Study On Sexual Reproductive Characteristic Of Wild Dichondra Repens Forst. In Southwest China

Dichondra repens J.R. Forst.& G. Forst is a perennial creeping plant belonging to the Convolvulaceae Dichondra.It is an ornamental broadleaf plant with a beautiful shape, easily established, widly adaptable.It is a high development value plant. Southwest of China is abundant with wild Dichondra repens. Some wild Dichondra repens with high value for lawn landscape,strong resistance can not produce seeds. It would hinder the pro-motion of wild Dichondra repens with high value lawn landscape.The objective of the study was find the reasons of low fecundity between the wild Dichondra repens SD200303(flowering,seed),and GD200503(flowering,no seed)from several aspects,such as floral biology, pollen viability, stigma receptivity and formation of female and male gametophyte,the main results are follows:1. The flower morphology of the two wild Dichondra repens materials were similar, but anther color were different, SD200303 is peachblow, GD200503 was yellow and the few style were abnormal (a flower,3 styles); flowering process of two wild Dichondra repens materials were basically same, florescence both in March to May, but early flowering and flower opening time were different, the early flowering GD200503 and SD200303 was early march,the middle and third decade of march;the flower opening time was 8:30-11:00,10:00-11:30.2. The pollen morphology of the wild two Dichondra repens materials all were same,the pollen grains long ellipsold, oval in equatorial view,3 lobed circular in polar view,3 colporate, tubercles on the sculpture, GD200503 have more abnomal pollen exist.3. The pollen germination rate was dectected by pollen germination in vitro showed that the pollen germination rate of SD200303 and GD200503 was 54.96% and 2.43%, pollen life span was 5h and 1h, respectively.4. The stigma receptivity of SD200303 was 3days after blooming, the stigma receptivity to achieve the strongest after blooming 4hours; the stigma receptivity of GD200503 was 2 days after blooming and the stigma receptivity was relative lower.5. The pollen-ovule ratio of SD200303å'ŒGD200503 was 266.5and209.25, respectively,;outcrossing index(OCI) was 3.The breeding system was characterized by outcrossing index (OCI), pollen-ovule ratio (P/O) and flower morphology,the result showed that breeding system of the wild Dichondra repens is facultative.6. The archesporial cell originated from a single cell,the embryo sac is the Polygonum type,the macrosporogenesis and female gametophyte of the two wild Dichondra repens materials didn't have genital obstacle in their development. Anther wall structure had epidermis,endothecium,middle layer and tapetum. The aborted rate of tapetum and microspore mother cell of GD200503and SD200303 was 40.4% andl 1.7%,respectively.7. The natural fruit set of SD200303 and GD200503 was 62% and 0%respectively.