Mitigation of Iron Toxicity and Iron, Zinc, and Manganese Nutrition of Wetland Rice Cultivars (Oryza sativa L.) Grown in Iron‐Toxic Soil

Abstract

AbstractWetland rice in many humid tropical regions of Asia, Africa, and South America are affected by iron toxicity, which mainly occur due to increase in Fe(II) concentration in soil solution resulting from drop of redox potential arising from anaerobic situations in submerged rice fields. The high quantity of ferrous ions in the soil solution upsets the mineral element balance in rice plants and affects its growth. A field experiment was carried out in acidic laterite soil (pH 5.1) having 400 mg kg−1 diethylene triamine pentaacetic acid extractable Fe for developing strategies to combat Fe toxicity and to study Fe, Zn, and Mn nutrition in rice. The treatments included four cultivars and six soil management options. Soil pH increased upon submergence and stabilized at 6.2 in compost treated plots and 6.8 in lime treated plots after eight weeks of flooding. Application of lime resulted significantly higher yields in all the four cultivars over control. Among the cultivars lowest Fe concentration both in grain and straw was recorded in tolerant as compared to susceptible cultivars. The ratio of Fe/Mn in rice plants was highest under control and reduced with Fe toxicity management treatments. It was further observed that Fe/Mn ratio of tolerant cultivars was lower as compared to susceptible cultivars irrespective of amendments. Similar relations were also recorded for Fe/Zn ratio under different Fe toxicity management interventions. Thus, the application of lime and limiting plant nutrients, such as K, Mn, and Zn along with tolerant cultivars could be important components of Fe toxicity management in Fe toxic acid lateritic soils.