【摘要】 自然条件下进行了土壤温度、水分、播深及覆沙地境对红砂和霸王种子萌发与幼苗生长的效应研究,结果显示,模拟阵雨期(人工洒水)覆沙和未覆沙试验小区白天播种层土壤温度均较高,尤其中午(14:00)覆沙小区1和4cm播种层土壤温度平均值分别高达43.2和37.3℃,未覆沙小区分别高达38.0和33.6℃。高温引发种子次生休眠是该期红砂和霸王种子不能萌发的主要原因。而且播种层土壤含水量日内下降十分明显,其中覆沙和未覆沙小区1 cm土层平均土壤含水量下降至0.11%和2.62%,也会引发种子产生次生休眠,成为红砂和霸王种子不能萌发的另一原因。自然连续降水期2种试验小区播种层平均土壤温度适宜,播种层土壤含水量高而稳定,满足了红砂和霸王种子萌发的适宜温度和较高水势的条件。因此,在干旱荒漠区进行荒漠草地的人工辅助建植,需要依靠连续性降水过程。自然条件下霸王发芽率最高的播深处理在覆沙小区为2 cm、未覆沙小区为1 cm;在2种试验小区内霸王幼苗生物量最大的播深处理均为2和3 cm。覆沙较未覆沙地境有利于霸王种子萌发和幼苗的生长。播种当年霸王地上生物量为红砂的75~117倍。更多还原

【Abstract】 Reaumuria soongorica and Zygophyllum xanthoxylum are important ultra-xenomorphic shrubs in the northwest arid desert region of China.In 2001,seeds of the two species were collected at maturity in the Alshan Region,Inner Mongolia,and kept at-5℃ until use.Study on the effects of soil temperature,soil water content,sowing depth and sand cover on seed germination and seedling growth for the two shrubs was conducted in their native habitats.The results showed that during a simulating shower period(manned shower),the average soil temperatures of the sowing layers were too high for seed germination.This was especially so at noon,where the average temperatures at the soil depths of 1 and 4 cm sowing layer in the sand covered and non-sand covered plots were 43.2,37.3℃ and 38.0,33.6℃,respectively.These high temperatures,which could have lead to secondary seed dormancy,were the primary reason for seeds not germinating.Further,the soil water contents of sowing layers reduced acutely.This finding was especially so for soil water contents in the 1 cm sowing layer treatments of the two plots,where it decreased to 0.11% and 2.62%,and could also have been a cause for secondary seed dormancy,also leading to seeds not germinating.However during the continual nature raining period,the soil temperatures of the sowing layers were as expected,with the soil water contents of the sowing layers high and sustainable.As such,the basic conditions of seed germination of the two shrubs were met in this period.Thus,the accessorial sowing planting in arid desert region must depend upon continual rainfall.The highest seedling emergence percentage for Z.xanthoxylum was obtained in 2 cm sowing depth treatment in the sand covered plot,and was obtained in 1 cm sowing depth treatment in the non-sand covered plot.The highest above biomass for the Z.xanthoxylum seedling was obtained at the 2 and 3 cm sowing depths in both trail plots.Comparatively,the sand covered plots had an advantage for Z.xanthoxylum seed germination and seedling growth over the non-sand covered plots.In the first growing year,the above biomass of Z.xanthoxylum was significantly higher than that of R.soongorica(P < 0.01),where it had 75～117 times of the biomass to R.soongorica.更多还原