Effect of Different Nitrogen Rates and Harvesting Periods on Lemongrass Performance

Lemongrass is a perennial lawn crop. Generally known as serai makan in Malaysia. It has various uses, from table consumption to essential oil and ornamental and pharmaceutical products. However, the use of medicinal crops can be characterized by several approaches such as harvesting period, climatic factors, moisture, light exposure, plant parts, logistics, storehouse, drying process, and other post-harvest processes. One way to enhance lemongrass herbage yield is by manipulating the N rate. Department of Agriculture (DOA) Malaysia recommends using 400 kg/ha of NPK green 15:15:15 for 6‒8 months, but this is a generalized blanket recommendation and not nutrient-specific. Therefore, a study was carried out on the effect of N and the harvesting period. The experimental design was a Randomized Complete Block Design (RCBD) with factorial. Analysis suggests that SPAD chlorophyll reading, slip number, and leaf blade number were significantly affected by N, harvesting period and interaction between N and harvesting period. SPAD readings at 150 and 180 days after transplant (DAT) only show significant improvement at 300 Kg N/ha. For slip numbers, the response at 210 DAT only showed significant improvement when at least 200 kg N/ha were applied, and the subsequent increment at 300 kg N/ha was at par. Leaves blade number response was unique for each harvesting period. Nevertheless, leaf blade numbers began to show a significant increment at 100 kg N/ha, and the increment of leaf blades between 200 to 300 kg N/ha was non-significant for all harvesting periods. These parameters exhibit significant positive linear responses towards N; some may have significantly unique responses to their harvesting period. Herbage yield was significantly affected by both N and the harvesting period, but there was no significant interaction between them. Herbage yielded the highest significant reading when 300 kg N/ha was applied, while the harvesting period contributed the highest significance at 240 DAT, while subsequent increment at 270 DAT was non-significant. Present findings may suggest that further study needs to be carried out to improve the current production manual, and consideration must be given to soil type, location, and climate conditions.