| Abstract Detail
Ecophysiology Gonzalez, Jose Vicente [1], Ely, Francisca [1], Rada, Fermin [3]. Anatomical and photosynthetic plasticity in juvenile and adult leaves of Chusquea mollis L. G. Clark (Magnifoliae, Chusqueinae, Bambusae). Chusquea mollis is a monocarpic woody bamboo that resembles more a large tussock grass than a woody bamboo, due its unbranched, densely clumped culms, with long, vertical leaves (60-80 cm), that grows in Venezuela and Colombia, along the ecotone formed between cloud forest upper limits the high altitude grasslands (páramos), between 2,650-3,400 m a.s.l. During the transition from juvenile to adults it is exposed to contrasting light regimes; plantlets and juveniles of the lower stratum develop at radiation levels <300 µmol m-2 s-1, whereas the adults growing in gaps and forest edges are exposed to levels of 600-1700 µmol m-2 s-1. These differences are likely related with the foliar dimorphism observed between juvenile and adults. Our objectives were to compare the leaf anatomy and photosynthetic response of juvenile and mature plants of pre and post reproductive stages, with the purpose of determining whether these phenotypic differences affect CO2 assimilation rates. The study was conducted in a population of C. mollis situated at 3,000 m, in the National Park Sierra Nevada (Venezuelan Andes). Net photosynthetic rates and light response curves were conducted between 9:00-11:00 h during the rainy season. Significant anatomical variations between juvenile and adults were accounted in all of the variables analyzed. Juvenile plants exhibited typical shade leaves: thin-walled adaxial epidermal cells impregnated of a thin cuticle; large, well developed fusoid cells, thin mesophyll with 3-layered chlorenchyma, scarce schlerenchyma associated to the vascular bundle sheaths and a solid midvein, composed by a large central vascular bundle, flanked by 4 smaller bundles. In contrast, pre and post reproductive adults had shorter, thick-walled, epidermal cells, impregnated of a thick, lignified cuticle, a higher stomatal density; round, almost isodiametric fusoid cells, 4-6 layered chlorenchyma, abundant schlerenchyma, associated to the vascular bundles and forming discontinuous subepidermal bands, hollow midveins due to the development of aerenchyma, with 30 or more small vascular bundles forming an atactostele of 4-5 concentric circles. Surprisingly, both juvenile and pre-reproductive adults had a similar photosynthetic response, with consistently low photosynthetic rates (1.62-2.67 µmol m-2 s-1), proper of shade plants exposed to low, medium and high radiation levels (60-90, 300-500 and 800-1,700 µmol m-2 s-1, respectively). The only differences observed between juvenile and adults were a higher quantum efficiency in juvenile plants at low radiation and slightly higher photosynthesis rates in post-reproductive adults (3.80-4.02 µmol m-2 s-1) subjected to radiation levels above 700 µmol photon m-2 s-1.
1 - Universidad de Los Andes, Instituto Jardín Botánico de Mérida , Avenida Alberto Carnevali, Núcleo Pedro Rincón Gutiérrez La Hechicera, Facultad de Ciencias 3cer piso Laboratorio de Anat, Mérida, Mérida, 5101, Venezuela
2 - Universidad de Los Andes, Instituto Jardín Botánico de Mérida , Avenida Alberto Carnevali, Núcleo Pedro Rincón Gutiérrez La Hechicera, Facultad de Ciencias 3cer piso Laboratorio de Anat, Mérida, Mérida, 5101, Venezuela
3 - Universidad de Los Andes, Instituto de Ciencias Ambientales y Ecológicas (ICAE), Avenida Alberto Carnevali, Núcleo Pedro Rincón Gutiérrez La Hechicera, Facultad de Ciencias 3cer piso Laboratorio de Ecof, Mérida, Mérida, 5101, Venezuela
Keywords:
Ecophysiology
Leaf anatomy
Woody bamboos
Venezuelan Andes.
Presentation Type: Oral Paper
Session: ECOPH1, Ecophysiology I
Location: Virtual/Virtual
Date: Thursday, July 30th, 2020
Time: 11:00 AM
Number: ECOPH1001
Abstract ID:243
Candidate for Awards:None |
