Intrarow Plant Spacing and Family × Environment Interaction Effects on Sugarcane Family Evaluation
- O. De Sousa-Vieira and
- S. B. Milligan
Progeny testing is practiced to select the best families (crosses) prior to individual plant selection and to guide decisions relative to hybridization and seedling planting in many crops including sugarcane (Saccharum spp. hybrids). Our research examined family, withinfamily, environmental, replication, and intrarow plant spacing sources of variation on the efficacy of progeny testing. Variance-component analysis indicated that family × environment (locations and years) interaction was a minor factor in reducing selection effectiveness. Within-family variance was the largest source of variation for the five traits considered. Partitioning genetic from environmental plant-toplant variation for plant weight and stalks per plant was not possible. For stalk weight, length, and diameter, 53 to 67% of this variance was due to within-family plant-to-plant variation. Family × plant spacing interaction was not important for any trait examined. Genetic correlations of family means for the same trait at different spacings were essentially unity. Response to selection estimates indicated selection among families using wide-spaced plants (82 em) was up to 31% more effective than family selection using narrow-spaced plants (41 cm). Since family × environment variances were minor compared with other sources of variation, testing effectiveness was mostly a function of plant number and spacing. Replicating across environments only marginally improved selection effectiveness. Predicted family gain for all traits except stalk diameter strongly suggests that selection using widely spaced plants would be more accurate than that using narrowly spaced plants.
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