橡胶树叶片氮素营养特性及其对施氮量的响应

Nitrogen Nutrition Characteristics of Rubber Tree Leaves and Its Response to Nitrogen Application Rate

以2 a橡胶树幼树为种植对象,采用单因素随机区组设计田间试验,设置3种施氮水平处理(低氮28 g/株、中氮56 g/株和高氮84 g/株),动态监测降雨量、日均气温、成熟叶氮含量、叶绿素含量等指标,各参数进行回归分析及相关分析。结果表明:①橡胶树叶片氮含量在周年生长期内整体呈下降趋势;不同施氮水平之间叶片氮含量差异不显著;②叶片叶绿素含量具有明显的季节变化特征,全年呈多峰型曲线波动;不同施氮水平间叶绿素含量差异不显著;③相关分析表明,叶片叶绿素含量与氮含量呈显著的正相关关系(P<0.05);叶片氮含量与日均温度及降雨量均表现出正相关关系,其中与日均温度呈极显著相关(P<0.01),与降雨量呈显著相关(P<0.05);叶绿素a、叶绿素b含量及叶绿素总量均与日均温度和降雨量表现出极显著正相关(P<0.01);叶绿素a/b周年平均值和施氮量之间呈极显著负相关关系(P<0.01),随着施氮量的增加叶绿素a/b降低。施用氮肥后叶片氮素和叶绿素含量均出现明显增加的趋势,叶绿素含量一定程度上反映了橡胶树叶片氮营养状况,但受到季节和气候等因素的影响。

Rubber tree saplings planted after 2 years were used as the planting material, and a single-factor randomized block design field experiment was conducted to set three treatments with different nitrogen levels(low nitrogen 28 g/plant, medium nitrogen 56 g/plant and high nitrogen 84 g/plant). The parameters of rainfall, daily average temperature,nitrogen content of mature leaves, chlorophyll content and other indicators were dynamically observed for regression analysis and correlation analysis. The nitrogen content of rubber tree leaves showed a decline trend during the annual growth cycle. The difference of nitrogen contents in the leaves between different treatments was not significant. The dynamic change of chlorophyll content in the leaves had obvious seasonal variations, and several peaks were observed throughout the growth cycle. There was no significant chlorophyll content difference between different nitrogen levels.The results of correlation analysis showed that chlorophyll content and total nitrogen content were positively correlated(P<0.05). The nitrogen contents in the leaves was positively correlated with rainfall and temperature, and its correlation with temperature was extremely significant(P<0.01) while its correlation with rainfall was significant(P<0.05). Chlorophyll a, chlorophyll b and chlorophyll content were all extremely correlated with rainfall and temperature(P<0.01).Chlorophyll a/b ratio was extremely negatively correlated with N application rate, and a decrease in chlorophyll a/b ratio was observed with an increase in N rate. Obvious increment of N content in rubber leaves were found after N fertilizer application. Chlorophyll content could be regarded as an indicator revealing N status of rubber leaves to some degree.However, season and climate factors should be considered together.