Chemical induced vigour for heterotic effects on yield and quality of essential oil in palmarosa (Cymbopogon martinii Wats)

The efficacy of a few selected synergistic combinations of ethephon as chem ical hybridizing agent for stimulatory heterotic effects on biomass and ess ential oil yield in palmarosa plants has been tested. Ethephon in solo trea tment as well as in various synergistic combinations with the two precursor compounds of m-coumaric acid/3-hydroxycinnamic acid-spermidine and putresc ine, and with four micronutrients, Fe-EDTA, CuSO4, ZnSO4, MnCl2 was "mist s prayed" during the vegetative and anthesis growth stages of palmarosa plant . Ethephon treatment along with spermidine (2%) or putrescine (2%) in conju nction with any of the four micronutrient (0.5% solution) exhibited maximum fresh herbage yield (99 kg/plot) and dry matter yield (32 kg/plot) as comp ared to the control values of 68 kg/plot, and 23 kg/plot, respectively. Fur ther, the treated plants possessed maximum total essential monoterpene oil( s) (2.3%) and geraniol (69%) as compared to control values of 0.66% and 57. 3%, respectively. The positive significant correlation coefficient values b etween geraniol content and leaf area index (r = 0.941 less than or equal t o = 0.01), and geraniol and dry matter content (r = 0.739 less than or equa l to p = 0.01) suggested the increased availability of photosynthates and o ther precursor metabolites for enhanced growth and oil content. The data su ggest that ethephon in synergistic treatment(s) of m-coumaric acid results into greater accumulation of endogenous ethylene in the anther leading to m ale sterility condition.