Physiological and Anatomical Basis of Differential Tolerance to Soil Flooding of Lotus corniculatus L. and Lotus glaber Mill

Abstract

Lotus corniculatus L. and Lotus glaber Mill. are warm-season legume species adapted to many kinds of environmental stress, including flooding conditions, whereas other popular forage legumes, like alfalfa or white clover, cannot thrive. This study evaluates the relationship between root aerenchyma, water relations and leaf gas exchange and the differential tolerance to soil flooding of L. corniculatus and L. glaber. Adult plants of these species, established independently in grasslands mesocosms, were subjected to 40 days of early spring flooding at a water depth of 6 cm. Both species presented constitutive aerenchyma tissue in the roots. Under flooding conditions, this parameter was 26.2% in L. glaber and 15.3% in L. corniculatus. In addition, flooded plants of L. glaber presented a leaf biomass 47.5% higher above water while L. corniculatus showed a leaf biomass 59.6% lower in the same layer, in comparison to control plants. Flooded plants of L. glaber maintained the stomatal conductance (g s ) and transpiration rate (E) for 25 days, although these parameters reduce slightly to 40À60% in comparison to controls after 40 days of flooding. In this species, a reduction in photosynthesis (A) in flooding conditions was detected only on the last day of measurement. In L. corniculatus, the same parameters (g s , E and A) were affected by flooding since day 18 of treatment, and values reached 25À40% in comparison to control plants after 40 days of flooding. Flooding did not affect above-ground biomass in L. glaber; while in L. corniculatus, above-ground biomass was 35% lower than in control plants. Our results confirmed that L. glaber is more able to cope with flooding stress than L. corniculatus, even in the presence of natural competitors. On the whole, this experiment provides information that can aid in the identification of anatomical and physiological parameters associated with flood-tolerance in this forage legume species, with economic potential for the agricultural areas subject to periodic flooding.

Leaf plasticity in successive selection cycles of 'Saracura' maize in response to periodic soil flooding

“…However, other authors did not observe changes in the amount and size of stomata in leguminous from flooded regions (Lotus corniculatus L. and Lotus glaber Mill.) (Striker et al, 2005), which shows that the stomata changes are not very clear in all of the species exposed to this kind of stress. Many studies have described that the ability of roots in absorbing water is affected by the lack of oxygen in flooded environments (Dell'Amico et al, 2001;Tournaire-Roux et al, 2003).…”

“…(Striker et al, 2005), which shows that the stomata changes are not very clear in all of the species exposed to this kind of stress. Many studies have described that the ability of roots in absorbing water is affected by the lack of oxygen in flooded environments (Dell'Amico et al, 2001;Tournaire-Roux et al, 2003). Higher functionality in the last cycles can favor higher water use efficiency, because they can get carbon dioxide gas with a smaller area of stoma opening, thus avoiding greater loss of water.…”

“…The distance between vascular bundles can be related to the more efficient transportation and distribution of carbohydrates and water to the mesophyll cells. Studies on parallel vascular bundles in grasses showed that C4-type species present smaller distance between the vascular bundles than C3 type (Ueno et al, 2006). Such characteristic, present in C4-type plants, conveys higher ability in photosynthate translocation and higher water distribution in environments with water restriction and high temperatures (Sage, 2004).…”

“…Control and C1, C3, C7 and C9 were statistically similar to each other, and corresponded to the highest averages. Although flooding may lead to water deficit (Dell'Amico et al, 2001;Tournaire-Roux et al, 2003), the last selection cycles showed thinner epidermis and cuticle. This modification may be due to low requirement of those selection cycles in retaining water, since they are probably more adapted and therefore establish a greater water conductivity in the flooded environment.…”

Effect of Nitrogen Nutritional Statuses and Waterlogging Conditions on Growth Parameters, Nitrogen Use Efficiency and Chlorophyll Fluorescence in Tamarillo Seedlings

“…Flooding has some severe consequences on plant growth and its survival strategies (Phukan et al, 2016). In this sense, the following physiological disorders have been reported under waterlogging: a lower plant growth (Aldana et al, 2014), leaf chlorophyll content (Rao and Li, 2003), and total plant dry weight (Florez-Velasco et al, 2015), as well as changes in the plant water status (Striker et al, 2005). Also, waterlogging can alter biomass allocation in plants (Wu et al, 2015) Plant nutritional status can significantly influence the plant acclimation to stressful environmental conditions.…”