Gas exchange and leaf specific mass of different foliar cohorts of the wintergreen shrub Aristotelia chilensis (Mol.) stuntz (Eleocarpaceae) fifteen days before the flowering and the fall of the old cohort
In the beginning of the spring Aristotelia chilensis sheds the old cohort, forms a new one and flowers. Fifteen days before the flowering and the fall we measured net photosynthesis (A), transpiration (E), water use efficiency (WUE), specific leaf mass (SLM) and area and mass of leaves per branch in...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Instituto de Tecnologia do Paraná (Tecpar)
2001-09-01
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| Series: | Brazilian Archives of Biology and Technology |
| Subjects: | |
| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132001000300009 |
| Summary: | In the beginning of the spring Aristotelia chilensis sheds the old cohort, forms a new one and flowers. Fifteen days before the flowering and the fall we measured net photosynthesis (A), transpiration (E), water use efficiency (WUE), specific leaf mass (SLM) and area and mass of leaves per branch in old and new cohorts. Under low irradiance the old cohort exhibited higher mean values of A and WUE on area bases (P<0.05). Under high irradiance A and WUE on mass bases were higher in new cohort due to its lower SLM (42.10 gm-2) in relation to old cohort (79.53 gm-2). Because old cohort showed 3.7 times more dry mass per branch it was able to counterbalance its lower performance on mass bases. It was concluded that old cohort was an important source of carbon during two powerful sink processes in the beginning of the spring: new leaves cohort construction and flowering.<br>No início da primavera Aristotelia chilensis perde as folhas da cohort mais velha, forma uma nova cohort e floresce. Quinze dias antes da floração e perda da cohort velha medimos: fotossíntese líquida (A), transpiração (E), eficiência do uso da água (EUA), massa específica da folha (MEF) e área e massa das folhas por ramo nas cohorts nova e velha. Sob baixa radiação a cohort velha apresentou valores médios maiores de A e EUA expressos em área (P<0.05). Sob alta radiação A e EUA expressos em massa foram maiores na cohort mais nova devido à sua baixa MEF (42.10 gm-2) comparada à cohort mais velha (79.53 gm-2). A cohort mais velha exibiu 3.7 vezes mais massa seca por ramo, compensando sua baixa performance expressa em massa. Concluímos que a cohort mais velha é uma importante fonte de carbono durante processos que representam fortes drenos na primavera: a construção de novas folhas e a floração. |
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| ISSN: | 1516-8913 1678-4324 |