Imbibition Response of Winter Wheat to Water-Filled Pore Space

Authors

Guillermo A. Studdert, Univ. Nac. de Mar del Plata, Buenos Aires, Argentina
Wallace Wilhelm, University of Nebraska-LincolnFollow
James F. Power, USDA-ARS

Document Type

Article

Date of this Version

November 1994

Comments

Published in Agron. J. 86:995-1000 (1994).

Abstract

Reduced temperature and increased bulk density associated with conservation tillage systems cause lower seed germination, seedling emergence, and early growth rates resulting in reduced plant stands. Prediction of the influence of soil condition on seed imbibition through simple soil measurements would help make agronomic decisions such as planting date and/or density. Our objectives were to evaluate the influence of soil water-filled pore space on winter wheat (Triticum aestivum L.) seed imbibition and to assess the possibility of describing the relationship through simple mathematical models. We measured the rate of water uptake by heat-killed wheat seeds at three levels of water-filled pore space (WFPS: 0.35, 0.60, and 0.85) and temperature (T: 278, 283, and 288 K) and two levels of bulk density (ρ_b: 1.25 and 1.40 Mg m^-3) in a Sharpsburg silty clay loam topsoil. The model proposed in 1972 by Blacklow to estimate seed water content (Ө_s(0)) after imbibing water for time t, Ө_s(t) (=m + ot) - (m - Ө_s(0))^-qt, was fitted to seed water content as a function of time and initial seed water content, Ө_s(0). This equation adequately described the process of water absorption (for 18 treatment combinations, R² ≥ 0.963). The model parameter o was related (R² = 0.88) to WFPS and ρ_b and q was related (R² = 0.78) to T and WEPS. The third parameter, m, was significantly but weakly related (P < 0.01, r² = 0.26) to initial seed weight. We showed that easily measured soil properties and simple mathematical models can be used to predict wheat seed imbibition under a variety of soil conditions.