Standardization of nursery technique and growth media foe peppermint (Mentha piperita L.)

Abstract

The study entitled “Standardisation of nursery technique and growing media for peppermint (Mentha piperita L.)” was conducted at the Regional Agricultural Research Station, Pattambi, Palakkad, Kerala, during 2024-2025. The investigation aimed to standardise the planting material and rooting media for peppermint seedling production in the nursery and to identify suitable growing media for grow bag cultivation. The research was carried out in two distinct phases. In the first phase, a nursery experiment was undertaken to standardize the planting material and rooting media for the nursery. The experiment was laid out in a Factorial Completely Randomized Design (CRD) with three replications. Factor 1 consisted of three types of stem cuttings - apical (S₁), middle (S₂), and basal (S₃) three node cuttings with leaves, while Factor 2 comprised five rooting media combinations: cocopeat (M₁), cocopeat + FYM (1:1) (M₂), cocopeat + vermicompost (1:1) (M₃), cocopeat + FYM + vermicompost (1:0.5:0.5) (M₄), and cocopeat + vermiculite + perlite (1:1:1) (M₅). The results indicated that both the type of cuttings and rooting medium had a significant influence on sprouting, rooting, and growth parameters. Among the treatments, apical three node cuttings with leaves planted in cocopeat + vermicompost (1:1) exhibited superior performance regarding the highest sprouting percentage (83.33%), earliest sprouting (5.5 days), longest shoots (10.84 cm), maximum shoot biomass (fresh weight 1.06 g; dry weight 0.32 g), longest roots (9.7 cm), and greater root biomass (fresh weight 0.29 g; dry weight 0.057 g). Hence, this combination was standardized for quality seedling production in peppermint nursery. The second phase focused on evaluating various organic growing media for peppermint grow bag cultivation under a CRD with eight treatments. The best treatment from experiment 1 i.e., three node cuttings from apical region with leaves in cocopeat + vermicompost (1:1) was transplanted to growbag for further field study. The treatment containing soil + cocopeat + vermicompost + bone meal + neem cake (1:1:1:0.005:0.005)

(T₈) recorded the highest values for major growth and yield parameters, including plant height (89.70 cm), number of leaves (574.27), number of primary (26.73) and secondary branches (20.07), root length (28.89 cm), and herbage yield (fresh: 337.67 g plant⁻¹; dry: 51.60 g plant⁻¹). Physiological parameters such as leaf area (11,572.18 cm² plant⁻¹) and total dry matter accumulation (60.04 g plant⁻¹) were also superior in this medium. However, essential oil and menthol content were not significantly influenced by the growing media. Economic analysis revealed that the medium containing soil + cocopeat + vermicompost + bone meal + neem cake (1:1:1:0.005:0.005) (T₈) recorded the highest gross return (₹12,156 per 100 m²), net return (₹2,856 per 100 m²), and benefit-cost ratio (1.31), indicating its commercial viability. Overall, the study established that three node apical cuttings rooted in cocopeat + vermicompost (1:1) provide the best planting material for peppermint nursery production. For growbag cultivation, the medium containing soil + cocopeat + vermicompost + bone meal + neem cake (1:1:1:0.005:0.005) can be recommended for achieving optimal growth, yield, and economic returns. These findings provide a scientific basis for the sustainable and efficient propagation and cultivation of peppermint.