氮肥形态对山苍子幼苗生长及生理的影响

Effects of nitrogen forms on growth and physiology of Litsea cubeba seedlings

【目的】筛选适宜的氮素肥料,为山苍子苗期施肥提供参考。【方法】以同一家系1年生山苍子幼苗为试验材料,设置不施肥、硝态氮、铵态氮、硝铵态氮、酰胺态氮、氨基酸态氮共6个处理,施肥处理结束3个月后,测定苗高、地径生长量、地上部生物量、地下部生物量、叶绿素a含量、叶绿素b含量和总叶绿素含量、叶片光合气体交换参数、光响应曲线参数和叶片养分含量指标,分析山苍子幼苗生长及生理特性对不同形态氮肥的响应。【结果】与不施肥的对照相比,不同形态氮肥处理均不同程度地促进了山苍子幼苗生长,增大了其生物量,以酰胺态氮处理的效果最为显著;仅酰胺态氮处理显著增加了叶片叶绿素的含量;不同形态氮肥对叶片光合作用的影响不同,所有氮肥处理均提高了净光合速率,酰胺态氮处理显著提高了气孔导度,硝态氮、铵态氮、硝铵态氮显著降低了蒸腾速率且显著提高了水分利用效率;酰胺态氮处理显著提高了最大净光合速率、铵态氮显著降低最大净光合速率,各处理中表观量子效率、光补偿点、暗呼吸速率无显著差异;所有氮肥处理均显著提高了叶片氮含量,硝铵态氮、酰胺态氮处理降低了叶片磷含量,除氨基酸态氮处理外其余氮肥处理显著提高了叶片钾含量。【结论】不同形态氮肥对山苍子幼苗生长和生理特性的影响不尽相同,按照肥效由优到劣排序依次为酰胺态氮、硝铵态氮、铵态氮、氨基酸态氮、硝态氮、对照,酰胺态氮更有利于促进山苍子幼苗生长发育。

【Objective】Screening suitable nitrogen fertilizer to provide reference for Litsea cubeba seedling fertilization.【Method】One-year-old L.cubeba seedlings of the same family were used as experimental materials.Six treatments were set up,including no fertilization,nitrate nitrogen,ammonium nitrogen,ammonium nitrate nitrogen,amide nitrogen and amino acid nitrogen.Three months after the end of fertilization treatment,the seedling height,ground diameter growth,aboveground biomass,underground biomass,chlorophyll a content,chlorophyll b content and total chlorophyll content,leaf photosynthetic gas exchange parameters,light response curve parameters and leaf nutrient content indexes were measured to analyze the response of L.cubeba seedling growth and physiological characteristics to different forms of nitrogen fertilizer.【Result】Compared with the control without fertilization,different forms of nitrogen fertilizer treatments promoted the growth of L.cubeba seedlings and increased their biomass to varying degrees,and the effect of amide nitrogen treatment was the most significant.Only amide nitrogen treatment significantly increased the chlorophyll content of leaves;the effects of different forms of nitrogen fertilizer on leaf photosynthesis were different.All nitrogen fertilizer treatments increased net photosynthetic rate,amide nitrogen treatment significantly increased stomatal conductance,nitrate nitrogen,ammonium nitrogen and ammonium nitrate nitrogen significantly reduced transpiration rate and significantly increased water use efficiency.The maximum net photosynthetic rate was significantly increased by amide nitrogen treatment,and the maximum net photosynthetic rate was significantly decreased by ammonium nitrogen treatment.There was no significant difference in apparent quantum efficiency,light compensation point and dark respiration rate among the treatments.All nitrogen fertilizer treatments significantly increased the nitrogen content of leaves.ammonium nitrate nitrogen and amide nitrogen treatments reduced the phosphorus content of leaves.Except for amino acid nitrogen treatment,other nitrogen fertilizer treatments significantly increased the potassium content of leaves.【Conclusion】The effects of different forms of nitrogen fertilizer on the growth and physiological characteristics of L.cubeba seedlings were not the same.According to the order of fertilizer efficiency from good to bad,they were amide nitrogen,ammonium nitrate nitrogen,ammonium nitrogen,amino acid nitrogen,nitrate nitrogen and control.Amide nitrogen was more conducive to promoting the growth and development of L.cubeba seedlings.