氮素指数施肥对白桦播种苗养分承载和光合作用的影响

Effects of N exponential fertilization on nutrient loading and photosynthesis of Betula platyphylla seedlings

为改善白桦苗木质量,本文采用常规施肥(CF)、指数施肥(EF)、1/2指数施肥(HEF)、2倍指数施肥(DEF)以及对照(CK)处理,研究容器苗中不同N施肥处理对白桦1年生播种苗生物量分配、养分含量动态和养分承载以及苗木叶片光合能力的影响。结果表明:1)生长结束后,EF处理提高了苗木生物量,同时改善了苗木根系生物量所占比例。EF处理苗木总生物量较CK提高23.87%(P<0.05),同时EF处理较CF和DEF处理苗木根茎比提高均为26.09%(P<0.05)。2)EF处理提高了苗木体内的养分承载,与DEF处理苗木养分含量差异不显著,但EF处理苗木养分含量较CF、HEF、CK处理分别增加29.65%、33.42%、113.74%(P<0.05)。3)苗木生长高峰期,EF处理提高了苗木叶片的光合能力。EF处理苗木叶绿素含量及光合速率较CF处理分别提高15.2%(P<0.05)、7.3%(P>0.05)。EF处理苗木叶面积高于CF处理14.3%(P<0.05)。4)5种施肥处理苗木N、P养分浓度及N、K养分浓度呈线性相关(P<0.01)。指数施肥提高了苗木P、K吸收,不同施肥处理对苗木P、K吸收效率由高到低均为EF>DEF>HEF>CF>CK。EF处理有效促进了苗木生物量积累,提高了苗木养分承载,同时明显提高了苗木体内P、K的养分利用效率,因此EF处理为最佳施肥方式。

In order to improve Betula platyphylla seedling quality,the biomass allocation,nutrient（ N,P,K）content dynamics,nutrient loading and leaf photosynthesis of B. platyphylla container seedlings under constant（ CF）,exponential（ EF）,half exponential（ HEF） and doubled exponential fertilization（ DEF）regimes and control（ CK） were studied in the first year growing. Results showed that： 1） at the end of the growing season,EF treatment improved the biomass of seedlings and the biomass proportion of root.The total biomass of seedlings under EF treatment was greater than that under CK（ P 〈 0. 05） in23. 87%. The biomass proportion of root under EF treatment was greater than that under both CF and DEF treatment（ P 〈 0. 05） in 26. 09%. 2） EF treatment improved the nutrient loading of seedling with no significant difference from that under DEF treatment. However the nutrient content of seedling under EF treatment was greater than that under CF,HEF and CK treatment in 29. 65%,33. 42% and 113. 74respectively. 3） During the peak periods of seedlings growth,EF treatment promoted photosynthetic characteristics of seedling leaf. Chlorophyll concentration and photosynthetic rate of B. platyphylla seedlings under EF treatment was greater than that under CF treatment in 15. 2%（ P 〈 0. 05）,7. 3%（ P 〉0. 05） respectively. Meanwhile,seedling leaf area under EF treatment was greater than that under CF treatment in 14. 3%. 4） The concentration of N,P and N,K nutrient under 5 fertilization treatments was linear correlation. Exponential fertilization improved the P,K uptake efficiency（ EF 〉 DEF 〉 HEF 〉CF 〉 CK） in seedlings. EF reffectively promoted biomass accumulation and improved nutrient loading,meanwhile,significantly increased P,K utilization. EF is the best fertilization regime for B. platyphylla seedlings.