碟果虫实种子萌发对策及生态适应性

Seed Germinative strategy and ecological adaptability of Corisperimum patelliforme

以荒漠地区1年生植物碟果虫实为材料,通过温度、光照、GA3和沙埋对其种子萌发和幼苗出土影响的研究,旨在探索其种子萌发对策及生态适应性。结果表明:(1)碟果虫实种子在0h光照的条件下,萌发的最佳恒温是20℃,萌发率为(18.00±1.41)%,最佳的变温是15℃/25℃,萌发率为(28.00±2.31)%。(2)除了5℃/25℃,碟果虫实在变温条件下的萌发率极显著高于恒温下的萌发率(P<0.01)。(3)碟果虫实种子萌发时属于需暗型,而且存在休眠现象。(4)在野外沙埋的条件下,碟果虫实的出苗率随着沙埋深度的增加极显著下降(P<0.05),适宜的出苗深度为0.00—2.00cm,最佳的出苗深度是0.50cm,出苗率为(16.80±2.85)%。(5)碟果虫实种子萌发具有迅速萌发和推迟萌发两种对策;根据种子萌发率和种子活力可以推断,碟果虫实具有持久性土壤种子库的特点。结合碟果虫实萌发时的自然生存环境和本研究的结果,显示出其种子萌发对策与栖息地的生境具有高度的生态适应性。

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℃（P〈0.01）;（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.