The Effect of Deficient Irrigation on Growth Period Duration and Phenology of Some ‎Cannabis Ecotypes

The present study has been conducted to investigate the duration of growth period of different cannabis (Cannabis sativa L.) ecotypes and their responses to water stress based on a factorial completely randomized experiment design in the greenhouse condition at the University of Tehran in 2017. Irrigation levels include 50%, 75%, and 100% of field capacity, with the ecotypes being Urmia, Sanandaj, Tabriz, Dasht-e-Moghan, Rasht, Khomein, Daran, Qom, Shahroud, Kerman, Tabas, and Saravan. Results show that Rasht and Khomein ecotypes have had the highest and lowest duration of germination phase and growth degree-days (GDD1), respectively. The highest duration of vegetative, flowering and maturation phases belong to Dasht-e-Moghan, Rasht, and Dasht-e-Moghan ecotypes with 71.33, 30, and 46.66 (days), respectively, at 100% field capacity. The lowest durations of these phases could be seen in Tabas, Tabriz, and Saravan ecotypes with 42, 16, and 17 (days), respectively, at 50% field capacity. Also, the highest values of growth degree-days for vegetative (GDD2), flowering (GDD3), and maturation (GDD4) phases  for Dasht-e-Moghan, Kerman, and Dasht-e-Moghan ecotypes with 1788, 836, and 1169 (0C.d), respectively, at 100% field capacity, with their lowest values belonging to Tabas, Tabri,z and Saravan with 1039, 413, and 448 (0C.d), respectively, at 50% field capacity. Based on growth period duration and cumulative growth degree-days (total GDD), Tabas and Dasht-e-Moghan ecotypes are found as earliest and latest ecotypes, respectively.