Occurrence of gerniol and geranyl acetate as major chemical constituents were reported in the essential oil of Cymbopogon commutauts (Steud.) Stapf. A selectant having H”80% total geraniol and coded as RRL (J) CC1 has been studied by way of quantifying growth response coefficient values of morpho-economic character, which was 1.0 signifying its good adaptability under subtropical environment. Leaf adaptation has been quantified as phyllochron which exhibited 519.6 and 775.6 degree-days for production of single mature leaf during first and second harvests, respectively. Floral adaptation was quantified as photoperiod response coefficient b=412 (degreedays/day-length). Based on two years pooled observation (2001-2002), regional crop models have been developed for prediction of essential oil production and its quality as total geraniol content (%) by using most-efficient energy indices viz., phenothermal index and thermo/photo ratio.