000			05434nam a22001817a 4500
999			_c160010 _d160010
082			_a631.4 _bSAN/DY
100			_aSanthi, G R
245			_aDynamics of iron and aluminium toxicity on rice (Oryza sativa L.) in saline hydromorphic soils of kaipad
260			_aPadannakkad _bDepartment of Soil Science and Agricultural Chemistry, College of Agriculture _c2017
300			_a219p.
502			_aMSc
520	3		_aAn investigation entitled “Dynamics of iron and aluminium toxicity on rice (Oryza sativa L.) in saline hydromorphic soils of Kaipad” was carried out at College of Agriculture, Padannakkad during the academic year 2015 to 2017. The objectives of the study were to investigate the status of iron and aluminium in saline hydromorphic soils of Kaipad, evaluate the performance of popular rice varieties to varying levels of iron and aluminium concentration at different salinity levels, and examine amelioration strategies for iron and aluminium toxicity. The study was carried out in four parts namely collection and soil analysis, incubation study, solution culture and pot culture experiments. As a part of the initial study, representative surface soil samples were collected from 15 selected locations of Kaipad areas comprising of Muttil and Cherukunnu panchayath during the first week of April 2016 to assess the different physical and chemical properties. The GPS data for the sites were also recorded. The pH of the soils varied from ultra-acidic to slightly acidic. The electrical conductivity during the summer months was very high. Among the macro and micro nutrients studied, very high available K and Ca values were observed and extreme toxicity of available Fe and Al were also recorded. An incubation study was conducted with four treatments at two levels of submergence (5 cm and 10 cm) in factorial CRD. The treatments were fixed based on the recommendations of KAU POP, 2011 viz. lime (T1); magnesium sulphate + 1⁄2 lime (T2); phosphogypsum + 1⁄2 lime (T3) and control (T4). The application of treatments showed a positive effect in reducing iron and aluminium toxicity. The toxic levels of available Fe were significantly reduced in T 1 at 30 and 120 DAI whereas, at 60 and 90 DAI, T3 was significantly superior in reducing the iron toxicity. The aluminium toxicity was reduced to minimum level at 30, 60 and 120 DAI in treatment T3. However at 90 DAI, the least aluminium content was recorded in the soil treated with lime alone. The solution culture experiment was conducted by maintaining Hoagland‟s nutrient solution containing 3 levels of iron (400, 800, 1200 mg L-1), 2 levels of aluminium (15 and 30 mg L-1) and 2 levels of salinity (5 and 10 dS m-1) along with one control in factorial combinations using CRD. The two selected varieties, Ezhome-1 and Kuthiru were evaluated for their tolerance to iron and aluminium toxicity coupled with salinity. Maximum iron coating around the roots with respect to the treatments were displayed in T12 (1200 mg L-1 iron, 30 mg L-1 aluminium and 10 dS m-1 salinity) solution. Increase in levels of iron, aluminium and salinity significantly reduced the plant height, root dry weight, root length and root CEC of rice plants. The pot culture experiment was conducted with seven treatments as amendments and two varieties Ezhome-1 and Kuthiru in factorial CRD during July to October 2016. The treatment combinations were: Lime (T1); Magnesium sulphate + 1⁄2 lime (T2); Phosphogypsum + 1⁄2 lime (T3); Lime + potassium silicate 0.25% + 0.25% boron (T4); Magnesium sulphate + 1⁄2 lime + potassium silicate 0.25% + 0.25% boron (T5); Phosphogypsum + 1⁄2 lime + potassium silicate 0.25% + 0.25% boron (T6) and control (T7). The leachate was collected and analysed by inserting a perforated pipe at the centre of each pot. The variety Ezhome-1 recorded maximum significant plant height at 30, 60 and 90 DAT. The number of productive tillers/ number of panicles, grains per panicle, grain yield, straw yield and 1000 grain weight were also significantly superior in Ezhome-1. Among the amendments, T6 recorded significantly superior plant height, grain yield, total Ca, B, Si and lowest Al content in rice. The treatment T 3 recorded maximum significant number of panicles, productive tillers, grains per panicle, straw yield, 1000 grain weight and lowest Na and Fe content in plant tissue. The treatments receiving phosphogypsum + 1⁄2 lime (T 3 and T6) were highly effective in reducing the toxic levels of available Fe and Al whereas, application of lime (T 4) was significantly superior in increasing the soil pH, available P and reducing the EC and exchangeable Na status of Kaipad soil. The saline hydromorphic soils of Kaipad are having severe constraints of acidity, extreme toxicity of iron and aluminium coupled with high salinity. These problems can be ameliorated using combinations of amendments including phosphogypsum, lime and foliar application of boron and silicon to enhance the growth and yield of rice crop. Adoption of aforementioned management strategy could help in improving the soil health and thereby increasing the yield potential of Kaipad rice.
650			_aAgriculture
650			_aSoil Science and Agricultural Chemistry
700			_aBinitha, N K (Guide)
856			_uhttp://krishikosh.egranth.ac.in/handle/1/5810143459
942			_2ddc _cTH