Herojit Singh Athokpam

Phytoremediation: Curing soil problems with crops

Among the different contaminants in the environment, heavy metals (HMs) are unique due to the fact that they cannot be broken down to non-toxic forms. According to the reports published worldwide, these metals are released into the environment by both natural and anthropogenic sources, especially, mining and industrial activities, and automobile exhausts (for lead). They leach into underground waters, moving along water pathways and eventually depositing in the aquifer, or are washed away by run-off into surface waters thereby, resulting in water and subsequently soil pollution. The HM contamination is increasing day by day because of increase in population, industrialization and urbanization. Therefore, posing a serious threat to health and environment. Researchers worldwide have used different methods for removing these hazardous elements. Although, these methods for cleaning up of contaminated environment including soil and water are usually expensive and do not give optimum results. Currently, phytoremediation is an effective and affordable technology used to remove inactive metals and metal pollutants from contaminated soil and water. It includes phytoextraction, rhizofiltration, phytostabilization, phytovolatization, and phytodegradation/ phytotransformation. This technology is ecofriendly and exploits the ability of plants to remediate pollutants from contaminated sites. More than 400 plant species have been identified to have potential for soil and water remediation. Among them, Thlaspi, Brassica, Sedum alfredii H., and Arabidopsis species have been mostly studied. Our paper aims to cover the causes of HM pollution and phytoremediation technology, including HM uptake mechanism and several reports describing its application at field level.

Critical Limits of Phosphorus in Relation to the Growth and Dry Matter Yield of French Bean (Phaseolus vulgaris L.) in Acid Soils of Thoubal District, Manipur (India)

Plants appear to face severe problems in getting phosphorus at early stage in their development. So, phosphorus deficiency symptoms most often occur in seedlings and young plants. Phosphorus is mobile within the plants and its translocation is from the older tissue to the growing points. This causes the deficiency symptoms appeared on the lower International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 7 Number 10 (2018) Journal homepage: http://www.ijcmas.com

Evaluation of Some Soil Test Methods for Available Phosphorus and Critical Level of French bean in Acid Soils of Thoubal District, Manipur (India)

Phosphorus is the second most important plant nutrient after nitrogen for agricultural production in most regions of the world. Phosphorus is used in the plant for energy storage and transfer, maintenance and transfer of genetic code and is structural component of cells and many biochemicals. Phosphorus deficiencies results in poor root growth, stunted top growth, reduced yield and crop quality along with delayed maturity (Mishra, 2012). In severe cases, phosphorus deficiency can cause yellowing and senescence of leaves. In many acidic soils in developing countries, phosphorus deficiency is the main limiting factor for crop production and therefore, requires the phosphorus fertilization for optimum plant growth and production of food and fibre (Attar, 2014). Phosphorus also reduces the harmful effect of excess nitrogen and imparts resistant to plant against disease. Supply of phosphorus to leguminous crops increase the numbers and size of root nodules and nitrogen fixing potentiality of Rhizobium, so it is essential for obtaining the higher yield of crop (Patil and Jadav, 1994).

Vertical Distribution of Micronutrient Cations in Imphal East and West District, Manipur (India)

Micronutrients play various important role in plant is well established. It plays an active role in plant metabolism i.e. cell wall development, respiration, photosynthesis, chlorophyll formation, enzyme activity, hormone synthesis, atmospheric nitrogen fixation, etc. The requirement of micronutrients for crop plants are relatively very small, however, if any deficiencies of it, the crop yield is drastically reduced. Micronutrients are very important for maintaining soil health and also increasing productivity of crops (Rattan et. al. 2009). However, exploitive nature of modern agriculture involving use of high analysis NPK fertilizers couple with limited use of organic manure and less recycling of crop residues are important factors contributing towards accelerated exhaustion of micronutrients from the soil (Sharma and Choudhary, 2007). Continuous negligence of micronutrient application and avoidance of organic manures are the major causes of International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 7 Number 08 (2018) Journal homepage: http://www.ijcmas.com

Critical Limits of Phosphorus in Soil and Pea Plant Grown in Acid Soils of Senapati District of Manipur, India

ISSN: 2319-7706 Volume 7 Number 09 (2018) Journal homepage: http://www.ijcmas.com A pot culture study was conducted in 20 acidic soils of Senapati District of Manipur, India during rabi season of 2013-14 to estimate the critical limit of P in soil and pea plant for predicting the response of pea (Pisum sativum L.) to P application as well as to study the effect of P application on dry matter yield and uptake of nutrients in pea crop. The experimental soil was acidic in nature, electrical conductivity of the soil was in safe limit for crop growth. The organic carbon status was almost high and soil was clay in textural class. Pot culture studied showed that the application of phosphorus @ 60 kg P2O5 ha -1 significantly superior (85 %) of the studied soils to any other treatments and 40 kg P2O5 ha -1 was significantly (15 %) to the total soils in dry matter yield of Pea variety Arkel. The critical limit of the P concentration in the pea was found 0.42 per cent. It was revealed that the critical level of phosphorus in the soils for growing of pea plants varied with the methods of phosphorus extraction. The critical level of soils ranged from 14.30 to 25 kg P2O5 ha -1 depending upon the methods of phosphorus extraction. K e y w o r d s Phosphorus, Critical limit, Acidic, Soil, Pea Accepted: 20 August 2018 Available Online: 10 September 2018 Article Info Int.J.Curr.Microbiol.App.Sci (2018) 7(9): 3106-3118

Profile distribution of micronutrient cations in citrus orchard of Ukhrul district, Manipur (India)

Profile distribution of DTPA-extractable micronutrient cations (Zn, Cu, Fe and Mn) and their relationship with various soil properties were studied in eighteen profiles of citrus orchard of Ukhrul district of Manipur. The content of DTPA-extractable Zn, Cu, Fe and Mn were higher in surface horizons and decreased with depth in most of the profiles and ranged from 0.08 to 0.76, 0.01 to 0.34, 8.0 to 54.0 and 1.6 to 20.4 mg Kg−1, respectively. Surface horizons contain sufficient amount of DTPA-extractable micronutrient cations except Zn. Distribution of Mn was influenced positively with EC in the first (0–20 cm) and second layer (20–40 cm), Cu was influenced inversely by organic carbon and positively by EC, Zn was influenced positively with CEC and Fe was influenced by clay content of the soils. Multiple regression analysis indicated that DTPA-extractable Zn, Cu, Fe and Mn were influenced by CEC, EC, clay and EC to the level of 0.25, 0.63, 0.25 and 0.41, respectively. However, only clay and EC contributed significantly towards these nutrient cations.