ON-FARM DIVERSITY OF FABA BEAN (Vicia faba L.) AND PRODUCTIVITY OF THE CROP IN INTERCROPPING SYSTEM WITH MAIZE (Zea mays L.) IN EASTERN ETHIOPIA

Abstract

Maize and faba bean are cultivated as both sole and intercropping systems by smallholder farmers in eastern Ethiopia. The farmers have been recently practicing intercropping of the two crops. However, productivity of the crops is low and evidence-based information is lacking on on-farm diversity of faba bean and productivity of faba bean-maize intercropping system. The general objective of this research was to investigate on-farm diversity and agro-morphological variability of farmers’ faba bean varieties and productivity of faba bean-maize intercropping system for enhanced and sustained productivity of both crops and the system. For this purpose, a survey and three field experiments were conducted in 2018 and 2019 main cropping year. The survey was undertaken to identify on-farm conserved diversity, traits and values of farmers’ faba bean varieties; and to assess the production attributes and gender roles in the production, management and conservation of farmers’ faba bean varietie. Two stratified agro-ecological zones of tepid moist mid-highland (M3) and tepid sub-humid mid-highland (SH3) were selected from the Zone. Three kebeles were selected from each agroecology. From each kebele, 12 general informants and two key informants were selected. The informants were interviewed using structured and semi-structured questionnaires, respectively. In the second study, the treatments included 21 farmers’ faba bean genotypes (13 from Ethiopian Biodiversity Institute collections from the zone, and eight from farmers’ fields in West and East Hararghe Zones).The qualitative and quantitative characteristics of the varieties were recorded to estimate the extent of morphological and agronomic variability. In the third study, the treatments consisted of one maize variety (Baate), four farmers’ faba bean varieties (Baqela Faranji, Baqela Habasha, Batte, and Gachena). The faba bean varieties were intercropped with maize in an additive design at three population densities (25%, 50%, and 75% of sole crop density) and sole maize and faba bean varieties. In the fourth study, the treatments consisted of the recommended 100% plant populations of maize (Baate) variety intercropped with 50% of the sole density of farmers’ faba bean varieties (Baqela Faranji, Baqela Habasha, Batte and Gachena) planted at three spatial arrangements (1M:1FB, 1M:2FB and 2M:2FB) and sole maize and sole faba bean varieties. All the field experiments were laid out in Randomized Complete Block Design with three replications. From the survey, eight farmers’ faba bean varieties were identified based on the names and descriptions given by farmers. The highest varietal diversity (Hꞌ = 1.35) was recorded at Gara Abdula kebele of M3 agroecology and the lowest diversity value (Hꞌ =0.81) was recorded at Obi Kutir 1 kebele of SH3 agroecology. Most farmers (94%) used informal seeds acquired from their families. Baqela Faranji was the most widely cultivated variety (33%) followed by Hadho (22%). All farmers practiced intercropping and crop rotation systems. Dabale variety gave the highest yield (1900 kg ha–1 ). Diseases (100%), weeds (89%) and land shortage (85%) were the main faba bean production constraints. Male adult and female adult family members play the greatest roles in the production and post-harvest management of the crop. In the second study, the results revealed a wide range of variations for days to flowering (38–49 days), days to maturity (110–129 days), hundred seed weight (33–95.9 g), seed yield per plant (4.98–45.31 g). The highest genotypic coefficients of variation (GCV) were observed for xix seed yield per plant (36.98%) and hundred seed weight (28.12%) and phenotypic coefficients of variation (PCV) for seed yield per plant (38.65%) and hundred seed weight (28.45%). The highest heritability coupled with a high expected genetic advance as percent of mean were obtained for hundred seed weight (97.66%) and (57.32%), seed yield per plant (91.56%) and (73.02%), and pod length (90.22%) and (26.17%), respectively. The principal components analysis showed the first three principal components accounted for 73.90% of the total phenotypic variance. The twenty-one genotypes were grouped into four clusters and the maximum distance was between clusters II and III (255.12). Results of the third study revealed that sole maize produced significantly higher aboveground dry biomass (19.11 t ha–1 ) and grain yield (6.16 t ha–1 ) than the intercropped maize. Maize intercropped with 25% of the sole faba bean produced significantly highest grain yield (5.56 t ha–1 ) than 50% and 75% density. Faba bean variety Gachena was superior to the other varieties in aboveground dry biomass (3.73 t ha–1 ) and seed yield (1.96 t ha–1 ). Land equivalent ratio showed a 22.2% yield advantage when maize and faba bean intercropped than sole-cropped. The highest gross monetary value (99318 ETB ha–1 ) and maize equivalent yield (6621.2 kg ha–1 ) were obtained from the intercropping maize with Gachena variety. Maize intercropped with faba bean resulted in a higher content of soil organic carbon (1.49%), total nitrogen (0.17%), and available P (11.86 mg kg–1 ) than maize that was sole-cropped. However, intercropped faba bean resulted in a higher soil pH value (7.66) and a higher cation exchange capacity (32.84 cmol(+)100 g soil–1 ) than the sole-cropped faba bean. It is concluded that intercropping maize with 75% plant density resulted in higher system productivity, economic return and soil nutrient status. The results of the fourth study showed that sole-cropped maize produced significantly higher grain yield (5.91 t ha–1 ) than intercropped maize (4.99 t ha–1 ). Maize intercropped with 2:2 spatial arrangements produced the highest grain yield (5.37 t ha–1 ). The 1:1 spatial arrangement was significantly superior in number of pods per plant (5.27), aboveground dry biomass (3.81 t ha–1 ), and seed yield (0.86 t ha–1 ) to the other spatial arrangements. Variety Gachena was significantly superior to the other varieties in number of pods per plant (5.49), aboveground dry biomass (3.77 t ha–1 ), and seed yield (0.88 t ha–1 ). Land equivalent ratio showed 26.8% yield advantage for 1row maize:1row faba bean spatial arrangement. The highest Gross Monetary Value (96308 ETB ha–1 ), Maize Equivalent Yield (6420.53 kg ha–1 ) and Monetary Advantage Index (17506) values were obtained from intercropping of Gachena faba bean variety with maize. A 1:1 spatial arrangement gave the maximum land equivalent ratio (1.27), Gross Monetary Value (94162 ETB ha–1 ), Maize Equivalent Yield (6277.49 kg ha–1 ) and Monetary Advantage Index (18761). Therefore, it is concluded that intercropping of Gachena faba bean variety in the 1:1 spatial arrangement with maize resulted in the highest productivity and economic advantage for farmers of the study area. Generally, Gachena faba bean variety intercropped with maize variety Baate at 75% of its sole crop population and at 1M:1FB spatial arrangement can be recommended for the farmers of the study areas of eastern Ethiopia