Direct transplanting of seedlings: Strategy for shortening the selection cycle of the sugar cane breeding programme at the Mauritius Sugar Industry Research Institute
| MSI04P4093 | |
| Mungur, H. | |
| School of Land and Food Sciences, The University of Queensland, Australia | |
| Direct transplanting of seedlings: Strategy for shortening the selection cycle of the sugar cane breeding programme at the Mauritius Sugar Industry Research Institute | |
| Thesis, Master of Agricultural Studies | |
| Thesis | |
| 2004 | |
| 72 p.:15 tbls, 38 figs | |
| En | |
| En | |
| At the Mauritius Sugar Industry Research Institute (MSIRI) approximately 100,000 seedlings are produced annually to start a new selection cycle. The current practice is to sow seeds in September/October, transfer the seedlings individually in plastic pots and transplant them manually in fields at a spacing of 0.6m x 1.5m, in March of the following year. Selection is done when the crop aged 13 months. In the context of a reduced labour force and other resources, new selection strategies are being investigated to bring down costs of production of varieties. A trial was laid down to study the feasibility and efficiency of transplanting seedlings directly in the field, to assess savings on scarce resources and its impact on the selection cycle. Seeds of five families were sown in August and were transplanted, in November of the same year, on raised beds (8m x 1m) at three different spacings in a split plot design, with spacing as the main plot. The treatments were: S1 - three rows per bed with 40cm between rows x 30cm within rows; S2 - three rows with 40cm between x 40cm within rows; and, S3 - two rows at 40cm between x 40cm within rows at population densities of 7, 5 and 3.3 seedlings/m2 for the three treatments respectively. Mortality rate was recorded monthly for the first three months after planting, and then again at selection time. Stalk number, stalk diameter, stalk length and visual selection score were assessed in September (10 months after transplanting) on all seedlings able to produce more than 10 cuttings to plant a two-metre plot in the first clonal stage. The same characters (plus Brix) were measured on all 717 genotypes included in the first clonal stage. Data analysis was done using the software Minitab and ASREML. Correlations of same character measured in the two selection stages were calculated. Broad sense heritabilities were calculated for all traits in the two selection stages. Mortality rate in the seedling stage was highest in the closest spacing (26.7 per cent). A total of 717 genotypes, 260, 245 and 212 from spacing S1, S2 and S3 respectively were promoted for evaluation in the first clonal stage. Differences between treatments were not significant for stalk number, stalk diameter and stalk length, although diameter and stalk number were slightly higher in the lowest density treatments. Families differed significantly for all the agronomic characters. No spacing x family interactions were detected for any of the characters measured. Visual selection proved to be effective (535 selected, 182 rejected) and increased with wider spacing with an effective selection rate of 23.1 per cent, 28.3 per cent and 42.8 per cent at close, intermediate and large spacing. Selectable genotypes at the intermediate spacing had slightly higher stalk diameter and length. Measured characters in the clonal stage showed a decreasing trend in stalk number and stalk length from close spacing to wider spacing. Stalk diameter and Brix were higher in the intermediate spacing genotypes. Performance of genotypes in the intermediate spacing was better than in the close and large spacing genotypes. Visual selection rate was reliable with 89 per cent of genotypes promoted to the second clonal stage belonging to the selectable group in the seedling stage. Heritability of stalk number was consistently low (0.04 and 0.03) in the two selection stages. Stalk diameter (0.54 and 0.53) and stalk length (0.58 and 0.60) were more heritable characters in both stages. Brix proved to be highly heritable (0.87). Positive correlations were obtained for stalk number, stalk diameter and stalk length. Genetic correlation was highest for stalk diameter and stalk length in the intermediate spacing genotypes. The genetic components in the expression of stalk diameter and length were higher for the intermediate genotypes. Intermediate spacing appears to be the best spacing for this method of transplanting seedlings. Direct transplanting at this spacing is estimated to save 890 man-days and 8.5 hectares of land each year. Compensation for land will be reduced. Quality of cuttings for planting clonal stages will be improved with shifting of selection at the seedling stage. More so, the selection cycle will be reduced by one year. | |
| Sugarcane Breeding Selection Selection cycle Stages of selection Sowing Potting Transplanting Shortening of selection cycle Heritability Correlations Direct transplanting Sowing time Selection time Statistical models Restricted Maximum Likelihood ASREML | |
| Mauritius | |
| Cane breeding and genetics | |
| Selection: Stages of selection | |
| 2004-09-17 | |
| En | |
| PB | |
| PB |