Imbibition Response of Winter Wheat to Water‐Filled Pore Space

Abstract

AbstractReduced 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 (ρb: 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 (θs) after imbibing water for time t, θs(t) = (m + ot) − (m − θs(0)) e−qt, was fitted to seed water content as a function of time and initial seed water content, θs(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 ρb, and q was related (R2 = 0.78) to T and WFPS. 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.