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| Author(s): |
Natália Oliveira Totti de Lara
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Botucatu. 2017-01-05. |
| Institution: | Universidade Estadual Paulista (Unesp). Instituto de Biociências. Botucatu |
| Defense date: | 2016-12-02 |
| Advisor: | Carmen Regina Marcati; Magali Ribeiro da Silva |
| Abstract | |
In tropics, the water availability is one of the main factors interfering in the cambial activity of plants. Recent studies, in the field, also indicate that day length and temperature are important signals of the cambial activity in tropical plants. This experimental study aims to contribute for understanding the role of these abiotic factors (water, day length and temperature) on cambial activity in 1-year-old plants of Cordiera concolor (Cham.) Kuntze (Rubiaceae). This species, evergreen and shrubby, is native and common in Cerrado of São Paulo, and have growth layers demarcated by axial parenchyma marginal bands. We conducted two experiments (n = 45 plants, each), under controlled water regimes and under natural day length and temperature, one in early spring, when the day length increases from 11 hours to 12 hours and mean temperature is 19,9ºC and another in late summer, when day length decreases from 12 hours to 11 hours and mean temperature is 23,9ºC, both for five weeks. Each experiment contained the same three water treatments, obtained from a water retention curve of cerrado soil, with 15 plants each: waterlogging (21% moisture), field capacity (8% moisture) and water deficit (3% moisture). At the end of each week, we randomly selected three plants of each treatment and collected the most developed region of the main stem. We obtained transverse and tangential and radial sections for cambial activity analyses. We identified cambial activity by mitotic figures and the presence of recently formed periclinal cell walls. We used fifteen sequential radial rows in the cambial zone to count the newly formed periclinal cell walls. We analyzed the data using generalized linear models (GLM) which allowed us to observe that in early spring, regardless of the amount of water, the cambial activity is increased by day length. In late summer, the amount of water influences the cambial activity, which we observed that (i) plants subjected to waterlogging had their cambial activity prolonged throughout the weeks; (ii) the plants in field capacity had their cambium dormant over the weeks and (iii) the plants in water deficit presented cambial dormancy since the first week. The temperature was not an important signal for cambial activity in both periods. Additionally, we observed, in the beginning of cambial activity, the production and differentiation of the parenchyma cells that compound the marginal bands, which means that the bands are initial. We conclude that water availability does not influence the cambial activity in the period when the day length increases over the weeks. In the period when the day length decreases, the water has greater influence on plants, modifying the relation of the cambial dormancy with the day length. (AU) | |
| FAPESP's process: | 13/05700-0 - Cambial activity in Cordiera concolor (Cham.) Kuntze (Rubiaceae) plants subjected to controlled water regime |
| Grantee: | Natália Oliveira Totti de Lara |
| Support Opportunities: | Scholarships in Brazil - Doctorate |