Effects of different N,P,K fertilization ratios on the growth and photosynthetic characteristics of Cunninghamia lanceolata seedlings
In order to select a suitable nutrient ratio for the growth of Cunninghamia lanceolata seedlings,the effects of different ratios of nitrogen (N),phosphorus (P) and potassium (K) fertilizers on the growth,photosynthesis physiology,root morphology and nutrient accumulation of C.lanceolata seedlings were investigated,thus providing a theoretical basis for the nutritional management of C.lanceolata during seedlings stage.In this study,a sim-plex-centroid experimental design was employed to investigate the different growth,photosynthesis characteristic,root morphology and nutrient accumulation responses of C.lanceolata seedlings under various fertilization ratios of N,P and K,namely,T1 (6︰3︰1),T2 (2︰7︰1),T3 (2︰3︰5),T4 (4︰5︰1),T5 (4︰3︰3),T6 (2︰5︰3) and T7 (1︰1.3︰0.7),along with non-fertilization treatment (CK) by using one-year-old C.lanceolata seedlings 'Yang 061' as the material.On this basis,the N,P,and K ratios suitable for the growth of C.lanceolata seedlings were screened by the subordinate function value method.The results were as follows.1) Compared with CK,the different fertiliza-tion ratios of N,P and K could promote the growth of the seedling height,ground diameter,biomass,and average root diameter of C.lanceolata to varying degrees.The total root length,total root surface area and total root volume of C.lanceolata seedlings under different fertilization ratios were all higher than CK except for those in T4 and T5 treat-ments.2) The different fertilization ratios of N,P and K could increase the contents of photosynthetic pigments to different degrees.The chlorophyll a/b value and photosynthetic pigment content in the leaves reached their maxi-mum values under T5 (4︰3︰3) and T7 (1︰1.3︰0.7) treatments,respectively.In addition,the nutrient element contents in different organs were increased as well under different fertilization ratios of N,P and K.3) The net pho-tosynthetic rate and water use efficiency in the leaves were increased to different degrees under different fertilization ratios of N,P and K as compared with CK,while the opposite was true for the transpiration rate and stomatal con-ductance.Meanwhile,the maximum fluorescence,variable fluorescence,potential photochemical efficiency of PS Ⅱ,photochemical quenching coefficient and the maximum photochemical efficiency of PS Ⅱ (except T2) in the leaves of C.lanceolata were increased to different degrees as well.4) The results of subordinate function value method showed that the value of T5 treatment (4︰3︰3) was the largest among different treatments.Taken together,T5 treatment (4︰3︰3) is the most appropriate ratios of N,P and K for the growth of 'Yang061'under current experi-mental conditions,and the satisfactory growth effects can be achieved.
fertilization ratiosCunninghamia lanceolataseedling qualityphotosynthetic characteristicsnutrient element
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