摘要:

A study has been made of the flowering requirements, for temperature and photoperiod, of a range of timothy strains, including American, British and Scandinavian material.All the strains tested are long‐day in their photoperiodic responses, and there is no “winter requirement” for low temperature (0–5°C.) or short days before flowering. There is, however, an inhibitory effect of high temperature in the greenhouse on flower formation, lf the temperature is too high, no heads are produced, although photoperiod may be adequate. Instead elongated indeterminate shoots are formed which often become stoloniferous.The effect of high temperature varies with the strain, and appears to be related to the May temperature of the region of origin. Under greenhouse temperatures of 55–65°F. American and Canadian commercial strains show little inhibition of flowering, but many plants of the Scandinavian strains fail to produce heads. The British hay strains show intermediate heading behaviour, but only an occasional plant of the diploid S.50 formed heads under these

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1958.tb00116.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

Heading behaviour of eight strains of timothy was observed in the sowing and first harvest years, after sowing on a series of dates between March and August.All strains produced heads in the sowing year. Only a very few plants failed to head when sown between 18 March and 29 April. With subsequent sowing dates the proportion of heading plants progressively declined, most markedly in S.50Phleum nodosum, least in the early‐headingP. pratensestrains. No heading occurred in the sowing year after the mid‐August sowing.The environment to which the later sowings are exposed differs from that of the earlier sown lots in that (a) the initial temperatures and daylengths are higher and (b) the decline in daylength occurs earlier in their development. One or both of these factors must be responsible for failure of heading among plants of the later sowings.The sequence of heading dates among the strains in the sowing year differed considerably from that in the same plants after overwintering, suggesting the action of some factor other than photo‐period in determining heading date in the sowing year.Variability in heading date within the strains was much greater in the sowing year than after overwintering, and increased with lateness of s

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1958.tb00117.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

A trial is described which was designed to test the hypothesis that measurements taken of the leaf‐plus‐shoot length of spaced plants may give a good indication of dry‐matter yield of strains ofDactylis glomerata, as determined by cutting and weighing the produce of sward plots.Two contrasting strains ofDactylis glomeratawere used: the British S.143, and the German von Kamekes. The strains were established during 1955 both as spaced plants (10 plants per plot) and as pure swards, with six replications of each. The two methods of establishment formed the main treatments, occupying whole plots, and each plot was divided into four sub‐plots each of which carried one of the combinations of the two strains with the following two management treatments: Treatment 1, cut at monthly intervals from 27 April to 23 August; Treatment 2, cut on 12 April and subsequently at the mean date of emergence of the inflorescence for each strain, followed by cutting at monthly intervals until the end of August.Spaced plants were measured before cutting by thrusting a measuring rod into the crown of the plant and measuring the leaf‐plus‐shoot length of one of the longer shoots. Produce cut from sward plots was weighed and sampled for dry‐matter content.Results from the swards showed that von Kamekes produced more dry matter in early spring, but that subsequently the advantage passed to S.143.Significant positive correlations were obtained in early spring between the sward yields and leaf‐plus‐shoot measurements from spaced plants. Subsequently there was no agreement between the two methods, and some significant negative correlations were obtained.The data are discussed in relation to the physiological stages of development of the strains, which suggests that:(a) In the spring period the main factor contributing to yield was shoot elongation, with the majority of the tillers in the reproductive phase.(b) In summer the main factor was new tiller formation, with the majority of tillers in the vegetative phase.(c) In the early autumn neither factor was dominant and both contributed to yield.Attention is drawn to the danger of comparing yields from spaced plants with yields from swards where the management may influence the results obtained, and to the difficulty of assessing hay yields by means of height measur

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1958.tb00118.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

Experiments are described in which a study was made of the top growth, root weight, nodule number, and type of nodules of white clover growing in a grass sward in the field. Soil cores were taken and the clover root‐system examined after removal of soil by washing.The most important factor governing the total number of nodules and the number of large (2 mm. or more in length) nodules under the sward was the amount of clover root‐material present.Nitrogenous fertilisers and the return of dung and urine by grazing sheep reduced the amount of clover root‐weight and consequently the number of nodules found under the pasture. 36 1b. of nitrogen applied in the early spring of 1956 had a beneficial effect on both clover top‐growth and nodulation. 80–100 1b. of nitrogen per acre had no effect on the number of nodules per gram of root. However, the application of 200 1b. of nitrogen per acre caused a significant decrease in the number of large nodules per gram of root.The numbers of large nodules present reached a midsummer peak where nitrogen was not applied.During the autumn many nodules showed part green and part pink colouration or were completely green or brown, an indication of a decline in nitrogen‐fixing ability. Decaying nodules increased considerably in number when the legume was being suppressed by nitrogen application and top growth was poor. The practical application of these results is discussed and methods of maximising the benefit from clover and fertiliser nitrogen ar

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1958.tb00119.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

An experimental silo unit consisting of four silos, each capable of holding 1000 kg. fresh grass, is described. The silos are suspended from a weighing apparatus enabling weight recordings to be taken at all stages during ensilage. The weighing apparatus is sufficiently sensitive to record a change in weight in the silo and contents of 100 grams.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1958.tb00120.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1958.tb00121.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1958.tb00122.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

The vigour of perennial ryegrass and cocksfoot after spraying with the sodium salt of MCPA during establishment was estimated from their yields in small‐plot cutting experiments on weedy land. Where the weed yields of control plots was of the order of a ton of air‐dry matter an acre (mostlySpergula arvensisL.), spraying at up to 1·2 1b. acid equivalent an acre caused twofold to threefold increases in grass yields. The optimum time to spray perennial ryegrass was at the three‐ to four‐leaf stage or 26 days after sowing; for cocksfoot, which appeared more susceptible to the herbicide, spraying at the tillering stage, or about 40 days after sowing, was best. Increasing the seed rates of ryegrass produced transitory increases in yields while decreasing weed yields. Increasing phosphate or nitrogen caused decreases in weed yields. Although the former gave a large increase in weed yield in the first cut this was offset by a large decrease in the second cut. There was an indication that the level of nitrogenous manuring affected the toxicity of the herbicide to the

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1958.tb00123.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

Foggage grazing trials with beef‐store cattle and in‐calf dairy heifers during four successive winters in Aberdeenshire are described. Many of the animals received only very small quantities of supplementary fodders, but their performance was satisfactory in all cases. During the last two winters, silage and oat straw contributed 40–50% of total food dry‐matter intake. It is suggested that this level of supplementary feeding would be satisfactory in practice.In a comparison of store‐feeding systems, four in‐wintered (housed) steers were 110 1b. per head heavier than their out‐wintered monozygous twins at the end of the winter‐feeding period. Live‐weight differences averaged 27 1b. per head one month later and were negligible at the end of summer. From the results of a metabolism trial it was concluded that the spring weight‐loss suffered by the housed cattle was due mainly to a reduction in the wei

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1958.tb00124.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

Yields were recorded from a potato crop grown in the first year following a grazing trial comparing four strains of white clover, previously described in this journal (2&3). The Kent clover strain, which was the most persistent and which had produced the greatest live‐weight increase per acre, gave the highest yield of potatoes. The Dutch white clover, which had been the poorest in the grassland trial, gave the lowest yield of potatoes.A 2 × 2 × 2 N, P, K fertilizer design was superimposed in the form of split plots. Nitro‐chalk at 5 cwt. per acre and muriate of potash at 2 cwt. per acre both caused significant reductions in yield, and this was thought to be due to the exceptionally high soil fertility status of the field. The fertilizer × clover interactions were non‐significant, and contributed little towards an explanation of the fundamental basis of the soil fertility differences caused by these four clover

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1958.tb00125.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY