Establishing optimal nutrient level of magnesium and boron in black pepper for optimization of productivity in Western Ghats of Kerala

Critical nutrient level of magnesium and boron in soil and plant biomass of black pepper (Piper nigrum) have been estimated in Western Ghats of Kerala by conducting field experiments in three seasons (2018-2020) by magnesium and boron fertilization. Nutrient management in black pepper plantations wins important value due to its wider use as spice all over the world. As black pepper plants are easily prone to Mg and B deficiency, its response to Mg in the form of magnesium sulphate and B as borax was evaluated in terms of yield, plant nutrient content and nutrient status in soil. Effect of Mg as well as B application on the other available nutrients and leaf nutrient content were also determined in the study. Response curves were fitted by plotting relative yield of black pepper with Mg and B in soil and index leaf. The graphical method of Cate and Nelson was used to derive the optimal concentrations of nutrients. The critical levels of magnesium in soil and black pepper leaves were established as 140 mg kg-1 and 0.44 % respectively. Optimum dose of magnesium sulphate for getting highest yield of black pepper was found as 120 kg ha-1 followed by MgSO4 @ 80 kg ha-1. Similarly critical limit of B in the soil and index leaf of black pepper were 0.58 and 21 mg kg-1 respectively. The maximum potential yield was obtained by applying boron as borax at 0.2% via foliar application and at a higher dosage of 2 kg per hectare through soil application.