Effects of winged perianth of Zygophyllum xanthoxylum on seeds germination in the field.

Seeds with the winged perianth intact and without the winged perianth were buried in different soil depth(0 cm,2 cm,5 cm)in Alashan on October,2007 and sampled once every 2 months.The results showed that seed germination and mortality of Zygophyllum xanthoxylum were significantly affected by winged perianth,and varied with the burial depth and duration.Seeds with the winged perianth intact buried on 0 cm did not germinate,but the seeds without the winged perianth germinated partly after June 2008;seeds with the winged perianth intact buried in 2 cm started germination since June 2008.However,the seeds without the winged perianth could germinate from Feb.2008,and the germination percentage was significantly higher than that of the seeds with the winged perianth except that in the Oct.In comparision 2 cm seeds,5 cm buried seeds germinatied earlier and showed a similar trend in the other germination characteristics.As the burial depth and time increasing,seeds without the winged perianth germination increased in the field but decreased under controlled conditons;however,seeds with the winged perianth germination increased both in the field and under controlled conditions.The mortality rate of seeds without the winged perianth were significantly higher than that of the seeds with the winged perianth during burial,For example,the mortality rate of the seeds without the winged perianth was 23.0% after 1 year burial,but the seeds with the winged perianth was only 10.0%,which indicated that the winged perianth of Z.xanthoxylum in favor of seeds preserved in the field and could make the seeds avoid the unsuitable environmental and establishing under suitable conditions.