Effect of plant growth regulators on the shoot growth of black pepper (Piper nigrum L.) stem cuttings under shade net conditions.

Abstract

The present investigation was undertaken to “Effect of Plant Growth Regulators on the Shoot Growth of Black Pepper (Piper nigrum L.) Stem Cuttings under Shade Net Conditions”, with effective treatment for producing high-quality planting material. The experiment was conducted during 2024-25 under a 50% shade-net structure using the black pepper variety ‘Panniyur-1’. The study was laid out in a Completely Randomized Design (CRD) comprising ten treatments, including three concentrations each of indole-3-acetic acid (IAA), naphthalene acetic acid (NAA), and indole-3-butyric acid (IBA), along with an untreated control, and replicated thrice. Observations on shoot growth parameters such as number of shoots per cutting, length of new shoot, number of leaves per shoot, leaf length, number of nodes per shoot, internodal length, and girth of new shoots were recorded at 30, 60, and 90 days after planting (DAS). The results revealed that application of plant growth regulators significantly influenced all shoot growth parameters compared to the control. Among the treatments, IBA at 1000 ppm consistently recorded superior performance by producing the maximum number of shoots per cutting, greater shoot length, higher leaf number, increased leaf size, more nodal formation, longer internodes, and thicker shoot girth at all stages of observation. This was followed by NAA at 1000 ppm and IAA at 1000 ppm, while the untreated control recorded the lowest values for most parameters. The enhanced shoot growth under auxin treatments may be attributed to improved root establishment, enhanced cell division and elongation, and efficient nutrient and water uptake under favorable shade-net microclimatic conditions. Overall, the study concludes that treatment of black pepper stem cuttings with IBA at 1000 ppm under shade net conditions is most effective for promoting vigorous shoot growth and producing quality planting material for sustainable black pepper cultivation.