Effects Of Organic Mulching On Morphological And Chemometric Characteristics In Differen-order Fine Roots Of Ligustrum Lucidum Plantation

Exploring the effects of organic mulching on morphological and chemometric characteristics in different-order fine roots,to provide scientific basis for understanding the process of fine roots nutrient utilization,and near-natural management of urban soil.This study conducted an experiment that introduced treatments of organic mulching?with a uniformed radius of 80 cm?at four levels?namely,CK,T1,T2 and T3 with the thickness of 0,5,10 and 20cm,respectively,i.e.with the coverage of 0,35,70 and 140 kg/tree?in a 16-year-old Ligustrum lucidum plantation in Nanjing.the morphological and chemometric characteristics of fine roots in different root orders were used to analyze by means of variance analysis,redundancy analysis and correlation analysis.The main results as follows:?1?Organic mulch,soil layer and growth period all have significant effect on the morphological characteristics of fine roots,and their interaction also has significant effect on the morphological characteristics of fine roots.The specific root length of fine roots are 0.82-56.78m·g^-1,specific root surface area are 48.09-636.92 m²·g^-1,the tissue density are 0.18-0.500.18-0.50 g·cm^-3.Compared with the CK,the specific root length and specific surface area of 1^stt and 2^nd-order roots with T1 increased by 12.09%-14.91%and the tissue density decreased by13.18%in May.The specific root length and specific surface area of fine roots increased by 10%-50.24%in August.The specific root length and specific surface area of fine roots increased by0.21%-47.03%and the tissue density decreased by 0.38%-16.55%in November.while the specific root length and specific surface area of fine roots decreased by 4.16%-39.78%and tissue density increased by 1.95%-22.95%in February.?2?Organic mulch,soil layer and growth period have significant effect on C,N and P content of fine roots,and their interaction has significant effect on C,N and P content of fine roots.The C concentration of fine roots are 546.1-830.6 g·kg^-1,the N concentration are 5.9-26.5g·kg^-1,the P concentration are 0.60-2.63 g·kg^-1.After organic mulching,compared with the CK,the content of C,N and P of fine roots in 20-40 cm soil layer increased by 1.46%-38.81%in May,the content of C,N and P of fine roots increased by 0.85%-37.78%in August;the content of C of fine roots in 0-20 cm soil layer increased by 3.76%-19.49%,the content of N,P of fine roots in 20-40 cm soil layer increased by 9.73%-26.97%in November;the content of C,N and P of fine roots decreased by 0.42%-38.18%in February.?3?Organic mulching,soil layer and growth period have significant effects on C/N,C/P and N/P of fine roots,and their interaction has significant effects on C/N,C/P and N/P of fine roots.The C/N of fine roots are 25.65-118.09,the C/P are 186.31-1139.22,the N/P are 4.20-15.44.After organic mulching,compared with CK,the C/N of fine roots at 0-20 cm soil layer increased by 1.33%-52.82%,while the N/P of fine root at 20-40 cm soil layer increased by 1.98%-46.38%,and the C/P of 5^th-order root at 0-40 cm soil layer increased by 1.21%-52.84%in May;the C/N of fine roots at 0-20 cm soil layer increased by 0.99%-25.55%,and the C/P and N/P of fine roots at 0-40 cm soil layer increased by 1.64%-36.66%in August;the C/N and C/P of fine roots at 0-20 cm soil layerincreased by 1.20%-38.16%in November;the C/N,C/P and N/P of fine roots at 0-20 cm soil layer increased by 1.30%-43.05%February.?4?Organic mulching mainly affects the morphological and chemometric characteristics of fine roots by changing soil temperature,water content,soil total C and soil total P.Among them,soil temperature is the dominant factor,which has a significant impact on the indicators of fine roots,and the morphological characteristics of fine roots are significantly correlated with the chemometric characteristics.In conclusion,organic mulching can improve the soil environment,increase the absorption capacity and nutrient cycling rate of fine roots in the growth period,and strengthen the defense of fine roots against the external environment in the dormancy period.Organic mulching also promoted the absorption capacity and turnover rate of fine roots in deep soil,and enhanced the accumulation of organic matter in surface soil.On the whole,organic mulching is an effective measure to promote soil near naturalization and improve urban ecological services.It is suggested to promote organic mulching in urban soil management.