Effects of Ambient Temperature and Soil Conditions on Life Cycle of Terrestrial Orchid, <I>Habenaria lindleyana</I> Steud.

Abstract

Study on effects of air temperature and soil condition on life cycle of terrestrial orchid, Habenaria lindleyana Steud. in deciduous dipterocarp forest at Chiang Mai University Education Centre “Hariphunchai”, Sribuaban Subdistrict, Muang District, Lamphun Province was conducted from November 2010 to November 2012.  It was found that the average soil temperature and air temperature in hot dry season were 34.0 ±3.3 and 34.1 ±3.2 °C, respectively, whereas those of rainy season were 29.4 ±2.2 and 29.5 ±2.2 °C and cold dry season were 30.0 ±3.5 and 30.4 ±2.9 °C, respectively. The soil moisture content of the hot dry season, rainy season and cold dry season were 58.5 ±14.1, 77.4 ±8.8 and 52.7 ±13.4%, respectively.  The soil pH, organic matter, total N, and available P concentration were similar in all different seasons, but the exchangeable K concentration in hot dry season was 544.11 ±125.12mg/kg which was greater than those of the rainy season and cold dry season (201.11 ±124.13 and 165.78 ±470.39 mg/kg, respectively).  The life cycle of H. lindleyana Steud. was observed.  Dormancy occurred during cold and hot dry season, late October until March. Plant emerged from soil in late March and continued to grow. New corm was produced in June, flower stalk emerged in late July, and flowers bloomed in September.  After that, plant continued to grow until October, then, all parts of above ground dried and went into dormant stage.