The Production of Tetraploid Swainsona formosa by Colchicine Mutagenesis

Swainsona formosa, a legume native to Australia, is a spectacular flowering plant that is used as a hanging basket, container or cut flower plant. Its breeding programme had been emphasized on the production of better flower quality through ploidy modification to produce tetraploid plants. Colchicine, an antimitotic chemical, had been sucessfully used to induce tetraploidyzation in S. formosa. Up to 50% of plants with double chromosome number (2n = 4x = 32) were produced by seedling application of colchicine at 0.01%–0.1%. Concentrations below 0.01% or above 0.1% were found not effective in inducing chromosome doubling. Tetraploid S. formosa were charaterized by larger leaflets, bigger size but lower density of stomata, larger flowers with longer peduncles and larger pollen grains with lower viability. In general, colchicine can be used effectively to induce polyploidyzation in S. formosa and this method should find application in breeding programme.

Constrained Structural Optimization of Electro-Thermal Microactuator Using Double Chromosome Genetic Evolution

This paper presents two design optimization models for U-type electro-thermal microactuator. The result shows that the unequal arm model has better performance than the equal arm model. The models were solved by finite element analysis that are verified and comparison to publish paper and then are utilized in optimum design. The feature of presenting work contains temperature constraints to avoid the harm of operating object and decrease stress concentration on flexure. For handling design constraints, a method named double chromosome genetic evolution (DCGE) is developed in gene based algorithm. The idea of the presenting constrained strategy was inspired from the gene evolved by double helix chromosome of expressing certain traits. The constrained evolutionary algorithm proposed in this work is efficient and reliable. It can be integrated into a broad field of engineering optimization.