Influence of different spacings, SNP concentrations and sources of nitrogen on catalase activity in African marigold cv. lsquo;Bidhan-2rsquo;

A factorial experiment was conducted with three different spacings, three different concentrations of sodium nitroprusside (SNP) and three different sources of nitrogenous fertilizers for two years during 2017 and 2018 at the Horticultural Research Station, Dr. Y.S.R. Horticultural University, Venkataramannagudem to find out their influence on heat stress tolerance of marigold cultivated during summer season. Statistically analysed data with respect to catalase activity revealed that spraying with SNP at 200 µM concentration recorded significant increase in catalase activity (34.03 and 7.84 µg of H2O2 g-1 min-1) followed by soil application of nitrogenous fertilizer in the form of calcium nitrate (20.44 and 6.37 µg of H2O2 g-1min-1) respectively after the 1st and 2nd sprays. However, soil application of calcium nitrate in combination with sprayings of SNP at 200 µM concentration recorded significantly higher catalase activity (39.06 and 9.48µg of H2O2 g-1 min-1) respectively at 20 and 40 days after transplanting of marigold. Spacings did not exert any significant influence on catalase activity.