Data/hora: 21/06/2024 23:55:36

Biblioteca(s): 	Embrapa Amazônia Ocidental; Embrapa Cerrados.	
Data corrente: 	14/06/2000	
Data da última atualização: 	14/06/2000	
Autoria: 	BRUNINI, O.	
Título: 	New devices for in situ measurements of soil and root water potentials and transport of water in the soil-plant system.	
Ano de publicação: 	1979	
Fonte/Imprenta: 	Guelph: University of Guelph, 1979.	
Páginas: 	144p.	
Idioma: 	Inglês	
Notas: 	Ph.D. Thesis.	
Conteúdo: 	A new device for in situ measurement of soil water potential was designed and evaluated. This device was based on measuring the dewpoint temperature depression of water vapour in equilibrium with a sample. A porous silver membrane serves as the hydraulic connection between soil and the measuring cavity, which encloses a four terminal thermofunction. The membranes were attached by screws to the copper body of the hygrometer; such a configuration minimized the temperature gradient from sensor to the referene junction. When the hygrometer was placed in soil column and soil temperature increased at rate of 1.3oC per hour, the maximum voltage offset was -0.04 uv (0.55 bars). The water potential, as measured with the hygrometer, whe it was submitted to a thermal gradient of 2.6oC per cm in a soil column, changed from -8.2 to -7.4 bars, corresponding to an error in water potential of less than 10%. The results indicated that the hygrometer had a very rapid response for water flow, with a time constant of 5 minutes. The time constant for salt diffusion was 8 minutes. This device has proven to be reliable for measuring soil water potential in the range of tensiometer readings and also in dry soils, making it possible to measure the free energy of the water in the soils in the range most useful for agricultural plants. When compared to a tensiometer or to low water suctions values, the agreement was very good (r2 = 0.96), and the maximum difference between the hygrometer measurements and the suction was 0.05 bars. The results of soil water potential measurements under corn plant hybrid 108 grown in a pot in a growth chamber environment have shown that this new device was able to follow the changes in soil water potential very well, which makes the study of the transport fo water in a soil plant system much more precise. The gradient in water potential between leaf and soil after the plant had been left several hours in the dark appeared to be related to uneven moisture distribution in the pot and the plant was responding to the average soil water potential. 	
Palavras-Chave: 	Measurements; Plant soil relation; Plant water relation.	
Thesagro: 	Medição; Raiz; Relação Água-Planta; Relação Solo-Planta; Transporte.	
Thesaurus Nal: 	roots; soil transport processes; water potential.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Cerrados (CPAC)	
Exemplares: 	CPAC - (16524-1) - ADD - TS - -- - T039/79 - BRU - T039/79 - DIS
CPAA - (23431-1) - ADD - TS - PP - T018/1979 -  - 1981.2207 - DIS