Screening of sugar cane seedlings against rust Puccinia melanocephala H. and P. Sydow: Inoculation and development of an assessment technique by video image analysis
| MSI99P1598 | |
| Moutia, Y. | |
| University of Mauritius, School of Agriculture, Réduit | |
| Screening of sugar cane seedlings against rust Puccinia melanocephala H. and P. Sydow: Inoculation and development of an assessment technique by video image analysis | |
| Project, BSc (Hons), Crop Science and Production | |
| Thesis | |
| 1994 | |
| 90 p., 14 tbls., 10 pl., 21 figs. | |
| En | |
| En | |
| The screening of varieties against sugar cane rust (Puccinia melanocephala H. and P. Syd.) forms an integral part of the breeding programme at the Mauritius Sugar Industry Research Institute. The development of a new approach involving artificial inoculation and assessment techniques by computer-assisted video image analysis has been the subject of this project. Rust spores for inoculation purposes in the glasshouse were efficiently collected by devising a vacuum pump arrangement that sucked them from infected leaf surfaces. About 1 g of spores could be obtained over a few hours. The spores were then passed through a sieve to remove debris prior to storage under different conditions. Maintaining the spores at -23°C under no humidity or at -80°C at 20-30 per cent humidity were the most appropriate conditions of preservation while ambient conditions of preservation were least effective. Estimation of spore concentration using a spectrophotometer or a precision balance instead of the traditional hemacytometer were evaluated. Weighing of dried spores was the fastest and most accurate method for determining inoculum concentration. The most appropriate age for seedling inoculation was found to be 90 days using a concentration of 2.2 x 10 5 spores/ml, although the viability of spores at the time of inoculation should be taken into account. The use of video image analysis to assess percentage area of leaf infected proved consistent and accurate. Analysis of data from progeny of bi-parental crosses showed that leaf 3 (the first leaf with more than 50 per cent of its surface unrolled being taken as leaf 1) was the best representative of overall infection of the seedling. These results would allow the screening process to be effected at a quicker rate than if all the leaves had to be evaluated. During the course of this investigation, two interesting observations were made. Firstly, on inoculating the rust pathogen on Czapek-cane leaf agar medium, urediniospores were observed. The possibility that P. melanocephala can be cultured on artificial medium would open new avenues in the study of the pathogen. Secondly, larvae of Mycodiplosis spp., grazing on rust pustules were observed for the first time in Mauritius. Its potential as a biocontrol agent needs to be investigated. | |
| SUGARCANE PUCCINIA MELANOCEPHALA VIDEO IMAGE ANALYSIS ANALYTICAL TECHNIQUES DISEASES | |
| MAURITIUS | |
| Sugarcane: Diseases and disease management | |
| 1994-08-02 | |
| En | |
| LIB | |
| CAT | |
| PATH |