SANGWAN, P. S.Kodikarage Manoj Sunanda Kodikara2021-08-072021-08-072020-07https://krishikosh.egranth.ac.in/handle/1/5810171537This research was conducted to study the effect of different P levels on availability of calcium and micronutrients in soils and their uptake by rice under wet and aerobic conditions. Soil pH significantly decreased up to 80 and 60 DAPA in wet over aerobic water regime and P application reduced the soil pH significantly up to 100 DAPA in surface soil. EC significantly increased in wet over aerobic water regime. At surface, available N was significantly higher at 40 DAPA only in wet over aerobic water regime and no effect of P application on available nitrogen was observed. Phosphorus availability was significantly increased in surface soil under wet over aerobic water regime. Available P in subsurface remained unchanged. Wet regime had significantly high soil available K over aerobic regime with P having no effect. Extractable calcium in surface or subsurface soils was not affected by water regimes. Water regime or P application caused no changes in available Zn, Mn, Cu but they increased available Fe in surface soils. Water regimes failed to affect Saloid-P and it increased with increase in rate of P whereas Al-P fractions significantly increased. Aerobic regime and P application recorded significantly higher Fe-P but the same was true for wet regime for Ca-P. P fractions followed the sequence: Ca-P > Fe-P > Al-P > Sa-P for both surface and subsurface soils. Wet regime showed significantly high plant height, numbers of effective tillers m-2, number of grains panicle-1, rice grain, straw and biological yield over aerobic regime but harvest index was high in aerobic regime while P application failed to affect plant height, numbers of effective tillers and 1000-grain weight. Nitrogen content in grain or straw was not significantly affected by water regimes while it was significantly affected by P application in grain only. Phosphorus content in grain and straw was significantly affected due to water regimes and P levels. Potassium content was significantly affected by water regimes but not with P levels. The content of Ca was significantly affected by P levels in grain only. Different water regimes and P levels exerted significant affect on uptake of N, P, K and Ca except concentration of Ca at P levels which was recorded to be non-significant. Levels of P application did not influence the micronutrient concentrations in grain or straw significantly except Fe in grain. While water regimes showed significant effect on Mn and Fe contents in both grain and straw while Zn content was affected significantly in straw.EnglishThesis