The effects of weather and nutrition on the yield of hay from Palace Leas meadow hay plots, at Cockle Park Experimental Farm, over the period from 1897 to 1980     

S. Y. COLEMAN  R. S. SHIEL  D. A. EVANS 《Grass and Forage Science》1987,42(4):353-358

The yield of hay on the Palace Leas meadow hay plots has increased significantly with time on the higher yielding plots but has remained constant on the lower yielding plots. Yield on the higher yielding plots shows a relatively low fluctuation from year to year, and yields of plots treated with farmyard manure show high intercorrelations with each other, but lower correlations with the other plots. Yield is influenced by weather, but even the most successful climatic parameter– maximum soil moisture deficit—only accounts for 30% of the year on year variation in yield. There are highly significant autocorrelations between yields within each of the farmyard manure, treated plots indicating cyclic effects with periods of up to 6 years, but these are not related to the cyclic patterns of manure application.  相似文献   

Potential seed yield of white clover varieties     

D. R. EVANS  T. A. WILLIAMS  W. ELLIS DAVIES 《Grass and Forage Science》1986,41(3):221-227

Fifteen varieties of white clover were sown in order to assess the seed yielding ability of new and potential varieties and to examine those plant factors which affect seed yield. Counts were made on number of inflorescences m^-2, proportion of ripe inflorescences and other inflorescence and seed characters. The data were used to compute potential seed yields.
Average potential seed yields were 276 and 76 kg ha^-1 in the first and second year, respectively. The decrease in the second year seed yields underlines the overriding effect of adverse weather conditions during the critical June to August period. The major effect was a reduction in the number of inflorescences produced, the number of florets per inflorescence and seeds per floret.
Some of the new listed varieties have a significantly higher seed potential than SI00, e.g. Menna (+ 38%) and Olwen (+28%), and this should facilitate the production of adequate seed supplies of British bred varieties.  相似文献   

Animal production evaluation of herbage varieties. 1. Comparison of Aurora with Frances, Talbot and Melle perennial ryegrasses when grown alone and with clover   总被引：1，自引：0，他引：1  

J. M. M. MUNRO  D. A. DAVIES  W. B. EVANS  R. V. SCURLOCK 《Grass and Forage Science》1992,47(3):259-273

Comparative herbage characteristics and sheep production (ewes and lambs until weaning and lambs thereafter) from swards of Aurora (very early flowering), Frances (early flowering), Talbot (intermediate flowering) and Melle (late flowering) varieties of perennial ryegrass ( Lolium perenne ) were studied under a continuous variable stocking management based on sward surface height guidelines. The varieties were assessed as grass-only (215 kg N ha⁻¹ fertilizer) and grass/clover (83 kg N ha⁻¹ fertilizer) pastures.
Over 2 years (1985-86) total annual lamb production per hectare from grass-only swards of Aurora was 19% more than that from Frances despite similar herbage productivity. Differences between the varieties in lamb output were more pronounced as grass/clover swards, with Aurora producing 29 and 18% more lamb than Melle and Talbot respectively and with Frances also giving 16% more than Melle. Overall lamb production from grass/clover swards was 10% more than that from the grass-only pastures, mainly due to 69% advantage in individual lamb growth rates after weaning. Herbage organic matter digestibility, during the post-weaning period, was higher on grass/clover than on grass-only swards, and similarly with Aurora versus the other varieties. Under a frequent cut simulated grazing regime the relative herbage productivity of the four varieties differed, with Aurora 13% less productive than Frances.
The results are discussed in relation to the limitations of assessing performance under cutting, and the significance of the interaction in animal productivity between the two sward types.  相似文献   

Growth and water relations of simulated swards of Lolium perenne L. selection lines with contrasting leaf osmotic potentials     

H. THOMAS  C. EVANS 《Grass and Forage Science》1991,46(4):391-397

Two selection lines of Lolium perenne , which had different leaf lamina osmotic potential (Ψ_s) when droughted in controlled environments, were grown as vegetative simulated swards in containers of soil 1·0 × 1·3 × 0·9 m deep in the glasshouse. Water was withheld during July, August and September.
Under irrigation the low-ψ_s line had leaf lamina and leaf base ψ^s 0·06 MPa lower than the high-ψ_s line. Under drought, the two lines did not differ significantly in lamina ψ_s but leaf base ψ_s was 0·16 MPa lower in the low line than in the high line. Upon rewatering, most of the osmotic adjustment in the leaf bases was lost within 2 d, but that in the laminae was more stable.
Herbage growth under irrigation was similar in the two lines until September, when it was greater in the highψ_s line. Drought reduced herbage growth, and also regrowth rates following rewatering, but the two lines did not differ in their sensitivity to drought.
Selection for low ψ^s also increased leaf extension rates, and reduced tillering and leaf water conductance of irrigated plants.
The results are discussed in relation to selecting for improved drought resistance on the basis of physiological characters.  相似文献   

The effects of ventilation on intercranial and cerebral perfusion pressures in isoflurane-anaesthetized horses     

RJ Brosnan  EP Steffey  RA LeCouteur  A Imai  GD Kortz 《Veterinary anaesthesia and analgesia》2002,29(2):91-92

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