摘要:

AbstractA detailed study of the spring growth curves of two forage grasses, tall fescue and cocksfoot, over three successive years showed a large variability of growth over the vegetative phase. This variability was evident at levels of fertilizer N which were considered to be non‐limiting (60 kg N ha‐1in autumn plus 120 kg N ha‐1in February).At this level of N there was a relationship between yield in the vegetative phase and accumulated temperatures from the last cut in the autumn which was described by a regression common to the three years. The slope of this regression represents the potential growth of a variety. At a lower level of N a separate regression was needed in each year to relate growth to accumulated temperature.Variation in spring growth was not related to accumulated net radiation. Growth in the reproductive phase was related to accumulated temperature and accumulated net radiation from the 10‐cm ea

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01596.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractIn a study of growth rates and developmental morphology of simulated swards of two contrasting white clover varieties, Katrina and Kent, it was found that both varieties continued to produce dry matter throughout the winter at Aberystwyth. The gross crop growth rate in the coldest periods was about 7 kg ha‐1d‐1. The rates of formation and loss of new leaves were approximately equal so that there was no net increase in weight until the latter part of March. This initial net weight increase in both varieties was observed in the same harvest interval, the most important factor being the difference in weight between the new leaf plus petiole unit and the weight of the unit which it replaced. The weight of laminae and petioles throughout the experiment was somewhat higher in Katrina which has come to be regarded as the ‘earlier’ variety.The prospects for improving spring production in white clover by variety improvement are di

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01597.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractA series of twenty‐four swards containing different proportions of white clover (0·20‐0·25) and perennial ryegrass were created by using different seed mixtures, herbicide applications and previous cutting Frequencies. These swards were used to study the diet of oesophageally‐fistulated wether sheep which grazed the various swards for a 30‐min period after 1, 2 and 3 weeks of regrowth.The proportion of white clover in the diet was generally greater than that in the sward. Fifty‐seven percent of the variation in the proportion of white clover in the diet could be attributed to the proportion of white clover in the sward. White clover and perennial ryegrass leaf and stem were grazed to the same height and the proportion of white clover in the grazed horizon of the sward explained 83% of the variation in the proportion of white clover in the diet. The proportion of white clover in the diet was greater than the proportion in the grazed horizon of the sward in week 3 of regrowth, but not in weeks 1 and 2, and greater when the proportion of white clover in the grazed horizon was lower than 0·20. Both these observations were interpreted as indicating selection for white clover by the sheep within the grazed horizon.There was a positive and linear relationship between the depth of the grazed horizon and sward height which, together with the relationship between the proportion of white clover in the grazed horizon and in the diet, would allow the prediction of the proportion of white clover of the diet from the height and the white clover content of the grazed horizon

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01598.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractIn subtropical latitudes temperate crops can be grown during the cool months but the growing season is restricted by the termination and beginning of hot weather. Postponing sowing date in south Florida from October to November to January resulted in 150, 130 and 110‐d growing seasons respectively. Dry matter (DM) yields of turnip, swede, rape and kale were lowered by each later sowing date and shorter growing season, and crude protein (CP) concentration was the same as for, or was increased by late sowing.In vitroorganic matter digestibility (IVOMD) of turnip, swede and rape leaves was not affected by sowing date, but roots of turnip and swede from the earlier sowings and longer growing seasons were more digestible. Yield of the four species depended on harvest management as well as date of sowing and length of growing season. Total yield of turnip and swede were unaffected by harvest management but multiple cutting resulted in greater leaf yields and smaller root yields, whereas stockpiling resulted in smaller leaf yields and larger root yields. Kale produced more DM when harvested once at the end of the winter growing season but rape produced the greatest DM yield when sown in October and harvest

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01599.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractPlants of white clover (Trifolium repensL.) cv. Blanca and red clover (T. pratenseL.) cv. Hungaropoly were grown singly in controlled environments. The effects of eight treatments on the two species were examined: 16‐ and 8‐h photo‐periods × 20/15 and 15/10°C day/night temperatures ×Rhizobium‐freeplants receiving nitrate N and inoculated plants receiving no combined N. Twice weekly measurements of the main axis leaf size, petiole length, rate of leaf production and the time period between the appearance of a leaf and its final size were carried out for 8 weeks after sowing.Increasing the day/night temperature from 15/10 to 20/15°C, or doubling the daylength from 8 to 16 h (doubling the daylength increased temperature by 1·2°C) accelerated the rate of leaf production and expansion and increased petiole length and the final area of leaves. Most aspects of main axis leaf growth were reduced in the inoculated plants dependent on their own N fixation compared with the nodule‐free plants receiving abundant nitrate N. The results suggest that the temperature above which white clover exhibits appreciable leaf growth in the field could be relatively high compared with grasses. Further research is required to define these differences and relate them to seasonal changes in

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01600.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractFour grass silages, all made in mid‐July from second‐harvest perennial ryegrass swards, were compared in a 16‐week feeding experiment with twelve Ayrshire cows. Two silages were unwilted and two wilted. All the silages received formic acid (‘Add‐F’) at the rate of 3 litres t‐1either with formalin at the rate of 1 litre t‐1or without formalin. The unwilted and wilted silages had mean dry matter (DM) concentrations of 200 and 243 g kg‐1, andin vitroD‐values of 0·293 and 0·272 respectively. The silages were offeredad libitumplus 6 kg concentrates per cow per day. The daily intakes of unwilted and wilted silage DM were 10·2 and 9·2 kg per cow respectively on the formic acid treatment, and 10·2 and 9·2 kg on the formic acid + formalin treatment. The mean daily milk yield on the unwilted silage treatments was 19·2 kg per cow which was significantly higher than the yield of 17·2 kg per cow on the wilted silage treatments. The formalin had no significant effect on milk yield. The four silage treatments had small and non‐significant effects on milk composition. It is concluded that the unwilted silages, which had excellent fermentation characteristics, were superior to the wilted sil

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01601.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractPreharvest application of 1 and 2 litres ha‐1IPA glyphosate (glyphosate) to a seed crop of S24 perennial ryegrass with moisture concentrations of around 400 and 340 g kg‐1(40 and 34% moisture content w/w) failed to significantly lower seed and straw moisture concentration at harvest and consequently did not affect combine rate. Addition of extra surfactants and ammonium sulphate to glyphosate did not significantly increase the rate of desiccation.The quality of harvested seed was impaired at both rates and application times. Germination was significantly lowered through the production of abnormal seedlings. The germination of seed harvested in the previous year from glyphosatetreated plots decreased with storage. Seed vigour, germination rate and field emergence were also significantly decreased as a result of glyphosate application. The effect of glyphosate on seed quality precludes its preharvest use as a desiccant in the ryegrass seed crop.Harvesting difficulties due to the production of secondary vegetative tillers may be overcome by swathing rather than direct combin

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01602.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractA technique for estimating the rate of disappearance of material from samples of dead herbage protected by simple nylon or wire mesh covers is described. Using this technique on a perennial ryegrass sward in southern England during August‐November, relative rates of disappearance close to 0·204 g g‐1d‐1(DM) were obtained, but the variability was high. When herbage killed with paraquat was used, the rate of disappearance was higher and the variability lower. There were only small differences in the temperatures recorded in a normal sward and within samples of dead herbage under mesh

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01603.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractElectrical capacitance and root diameter techniques for estimating root dry weight were evaluated in one test with red clover plants grown on slant‐boards in plant growth chambers for 37–77 d, and in six tests with alfalfa grown in the field for 55–165 d. Root dry weights of red clover were estimated satisfactorily with regression equations from both diameter (R2=90%) and capacitance (R2=76%) measurements. Root dry weights of alfalfa were estimated satisfactorily throughout the entire season from diameter values (R2from 51 to 92%). Alfalfa root weight was significantly (P<0·25) related to capacitance values at the beginning and at the end of the season but not at mid‐season. Electrical capacitance measurements were similar for intact root systems and roots severed 4 cm below the crown in separate experiments with red clover and with alfalfa. The root diameter technique provided an accurate, rapid and inexpensive method of estimating root size throughout the first season of growth. The root capacitance method provided satisfactory estimates of roots at certain times during the summer. Neither method would be useful if a large portion of the root was naturally

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01604.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Book review in this articleForage Evaluation: Concepts and TechniquesEdited by J. L. Wheeler and R. D. MochrieImproved Feeding of Cattle and SheepBy P. N. Wilson and T. D. A. BrigstockeNitrogen Cycling in West African EcosystemsEdited by T. RosswallLand EvaluationBy S. G. McRae and C. P. Burnham

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1982.tb01605.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY