Under 3 light intensities of 100% natural sunlight (NS),37% NS and 16% NS respectively,the experiment was conducted to investigate the effects of light and clipping intensity (non-clipping,stubbled 30 cm,stubbled 20 cm,stubbled 10 cm and stubbled 3 cm) on compensatory growth of two-year-old Caragana korshinskii seedlings.The results showed that: 1) High light and clipping treatment facilitated compensatory growth of C.korshinskii seedlings.Both the sprout number and basal stem diameter of sprout of clipped seedlings maximized under high light intensity,while a decreasing trend was observed with the increasing of clipping intensity.2) Shoot height (SH),basal stem diameter (BSD),taproot length (TRL),and lateral root number (LRN) of clipped seedlings all presented in the order of 100% NS>37% NS>16% NS in all clipping treatments.SH and BSD of clipped seedlings were lower than those of control and declined with the clipping intensity increasing.Slight clipping treatment accelerated taproot growth and increased LRN,while they were inhibited when clipping intensity increased.3) High light facilitated the accumulation of biomass of clipped seedlngs,but a decline of total seedling biomass was detected with the increasing of clipping intensity,in another words,biomass accumulation of clipped seedlings appeared as under-compensatory growth.With the decline of light intensity,the compensation index of biomass of clipped seedlings increased and only slightly fluctuation among different intensities of clipping under the lower intensity of 16% NS,suggesting that the biomass accumulation of clipped seedlings mainly depended on new carbohydrate from photosynthesis under high light intensity and on nutrient supply from the root system and stubble under relative low light intensity.The results indicate that the ability of compensatory growth of clipped C.korshinskii seedlings declined with the increasing of clipping intensity and appeared as under-compensatory growth,and that high light can facilitate compensatory growth and biomass accumulation of clipped C.korshinskii seedlings.This result would provide reference for seedling cultivation,forage production and management of grassland ecosystem.%在3个光强,100%自然全光照(natural sunlight,NS)、37% NS和16% NS的遮阴条件下,研究了5个刈割强度处理(留茬高度为30、20、10、3 cm和不刈割)对柠条(Caragana korshinskii)幼苗补偿生长的影响.结果表明,1)强光照和刈割均促进幼苗刈割后的补偿生长,刈割处理后幼苗的萌条数和萌条基径都在强光下最大,但随着刈割强度的增大呈减小趋势.2)幼苗株高、基径、主根长和侧根数在所有刈割处理均表现为100% NS>37% NS>16% NS;刈割处理幼苗的株高和基径均小于不刈割对照,且随刈割强度的增大而减小;尽管轻度刈割促进幼苗主根生长和侧根数增加,但二者都随刈割强度的增大而受到抑制.3)强光照有利于幼苗刈割后的生物量积累,但幼苗总生物量在不同光照条件下都随刈割程度的增大逐渐减小,即表现为欠补偿生长;幼苗生物量补偿指数随着光照强度的减弱而增大,在16% NS下不同强度刈割处理间变化不大,表明幼苗刈割后的生物量积累在强光下主要依赖于光合作用新合成的光合产物,而在弱光下主要依赖于根系和残留树桩贮藏的营养物质.研究表明,柠条幼苗刈割后的补偿生长能力随着刈割强度的增大而减小,且表现为欠补偿;强光照对柠条幼苗刈割后的补偿生长具有促进作用.本研究可为柠条的幼苗培育、饲草生产和草地生态系统管理提供参考.
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