Effect of plant density on vegetative growth, tuber yield and essential oil content in Coleus barbatus

The present investigation was undertaken to assess the impact of plant density on different vegetative and economic yield of medicinal Coleus. A field experiment was designed in randomized block design with five treatments and four replications. The study consisted of five levels of spacing (T1 = 30 cm × 30 cm; T2 =45 cm× 30 cm; T3= 30 cm × 45 cm; T4= 45 cm × 45 cm and T5= 60 cm × 45 cm). All traits pertinent to vegetative growth and herbage yield were significantly influenced by different plant densities. Gradual increase in all parameters with increased spacings were observed except tuber yield per plot and oil yield per plot. The maximum plant height (62.36 cm), spike length (33.51 cm) and leaf area (436 cm2) were recorded at 1,11,111 plants per ha (30 cm × 30 cm spacing) and minimum at 37,037 plants per ha, 60 cm × 45 cm spacing (44.10 cm; 25.95 cm and 264 cm²) respectively. The maximum tuber yield (24.37 q/ha), and essential oil yield (3.03 l/ha) were recorded in 1,11,111 plants/ha and minimum at 37,037 plants/ha (9.78 q/ha and 1.67 l/ha) respectively. However, marketable tuber diameter (12.61 cm) and oil yield (0.143%) were found better in spacing 60 cm × 45 cm compared to T3 (11.03 cm; 0.122%) and T4 (11.70 cm; 128%).