Foliar Nutrients Of Different Varieties Of Camellia Oleifera And Soil Fertility And Their Stoichiometric Characteristics Of Qianshan In Anhui

Camellia oleifera Abel is an essential woody oil tree species in China;its oil contains over90%unsaturated fatty acids and is known as the"Oriental olive oil."The Camellia industry in Qianshan City,Anhui Province,has developed rapidly in recent years.However,the industry faces various challenges,including extensive management,imbalanced soil nutrients,low-yield forest land,and poor benefits.Therefore,it is crucial to comprehensively understand the current soil and leaf nutrient status in regional oil tea forests,including the functional changes of soil and leaf traits among main cultivars.This understanding is essential in improving Camellia oleifera yield and quality,promoting the development of the Camellia industry,increasing the income of forest farmers,and alleviating poverty.This study aimed to investigate the Camellia forests in Qianshan City,Anhui Province,and establish investigation plots in the city’s principal producing areas of oil tea forests.We utilized the ASI soil nutrient status system and carbon-nitrogen-phosphorus stoichiometry to study the nutrient limitation factors of the region’s Camellia oleifera soil and leaves.Additionally,we studied the functional traits of leaves and soil nutrient characteristics of four primary Camellia oleifera cultivars in Qianshan City.The objective was to provide theoretical and technical support for soil nutrient management and low-yield forest transformation measures in Camellia forests in Qianshan City.The main research conclusions are summarized as follows:（1）The soil of the Camellia oleifera forest in Qianshan is overall acidic,with significant variations and a scarcity of available nutrients.In both the 0-10 cm and 10-30 cm soil layers,most of the soil chemical properties showed moderate or greater variation,with strong variation observed in SOC,NO₃^--N,A-P in the 0-10 cm soil layer,and SOC,A-Ca,A-P,and NO₃^--N in the 10-30 cm soil layer.According to the ASI grading standard for soil available nutrients,the proportion of low-level A-N,A-K,A-Ca,and A-Ca in both soil layers exceeded50%,indicating nutrient scarcity.The N:P ratio in the 10-30 cm soil layer（8.88）was higher than the average N:P ratio of Chinese soil（5.2）,and the C:P ratio in both soil layers（88.0and 471.0）was higher than the average C:P ratio of Chinese soil（61.0）,indicating a lack of phosphorus in the Camellia oleifera forest soil.（2）The nutrient content and stoichiometric ratios of C,N,and P in Camellia oleifera leaves showed mild to moderate variability,with smaller variations compared to the phychemical properties of the soil.The contents of elements such as N,P,and K in the leaves（11.98 g/kg,0.34 g/kg,and 5.47 g/kg）were lower than the national average（20.2 g/kg,2.0g/kg,and 15.09 g/kg）,indicating a lack of nutrients.Stoichiometric ratio analysis showed that the average N:P ratio in the leaves of the Camellia oleifera forest was greater than 16,suggesting that the growth of the Camellia oleifera forest may be limited by a lack of phosphorus.This result is consistent with the investigation results of soil C,N,P,and their stoichiometric ratios.（3）There were significant differences in leaf morphology,chlorophyll（chlorophyll a+b,carotenoids）,leaf nutrients（C,N,P,Ca,Mg）,and C,N,P stoichiometric ratios among different Camellia oleifera cultivars in the Changlin series,but a consistent pattern was lacking,and each variety had its own advantages.The TN content of the leaves of the four Camellia oleifera cultivars ranged from 10.09-11.66 g/kg,all lower than the national average of 20.20 g/kg;the TP content ranged from 0.20-0.37 g/kg,all lower than the national average of 1.21 g/kg,indicating a lack of N and P nutrients.Based on the C,N,and P stoichiometric ratio analysis of the leaves of the four Camellia oleifera cultivars,their growth was mainly limited by P,which is consistent with the results of the field investigation.Overall,there were significant differences in leaf functional traits among the four different Camellia oleifera cultivars,especially between Changlin 23 and the other cultivars.（4）The different Camellia oleifera varieties in the Changlin series exhibit significant differences in soil properties.In the 0-10 cm soil layer,there are significant differences in soil p H,EC,SWC,TN,K,Ca,Mg,NH₄⁺-N,NO₃^--N,and C:N;in the 10-20 cm soil layer,there are significant differences in soil SWC,SOC,TN,K,Ca,Mg,NO₃^--N,C:N,C:P,and N:P.Chemical stoichiometry analysis of C,N,and P indicates that the soil N:P ratio of the four Camellia oleifera varieties is less than 14,indicating that the soil of the Camellia oleifera forest is more likely to be limited by N rather than P.There is no significant correlation between the stoichiometric characteristics of C,N,and P elements in Camellia oleifera leaf and soil.From the perspective of soil ecological and chemical characteristics,there is no significant difference in different Camellia oleifera varieties in the 0-10 cm soil layer,but significant differences exist in the 10-30 cm soil layer,with the impact of the Changlin series being greater in the 10-30 cm soil layer than in the 0-10 cm soil layer.