Effect of Spacing on Yield of Kalmegh (Andrographis paniculata (Burm. f.) Nees) in the Upper Southern Region

Abstract

Andrographis paniculata is widely used in both human consumption and animal feed industries. Andrographis paniculata is naturally found throughout the upper Southern region of Thailand. However, comprehensive studies on its active compounds and commercial cultivation practices have not been reported yet. However, there is a lack of information on production and harvesting technologies specifically suitable for the area. Therefore, this research aims to investigate the effects of different planting distances on the growth and conducted from October 2022 to September 2023 at the Office of Agricultural Research and Development Region 7, Kanchanadit District, Surat Thani Province. The experimental design was a split plot with three replications, where the main plots consisted of five local varieties of Andrographis paniculata: Nakhon Si Thammarat-1, Krabi-1, Surat Thani-1, Phang Nga-1, and Phang Nga-2. The subplots included five different planting distances: 20x20, 30x30, 40x40, 50x50, and 60x60 centimeters. The experiment results showed that the five varieties of Andrographis paniculata had significantly different fresh and dry weights. The top three varieties with the highest fresh and dry weights were Nakhon Si Thammarat-1, Surat Thani-1, and Phang Nga-1. Additionally, the study found that planting Andrographis paniculata at a spacing of 20 x 20 centimeters resulted in the highest fresh and dry yield per rai. It was found that the Nakhon Si Thammarat-1 varieties at a spacing of 20 x 20 centimeters gave the highest fresh weight of 3,800 kilograms per rai, followed by Surat Thani-1 at a spacing of 50 x 50 centimeters and Phang Nga-1 at a spacing of 60 x 60 centimeters, giving fresh weight of 3,000 and 2,500 kilograms per rai, respectively. In terms of dry weight, it was found that Nakhon Si Thammarat-1 varieties at a spacing of 20 x 20 centimeters gave the highest dry weight of 540 kilograms per rai, followed by Surat Thani-1 at a spacing of 50 x 50 centimeters and Phang Nga-1 at a spacing of 40 x 40 centimeters, giving dry weight of 422 and 341 kilograms per rai, respectively. And from the analysis of the total lactone amount, it was found that 5 varieties of Andrographis paniculata gave a total lactone amount that was not statistically different. Andrographis paniculata, the top three varieties with the highest total lactones were Phang Nga-1, Surat Thani-1, and Krabi-1, giving average total lactone amounts of 19.41, 19.08, and 18.99 grams per 100 grams of dry weight, respectively.