Responses of Soybean to Oxygen Deficiency and Elevated Root-zone Carbon Dioxide Concentration

Abstract

Root flooding is damaging to the growth of crop plants such as soybean (Glycine max L.). Field flooding for 3 d often results in leaf chlorosis, defoliation, cessation of growth and plant death. These effects have been widely attributed solely to a lack of oxygen in the root-zone. However, an additional damaging factor may be CO(2), which attains levels of 30 % (v/v) of total dissolved gases. Accordingly, the effects of root-zone CO(2) on oxygen-deficient soybean plants were investigated in hydroponic culture. Soybean plants are shown to be very tolerant of excess water and anaerobiosis. No oxygen (100 % N(2) gas) and low oxygen (non-aerated) treatments for 14 d had no effect on soybean survival or leaf greenness, but plants became severely chlorotic and stunted when the roots were exposed to no oxygen together with CO(2) concentrations similar to those in flooded fields (equilibrium concentrations of 30 %). When root-zone CO(2) was increased to 50 %, a quarter of soybean plants died. Those plants that survived showed severe symptoms of chlorosis, necrosis and root death. In contrast, rice (Oryza sativa L.) plants were not affected by the combination of no oxygen and elevated root-zone CO(2.) A concentration of 50 % CO(2) did not affect rice plant survival or leaf colour. These results suggest that the high susceptibility of soybean to soil flooding, compared with that of rice, is an outcome of its greater sensitivity to CO(2).

Intervalo hídrico ótimo no perfil explorado pelas raízes de feijoeiro em um latossolo sob diferentes níveis de compactação

“…Em períodos de maior umidade, os solos compactados, por possuírem menor quantidade e continuidade de poros, podem apresentar deficiência de oxigênio para as raízes das plantas (Lapen et al, 2004). Além da falta de oxigênio (Drew, 1983), o aumento na concentração de CO 2 no ambiente radicular afeta as plantas (Boru et al, 2003;Greenway et al, 2006 . Essa camada limitante, ocasionada pela compactação, também apareceu na área escarificada, o que pode ser atribuído à dificuldade de coleta de amostras com estrutura preservada em condições de solo mobilizado; isso normalmente induz a coleta nas zonas menos alteradas, as quais não sofreram desestruturação pela haste do escarificador devido à sua alta resistência ou compactação e, dessa forma, isso se reflete em maior densidade.…”

Hypoxia-Responsive Root Hydraulic Conductivity Influences Soybean Cultivar-Specific Waterlogging Tolerance

“…Some researchers have indicated that high carbon dioxide levels [30] [31] [32] or impaired mineral diffusion [33] in the rhizosphere are key factors influencing crop waterlogging injury. Additionally, low partial pressure of oxygen around the roots [17] [34] should be considered an important factor in the development of waterlogging injury in soybean plants.…”

Growth characteristics of 2-year-old cultivars in Korean ginseng (Panax ginseng C. A. Meyer) conditioned artificial wet injury

“…습해는 주로 뿌리에서 나타나며, 수분 과잉이 지속됨에 따라 뿌리에서 산소부족과 환원성 유해물질 등이 집적되고 (Park et al, 1999), 이것이 뿌리의 호흡을 저해하여 수분이나 양분의 흡수 및 이동을 억제하고 결국 양분 부족 등의 이유로 작물 체의 생장량이 감소된다 (Boru et al, 2003). 였다 .…”