vulgaris were evaluated as cash and trap crops. The two trials are each 168×56m large and encompass four intercropping management systems (traditional, 3 combinations maize + legumes), laid out in a split-splot design with four repetitions. In each experimental unit, growth and yield parameters of intercropped legumes and their interactions with the yield parameters of the companion fruit trees were determined. The experiments are located in San Felipe (15o16´628´´ north latitude, 92o37´479´´ west longitude and 128 m.a.s.l.) and in Cintalapa (15o19´431´´ north latitude, 92o37´369´´ west longitude and 184 m.a.s.l.). The results demonstrate the potential of leguminous crops to improve the ecological stability in traditional fruit orchards. Cajanus cajan achieved the highest yield of dry biomass (11.04 t/ha) and the treatment with Phaseolus vulgaris produced 0.73 t/ha. The soil cover integrating leguminous crops increases soil fertility and benefits insect populations. Mango yield was highest in combination with Phaseolus acutifolius (9.13 t/ha) and Cajanus cajan (7.42 t/ha). Additionally, more abundance and diversity of insect population was observed when intercropping leguminous crops between the mango trees. Keywords: Chiapas, fruit orchards, insect population, legumes, mango yield, Soconusco, soil cover
1. Introduction Legume crops intercropped in tropical fruit tree production may act as important cash and trap crops. Apart from fixing atmospheric N2, recycling nutrients and improving soil nutrient availability, they also help reducing erosion risks and organic matter losses (Lehmann et al., 2000). Moreover, legume cover crops may also attract insects through attractive blossoms, which in turn favour the pollination of mango. In the Soconusco, the fruit-growing extends actually over 60000 ha and is characterized by high diversity home gardens on the one hand, and by export orientated planting of mangoes (Mangifera indica), bananas (Musa acuminata, M. paradisiaca), papaya (Carica papaya) and rambutan (Nephelium lappaceum) on the other hand (Vanderlinden et al., 2004; Pohlan et al., 2000). Both types of fruit cropping systems are characterized by intensive mechanical and chemical cultivation of soil and by indiscriminate use of chemical products for weed and insect control. This combination has generated temporary high incidence of trips populations, recurrent problems with fruit flies and hence, high production costs in mango plantations (23000 ha). These agro-ecosystems became unstable. In spite of all applied technologies, the average yield of the predominant variety Ataulfo, is approximately 5 t ha-1, which is lower than the national average (9 t ha-1) and the world average (7 t ha-1) (FAOSTAT). The interesting and very important question under these conditions is to find new strategies for soil conservation and soil fertility, for balancing and diversifying both the natural insect fauna and the weed flora, and for integrating cash and trap crops into the fruit areas (Pohlan, 2002; Pohlan and Borgman, 2000; Gamboa and Pohlan, 1997; Nestel and Altieri, 1992). This awakened our interest for conducting field experiments between 2005 and 2006 in the Soconusco Region of Chiapas, Mexico, with special attention to: i) Evaluate the effects of different intercropped crops on the fruit development, ii) Analyze the influence of intercropped crops on the yield of mango and ii) Determine the potential of different intercropping systems and biomass production.
2. Materials and Methods The investigations were started in the first rainy season in 2005 in two typical mango orchards in the Soconusco, Chiapas, Mexico. The experiments are located in San Felipe (15o16´628´´ north latitude, 92o37´479´´ west longitude and 128 m.a.s.l.) and in Cintalapa (15o19´431´´ north latitude, 92o37´369´´ west longitude and 184 m.a.s.l.). In this region the daily average temperature oscillate between 26.5 and 28.7 ºC, and the annual precipitations between 2500 and 3200 mm. The predominant soils in the study area are Acrisols associated with Andosols, as well as Lithosols and Regosols. The experimental design consisted of a split-plot system with a total area of 9408m². Each experiment (168 x 56m) includes eight intercropped treatments, arranged as a strip design with six repetitions, each subplot measuring 14 x 14m (fig. 1). The two experiments were installed in commercial mango fruit orchards with more than 5ha. The fruit plantation in Cintalapa was planted in the year 1995 with cv. Ataulfo at a spacing of 14 x 14m. In San Felipe, the mango orchard was planted in 2000 at a spacing of 25 x 25m. This arrangement allows comparing plant and insect biodiversity in the
traditional fruit cropping system without permanent soil cover with alternative experimental fruit systems intercropped by cash and trap crops. Since 2005, the effects of rotating different intercropping systems with maize (1° cycle) and leguminous crops (2° cycle), on weed abundance, biomass and diversity and also on growth and yield parameters of the corresponding annual crops and fruit species were evaluated weekly (Table 1). Table 1. Intercropped treatments in the fruit experiments during two crop cycles Factor A First crop cycle intercropped with: a1 maize (Zea mays) a2 maize + pumpkin (Cucurbita maxima) Factor B Second crop cycle intercropped with legumes: b1 Phaseolus acutifolius Genotype “Frijol Escumite” b2 Cajanus cajan (Pigeon Pea) b3 Phaseolus vulgaris Genotype “Frijol de Vara” b4 Without legumes (only maize straw fallow)
Figure 1. Experimental design of first and second crop cycles The present investigation reports the results of the 2° cycle of annual crops and their effects on fruit quality and yield in intercropped mango. The legumes were sown after maize harvest between the maize rows (fig. 1). Each treatment is divided in six sub-plots or repetitions. In
each repetition, one evaluation point for weed and crop measurements were fixed. All data were tested for normal distribution. Taking succession as one factor and legumes crops as a second factor, analyses of variance (ANOVA) were performed and means separated with the LSD .05 statistics. All statistical analyses were performed with the help of the SPSS 11.0 and “Statgraphics Version 5.1” packages.
3. Results and Discussions The effects of the intercropped legumes on the suppression of weeds and their biomass production are clear at the end of the 2nd cycle (December 2005), whereby dicotyledonous weeds dominated monocotyledonous weeds. The weed biomass was smallest under pigeon peas, where pigeon pea compete strongly and achieved the highest yield of dry biomass (11.04 t/ha), themselves the treatment with Phaseolus vulgaris produced only 0.73 t/ha. The vigorous growth of the legumes after maize growing resulted in very strong suppression of weeds, the biomass of which reached only 16.7 to 32 g m2 (fig. 2). Additionally, the soil cover integrating leguminous crops increases soil fertility and benefits insect populations. 90
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Figure 2. Effects of intercropped system on weed and soil cover biomass production in mango orchards (Cintalapa) Mango yield is influenced by ecophysiological conditions, variety and cropping methods and otherwise by the yield parameters tree density, number of panicles per tree, fruit number per panicle and fruit weight. In the Soconusco, more than 90 % of mango areas are planted to cv. Ataulfo, producing yearly approximately 5 t ha -1 in the last 10 years. The temporary inundation, caused by the hurricane Stan in San Felipe, provoked an untypical flowering of mango trees in one part of the experimental area, which was then
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removed from this analysis. The mango yield parameters in Cintalapa were strongly influenced by the type of intercropped system. The number of fruits per panicle was highest from start to end of fruit development in plots intercropped with Cajanus cajan and Phaseolus Escumite. This result can be improved by better nutrient balance and higher insect population. Similar effects were observed for number of panicles per tree. Once more, the plots with Cajanus cajan and Phaseolus Escumite have significant higher values Additionally, 120 panicles per tree were found in the traditional (commercial) treatment implying a twofold application of KNO3 as flowering stimulation (fig 3). These applications provoked also good fruits weight in plots with traditional system (fig. 4).
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Figure 3. Effects of different intercropped legume crops on the panicles per mango tree in Cintalapa
Figure 4. Effects of different intercropped legume crops on the weight of mango fruit in Cintalapa.
The significant highest mango yields in the treatments with Phaseolus Escumite (9.7 t ha -1) and Cajanus cajan (7.86 1 t ha-1), showed the importance of successful pollination, normal fruit drop and balanced nutrition of mango trees (fig. 5). It is to be hoped, that these results can encourage farmers to change their traditional fruit growing for agro-ecological systems. 200
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Figure 5. Effects of different intercropped legume crops on the mango yield in Cintalapa.
4. Conclusion Weed biomass production is influenced by different site conditions and intercropped treatments and changes during the cropping cycles from dominant monocotyledonous to dicotyledonous species. The biomass of Cajanus cajan and Phaseolus acutifolius (Frijol Escumite) and their incorporation to the ecosystem produced positive effects on the quality and yield of mango. Likewise the intercropping of mango with Cajanus cajan or Phaseolus vulgaris influences the insect diversity in these systems. Cajanus cajan presented a high resistance toward the excess of humidity during the period of hurricane Stan. This study demonstrates high potential of Cajanus cajan and Phaseolus acutifolius (Frijol Escumite) to improve sustainability of fruit orchards in the Soconusco, Chiapas. These legumes are an alternative for stable economical income, low management costs, labour opportunities during the whole year and offer additional self-consumption diet for farmer families. References Gamboa, W.; Pohlan, J.: La importancia de las malezas en una agricultura sostenible del trópico. Der Tropenlandwirt / Beiträge, 98. Jahrgang, April 1997, 117-123. Lehmann, J.; da Silva, J.P.; Trujillo, L.; Uguen, K. 2000. Legume cover crops and nutrient cycling in tropical fruit tree production. Acta Horticulturae, Number 531, 65-72. Nestel, D.; Altieri, M. A. 1992. The weed community of Mexican coffee agroecosystems: effect of management upon plant biomass and species composition. Acta Ecologica 13: 715–726. Pohlan, J. 2002. Begleitwirkungen von Unkräutern im Ökosystem Kaffee in Chiapas, Mexiko. Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz, Sonderh. XVIII, 175182. Pohlan, J.; Borgman, J. 2000. Traditionelle Praktiken der Unkrautbekämpfung in bedeutsamen Kulturen Mittelamerikas – Ursache von Verlust der Bodenfruchtbarkeit und Erosion. Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz, Sonderheft XVII, 761-768. Pohlan, J.; Borgman, J.; Gehrke Velez, M. R. 2000. Perspectives of Sapotaceae species for fruit production in the Soconusco Region, Chiapas, Mexico. Acta Horticulturae, Number 531, 45-52. Vanderlinden, Eva Johanna Maria; Pohlan, H. A. J.; Janssens, M. J. J. 2004. Culture and fruit quality of rambutan (Nephelium lappaceum L.) in the Soconusco region, Chiapas, Mexico. Fruits, Vol. 59, (5), 339-350.
