Studies On Polyploid Induction Of Melilotoides Ruthenica Strains

Melilotoides ruthenica a kind of perennial herb, which belongs to Leguminosae. Melilotoides ruthenica was ont only rich in protein,but also had some better points than Medicago sativa L,such as adaptability,drought and cold resistances. Meanwhile, Melilotoides rthenica was rich in genetic diversity and had close genetic relationship with Medicago sativa L, so it can be used to improve Medicago sativa. One of key procedure for the use of the plant as breeding donor was to inducing polyploidy of Melilotoides rthenica,so that the chromosomes of each other were balanced.Considering all these,the consequence of the study would be very significant.Three improved Melilotoides ruthenica strains,namely 90-36(B1),93-21(B2),00-61(B3), selected by Grassland Research Institute of Chinese Academy of Agricultural Science,were chosen as materials and were treated with colchicines.This study was conducted from two levels,i.e callus and seeds of three strains. Polyploidy plants were identified by observing the morphological changes and detecting the chromosomes.The main results were as follows:1. Under the condition of tissue culture,the Melilotoides ruthenica strains was treated with colchicines to induce polyploidys.The treatments included four concentrations (0.03%,0.05%,0.08%,0.15%) and two time (5d,10d).The tetraploid plantlets were distinguished by observing the morphological changes and detecting the chromosomes. The results showed that, for the 3 strains,the suitable treatment was in 0.08% colchicines solution for 5days.2. The seeds of three strains were treated with colchicines in three level of concentrations (0.05%,0.10%,0.20% ) and three level of time (24h,48h,72h). The variance analysis of the rate of germination and distortion on the strains were significient at 5% probability level between induced seeds and the CK by means of calculating the germination and observing the morphological changes.The morphological features of the distorted seedlings had some differences,namely:the growth of seedlings being very slow, the hypocotyl of seedlings hickened in the form of rode,the tip of the radicle inhibited evidently,the cotyledon being hypertrophy,the leaf color being dark green,and curled,the leaf base was widened very obviously.At the same time,the true leaf was appeared late for the CK;After drying ambient environment, the dry weight of distorted seedlings was heavier than the CK.The rate of emergence of the three strains'seedlings after being treated with different concentrations of colchicines was not evident,but the rate of seedling growth was influenced very deeply. Meanwhile, the growth of seedings were inhibited obviously in some time.3. Detecting the chromosomes of three strains'cell of root tips by means of conventional chromosome tablet techniques.The result indicated that the different chromosomes types were induced by the different treatments of colchicines.Drawing the conclusions were that,the suitable treatment for the strain-B1'seeds was in 0.10% colchicine solution for 24h-48h; the suitable treatment for the strain-B2'seeds was in 0.10% or 0.20% colchicines solution for 48h; the suitable treatment for the strain-B3'seeds was in 0.20% colchicine solution for 48h.