Abstract
Upland rice production in sub-Saharan Africa is highly influenced by Aluminum toxicity. NERICA4 as one of the interspecific progenies between O. sativa and O. glaberrima has been extended for vast rainfed area in Africa. However, its response to aluminum in acid soil is not well understood. Therefore, using a completely randomized design, response mechanism of NERICA4 to aluminum toxicity was examined. NERICA4 along with susceptible (Kasalath) and tolerant (Nipponbare) control varieties were exposed to aluminum toxicity (200 μM Ca2+, 100 μM Al3+ and 200 μM Ca2+ or 200 μM Al3+ and 200 μM Ca2+ or 0, 0.6, or 1.2 mM AlCl3) at root developmental and seedling stages. NERICA4 was highly responsive to Al stress. At 1.2mM treatment it was characterized by a lower decrease in root elongation compared to Kasalath from control however, higher than Nipponbare. Additionally, NERICA4 absorbed significantly low Al ions to root and shoot compared to Kasalath but higher than that of Nipponbare. This might have caused a low reduction in shoot biomass of NERICA4 and Nipponbare (12%) compared to Kasalath (17%), relative to control, suggesting the tolerance in NERICA4. The degree of root staining reflecting aluminum absorption was stronger in the susceptible cultivar and weaker in NERICA4, signifying that NERICA4 may inhibit aluminum absorption in the roots. In conclusion, our study will have a major impact in the adoption of NERICA4 rice cultivar in upland rice growing regions of Africa with frequent soil-acid conditions.
