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Water diffusivity of germinating soya-bean, cow-pea and blackgram seeds at both large and small times

Published online by Cambridge University Press:  27 March 2009

H. S. Sen ,
A. V. Suriya Rao ,
K. R. Mahata  and
P. C. Das
H. S. Sen
Affiliation:
Department of Soil Science and Microbiology, Central Rice Research Institute, Cuttack 753006, India
A. V. Suriya Rao
Affiliation:
Department of Soil Science and Microbiology, Central Rice Research Institute, Cuttack 753006, India
K. R. Mahata
Affiliation:
Department of Soil Science and Microbiology, Central Rice Research Institute, Cuttack 753006, India
P. C. Das
Affiliation:
Department of Soil Science and Microbiology, Central Rice Research Institute, Cuttack 753006, India
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Summary

Theory for the non-steady-state diffusion flow of a spheroidal body is discussed and solutions are presented for estimating the time-dependent diffusivities at small and largo times following sowing in soil of germinating soya-bean, cow-pea and blackgram seeds. The validity and also the limitations of the equation for large times to estimate time-dependent diffusivities are discussed. Assuming that the time of germination was at infinity it was possible to reduce the equation for small times to a simple form. Thus, with the help of these two equations it was possible to study changes in the diffusivity of seeds at different soil matric potentials throughout the period, immediately after sowing until germination. The diffusivities showed gradual decrease at 0 bar potential for soya-bean and cow-pea, and increase at – 2 and – 10 bar potentials for soya-bean, cow-pea and blackgram seeds with time. The decrease in diffusivity with time under non-stress soil water condition is explained as predominantly a physiological phenomenon of the seed due to the increase in seed water content with time, while its increase with time under water stress conditions is probably because of the decrease with time of the initially large seed-coat resistance and tortuosity showing small values of diffusivity. The discussion suggests that the role of area of contact on the water uptake of the buried seeds as reported so far is contradictory and, therefore, not convincing.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 98 , Issue 1 , February 1982 , pp. 209 - 213
Copyright
Copyright © Cambridge University Press 1982

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References

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