Assessing the Growth Response of Gimakalmi (Ipomoea Aquatica) under Alternative Wetting and Drying (AWD) System as Influenced by Plant Growth Regulator (PGRs) Application in the Rooftop Garden

Growth responses of Gimakalmi (Ipomoea aquatica) was explored under an Alternative Wetting and Drying (AWD) irrigation system supplemented with Plant Growth Regulators (PGRs), specifically gibberellin. The experiment was conducted in a controlled rooftop garden environment at Habiganj Agricultural University, during the Boro season (January-June 2024), to assess the effects of different water supply and PGR treatments on the growth and yield of Gimakalmi.The soil at the experimental site was characterized as silt loam, with a pH of 6.14, 2.25% organic matter, 0.12% total nitrogen, 7.88 mg kg⁻¹ of accessible phosphorus (P), 0.14 me 100 g⁻¹ of exchangeable potassium (K), and 10.77 mg kg⁻¹ of available sulfur (S). The experiment followed a randomized complete block design with four treatments, each replicated three times. The treatments included: T0- Control, T1- 100% Recommended Fertilizer Dose (RFD) + PGR, T2- PGR + AWD water supply, and T3-100% RFD + PGR + AWD water supply. Chemical fertilizers were applied during final soil preparation. The AWD method was used for irrigation, and PGRs were applied in a single dose. Results indicated that the combination of AWD and appropriate PGR application significantly enhanced the growth of Gimakalmi. At 7 days after sowing (DAS), the control (T0) treatment recorded the lowest leaf number of 3.83, while the highest leaf number of 7.50 was observed in the T3 treatment (100% RFD + PGR + AWD). This trend continued at 14 DAS, with the control showing 6 leaves and T3 showing 12.16 leaves, and at 21 DAS, where T0 had 7.66 leaves and T3 had 14.16 leaves. Similarly, plant height was significantly higher in T3, with the control treatment measuring 3.16 cm (7 DAS), 8.16 cm (14 DAS), and 14.66 cm (21 DAS), while T3 showed plant heights of 6.83 cm (7 DAS), 24.66 cm (14 DAS), and 28.33 cm (21 DAS).In terms of yield, T3 outperformed all other treatments. The yield ranged from 5.68 tha⁻¹ in the T0 (control) treatment to 11.51 tha⁻¹ in T3 during the first harvest (21 days after sowing). In the second harvest (36 days after sowing), the yield ranged from 3.96 tha⁻¹ in T0to 9.95 tha⁻¹ in T3, and in the third harvest (50 days after sowing), the yield ranged from 4.45 tha⁻¹ in T0 to 11.35 tha⁻¹ in T3.The results clearly show that T3 (100% RFD + PGR + AWD) significantly enhanced both the growth and yield of Gimakalmi, and the AWD system contributed to improved water-use efficiency, making it a viable solution for sustainable urban agriculture. This research provides valuable insights into optimizing growth conditions for Gimakalmi in rooftop gardens and emphasizes the potential for water conservation, which is crucial for urban farming.