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ARS Home » Northeast Area » Kearneysville, West Virginia » Appalachian Fruit Research Laboratory » Innovative Fruit Production, Improvement, and Protection » Research » Publications at this Location » Publication #324150
Title: Relationships between SAP-flow measurements, whole-canopy transpiration and reference evapotranspiration in field-grown papaya (Carica papaya L.)

Author
item FERRAZ, TIAGO MASSI - Universidade Estadual Do Maranhao
item NETTO, ALENA TORRES - State University Of North Fluminense
item DE OLIVEIRA REIS, FABRICIO - Universidade Estadual Do Maranhao
item PECANHA, ANDERSON LOPES - State University Of North Fluminense
item DE SOUSA, ELIAS FERNANDES - State University Of North Fluminense
item MACHADO FILHO, JOSE ALTINO - Instituto De Pesquisa E Reabilitacao De Animais Marinhos
item RODRIGUES, WEVERTON - State University Of North Fluminense
item Glenn, David
item CAMPOSTRINI, ELIEMAR - State University Of North Fluminense

Submitted to: Theoretical and Experimental Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/30/2015
Publication Date: 12/14/2015
Citation: Ferraz, T., Netto, A., De Oliveira Reis, F., Pecanha, A., De Sousa, E., Machado Filho, J., Rodrigues, W.P., Glenn, D.M., Campostrini, E. 2015. Relationships between SAP-flow measurements, whole-canopy transpiration and reference evapotranspiration in field-grown papaya (Carica papaya L.). Theoretical and Experimental Plant Physiology. DOI: 10.1007/s40626-015-0049-z.

Interpretive Summary: Measuring plant water use is difficult and expensive, requiring sophisticated technology and labor. The flow rate of water in the stem of plants can be determined by measuring the rate of cooling that occurs from a heat probe. The objective of this study was to measure the relationship between xylem sap flow measured by the heat probe method and whole canopy transpiration measured by enclosing the plant and accurately measuring water use in ‘Gran Golden’ papaya (Carica papaya L.). While there was a correlation between the heat probe method and true water use measured by enclosing the plant, the practical value was very limited. The concept of sap flow to measure transpiration has value in papaya production but supplementary studies will be necessary to improve the accuracy and estimation of the whole-canopy transpiration in the papaya plant.

Technical Abstract: Whole-canopy gas exchange measurement in papaya can provide a scientific basis to optimize irrigation, and fruit yield and quality. The objectives of this study were to: 1) verify the relationship between xylem sap flow measured by the heat coefficient method and whole canopy transpiration in ‘Gran Golden’ papaya (Carica papaya L.), 2) examine the relationship between xylem sap flow determined from calculations based on forcing water flow through a stem section and whole canopy sap transpiration, and 3) verify the relationship between transpiration measured in a plant chamber and calculated reference evapotranspiration (ET0). The experiment was conducted in a commercial planting at the Caliman Agrícola SA farm, Sooretama, ES, Brazil, in summer and winter. Whole-canopy gas exchange was measured in custom-built, flow-through whole-canopy Mylar chambers. There was a correlation (r2=0.65) between xylem sap flow measured with the heat coefficient (K) method and whole-canopy transpiration rate measured in the chambers. However, sap flow methodology could not convert this correlated response into an accurate estimate of papaya transpiration measured with whole canopy chambers. The sap flow methodologies were linearly correlated with whole canopy transpiration but each would require additional calibration to the crop. ET0 was correlated with whole canopy transpiration in winter but not in summer, likely due to stomatal control of transpiration as a result of the high leaf temperature and ET0 in summer. The concept of sap flow to measure transpiration has value in papaya production, but supplementary studies will be necessary to improve the accuracy and estimation of the whole-canopy transpiration in the papaya plant.