Legume production in semi-arid areas: Comparative study of the physiology of drought tolerance in common bean (Phaseolus vulgaris L.) and mungbean (Vigna radiata (L.) Wilczek)

• Main Author: Bourgault, Maryse
• Format: Dissertation
• Language: English
• Subjects: agriculture, agronomy; biology, plant physiology
• ISBN: 0494568941; 9780494568941

Context. Approximately one billion people live in semi-arid and arid regions, and of these about 40% live on less than a dollar a day. Legumes crops are an important component of sustainable agriculture, but they are often grown under intermittent or terminal droughts. Thus, improving drought tolerance in legumes has the potential to improve food security and sustainability of agricultural systems.
Objective. This study compares the response of two legume crops, common bean (Phaseolus vulgaris L.) and mungbean ( Vigna radiata (L.) Wilczek), to water stress conditions under field and controlled-environment conditions.
Methods. Field experiments were conducted in the Fergana valley, Uzbekistan, and controlled environment experiments were conducted at the Macdonald campus of McGill University, Ste-Anne-de-Bellevue, Canada, and at the Hermitage Research Station in Warwick, Australia.
Results. Our results demonstrate that alternate furrow irrigation maintains yields, yet decreases water applied by 25%. In addition, mungbean showed the highest yields in the moderate deficit irrigation treatment in 2003 and severe deficit irrigation treatment in 2004 under field conditions in Uzbekistan. Common bean also showed a capacity to maintain yields under moderate deficit irrigation in both years. Further characterization of the legume responses to water deficit stress in controlled-environment experiments indicated that mungbean's higher tolerance is attributable to higher transpiration efficiency, a more conservative water use in the vegetative stage, and a higher root-to-shoot ratio when compared to common bean. Root characteristics might also play an important role, although we have observed a large variability between genotypes. An additional field experiment in Uzbekistan demonstrated that an early maturing Canadian soybean cultivar could be grown after the harvest of winter wheat, and thus contribute to food security. It has also been demonstrated that inoculation with rhizobia increases yields of soybean.
Conclusion. Legumes can be grown after the harvest of winter wheat in Uzbekistan, and mungbean is better adapted to drought than common bean. Short season soybean could also be produced in this cropping sequence.