摘要:

AbstractBotanical analyses were carried out on the herbage from plots of twelve early cultivars of perennial ryegrass (Lolium perenne) cut in their fourth year and the results related to visual persistence assessments carried out on the cultivars at the end of the second and third harvest years. Persistence assessments were found to be highly and positively correlated with the yields of sown cultivars (r=+0.96***,r=+0.99***) and to be highly and negatively correlated with the yields of unsown herbage species (r =+0.98***, r =−094***). The plots of the less persistent cultivars were invaded by unsown grass species and docks which contributed in varying degrees to total DM yield, reducing the correlation of total yield with persistence. Assessments of botanical composition of swards made at the end of the second year provided reliable predictions of the relative persistence of the cultivars. The results of the investigations indicated that assessment of persistence, as well as yield potential, is fundamentally important in cultivar evaluatio

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1976.tb01107.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractTen varieties of forage grasses, including perennial and Italian ryegrasses, tall and meadow fescues, cocksfoot and timothy, grown in seed‐production drills were sequentially harvested from 14 days after peaks of flowering. Seed germination capacities were generally good in seed samples harvested early in the mattiration period, with the exception of timothy. PeaJc yields of germinable seed were usually obtained some time after shedding had begun; delay in harvesting resulted in further seed losses, some of which were substantial. The maxima of individual seed weights mostly did not coincide with, and were frequently later than the peaks of germinable seed yields. Endospenns did not generally harden until after the maxima of germinable seed yields. Endosperm development stages were found to be reliable guides to assessment of correct harvest date, and it is suggested that examination of endosperm consistencies be used to corroborate assessment of harvesting times tising moisture meter

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1976.tb01108.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe insecticide dimethoate was applied to a sward of S23 perennial ryegrass over a period of 2 years at three dose rates and at five frequencies of application. Annual DM yield was increased by up to 5% in the first year and by up to 17% in the second. The value of the additional yield is compared with the cost of obtaining it.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1976.tb01109.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractSix castrated male sheep were used in a two‐period crossover experiment to investigate the effect of mincing on the voluntary intake and digestibility of a silage. The silage was a high‐quality material, containing 68 % digestihle organic matter in the dry matter, prepared from S24 perennial ryegrass cut with a precision chop forage harvester and ensiled with the addition of 2.3 1 t−1formic acid as preser vative. The median size of particles in the unprocessed silage was 10–20 mm and in the minced silage 2–3 mm.The intakes of dry matter, organic matter and nitrogen for the minced silage were greater than for the unminced material, and for dry matter and organic matter intakes the differences were signi ficant (P005).It is concluded that with high‐quality silage diets there is a physical component in the mechanism for the control of voluntary food intake. It is suggested that for sheep, depressions in the digestibility of dietary constituents are unlikely to occur until silages are chopped to a median parti

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1976.tb01110.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe size of the root system was measured by means of electrical capacitance in relation to the soil in field experiments with three varieties of tetraploid red clover over a period of 3 years. The root system was greatest in the first year, smaller in the second year and least in the third year. The plants that gave an above‐average yield in any cut always had above average‐sized root systems in the preceding period, but usually after cutting, the size of their root systems decreased, an effect which was accentuated by plants drying out. The plants that dried out during the experimental period always had below average‐sized root systems in preceding periods. It was found in four cuts that the herbage dry matter of the plants with larger roots contained a smaller proportion of nitrogenous materials and ash, and more fibre, but the yield of all measured nutrients and elements increased. The ash of the herbage DM of these plants contained more potassium, calcium and magnesium. The quantity of mineral materials absorbed per unit of size of root systems was higher in the plants with larger root sy

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1976.tb01111.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe acetylene reduction assay was used to follow seasonal changes in nitrogen fixation activity in a white clover‐perennial ryegrass ley in Northern Ireland. The annual estimate for fixation by the ley was 268 kg ha−1(239 lb/acre) nitrogen virtually all of which was fixed during March to October. Nitrogen fixation was curtailed drastically after the ley was cut but recovered as new foliage expanded on the clover. Glasshouse experiments described the effects of temperature, shading and defoliation on nitrogen fixation by white clover, and indicated that these factors might be important in modifying symbiosis under field conditi

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1976.tb01112.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractA simple instrument for estimating the yield of herbage from measurements of height has been tested in cutting and grazing experiments. The instrument consists of a verticle graduated shaft and two linked aluminium discs which settle on the herbage. The height of the discs from the ground is recorded. Highly significant relationships were established between the yield and the height of herbage. Linear regressions explained 80–90% of the variation in the cutting experiments, and 39–62%in the grazing experiments. The errors attached to the estimated yields were high, but, because of the simple construction, low cost and rapid operation of the instrument, it is concluded that it has many useful functions in grassland research and managem

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1976.tb01113.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1976.tb01114.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Book Reviewed in This Article:Soil Physical Conditions and Crop ProductionMinistry of Agriculture, Fisheries and Food Technical BulletinStudy of Agricultural SystemsEdited by G. E. Dalton.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1976.tb01115.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY