Effect of Foliar Spray of Iron (Fe)- Fortified Humic Substances and Humic Acid on Growth, Nodulation and Yield of Groundnut (Arachis hypogaea L.) in a Calcareous Vertisol

The response to foliar application of Fe-fortified humic substances (HS) and humic acid (HA) on the growth, nodulation and yield characteristics of groundnut (Arachis hypogaea L.) var. TMV 2 in a calcareous Vertisol was studied in a pot culture experiment. There were 16 treatments viz., Absolute control (T1), only RDF (T2), RPP: RDF +FYM @ 7.5 t + FeSO4 @ 25kg ha-1+ ZnSO4 @ 25 kg ha-1 (T3), RDF + Foliar FeSO4.7H20 @ 0.5% (T4), and T5 to T16, where two different concentrations, 0.25 and 0.50 % of humic substances (HS) (Humic acid + Fulvic acid) and humic acid (HA) were fortified separately with 250, 500 and 750 ppm Fe. Among all treatments, higher values of growth parameters like number of leaves, branch count and yield parameters like number of pods (19.33 pods plant-1), pod weight (18.84 g plant-1), kernel yield (12.85 g plant-1), shelling % (68.25 %) and 100 kernel weight (33.28 g) were recorded in the treatment RDF + Foliar Fe- fortified HS (0.50 % HS+ Fe @ 500 ppm) (T9) followed by treatment with RDF + Foliar Fe- fortified HA (0.50 % HA+ Fe @ 500 ppm) (T15). The plant height and dry matter yield were recorded maximum under foliar spray of 0.25 % HS fortified with 500 ppm Fe (T6) (21.83 cm and 6.27 g plant-1 at 60 DAS; 33.83 cm and 36.75 g plant-1 at harvest, respectively). For nodulation parameters, T3 (only RPP) recorded the best results and remained statistically on par with treatment T9.