Legumes Cultivars for Stress Environments

Abstract

Predictions of future climates indicate big changes in temperature, rainfall pattern, humidity and moisture regimes over the next 50 years. These climate changes will greatly influence the entire cropping system in all continents and affect the performance of cultivars of different field crops including legumes. Future legume cultivars will need to maintain or even to be higher yielding under the expected climate changes. The most important way to increase the grain yield of cool season food legumes per unit area under stress environments will be the development of cultivars with resistance to multiple abiotic stresses in the context of sustainable integrated legume production, insect and pest management, nutrients management and irrigation use if available. One option with potential in these more stressful environments is to shift the legume sowing time from spring to autumn or winter to escape terminal drought. More emphasis during cultivar development will need to be placed on drought resistance mechanisms viz.: (I) morphological mechanisms like drought escape through early phenology, drought avoidance by maintaining water uptake and reducing water loss, matching water use and availability by increasing phenotypic flexibility etc. (II) physiological mechanisms improving water use through improved cell and tissue water conservation, antioxidant defense, cell membrane stability, plant growth regulator alterations and increased use of compatible solutes; and (III) molecular mechanisms viz. aquaporins, stress proteins, signaling and drought tolerance. This chapter is aimed at highlighting morphological and some physiological characteristics of stress resistant cultivars as well as stress avoidance in lines with early phenology and drought-avoidance root characteristics in chickpea, grass pea, lentil, lupines, faba bean and pea. Additionally cold tolerant cultivars and lines have been bred for early winter and autumn sowing. Cicer L., Lathyrus L., Lens Mill. and Lupinus L. are generally relatively drought resistant genera, while Pisum L. and Vicia L. are generally regarded as drought sensitive genera. Among these genera, pea and chickpea have the longest history of research for more than a century in Austria and India, respectively. Many drought resistant cultivars and lines have been reported in the literature, but few have been tested for field performance in their target areas. Recently studies have focused on breeding for stress tolerance in the cultivated species and for the introgresion of important alleles from wild species. Wild relatives especially in the primary and secondary gene pools should be taken into account in short- and medium-term breeding goals. Gene pyramiding for multiple resistances to abiotic and biotic stresses should be intensified via marker assisted selection using molecular approaches.