Advanced search
Start date
Betweenand


Water redistribution by citrus roots under drought

Full text
Author(s):
Marcela Trevenzoli Miranda
Total Authors: 1
Document type: Master's Dissertation
Press: Campinas, SP.
Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
Defense date:
Examining board members:
Rafael Vasconcelos Ribeiro; Eduardo Caruso Machado; Sara Adrián López de Andrade
Advisor: Rafael Vasconcelos Ribeiro
Abstract

Citrus plants are subject to a seasonal variation of water availability in many growing areas, an effective strategy to mitigate the impacts of citrus water scarcity is the use of drought tolerant rootstocks. It is important to understand which characteristics make some rootstocks more tolerant than others so that alternative rootstocks with similar phenotypic and physiological characteristics are selected. Hydraulic redistribution is a passive movement of water in roots following a gradient of water potential, in moist soil sites water is uptaken by roots and then released in tissues in contact with drier soil. Osmotic adjustment is another physiological strategy, characterized by an active cell accumulation of solutes in response to a reduction of water availability in the environment. A reduction in osmotic potential facilitates the extraction of water in dry soils and maintains the cells turgor. In this context, the aims of this work were to evaluate the hydraulic redistribution in two rootstock species, as well as to verify if the osmotic adjustment is associated with this phenomenon. Seedlings of Valencia sweet orange were inarched with Rangpur lime and Swingle citrumelo rootstocks, each seedling had two root systems to simulate a situation where only part of the roots had water availability while the other part was under water limiting conditions. The experiments allowed us to verify that both species redistributed water and that Rangpur lime has greater capacity to send water to the roots under drought. The greater ability to redistribute water of Rangpur lime in comparison to Swingle citrumelo was associated to a greater absorption of water by the moist roots caused by a decrease in osmotic potential. Valencia sweet orange canopies grafted on Rangpur lime also showed a stomatal sensitivity to the variation of water availability, suggesting that roots under drought signaled for stomatal closure even though water was supplied by the moist part and leaves were hydrated. The gas exchanges of the canopy grafted on Swingle citrumelo were not significantly affected by the reduction of water availability, keeping the stomata open during the experimental period. When comparing rootstocks, physiological modifications and mechanisms described led to a greater drought tolerance of Rangpur lime (AU)

FAPESP's process: 16/02199-7 - Root water redistribution in citrus plants under water deficit
Grantee:Marcela Trevenzoli Miranda
Support Opportunities: Scholarships in Brazil - Master