Abstract: Field experiment was laid out in Randomized Block Design (RBD) at UPASI tea experimental farm, with eight treatments and three replications. Amino acid content in tea leaves increased due to soil application of magnesium, but the 50% potassium reduction fields are reduced the amino acid content. The amino acid content significantly increased the soil applied magnesium when compared to the standard practices. The blocks which received the foliar application of micronutrient along with magnesium decreased the amino acid content when compared to the standard practices and control. The externally added magnesium increased the formation of 2-oxoglutarate and simultaneously another product aspartate/alanine was increased. The catechins content increased in 300 kg soil applied magnesium treatment and then decreased in 50% reduction of potassium fertilizer treatments. The TF value of made tea increased in 300 kg magnesium application plots and but decreased in the case of 50% reduction of potassium fertilizer. The control blocks having lower TF value when compared to the standard practices, because the K fertilizer is the important to increase the TF value. The maximum quantity of TF value obtained in the case of 300 kg soil applied blocks. The similar kind of trend was observed in TR values. Flavour index was made tea was higher in magnesium treated blocks, when compared to the control and NPK application. The magnesium content of tea leaves positively correlated with amino acid and amino acid transferase enzymes. This study further confirmed that antagonism exiting between K and Mg and synergism existing between P and Mg.