Received: Mar 13, 2024 / Published: Jun 28, 2024
Jiaogulan (Gynostemma pentaphyllum (Thunb.) Makino) is distributed mostly in mountainous areas, in shaded and humid places at 300-3200 meters above sea level. This study was conducted to determine the appropriate application dose of nitrogen for the growth of Jiaogulan under different shading conditions. The experiment was arranged in a split-plot design with three replications in 2021. Nitrogen application dose was the main factor with three levels: N1, N2, N3 of 90, 120 and 150kg of N ha-1, respectively. The shading condition was the sub-factor with two regimes: S1 - no shading and S2 - 30% shading (30% reduction in solar radiation using black netting). The observation parameters included main stem length, number of leaves, and number of primary branches. The physiological indicators (LAI, SPAD, dry mass) were measured at 30, 60, 90, and 120 days after transplanting. Yield and total content of saponins and flavonoids were determined at harvesting time. The results showed that the application of the 30% shading condition combined with increasing nitrogen application doses had positive effects on the growth and yield of Jiaogulan. The highest yield was obtained in the treatment combining the 30% shading condition and N3 nitrogen application level. The total flavonoid and total saponin contents did not significantly differ among the treatments. Thus, in the spring-summer season, a combination of a 30% shading condition and nitrogen application of 150 kg N ha-1 should be applied to produce good growth and high yield as well as ensuring the quality of Jiaogulan.
