A Study on phenology of Atriplex griffithii for optimal management in the Aftar rangelands of Semnan

In order to find some phenological phenomena of Atriplex griffithii with climate properties such as as temperature and precipitation, this study was carried out in the north-east of Semnan province from 2001 to 2004. In this survey, 10 Atriplex griffithii were selected and marked. Phonological stages (germination, vegetative, flowering, seeding, and regrowth) were measured in 15-day periods while reproductive traits were measured in 7-10 day intervals. Analysis of climatic data and recorded phonological stages showed that the growth of Atriplex griffithii varied with the fluctuations of drought and temperature in different seasons and two distinctive stages (vegetative and seeding) were recognized for each year. The first growth stage started from late winter and continued to mid-August and the second growth stage started from second half of August and ended in second half of December. Flowering started from May and seeds matured in June. Phonological stages also differed among geographical directions due to differences in rainfall, temperature and evaporation rate as flowering and seeding stages in southern slopes occurred in May and June and in northern slopes were in October and November, respectively. Obtained results can help range managers to set a time calendar for livestock entry and exit and also grazing season.