| Autor: |
Horgan FG; EcoLaVerna Integral Restoration Ecology, Bridestown, Kildinan, T56 P499 Co. Cork, Ireland.; Escuela de Agronomía, Facultad de Ciencias Agrarias y Forestales, Universidad Católica del Maule, Casilla 7-D, Curicó 3349001, Chile.; Centre for Pesticide Suicide Prevention, University/BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh EH16 4TJ, UK., Bernal CC; International Rice Research Institute, Makati, Manila 1226, Metro Manila, Philippines., Ramal AF; School of Environmental Science and Management, University of the Philippines, Los Baños 4030, Laguna, Philippines., Almazan MLP; International Rice Research Institute, Makati, Manila 1226, Metro Manila, Philippines., Mundaca EA; Escuela de Agronomía, Facultad de Ciencias Agrarias y Forestales, Universidad Católica del Maule, Casilla 7-D, Curicó 3349001, Chile., Crisol-Martínez E; EcoLaVerna Integral Restoration Ecology, Bridestown, Kildinan, T56 P499 Co. Cork, Ireland.; Association of Fruit and Vegetable Growers of Almeria (COEXPHAL), Carretera de Ronda 11, 04004 Almeria, Spain.; Department of Zoology, Ecology and Plant Science, University College Cork, Butler Building, Distillery Fields, North Mall, T23 N73K Cork, Ireland. |
| Abstrakt: |
Three-line hybrid rice is produced by crossing male sterile (A line) rice with a fertility-restorer (R line). Fertile lines (B lines) are also required to maintain A line seed for breeding programs. We used a range of hybrids and their parental lines to assess the frequency and nature of heterosis for resistance to the whitebacked planthopper ( Sogatella furcifera ), brown planthopper ( Nilaparvata lugens ) and yellow stemborer ( Scirpophaga incertulas ). Heterosis is defined as trait improvement above the average of the parental lines as a result of outbreeding. Based on the results from a greenhouse study that challenged hybrids and their parental lines with each herbivore species, we found that susceptibility to planthoppers was associated with one of the eight A lines tested, but resistance was improved by crossing with a relatively resistant restorer. Higher frequencies of heterosis for susceptibility in comparisons between hybrids and their B lines suggest that susceptibility was not related to the cytoplasmic genomes of the associated sterile A lines. Furthermore, because none of the parental lines possessed currently effective resistance genes, improved resistance against planthoppers was probably due to quantitative resistance. In a related field trial, hybrids had generally higher yields than their fertile parents and often produced larger grain; however, they were often more susceptible to stemborers, leaffolders ( Cnaphalocrocis medinalis ) and other caterpillars ( Rivula atimeta ). This was largely a consequence of hybrid heterosis for plant biomass and was strongly affected by crop duration. We make a series of recommendations to improve hybrid breeding to reduce the risks of herbivore damage. |
