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Variation in Taproot Elongation Rate as Influenced by Composition of the Soil Air 1
Author(s) -
Huck M. G.
Publication year - 1970
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1970.00021962006200060042x
Subject(s) - taproot , elongation , meristem , zoology , chemistry , horticulture , agronomy , botany , biology , shoot , ultimate tensile strength , materials science , metallurgy
Elongation rates of cotton and soybean taproots were measured while the O 2 content of a gas stream passing through the soil surrounding the roots was varied. Elongation rates were comparable to controls at all O 2 concentrations above 10%. Elongation ceased completely within 2 to 3 min after all O 2 was purged from the system with 100% N 2 gas, and returned to normal shortly after 21% O 2 was returned to the system, provided the period of anaerobiosis had not exceeded 30 min. Longer periods of complete anaerobiosis resulted in killing of a certain percentage of root tips until approximately 100% of the primary taproots were killed at 3 hr without O 2 for cotton and 5 hr for soybeans. Oxygen levels from 2 to 5% resulted in an initial reduction in rate of taproot extension, followed by a gradual return to elongation rates comparable with controls. Although 3 to 5 hr of complete anaerobiosis evidently killed the terminal meristematic region of the taproots, new lateral growth developed from the cortex within a day or two after cessation of growth of the terminal meristems. Distribution of roots through a volume of soil may thus be influenced by oxygen availability and its distribution through time and space.