effect of soil moisture regimes under controlled conditions on growth and biomass in mentha species

shortage of water in arid and semiarid regions of the world can reduce growth and production of medicinal and aromatic plants, especially mentha species. in order to evaluate response of mint species to water deficit stress, an experiment was carried out using a completely factorial-randomized design with five replications at college of agriculturae, ferdowsi university of mashhad, iran. the factors studied included three mint species (peppermint ‘mentha×piperita’, wildmint ‘mentha longifolia’, spearmint ‘mentha spicata’) that were exposed to four levels of irrigation treatments (control (100%), 80%, 60% and 40% of field capacity (fc)). in this study in 100% of fc spearmint’ green area was 50% more than 80% of fc, while in wildmint and peppermint mentioned parameter in control treatment were 2.5 and 2 times more than 80% of fc, respectively. however no difference observed between 100 and 80% of fc on aboveground to underground dry matter ratio in spearmint, but this parameter in control treatment of wildmint and peppermint were 50% more than 80% of fc. results showed that growth of all three species were significantly decreased when soil moisture reduced to lower than 100 of fc, but peppermint and wildmint were more sensitive than spearmint to depletion of soil water during growing season.