Performance of early maturing vetiver ( Chrysopogon zizanioides (L.) Roberty) (cv. CIMAP-Khusinolika) for productivity and nutrient use efficiency under different fertilizer levels

Optimizing nutrient management is essential for enhancing both the productivity and essential oil quality of short-duration vetiver (Chrysopogon zizanioides (L.) Roberty) varieties. Despite this importance, limited data exist regarding the fertilizer requirements of early-maturing genotypes, underscoring the need for systematic evaluation to identify nutrient levels that maximize yield and nutrient use efficiency. Accordingly, the present study was conducted at the CIMAP Research Center, Bengaluru, during the 2021–22 and 2022–23 growing seasons with the objective to determine the optimal inorganic fertilizer dose for the early-maturing vetiver variety ‘CIM-Khusinolika,’ aiming to achieve higher root yield and enhanced essential oil composition. The study showed that applying NPK fertilizer at 125:50:50 kg ha−1 significantly enhanced vetiver performance and nutrient use efficiency. This treatment (125:50:50 kg ha−1) produced the tallest plants (139.68 cm), the highest number of tillers per plant (66.34), and longest roots (57.29 cm), outperforming 150:50:50 kg ha−1 and control. Dry root weight peaked at 30.09 q ha−1 with 125:50:50 application, slightly higher than 29.08 q ha−1 recorded with 150:50:50. Agronomic use efficiency of nitrogen, phosphorus, and potassium ranged from 8.92 to 12.72, 23.18 to 32.32, and 23.38 to 31.32, respectively. Applying 40 kg ha−1 of potassium and phosphorus increased yield by about 108% and 111%. Essential oil content ranged from 1.96 to 2.09%, with key compounds like Khusinol (47.60–50.40%), (E)-Isovalencenol (4.83–5.50%), α-Vetivone (3.57–4.30%), and β-Vetivone (2.00–2.43%). Thus, appropriately nutrient application is crucial to maximize the economic benefit and reduce the detrimental environmental impact of over-fertilization.