Intra-cultivar variation in cotton: response to single-plant yield selection at low density
| Autor: | Constantinos Tzantarmas, Ioannis S. Tokatlidis, J. T. Tsialtas, C. Tsikrikoni, Anastasios Lithourgidis |
|---|---|
| Rok vydání: | 2010 |
| Předmět: | |
| Zdroj: | The Journal of Agricultural Science. 149:197-204 |
| ISSN: | 1469-5146 0021-8596 |
| Popis: | SUMMARYIn a 5-year study (2004–2008), the possibility of exploiting intra-cultivar variation in cotton(Gossypium hirsutum L.) was investigated. Honeycomb single-plant selection for seedcotton yield wasemployed within three cultivars at a low density of 1·15plants/m 2 . First- and second-generationprogeny lines (1GPLs and 2GPLs) were evaluated for seedcotton yield at low density at three sites,whereas third-generation progeny lines (3GPLs) were tested at the crop density of 10plants/m 2 acrosstwo sites and 2 years. Significant differentiation for seedcotton yield was discovered within cultivar(cvar) Christina and cvar Corona at both low and crop densities, and within cvar Flora at low density.In addition, significant intra-cultivar heterogeneity for fibre quality properties was found at cropdensity. The 1GPLs and 2GPLs grown at low density showed increases in seedcotton yield of 16 and19%, respectively, in cvar Christina, and of 2·6 and 3·7%, respectively, in cvar Corona. In cvar Flora,the 1GPLs and 2GPLs yielded 10 and 3·3% lower than the mother cultivar, respectively. When grownat standard crop density, across sites and years, 12 and 5·2% higher yield was obtained by theChristina-derived 3GPLs and the Corona-derived 3GPLs, respectively, when compared with theoriginal cultivars. These results provide evidence that elite cultivars are not homogeneous but ratherheterogeneous material, within which selections can be made to maintain or improve uniformity andfurther improve desirable agronomic traits.INTRODUCTIONThe development of improved cultivars is time con-suming and costly. Thus, the way breeders’ seed istreated is of importance for the maintenance ofvarietal uniformity and the avoidance of degener-ation. Elite cultivars have long been believed to berelatively permanent with limited or no importantgenetic variation. Numerous studies in several crops,however, have indicated significant intra-cultivargenetic variation, based upon either phenotypic dif-ferentiation (e.g. Sprague et al. 1960; Byth & Weber1968; Grogan & Francis 1972; Tokatlidis et al. 2006;Fasoula & Boerma 2007) or on molecular techniques(Zhang et al. 1995; Olufowote et al. 1997; Gethi et al.2002). However, the genome undergoes constantrenewal, remodelling and restructuring. The processesof intragenic recombination, unequal crossing-over,DNA methylation, excision or insertion of trans-posable elements and gene duplication, contribute tonewly developed genetic variation (McClintock 1984;Rasmusson & Phillips 1997; Cullis 2005; Morganteet al. 2005). Moreover, during the whole process ofcultivar maintenance and multiplication, contami-nating and degrading forces such as outcrossing,mixing, volunteer plants, natural selection and seed-borne diseases all change the gene pool for the worse,and it is even possible for a complete loss of theimproved features of the cultivar to occur (Laverack1994; Parlevliet 2007). Improved cultivars may losetheir identity and healthiness because of the afore-mentioned molecular and mechanical parameters.Peng et al. (1999) found that the maximum yield ofthefamousricecultivarIR8inthePhilippinesreducedby 20% over a period of 30 years. On the other hand |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|