English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

Herbage production in the California annual grassland has been correlated with seasonal weather, particularly fall and spring rainfall patterns. To further examine the relationship between herbage production and rainfall pattern, 3 soil water regimes (-1, -7, -15 bars) simulating expected rainfall and drought events in annual rangelands were applied in seminatural annual grassland communities. Soft chess (Bromus mollis) tillers grew longest under the -7 bar water regime treatments while total plant growth was greatest under the -1 bar treatment. Tiller length and total growth of slender oat (A vena barbata) were greatest under the -1 bar treatment. Vegetative growth of slender oat was less sensitive to seasonlong soil water regimes than soft chess. The two species required different soil water conditions for maximum spring growth; soft chess put on spring growth most rapidly in the -7 bar treatment while slender oat grew fastest in the -1 bar treatment. Periodic water stress during the growing season did not reduce spring herbage production. Maximum growth and herbage production occurred only when soil water was available after March 15. Withholding water after March 15 reduced herbage production by 46%. Annual range species dominate open grassland and woodland understory on about 10 million hectares in California. Forage production and botanical composition of the forage vary annually because the herbaceous vegetation begins each growing season as seedlings. Researchers have long attributed variation in range productivity to seasonal weather conditions. Talbot and Biswell (1942) concluded that climatic factors were the main cause for yearly fluctuations in forage yield at the San Joaquin Experimental Range in the southern Sierra foothills. Murphy (1970) found a significant correlation between yield and early growing-season rainfall at the Hopland Field Station in northern coastal California, but Duncan and Woodmansee (1975) failed to find any seasonal correlations at the San Joaquin Experimental Range. Pitt and Heady (1978) concluded that warm fall and spring temperatures coupled with adequate fall and spring precipitation at Hopland resulted in the greatest yield, but it is yet to be determined whether such empirical models can explain annual differences in productivity on drier inland annual rangelands such as the San Joaquin Experimental Range. Peak standing crop increases with increasing average annual rainfall along a south-north rainfall gradient of 125 to 2,000 mm per year (Bartolome 1980). Annual rangeland at the Sierra Foothill Range Field Station in the central Sierra foothills produces 2,000 to 2,700 kg/ha/yr if soil water is limiting in April or May and The authors are visiting assistant professor, Department of Agronomy, Oklahoma State University, Stillwater 74078 and associate professor, Department of Agronomy and Range Science, University of California, Davis 95616. The authors thank Dr. H.F. Heady, Dr. J.W. Bartolome, and Dr. L.J. Waldron, College of Natural Resources, University of California, Berkeley, and Dr. W.A. Williams, Department of Agronomy and Range Science, University of California, Davis, for their advice and critique of the manuscript. This research was supported in part by NSF Grant No. DEB 7823641 and the California Agricultural Experiment Station. Manuscript received September 22, 1981. thereafter, but produces 2,800 to 4,600 kg/ha/yr if soil water is available until June or July (Evans et al. 1975). Drought and rainfall pattern are undoubtedly controlling factors for herbage production in California annual grasslands, but mechanistic studies of the responses of annual species to soil water conditions are nearly lacking. In a greenhouse pot study, Gerakis et al. (1975) showed that subterranean clover (Trifolium subterraneum L.) is more drought tolerant than either soft chess (Bromus mollis) or redstem filaree (Erodium botrys). We examined plant growth parameters as they were affected by different soil water regimes designed to simulate winter and spring drought events in California annual grasslands.

Response of Soft Chess (Bromus mollis) and Slender Oat (Avena barbata) to Simulated Drought Cycles