摘要:

AbstractIn two experiments in established swards of perennial ryegrass and white clover, plots were treated with pesticides to control slugs, leather‐jackets, weevil larvae and lucerne flea as selectively as possible. Other plots were treated to control ail of these pests.Chlorpyrifos application in early summer (to control weevil larvae) and methiocarb pellets (to control slugs) also gave partial control of leather‐jackets. Other effects on non‐target species were considered to be unimportant, as pest status could not be attributed to the species. A high level of control of lucerne flea by methiocarb pellets, noted previously, was confirmed.At both sites combined treatment against insect pests and slugs produced large increases in clover content and yield over a 3‐year period, in comparison with untreated plots, although clover tended to decline In alt plots. At one site, where the clover content of untreated plots reached 33% at one stage, specialist clover herbivores such as weevils and lucerne flea were more common. Treatments directed against weevils and slugs gave the highest clover yields, and leatherjacket control may also have contributed, particularly when the population reached 0.9 m ha−1in the final year. At the other site, where the clover content was low (ultimately 01.1–6%), leather‐jacket populations reached 2.1 m ha−1and slug numbers were also relatively high. Control of these species contributed most to the relative increase in clover co

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1989.tb01919.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe growth ofTrifolium semipilosumFres. var.glabrescensGillet cultivar Safari, andTrifolium repensL., cultivars Haifa and Grasslands Huia was compared in controlled temperature glasshouses at 15/10, 21/16, 27/22 and 33/28°C (day/ night), and over eighteen months under four‐weekly cutting in the field. In glasshouses, white clovers grew better than Safari at all temperatures except 27/22°C. Stolon production and partitioning of dry matter to stolons was greater, and petiole production and partitioning of dry matter to petioles was less for Safari than for white clovers. Haifa and Huia differed primarily in individual leaf weight, individual leaf area and leaf numbers; with Hula and Safari, but not Haifa, exhibiting a reduction in leaf size in response lo defoliation. In the field, growth of Safari was poor. Growth responses of Haifa and Huia in the field were related to seedling vigour, dry matter partitioning between leaves and stolons, and response to defoliation at low temperatures. It was concluded that there were major differences in growth, dry matter partitioning, morphology and response to temperature betweenT. semipilosumandT. repens.These differences particularly influence climate adaptation and competitive ability at the seedling st

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1989.tb01920.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractField trials were conducted in 1985 and 1986 to assess the effects of the growth regulator RSW0411 on aLolium perenneL. (perennial ryegrass) seed crop. Applications were made at spikelet and floret initiation, and at 1, 2, 3 and 4 kg active ingredient ha−1.Seed yield increases in 1985 were associated with increased reproductive tiller numbers and seed numbers, but in 1986 there were no seed yield responses.Lodging was less severe in 1986, and there was less secondary filtering during seed maturation. In 1985, fertile tiller numbers were lower in control plots at harvest. These results are discussed in relation to the seasonal disparity in seed yield response.RSW0411 application significantly decreased culm lengths by shortening the basal internodes, and this effect was greater with higher application rates. Stem width was increased in 1985 at the base and middle of the stem, and earlier applications increased the basal width by more than later applications.Germination was not affected by RSW0411 treatment, except when applied at 4 kg active ingredient ha−1in 1985, when there was a small decrease. This was related to a low 1000‐seed weight, and is discussed in relation to seed maturity at ha

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1989.tb01921.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractApplying nitrogen (N) fertilizer to grass generally increases N concentration in herbage. Not as well documented, however, are N fertilizer effects on concentrations of N in plant cell walls and lignocellulose. The objective four study was to ascertain how N fertilizer applied with or without a nitrification inhibitor would affect N concentrations in the cell wall (neutral‐detergent fibre (NDF)) and lignocellulose (acid‐detergent fibre (ADF)) of smooth bromegrass(Bromus inermisLeyss). Nitrogen fertilizer ((NH4)2SO4) was applied at 0, 125, or 230 kg N ha−1in combination with 0, 2–5, or 50 kg ha−1of nitrapyrin (2‐ chloro‐6‐(trichloromethyl) pyridine) to smooth bromegrass in April of 1985 and 1986. Herbage was harvested at 2, 4, 6 and 8 weeks after treatment. Freeze‐dried herbage samples were analysed forin vitrodigestible dry matter (IVDDM), total N, and N in neutral‐ and acid‐detergent fibre (NDFN and ADFN, expressed as g kg−1NDF and ADF, respectively). Nitrapyrin had no effect on IVDDM, total N, NDFN or ADFN, Nitrogen fertilizer increased concentrations of total N in herbage dry matter, and increased N concentrations in NDF and ADF. Most of the increase in total N concentration occurred in the neutral‐detergent soluble portion. When NDFN and ADFN concentrations were expressed on a total N basis (g k g−1of total N), N fertilizer had no effect. Available fibre N (AFN; calculated as NDFN minus ADFN, each expressed as g kg−1total N) was not affected by N fertilizer. The average AFN concentration was 93 g kg−1total N. Nitrogen fertilizer did not affect herbage quality; however, age of herbage had ma

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1989.tb01922.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractData are few on concentrations of nitrogen (N) in the cell wall and lignocellulose (neutral‐ and acid‐detergent fibre (NDF and ADF), respectively) of herbage. Herbage N can be partitioned into neutral‐ and acid‐detergent soluble and insoluble N to crudely estimate rapidly degradable (N soluble in neutral detergent), slowly degradable (neutral‐detergent fibre N (NDFN) minus acid‐detergent fibre N (ADFN), herein termed available fibre N (AFN)), and indigestible N (ADFN) in the rumen. Our objective was to examine the effects of herbage species, maturity stage, and plant part on N in the NDF and ADF of lucerne (Medicago sativaL.), red clover (Trifolium pratenseL.), timothy (Phleum pratenseL.), and smooth bromegrass (Bromus inermisLeyss.). Herbage was harvested at four 2‐week intervals during spring of 1984 and 1985. Leaves, stems and total herbage were analysed for total N, and N in NDF and ADF. Concentrations of N in ADF in leaves, stems, and total herbage of lucerne and clover were twice that of grass ADF. This may be due to greater lignin concentrations generally reported in legumes. Concentrations of NDFN in leaves of lucerne, clover, timothy, and bromegrass were 9–8, 26.4, 8.6, and 6.4 g kg−1of NDF, respectively, averaged over harvests and years, whereas stem concentrations were 4.2, 4.6, 32, and 2.4 g kg−1of NDF, respectively. Leaf concentrations of ADFN in lucerne, clover, timothy, and bromegrass were 4.6, 5.3, 20, and 1.6 g kg−1of ADF, respectively, averaged over harvests and years, whereas stem concentrations were 3.4, 33, 14, and 14 g kg‐’of ADF, respectively. As a proportion of the total N, NDFN and ADFN increased with plant maturity in leaves, stems, and herbage. In stems, 49% of NDFN was ADFN, whereas in leaves only 21% of the NDFN was ADFN. The larger portion of ADFN in stems probably reflects the larger proportion of lignified xylem and other structural tissues, which have a greater proportion of lignified secondary cell walls, whereas the greater proportion of NDFN in leaves may mirror the greater amount of mesophyll cells with primary cell walls. More than 80% of the total N in leaves, stems, and herbage was in the cell solubles, which may be rap

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1989.tb01923.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThree silages were prepared from herbage treated with either an inoculant (Ecosyl, Imperial Chemical Industries plc) at 3.21 t−1, formic acid (850 g kg−1, Add F BP Chemicals International Ltd) at 2·3 1 t−1, or no additive (control). The herbage used was the first regrowth from perennial ryegrass swards. It was ensiled unwilted, and had mean dry matter and water soluble carbohydrate concentrations at ensiling of 154 and 24·1 g kg−1respectively. Time course studies showed only minor effects of additive treatment on fermentation patterns within the silo and all three silages had good fermentations. Over an 88 d feeding period, commencing on day 7 of lactation, forty‐eight British Friesian cows were used to evaluate the silages in a three‐treatment, randomized‐block design experiment. The animals were stalled individually, offered the silages ad libitum, and in addition received 5 kg d−1of a supplement containing 196 g kg−1crude protein. On the basis of the data recorded during the final 28 d on treatment the animals receiving the inoculant‐treated silage consumed 12 and 10% more silage dry matter and produced 2·1 and 2·3 kg d−1more milk than those given the control and formic acid‐treated silages respectively. Over the total experimental period the milk yields were 1957, 1894 and 2094 (±41·3) kg for animals receiving the control, formic acid‐ and inoculant‐treated silages respectively. Animals offered the formic acid treated silage produced milk of significantly higher fat concentration than those given the other two silages. Total ration digestibility studies, conducted with three cows per treatment, indicated no significant differences in digestibility coefficients, nitrogen utilization or metabolizable energy concentrations of the three treatment diets. It is concluded that the higher milk yield recorded with the inoculant‐treated silage, and the higher milk fat concentration with the formic acid‐treated silage, over that obtained with the control silage, were due to the increases in ME intake of 5 and 16 MJ d−1for the formic acid and

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1989.tb01924.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThree contrasting white clover varieties, Olwen (large‐leaved), Menna (medium‐leaved) and S184 (small‐leaved) were sown with and without a grass companion in 30 cm drills. Two grazing and one mechanical spring defoliation managements were imposed. Counts of the total number of inflorescences and of the percentage in various ripeness categories were made throughout the period of seed crop development to determine the pattern of inflorescence development and optimum harvest date. Inflorescence numbers were greatest in cv. S184 and least in cv. Olwen and, in general, varieties produced both more inflorescences and a greater proportion of ripe inflorescences when grown under spring defoliation managements similar to those for which they were bred. Thus, cv. Olwen produced more ripe inflorescences, and a lower proportion of brown inflorescences (semi‐ripe), after mechanical defoliation while cv. Menna produced more ripe inflorescences following mechanical defoliation and rotational grazing. However, cv. S184 produced more ripe inflorescences under both grazing managements than under mechanical defoliation. Optimum harvest date was not affected by management or variety, total inflorescence number and maximum ripe inflorescences having reached a peak on 11 September. However, varieties differed in the proportion of ripe and brown (semi‐ripe) inflorescences on this date, with cv. Menna and cv. S184 containing a significantly higher proportion of brown inflorescences than cv. Olwen, The implications of these differences in inflorescence development, the proportions of inflorescences in the various ripeness categories and their contribution to seed yield are discussed in relation to the management of white clover seed crops and harvesting method under UK climatic c

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1989.tb01925.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractAn experiment is described in which the effects of different spring managements on the potential seed yield and seed yield components of three white clover cultivars of contrasting leaf types were assessed. Cv. S184, the small‐leaved variety, produced more but smaller inflorescences than CVS Olwen, a large‐leaved variety, or Menna, a medium‐leaved variety. However, cv. Olwen, produced inflorescences with more florets, seeds per inflorescence and a higher seed yield per ten inflorescences than the other cultivars. Both potential seed yield and the individual yield components were influenced by management. Cv. Olwen produced more inflorescences and a higher potential seed yield under a cutting system than under grazing systems, which reduced the number and size of the inflorescences. Cvs S184 and Menna were less influenced by management system and performed similarly under cutting and grazing. The highly significant relationship between the number of ripe inflorescences and potential seed yield showed clearly that high seed yields are only achieved if the crop is harvested when the number of ripe inflorescences is at a maximum. The relatively short duration of the period of maximum ripe inflorescences emphasized the importance of determining the correct harvesting date, although weather conditions also play an important part in deciding when to harvest. Florets per inflorescence, seed set and 1000 seed weight remained relatively constant over the harvest period, and were not influenced by harvest date. The results are discussed in relation to the management of white clover seed crops and the importance of climatic conditions during seed produ

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1989.tb01926.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractMeteorological factors influencing the temporal changes of digestibility of grasses in spring and early summer are discussed. Annual observations in England of the digestibility of three grasses are then related to the relevant meteorological variables using two multiple regression analysis methods. The resulting regression relationships are tested on independent data, and finally sets of regression coefficients are recommended for predicting from synoptic meteorological data the weekly progress of digestibility in different areas of England: a simplified set of regression relationships for predicting digestibility values a few days ahead which require forecasts of only temperature in order to be applied operationally is also given.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1989.tb01927.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractChanges in the weight per unit length along the first and second fully‐expanded laminae ofLolium perenne, Agrostis stolonifera, Holcus lanatusandPoa trivialiswere experienced in tillers harvested in April and June 1987 from a permanent pasture under contrasting nitrogen treatments. Schematic models representing the weight distribution along the laminae of the different species are presented. From these models, predictions of the weight of any given proportion of the lamina length have been calculated. The weight of segments of lamina have been estimated, using the appropriate lamina model for a species, and these estimates provided consistently greater precision than estimates of lamina weight when no correction for lamina shape was considered, the length of a segment of lamina simply being multiplied by the mean overall weight per unit length of the lamin

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1989.tb01928.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY