Abstract
ABSTRACT Common bean (Phaseolus vulgaris L.) is an important source of protein and carbohydrates, besides being rich in several mineral nutrients. In a flooding situation, the low availability of oxygen may result in hypoxia or anoxia condition. Therefore, this study aimed to evaluate the responses of the common bean cultivar BRSMG-Uai subjected to hypoxia in different phenological phases, analyzing its responses in terms of growth, productivity, carbon and nitrogen metabolism. Thus, seeds of common beans were germinated and when the seedling reached growth stage V1, they were transferred to plastic boxes containing 40L of nutritive solution with steady aeration. Distinct series of plants were exposed to air-restriction on their roots for nine days, in three different phenological phases V3/V4, R6 and R7. Samples were collected for biochemical and growth analyses in a completely random design (n=6). The plants subjected to low availability of oxygen presented a reduction in bean number, displaying the greatest loss in productivity in V3/V4, conferring the highest sensitivity to hypoxia in this phase. On the other hand, there was an increase in sugar concentration in leaves, and it was also possible to observe an increase in hydrogen peroxide in leaves and roots, concomitant with a decrease in superoxide dismutase activity in all phenological phases. There was also an increase in ascorbate peroxidase activity in roots in R6, as well as in nitrate reductase activity. We conclude that the cultivar BRSMG-Uai presents sensitivity to low oxygen availability, and the phenological phaseV3/V4 is the most critical for it.
Highlights
Global climate changes tend to worsen problems related to rain patterns in many regions in the world and this may probably lead to increase floods and soil waterlogging (Debortoli, 2017; Hirabayashi et al, 2013)
For the best of our knowledge, there are no studies focused on the identification of the most critical period of common bean to low availability of oxygen and there are no reports up to date for the cultivar BRSMGUai about its responses to hypoxia during its different phenological phases
The effect of hypoxia by suspension of aeration in the hydroponic cultivation was evaluated for this cultivar through variables that perform crucial roles in growth, grain production, carbohydrate metabolism, antioxidant metabolism and nitrate assimilation (NO3-)
Summary
Global climate changes tend to worsen problems related to rain patterns in many regions in the world and this may probably lead to increase floods and soil waterlogging (Debortoli, 2017; Hirabayashi et al, 2013). In the roots, there is a lower cell energy production, restricting the absorption of water and nutrients; the inhibition of aerobic respiration results in an increase of lactate and ethanol in the cell cytosol (Perez-Jimenez, 2017; Dumont; Rivoval, 2019). In this case, the enzyme nitrate reductase (NR), which is in charge of reducing nitrate into nitrite, may become an alternative pathway to act in the regeneration of the reducing power NAD+ (Fukao et al, 2019)
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