Geographical variation in predictive seedling emergence in a perennial desert grass

Abstract

Summary1 Mechanisms that link germination and emergence to environmental cues associated with seedling success (predictive germination) would be expected to evolve when seedlings have a greater mortality risk than seeds, but may be less important in perennial plants than in annual plants.2 We investigated variation in predictive seedling emergence among divergent populations of a short-lived perennial desert grass, Digitaria californica, from sites that diered in climatic and edaphic factors. This species is native to environments in which the amount and duration of adequate soil moisture may control germination and seedling establishment success. 3 We utilized a special irrigation system that permits application of a range of amounts of water within a single experiment in a glasshouse. Emergence data were subjected to probit and survival analyses to describe dierences among the populations in response to applied water. 4 Signi®cant variation in predictive emergence was shown to exist among populations of D. californica when measured as amount of water required for 50% emergence following 3 days of water application, or as time required to achieve this level of emergence. Both climatic and soil characteristics were important with populations that originated from sites with less summer precipitation, and soils with higher water-holding capacity tended to have lower water requirements for emergence. 5 The report demonstrates the existence of subtle variation in predictive emergence among populations of a perennial grass representing a relatively narrow range of ecological amplitude. It also establishes the usefulness of line-source irrigation and probit analysis procedures in studying seedling emergence behaviour.

Epidermal conductance as a component of dehydration avoidance in Digitaria californica and Eragrostis lehmanniana, two perennial desert grasses

“…Caryopses from D. californica populations were collected at Robles Junction, Arizona (32.041N, 111.181E; mean annual precipitation: 320 mm) in 1990 and Van Horn, Texas (31.021N, 104.491E; mean annual precipitation: 294 mm), USA in 1958. To minimize the effects of environment of seed production on progeny performance, seed of this species used in these experiments was produced in a greenhouse in Tucson, AZ in 1996 (Smith et al, 2000). Caryopses of E. lehmanniana were collected at the Santa Rita Experimental Range (SRER, 31.501N, 110.501E; mean annual precipitation: 361 mm), 45 km south-east of Tucson, Arizona in 1996.…”

Effects of soil moisture profile on seedling establishment in the psammophyte Hedysarum laeve in the semiarid Otindag Sandland, China

“…Thus, the capacity of plants to germinate when soil moisture is high (predictive germination strategy) may increase the probability of successful seedling establishment and reduce the mortality of seeds and seedlings (Philippi and Seger, 1989;Smith et al, 2000;Yang et al, 2005). Moreover, seedling survival and growth are greatly improved by morphological and functional traits that increase the ability of the root system to absorb and transport water efficiently (Folk and Grossnickle, 1997;Mattsson, 1997).…”

Effects of density on timing of emergence and its consequences for survival and growth in two communities of annual plants

“…Variation in the timing of seedling emergence is one such well-studied factor (Salisbury, 1963;Howell, 1981;Kalisz, 1986;Miller, 1987;van der Toorn and Pons, 1988;Biere, 1991;Rees, 1994;Murray, 1998). This is a plant life history trait that is expected to influence subsequent probability of survival, and reproductive output (Weiner, 1985;Rice, 1987;Clauss and Venable, 2000;Smith et al, 2000). In addition, timing of emergence has a profound effect on the outcome of competition both within and between species (see Refs.…”