Chin J Plan Ecolo ›› 2011, Vol. 35 ›› Issue (7): 779-788.doi: 10.3724/SP.J.1258.2011.00779
• Research Articles •
MENG Peng1,2, LI Yu-Ling1*, YOU Guo-Chun2, and ZHANG Shuo2
Aims Microenvironmental factors such as relative humidity, temperature and light intensity have significant effects on rooting. Our objective was to study the impact of microenvironmental factors on rooting of cuttings of Juniperus scopulorum (Rocky Mountain juniper), a native of western North America.
Methods We used the softwood of eight-year-old J. scopulorum in a split plot experiment with five plots in river sand and peat substrates and two subplots in each plot with different cutting densities of 400 cuttings·m–2 (thin) and 1 666 cuttings·m–2 (dense). Data were analyzed using SPSS software.
Important findings The rooting site, rate of callus-formation, rooting percentage, survival rate after training, root effect index (REI), rooting dispersion index (RDI) and fractal feature of J. scopulorum cuttings in the two densities were significantly different. Analysis of rooting percentage, survival rate after training, REI and RDI indicated that the integrated effect in dense cuttings was better than thin cuttings. The rooting ability of thin density cuttings was worse, but degree of rooting dispersion was higher. The average rooting fractal dimension of dense cuttings was significantly 1.24 times higher than of thin cuttings, and dense cuttings had changed rooting position and mechanism. Cuttings often produced induced roots in dense cuttings and primordial roots in thin cuttings. Different cutting densities resulted in significant different microenvironments of cuttings, whereas the regulating effect of different media in same density on microenvironment was limited. The microenvironmental humidity of dense cuttings was higher (up to 83.5%), while temperature and photosynthetically active radiation (PAR) were lower, leading to higher net photosynthetic rate (Pn) and lower transpiration rate (Tr). Within 60 days after insertion, Pn of cuttings in both dense and thin cuttings were rising, and the difference between them increased quickly with time. After 60 days, both were declining, and the difference between them remained relatively constant. Transpiration rate of dense cuttings remained relatively unchanged from 0 to 30 days, while Tr in thin cuttings displayed a rapid increase during the same periods. Transpiration rate of dense cuttings rose sharply in 30–60 days and peaked on the 60th day, but it was still lower than in thin cuttings. These results implied that the effect of microenvironmental factors on rooting of J. scopulorum cuttings was achieved by influencing physiological indexes and that disparity of nutriment status in the two cutting densities was a major cause of differences in the rooting mechanism.
MENG Peng, LI Yu-Ling, YOU Guo-Chun, and ZHANG Shuo. Effects of microenvironmental factors on rooting of Juniperus scopulorum cuttings[J].Chin J Plan Ecolo, 2011, 35(7): 779-788.
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