Seed Germinative strategy and ecological adaptability of Corisperimum patelliforme

Corispermum patelliforme,an annual plant species found in arid desert areas of the North China and Mongolia,is an important economic species used for wind-breaking,sand fixation,pasture and fuel purposes.Seed germination and seedling emergence are the critical stages of life cycle for the species.The study was conducted at Minqin National Studies Station for Steppe Ecosystem in Gansu Province of China.In order to examine seed germinative strategy and ecological adaptation of Corisperimum patelliforme,experiments of the effects of temperature,GA3 and light on seed germination in the laboratory conditions were conducted.The effects of sand burial depths and GA3 on seedling emergence were simultaneously studied in the field.Mature seeds of C.patelliforme were collected from the dry plants of natural populations in the desert area of Minqin Oasis Basin in October 2005.The seeds were then stored in a shaded and ventilated room at temperature of 13—30℃ before use in May 2006.To reduce the effects of other factors on seed germination and seedling emergence,the seeds for germination and sand-burying experiments were treated by using soil siege wiping the big other seeds,eggs and branches off and treated by fungicide Phygon before the germination process.Experiments were carried out with three groups of 50 seeds each,on Whatman No.1 filter paper,in 90 mm diameter Petri dishes.Germination was checked every 24h and seedlings were removed.Light treatments included 0h light,12h light and 24h light.Temperature treatments included constant and changing temperatures,including 15℃,20℃,25℃ and 30℃ of constant temperatures and 15/25℃,10/30℃,15/35℃and 5/25℃ of changing temperatures.A comparative experiment was carried out for the changing temperatures after seeds were soaked by H2O and GA3 for 2 hours.The sand-burying experiment was conducted in the field at sand burial depths of 0.5,1.0,2.0,3.0,and 5.0 cm.A comparative experiment of sand-burying was also conducted under the same sand burial depths after seeds were soaked by H2O and GA3 for 2 hours. The results showed that:(1) the optimum constant temperature for germination was 20℃ for the seeds which had been stored in dark under laboratory conditions,and the germination percentage reached(18.00±1.41)%.The optimum changing temperature for seed germination was 15℃/25℃ in dark and the germination percentage was(28.00±2.31)%;(2) the seed germination rate in changing temperatures was significantly higher than that in constant temperatures in dark,except that under 5℃/25℃(P0.01);(3) C.patelliforme seeds were dark-demanders for germination and have dormancy characteristic;(4) the seedling emergence dramatically decreased with the increase of sand burial depths in the field.The suitable depth for seedling emergence was 0.00—2.00 cm and the optimum depth was 0.50 cm with the highest seedling emergence of(16.80 2.85)%;and(5) C.patelliforme had two distinct germinative strategies,i.e.,quick germination and dormancy.The results implied that,based on the germination characteristics and seed vigor,C.patelliforme had a permanent soil bank.The results showed that germinative strategies of C.patelliforme were highly adaptive to its habitats.