不同铵硝比对高山杜鹃侧枝生长和生理特性影响OA北大核心CSTPCD

To study the effect of nitrogen form on the growth of side branches of alpine Rhododendron,3-year potted alpine Rhododendron Fen Jing-ling powder fairy was used as experimental material.A single nitrogen source treatment was used as the control,and the effects of 5 different nitrogen form ratios(ammonium and nitrate ratio:T1∶100∶0,T2∶75∶25,T3∶50∶50,T4∶25∶75 and T5∶0∶100,respectively)on collateral growth,photosynthetic characteristics,metabolic enzyme activity and nutrient accumulation in vegetative growth period were studied in pot.The results showed that there were differences between different nitrogen ratios on the dry matter accumulation of lateral branches,seedling height increment,and lateral branch length of Fen Jing-ling at different growth stages,among which the T3 treatment had the highest dry matter accumulation of lateral branches at the stage of lateral bud germination and the T2 treatment had significantly higher seedling height increment and lateral branch length than the other treatments at the stage of shoot lateral branches and semi-lignification of lateral branches.During the semi-lignification stage of lateral branches,compared with T1 treatment,T2 treatment significantly increased net photosynthetic rate,transpiration rate,stomatal conductance,water use efficiency,and phosphorus content while reducing intercellular carbon dioxide concentration.The absorption of Fe element in leaves was the highest in T1 treatment,and the absorption of Mg element was the highest in T5 treatment.In addition,nitrate reductase activity increased with the increase in nitrate nitrogen ratio at different growth stages,with the highest enzyme activity occurring during the tender branch stage.In summary,the effects of different nitrogen ratios on the growth and physiological characteristics of the side branches of the Rhododendron Fen Jing-ling vary.The mixed nitrogen source treatment promoted the growth of the side branches compared to a single nitrogen source treatment,with an ammonium-nitrogen ratio of 75:25 being more conducive to the growth of the side branches,improving nutrient accumulation and photosynthetic efficiency.This study provides a theoretical basis for optimizing nitrogen fertilizing strategies and nitrogen application methods suitable for the growth and development of alpine rhododendrons,thereby improving the cultivation and management level of seedling quality.