Chin J Plant Ecol ›› 2010, Vol. 34 ›› Issue (3): 340-347.DOI: 10.3773/j.issn.1005-264x.2010.03.011

• Research Articles • Previous Articles     Next Articles

Effect of simulated ortet density on growth and clonal propagation of Iris japonica

WANG Yong-Jian1, ZHONG Zhang-Cheng2,*()   

  1. 1College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China
    2Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), School of Life Science, Southwest University, Chongqing, 400715, China
  • Received:2009-06-20 Accepted:2009-09-12 Online:2010-06-20 Published:2010-03-01
  • Contact: ZHONG Zhang-Cheng


Aims Intra-species ortet competition has significant effects on growth, sexual reproduction and clonal propagation of clonal plants. Iris japonica is widely distributed along open area of forest edges and under sparse forest canopies with higher light and water conditions in southern China. It affects other herbs by its dominance through clonal propagation. Our objective was to determine the effect of different initial ortets of I. japonica on clonal propagation and growth. Findings could provide a theoretical foundation for the management of understory vegetation with I. japonica.

Methods From September 2007 to June 2008, we conducted a simulation experiment of I. japonica in which we replaced a ortet by an independent one-year ramet. We set up three treatments: one initial separate ortet (O), two initial separate ortets (T) and four initial separate ortets (F) in 0.7 m × 0.7 m, which represented the effect of intra-species ortet competition. Each treatment had 10 repeats, and we quantitatively measured characters of clonal propagation, leaves and biomass and allocation of clonal propagation in different treatments. Data were analyzed using SPSS software.

Important findings The number of new ramets per ortet of I. japonica was higher, and number of dead ramets per ortet was lower in O treatment than in T and F treatments. Number of primary and secondary daughter ramet (per ortet) and length, surface, volume and length per density of fine rhizomes and roots of I. japonica decreased with the increase of initial ortet (ortet competition). The number of highly withered and total withered leaves of mother ramet, and number of moderately withered, highly withered and total withered leaves of daughter ramet of I. japonica increased with the increase of initial ortet (ortet competition). Leaf area and number of leaves per ortet and number of leaves for daughter ramet per ortet of I. japonica significantly decreased, and leaf area ratio (LAR) per ortet significantly increased with the increase of initial ortet (ortet competition). Biomass of fine rhizomes, coarse rhizomes, clonal propagation, aboveground, belowground and total plant and allocation to fine rhizome and belowground of I. japonica significantly decreased, and allocation to coarse rhizome of mother ramet and aboveground significantly increased with the increase of initial ortet (ortet competition). In sum, with the increase of ortet competition, growth of I. japonica and status of its leaves were inhibited, and clonal propagation became weaker. Thus, it could increase LAR and allocation of coarse rhizome of mother for resources reserve to growth and sexual reproduction in coming year.

Key words: clonal propagation, competition, Iris japonica, resource allocation