Morphology And Nanomechanical Properties Of Cortex Collenchyma And Xylem Of Young Stem On Apple Tree

Shaping and trimming of furit trees, which can highly promote the yield of fruittrees, are drawing more and more attention these years,but the cut produced are quite vulnerableto fungi and bacteria.Therefore protrcting the cut of fruit trees is important.Forinvestigate mechanisms of the resistance of furit trees and the fungal invasioninduced bymechanical damage, AFM was applied inthis research to study the changein roughness and mechanical properties on the surface of Collenchyma tissue and xylemparenchyma of apple. The results obtained are as below1. The cut surface roughness and hardness and Young’s Modulus of the xylemparenchyma differed with their atmospheric exposure times to air. In an area of1×1μm~2，theRMS roughness gradually increased from17.63±2.72nm to33.42±1.54nm by the zerohour to the forty eighth hour in air. The cut surfaces lost water and wrinkled with time so thattheir roughness gradually increased. Within the0th～48th h, the surface hardness graduallyincreased from0.15±0.02N/m to0.49±0.02N/m, within the deformation interval [30,60nm],the average Young’s Modulus gradually increased from0.95±0.13Mpa to4.71±0.09MPa，indicating that the xylem parenchyma lost water,and gradually increased in surface hardnessand Young Modulus, because their exposure times to air increased.2. The cut surface roughness and hardness and Young’s Modulus of the collenchymasdiffered with their atmospheric exposure times to air. In an area of1×1μm~2，the RMSroughness gradually increased from14.45±3.54nm to31.07±2.01nm from the zero hour tothe forty eighth hour. The cut surfaces lost water and wrinkled with time so that theirroughness gradually increased. Within the0th～48th h, the surface hardness graduallyincreased from0.19±0.03N/m to2±0.03N/m, within the deformation interval [30,60nm],the average Young’s Modulus gradually increased from2.77±0.38Mpa to9.48±0.36MPa，indicating that the collenchymas lost water,and gradually increased in surface hardness andYoung Modulus, because their exposure times to air increased.