Efecto de la orientación preferencial sobre las estructuras reproductivas y vegetativas en Myrtillocactus geometrizans
Orientation of reproductive and vegetative structures in cacti optimizes the caption of photosynthetically active radiation (PAR) favoring the branch growth and development. It minimizes the excessive warming that could affect the photosynthetic system, and exposes the floral buds to an adequate tem...
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| Formato: | tesis de maestría |
| Estado: | Versión publicada |
| Fecha de publicación: | 2010 |
| País: | México |
| Recursos: | Universidad Autónoma Metropolitana |
| Repositorio: | Repositorio Institucional de la UAM Iztapalapa |
| Idioma: | español |
| OAI Identifier: | oai:bindani.izt.uam.mx:dn39x1713 |
| Acesso em linha: | https://doi.org/10.24275/uami.dn39x1713 |
| Access Level: | acceso abierto |
| Palavra-chave: | info:eu-repo/classification/LEM/Garambullo info:eu-repo/classification/LEM/Succulent plants Reproduction info:eu-repo/classification/LEM/Plantas suculentas -- Reproducción info:eu-repo/classification/LEM/Myrtillocactus geometrizans info:eu-repo/classification/LEM/Cactus info:eu-repo/classification/cti/2 |
| Resumo: | Orientation of reproductive and vegetative structures in cacti optimizes the caption of photosynthetically active radiation (PAR) favoring the branch growth and development. It minimizes the excessive warming that could affect the photosynthetic system, and exposes the floral buds to an adequate temperature for their development, thus favoring pollination. This study describes and analyzes the preferential orientation effects in the production of reproductive (buds, flowers and fruits) and vegetative structures (branch number and growth) of Myrtillocactus geometrizans in two slopes with contrasting orientations (i.e. north and south) in The Barranca de Metztitlán Biosphere Reserve, Hidalgo, México. Also the microclimatic conditions (temperature and relative humidity) for both slopes are described. The results showed that the majority of reproductive structures have a preferential southern orientation, where temperature and relative humidity were higher. Conversely floral buds showed a more uniform distribution. Orientation of reproductive structures was significantly different between slopes, and it showed a southern preference. The highest bud production was found in the south slope. Orientation among individual’s sections, the differences were less evident but significant. South and north individual sections produced more buds than the east one, but the west section did not differ with anyone. This result coincided with a preliminary description of bud distribution and orientation. Similarly, the higher flower production was found in the south slope and the south individual section as well. However, fruit production was not different between slopes although it was concentrated in the individuals south section, similarly to the observed flower pattern. The relatively uniform floral bud distribution contrasting with the distribution pattern observed for flowers and fruits, suggest that adequate temperature and relative humidity conditions were restricted to stems and branches with south orientation. Furthermore, if PAR interception is higher in ribs and/or branches with south orientation, the reproductive structures in the other sections, particularly the north one, could be under resources limitation. The preferential flower and fruit orientation pattern could be a consequence of this limitation. However, other factors might also influence the flower and fruit development in other orientations. Floral attributes such as form, size and amount of reward influencing pollination could vary with orientation, and therefore may affect the fruit production success. Future studies should explore if those factors could be involved in the observed orientation patterns in M. geometrizans. Branch development and branch number were different between both slopes. Individual branches in the southern slope showed a higher growth rate. In the north slope, individuals cover and branch number were larger than in the south one. In both slopes, the south section showed a larger average branch number. The probable causes of the individual architectural and annual branch growth differences include variations in the solar radiation interception regime, direct responses to microclimatic conditions and light competition with other plant species. This work is an original contribution to the study of reproductive and vegetative structures orientation in an intertropical cactus species. |
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