M. H. Rashed
Soil Resources Development Institute, Regional Laboratory, Cumilla
T. S. Hoque
Department of Soil Science, Bangladesh Agricultural University, Mymensingh-2202
M. M. R. Jahangir
Department of Soil Science, Bangladesh Agricultural University, Mymensingh-2202
M. A. Hashem
Department of Soil Science, Bangladesh Agricultural University, Mymensingh-2202
Critical limit, Crops, Manganese, Micronutrient, Soils
Crop-Soil-Water Management
Manganese plays a vital role in biological systems because it exists in a type of oxidation state and is concerned inactivation of multiple enzyme systems (Mukhopadhyaya and Sharma, 1991). It is analogous to metallic elements as magnesium (Mg2+) as each ion connects adenosine triphosphate with complexes of enzymes like phosphotransferase and phosphokinase. Dehydrogenase and decarboxylase in the Krebs cycle and ribonucleic acid polymerase are also activated by Mn2+ (Marschner, 1995; Burnell, 1988). Manganese plays an effective role in nitrate reduction; nitrate accumulates in the leaves which causes Mn deficiency. Lack of Mn causes lignin deficiency in plants and it takes on a deadly shape at the roots of the plant, reducing its resistance to invasion fungi infection (Marschner, 1995). The role of Mn in lipid metabolism is not clear though (Ness and Woolhouse, 1980). Hydrogen peroxide is produced with the help of the peroxidase enzyme, which is another Mn-dependent enzyme that helps prevent pathogens. Hydrogen peroxide is not only associated with cell wall stability but is also toxic to pathogens (Heine et al., 2011) and acts as a fungicide (Graham and Webb, 1991). Manganese is an essential micronutrient that, relative to iron, is required by plants in the second-largest quantity. Crops can be divided into three major groups on the basis of the Mn requirement, such as high Mn responsive, medium Mn responsive and low Mn responsive (Brouder et al., 2003). In plants, every essential nutrient has a particular role to play and its existence in the above critical concentration is a must for a plant to complete its life cycle. Not only for soil and crop species but also for different varieties of a given species, the critical limits or levels can differ (Singh and Agrawal, 2007). Soils, crops and methods of extraction are essential factors in deciding the critical limit of nutrients. The signs of Mn toxicity differ widely as the most common symptoms among plant species with chlorotic leaves and necrotic spots (Millaleo et al., 2010). The concentration of toxic Mn is highly dependent on plant species and genotypes (Broadley et al., 2012; Fernando and Lynch, 2015). Excess Mn may be stored in vacuoles (Dou et al., 2009), cell walls (Fuhrs et al., 2010), and distributed to various leaf tissues (Fernando et al., 2006). Nutrient deficiencies are subjective and excessive amounts of another element are indicated by a deficiency of one element. Thus, as a consequence of nutrient deficiency or imbalance, plants exhibit external signs of intense hunger. Manganese deficiency is found in plants without strong visual signs. Soil applications are short-term and costly at best but can lead to significantly higher crop production. Manganese transmission along with other chemical fertilizers can in some cases, increase the level of soil testing or prevent Mn deficiency. However, broadcast applications of Mn fertilizer or attempts to build soil test Mn levels are not recommended particularly on high pH and high organic matter-containing soils because of their capacity to fix Mn rapidly. The application of Mn fertilizers in bands or rows is more efficient than the broadcast application. After application, most of the fertilizers create an acid environment in the soil and if Mn is added into the band, this environment can help prevent it from being bound up and inaccessible (Murdock et al., 1977). Mixing Mn in a fertilizer band with ammonium nitrogen increases its availability. Although the use of Mn fertilizer alongside the line is better than broadcasting, in many cases it is still an improper practice. By minimizing interaction with soil particles, foliar application of Mn decreases chemical fixation. Foliar application of Mn in soybeans remains an important and economically sound choice to prevent yield loss and nutrient imbalance in calcareous soils, as proposed by Moosavi and Ronaghi (2011). Seed treatment (seed coating and priming) is a pragmatic and cost-effective method of micronutrient application (Farook et al., 2012). Recently, Ullah et al. (2017) demonstrated that Mn application in rice as a seed treatment (seed coating or seed priming) was better and more economical than soil or foliar application as this method improved the yield-related traits, rice yield, water productivity and grain Mn contents of fine-grain aromatic rice grown in both conventional and conservation production systems.
Environ. Sci. & Natural Resources, 12(1&2): 225-242, 2019
Journal