Effect of varying inoculum densities of Meloidogyne javanica on biomass and forskolin content of Coleus forskohlii
摘要
This research investigates the effects of different inoculum densities of the root-knot nematode, Meloidogyne javanica on the growth and biomass parameters of Coleus forskohlii var. Selection-K, and determines the critical thresholds at which root-knot nematode significantly deter the plant health. Inoculated coleus cuttings with varying levels of M. javanica (100–8000) kg-1 soil significantly reduced the plant growth and biomass (16–52%), forskolin (26–47%) over control. While at the lower nematode inoculum levels (250–500 J2), fresh weight and tuber production not only sustained the stress but exhibited a slight enhancement (0.4–2.3%) when compared to the control plants. Moreover, we found with the help of principal component analysis that the damaging threshold for M. javanica in C. forskohlii is 1000 J2 kg− 1 soil as this level marked significant reduction in overall plant growth, biomass accumulation and forskolin content. This finding highlights the critical threshold at which root-knot nematode infestation begins to severely reduces both biomass and medicinal value of coleus, that warrant further investigation for its potential agricultural significance.