Pre-hardening nutrient status affects efficacy of fall fertilization of Quercus variabilis seedlings

• 作 者: 李国雷 祝燕 R.Kasten Dumroese 刘勇
• 机 构: 北京林业大学省部共建森林培育与保护教育部重点实验室 北京 100083 US Department
• 出 处: 第十届中国林业青年学术论坛
• 发表日期: 2012年5期

　　This study examined how seedlings of deciduous tree species respond to fall fertilization during their hardening period.Cork oak (Quercus variabilis) container seedlings were reared for 23 weeks pre-hardening under prescribed fertility schedules with accumulated totals of 25,100,150 mg N/seedling.Seedlings were sampled to determine their nutrient state pre-hardening,and were then fertilized during hardening with 0,12,and 24 mg N/seedling for 4 weeks.For the seedlings without supplemental N during hardening,N increment in stem and root was 8.68,12.95 and 17.09 mg/seedling,respectively.Thus N concentration in stem and root increased in spite of substantial growth during hardening.The fact that fall fertilization was necessary to avert the nutrient dilution effects for evergreen tree species was not shared by deciduous trees.28.6%-34.7% of N was retranslocated from foliar tissues into the stem and root and accounted for 41.7%-87.0% of total N increment of stem and root,indicating that foliar N retranslocated averted N dilution.Fall fertilization was more effective in increasing plant nutrient reserves when seedlings were low-level nutrient loaded at 25 mg N/seedling.For the seedlings fertilized at 150 mg N/seedling pre-hardening,fall fertilization during hardening was toxic to stem dry mass and height.This also strongly suggests that the role of fall fertilization during hardening on seedling quality could be influenced by the nutrient level pre-hardening.