Influence of Nitrogen and Growth Regulators on Nutrient Uptake and Final Available Nutrient Status of Paired Row Pigeonpea Intercropping with High-density Cotton in Vertisols of Southern India

The paired row pigeonpea intercropping system, the space between the two paired rows of pigeonpea is effectively utilized for growing high-density cotton. This experiment was conducted at Agricultural Research Station (ARS) Tandur, Vikarabad during Kharif 2023-24 and 2024-25. The experiment was laid out in a split-plot design with three replications. The main plots (three) with paired rows of pigeonpea combined with three spacings of high-density cotton arranged in six subplots. Among the main plots, at 60 and 90 days after sowing (DAS), and at harvest, the highest nitrogen, phosphorus, and potassium uptake was recorded under the high-density cotton spacing of M1 (60 cm x 15 cm) during both years of experiment as well as in the mean data whereas the lowest uptake was observed with the wider spacing of M3(100 x 15 cm). Among the subplots, the highest NPK uptake and final available soil NPK were recorded with the application of 125% RDN + Mepiquat chloride (50 ppm) at square formation and flowering stage (S3). This was followed by the treatment 125% RDN + Cycocel (60 ppm) applied at square formation and flowering stage (S6) during both years and in mean data. The lowest values were obtained with the application of 100% RDN + Cycocel (60 ppm) at square initiation, peak square formation and flowering stage. The highest final available NPK (247, 37.7 and 297 kg ha-1) during 2023-24 and (242, 35.1 and 291 kg ha-1) during 2024-25 recorded was spacing of M3 (100 x 15 cm). Among subplots the highest final available NPK (246, 38.4 and 301 kg ha-1 during 2023-24 and 242, 35.7 and 293 kg ha-1 during 2024-25) were obtained with the application of 125% RDN + Mepiquat chloride (50 ppm) at square formation and flowering stage (S3). The results of the current study will contribute efficient nutrient management for the sustainability of productivity in intercropping systems, especially under high-density planting conditions. In a pigeonpea-based intercropping system, optimizing nitrogen levels and growth regulators is crucial for enhancing nutrient uptake and maintaining soil fertility.