Evaluation of Micronutrient Mixture as Seed Treatment and Foliar Nutrition in Grain Cowpea

Abstract

Background: Micronutrient formulation is a liquid mixture of micronutrients which can be used as a fertilizer. It is a mixture of two solutions viz., solution A and solution B. Solution A is a mixture of zinc sulphate (50 gL-1), boric acid (10 gL-1), copper sulphate (20 gL-1), manganous sulphate (0.5 gL-1), ferrous sulphate (10 gL-1) and ammonium molybdate (0.5 gL-1) whereas solution B is an organic acid which act as a chelate. The mixture can be diluted to specific concentrations for application. The objective of the study was to evaluate the effect of micronutrient formulation as seed treatment and foliar nutrition. Methods: The study was conducted at College of Agriculture, Padannakkad, Kerala Agricultural University and Regional Agricultural Research Station, Pilicode during 2018–19. The investigation was carried out in three parts: (i) standardization of micronutrient formulation for cowpea (ii) seed treatment study (iii) field experiment. The proportion of mixing micronutrient formulation and the duration for seed treatment was standardized in experiment I. In experiment II, a seed treatment study was carried out in a completely randomised design with seven treatments and three replications which included seed treatment with micronutrient formulation @ 0.25, 0.50, 0.75, 1, 1.5 and 2 percent as T1, T2, T3, T4, T5 and T6 respectively. T7 (seed treatment with water) was the control. Three, a field experiment was carried out in randomized block design (factorial) with twelve treatments and three replications. The treatment consisting of combination of four levels of seed treatment - factor A [no seed treatment (S1), seed treatment with rhizobium (S2), seed treatment with best concentration from experiment 1 (S3) and second best seed treatment from experiment 1 (S4)] and three levels of foliar application of micronutrient - factor B [no foliar application (F1), one foliar application at 15 DAS (F2) and two foliar applications at 15 and 30 DAS (F3)]. Result: Through lab experiments, solution B was standardized and the formulation was developed by mixing solution A and solution B in the ratio 1:2. Duration for seed treatment was also standardized as 6 hours. Thus micronutrient formulation was standardized. In seed treatment study, seeds treated with 2% micronutrient formulation (T6) showed highest plant height at three leaf stage (24.23 cm) and seedling vigour index (2423). In the field experiment seed treatment with 2% micronutrient formulation (S3), foliar spray at 15 and 30 days after sowing (F3) and their interaction (S3F3) was found to be highly effective to the crop in terms of plant height, stem diameter, number of pods per plant, pod weight per plant, grain yield and nutrient content in grain. These results clearly indicate the role of micronutrient formulation in enhancing the growth, yield and nutrient content of cowpea.

Agronomic biofortification of forage crops with zinc and copper for enhancing nutritive potential: a systematic review

“…In this method, the seeds are exposed to a mineral nutrient solution with subsequent redrying to the initial moisture content. The approach results in improved micronutrient status and a pre‐activation of metabolic pathways that lead to a higher biomass of crop 31 …”

“…Seed treatment of cowpea through micronutrient mixture of Zn, Cu, iron (Fe), manganese (Mn), boron (B), molybdenum (Mo) along with organic acid improved the concentration of Zn, Cu, Fe, Mn, and B in grain. This was due to the higher availability of micronutrients due to application of micronutrient mixture through seed treatment 31 …”

“…A micronutrient formulation of two mixtures containing ZnSO 4 , CuSO 4 , ferrous sulfate, manganous sulfate, boric acid, and ammonium molybdate in one mixture and organic acid in the other mixture was employed for seed treatment of cowpea 31 . Seed treatment significantly influenced the number of pods per plant and yield of cowpea.…”

“…The approach results in improved micronutrient status and a pre-activation of metabolic pathways that lead to a higher biomass of crop. 31 Globally, several researchers have worked on the agronomic biofortification of forage crops with Zn and Cu using the aforementioned methods. The biofortification of forage crops with Zn and Cu leads to better yield and improved quality of the forage crops, which is discussed in the following sections.…”

“…This was due to the higher availability of micronutrients due to application of micronutrient mixture through seed treatment. 31…”