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Oxygen Consumption Rates Predicted from Respiration, Permeability and Porosity Measurements on Excised Wheat Root Segments 1
Author(s) -
Luxmoore R. J.,
Stolzy L. H.
Publication year - 1972
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1972.0011183x001200040013x
Subject(s) - respiration , respiration rate , zoology , biology , porosity , oxygen , permeability (electromagnetism) , oxygen permeability , botany , horticulture , chemistry , materials science , composite material , genetics , organic chemistry , membrane
Respiration rates were determined at 3.9, 20.8, and 79.9% oxygen concentration for consecutive excised root segments of ‘Ramona,’ ‘Inia,’ and ‘Yecora’ wheat ( Triticum aestivum (L.) em Thell.). From these data, the maximum respiration rate, the O 2 concentration at which respiration was half of the maximum rate, and the root permeability to O 2 were derived for segments up to 9 cm from the root tip. The gas filled porosity of each segment was measured by the pycnometer method. Maximum respiration rate and permeability decreased with distance from the root tip to a relatively constant value at 2 to 3 cm from the tip, whereas root porosity increased to a maximum value of about 10% at 3 cm from the root tip. The O 2 concentration for half maximal respiration rate was about 10% for root segments of Ramona and Inia cultivars and about 7% for Yecora. The data for Yecora were more variable than for the others. These root characteristics were used in a model of root O 2 relations to obtain estimates of mean respiration rate of wheat roots under simulated field conditions at three soil temperatures. Mean root O 2 consumption rate decreased with increase in root length to a relatively constant value for roots longer than 50 cm. Under well aerated conditions, O 2 consumption rates were higher for roots with smaller radii, whereas with flooded conditions respiration rates increased with root radii. Predicted mean respiration rate was higher with increase in soil temperature.