| Amorphophallus albus is a new species that is discovered and named by Liu Peiying and Chen Jinfeng in 1984, and is now also cultivated in China on a large scale for economic purposes. This species is peculiar to our country, and its natural distribution region is Jinshajiang Stream Valley Zone, mainly concentrated in the southwest of Sichun Province and the north of Yunan Province. A. albus is the best species among Amorphophallus genus, and its KGM content is the highest, so the commodity value of A.albus is very high. However, because of the dwarf plant and over developed rhizome, the tuber weight per A. albus plant is lower, which affects seriously the improvement of output and economic benefit. At the same time, accompanying with the enlargement of produce scale, the problems of short of seed resource and degeneration of germ plasm also appear. These questions restrict the development of A. albus industry. So the selection and breeding of new varieties and multiplication of excellent varieties are imperative under the situation.Polyploid breeding is an important approach to get excellent varieties with high quality and high yield. So polyploid breeding can improve output and quality of A. albus. This experiment first adopted colchicine to treat A. albus in vivo, and then on the base of optimizing the tissues culture, adopted colchicine to treat shoots and calluses in vitro to induce polyploids. The main results can be summarized as follows:1. Tissue culture regeneration system of A. albus was established and consummated, in order to offer bases for in vitro induction of polyploidy plants with colchicines. The corm of A.albus was used as explants for callus induction, bud differentiation and plant regeneration. It showed that the corms give a callus induction frequency of 93.3% when chultured on MS medium supplemented with 6-BA1.0 mg/L and NAA0.5 mg/L. And when cultured on MS medium supplemented with 6-BA 2.0 mg/L and NAA0.5 mg/L, the highest bud differentiation rate of 96.7% was obtained. Insubculture stage, vitrification of callus and shoot can be reduced or avoided when 6-BA concentiation was 2.0 mg/L and 1.0 mg/L in turns. And addition of activated cabon 5g/L and polyvinylpyrrlidone 1g/L can control browning efficiently. The buds above 3cm were cutted and inoculated into MS medium without hormone, and began to root after one week, and radication rate was up to 100%. The rooted plantlets with leavies unfolding completely were potted into different media for acclimatization before planting in the soil, and 84.0% of plantlets were survived when transferred to vermiculite- cow dung (1 : 1) medium.2. In vivo, two methods, soaking seeds and dropping apical buds of rhizomes, were adopted to induce polyploidy of Amorphophallus albus in vivo. The results showed that the induction efficiency of soaking seeds was superior to that of dropping rhizome apical buds. The treatment of soaking seeds 72h with 0.20% colchicine solution had the best induction effect, having the highest induction rate with relative high seedling rates, up to 21.7%. And the highest frequence of quadplex plaints of dropping rhizomes buds were 20.0%, when rhizomes buds were dropped with 0.40% colchicine solution for five days. The results of conventional plant tip root squashing method suggested that most of polyploids induced were chimera materials. Only one tetraploid of A. albus was obtained by soaking seeds for 48 hours with 0.20% colchicine solution, while most polyploids became diploids again.3. In vitro, the method of conchicine treatment combining with tissue culture was used to induce polyploids. The results showed that this method can enhance the induction efficiency of colchicines, improve survival rate and multiplication coefficient. The treatment of co-culture shoots in vitro with high concentration and short time had good induction efficiency, and the combination of 100mg/L and five days had the highest induction rate, up to 23.5%. While calluses were sensitive to colchicines, the treatment combination of high concentration and long time led to higher death rate and lower buds differentiation rate. The treatment of 40mg/L colchicine concentration co-culture calluses for 10 days got the highest induction rate, being 23.3 %.4. The effect of dimethyl sulfoxide (DMSO) on induction efficiency was studied. The results showed that after adding DMSO to colchicine solution, the variance rate increased 1.3%~10.1%, and the frequence of quadplex plants of soaking seeds increased 8.3%～25.2%. This suggested that conchicine solutions supplemented with 2% DMSO can improve the induction rate of conchicine effectively, and decrease the rate of plant chimeras distinctly.5. The biological characteristics of tetraploid A. albus were studied in this experiment. Compared with diploids, tatraploids had typical polyploidy morphological characteristics, including diameter of petiole bigger, leaf wider and thicker, and leaf index smaller. The leaf color of A. albus polyploidy plants became dark green, and the stomatas and guard cells of leaf became bigger evidently, about 1.23～1.45 times of those of diploids. While the density of stomatas decreased, only 68% times of that of diploids. So both morphological characteristics and stomatas density can be used as important characters to identify polyploids from diploids.6. Karyotypes of the diploids and the induced polyploids of A. albus were analysised. The chromosomes were composed of median centromere (m), submedian centromere (sm) and subterminal centromere (st). The keryotype formation of diploids was 2n=2x=26=16m+8sm+2st, while that of tetraploids was 2n=4x=52=32m+16sm+4st. The ratio of the longest chromosome and shortest chromosome of diploids was 2.29 and that of tetraploids was 2.36, both between 2 and 4. The arm ratio of chromosomes of diploids was 1.71, while that of tetraploids was 1.62, and the ratio of chromosomes, which arm ratio was over 2, of both diploids and tetraploids, was 23.08 %. So both diploids and tetraploids belonged to Type 2B, and tetraploid plants induced by colchicine were the autotetraploids derived from diploids of A. albus doubled directly.
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