Effects of Photoperiod and Drought on Flowering and Growth Development of Protein-Rich Legumes under Atlantic Environments

Legumes have an important role in European agriculture. They assimilate N2 to sustainably support maximum crop growth, in turn providing high-protein food for human consumption and livestock feed. However, the extent of the area for legume cultivation in Europe has declined due to the lower economic competitiveness of legumes in relation to other crops, particularly of cereals and oilseed. To increase yields, there is a need to increase the genetic diversity of legumes in terms of adaptation to environmental stresses. We attempted to address this by conducting field and controlled experiments under drought vs. nondrought and different photoperiod conditions. The current study identified the physiological and agronomic traits correlated with productivity and quality performance in five economically important grain legume species (Pisum sativum, Phaseolus vulgaris, Cicer arietinum, Lupinus spp., and Vicia faba). In all species, the days to flowering and seed yield were affected by temperature and photoperiod. For cool-season legume species, long-day photoperiods were favorable and days to flowering was negatively correlated with the average air temperature. For the warm-season legumes, short-day photoperiods and warm temperatures were favorable. Under drought stress, the C/N balance, leaf nutrient (Ca, Fe, and K) concentrations, and yield were significantly reduced, contrary to Zn accumulation, and this information may contribute to improving our understanding and ability to develop sustainable growth. Based on our results, we conclude that the drought-tolerant and photoperiod-insensitive legume genotypes identified in this study constitute valuable starting materials for future programs aimed at improvement of legume productivity at a global/regional scale, which helps to strengthen the competitiveness and economic growth of legumes for European farmers.