On-farm management and participatory evaluation of pigeonpea (Cajanus cajan [L.] Millspaugh) diversity across the agro-ecological zones of Benin Republic

Background: Pigeonpea is a multipurpose food legume that contributes to food security in Benin. However, its production declined and some landraces are being threatened with disappearance. For establishment of conservation and breeding programs previous ethnobotanical surveys on pigeonpea were done in Benin but restricted to south and central regions. Knowing that pigeonpea is also grown in northern Benin, and that the varieties cultivated in this region can show agronomic performances, it is therefore important to evaluate the diversity of this legume in this region. However, an exhaustive documentation of pigeonpea diversity grown in Benin Republic are necessary for effective breeding and conservation programs. Therefore, this study aimed to document genetic diversity of pigeonpea, across the agro-ecological zones of Benin Republic for its promotion and valorization. Methods: 500 producers of pigeonpea belonging to thirteen sociolinguistic groups were selected through 50 villages. Data were collected using methods and tools of participatory research appraisal. Folk nomenclatures, taxonomy of pigeonpea and seed system were investigated. The distribution and extent of pigeonpea landraces were evaluated using Four Square Analysis method. A comparative analysis of pigeonpea uses categories, production systems, pigeonpea production constraints, famers’ preference criteria and participative evaluation for existing landraces across agro-ecological zones was done. Result: Folk nomenclature and taxonomy were mainly based on seed coat colour and size. Seven pigeonpea use category were recorded including sacrifice, grain processing and fertilization. The results showed that pigeonpea seed system is informal. Based on seed characteristics, fifteen landraces were recorded with seven new landraces. The Sudano-Guinean zone contained the highest number (11) of landraces. The average number of landraces per village was 2.7. A high rate of landraces threatened with disappearance was observed across the ecological zones. Ten constraints are known affecting pigeonpea production in Benin with pests and diseases as the most important in all agro-ecological zones. This study revealed that pigeonpea cultivation is increasing in the Sudanian zone. Varieties to be produced must be selected on the basis of 11 criteria among them precocity and resistance to pests and diseases, in the three ecological zones and adaptability to any type of soil in the Sudanian zone were the most important. The participatory evaluation revealed the existence of a few performing cultivars. Conclusions: Our results show that to implement a pigeonpea genetic conservation program in Benin, it would be necessary to take into account the diversity, production constraints and criteria of varietal preference, which varied according to agro-ecological zones. In situ and ex situ conservation strategies are important to preserve pigeonpea landraces. Morphological and molecular characterizations of identified cultivars are highly recommended to help select suitable varieties for breeding programs.