Identification of Iron Deficiency-Induced Chlorosis Tolerant Lines from Wild Rice Germplasm

The cultivation of transplanted rice has led to depletion of groundwater levels in many parts of the world. Direct-seeded rice under aerobic conditions is an alternative production technology that requires much less water. However, under aerobic conditions, iron in the soil is oxidized from ferric to ferrous, which is not easily available for rice, resulting in iron deficiency-induced chlorosis (IDIC) and a drastic reduction in seed yield. Cultivated rice genotypes have limited variations for IDIC tolerance, therefore, wild Oryza germplasm could be a better source for IDIC tolerance. In this study, 313 Oryza accessions were evaluated for IDIC tolerance at the tillering stage under aerobic conditions using IDIC rating, SPAD value, and iron content in leaves. Based on these parameters, twenty IDIC tolerant lines were selected. These 20 lines exhibited no chlorosis, high SPAD values, and iron content, while 8 cultivated controls showed mild to high chlorosis symptoms and low SPAD and iron content. In a subsequent year, the selected lines were evaluated again to confirm their tolerance, and they exhibited similar levels of tolerance. These accessions may be useful for developing IDIC-tolerant cultivars for aerobic rice cultivation, and future study to understand the molecular mechanism of IDIC tolerance in rice.