摘要:

AbstractLaboratory experiments gave useful indications of the effectiveness of insecticide treatments to control larvae of frit fly (Oscinella fritL.). Lightly infested field experiments provided confirmatory evidence. Several seed treatments, insecticide granules combine‐drilled with the seed and post‐emergence sprays were very effective. The feasibility of delivering granules with seed must be confirmed for each granular formulation. Post‐emergence sprays were most effective if applied at approximately the time of oviposition but several also gave a strong residual effect if applied earlier and a remedial effect if applied after larval establishment in the seedlings. More detailed conclusions are disc

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1985.tb01752.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractFour experiments were conducted to assess the performance of ranked set sampling relative to random sampling for the estimation of herbage mass and clover content in grazed swards. The expected theoretical efficiencies were not observed due to the method of selection of quadrats and the nature of the distribution of herbage mass. Nevertheless there should be worthwhile improvement in precision over random sampling, provided that the quadrats within a set are as well spaced as possible, allowing, if necessary, for visual comparison.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1985.tb01753.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractThe responses in dry matter (DM) production and changes in nutrient concentration in the shoots of white clover (cv. New Zealand Grasslands Huia) to additions of lime, N, P, K and Mg were investigated in pot and field experiments in a deep peat soil and to additions of N, P, K in two other hill soils in pot experiments. DM production and nutrient concentrations were assessed also for perennial ryegrass in the field experiment. There was no response by white clover to N, but in all soils, and in particular a deep peat, production of shoot DM was increased greatly by lime, P and K, and slightly by Mg. Interactions between lime and P and between P and K were observed. Critical concentrations of nutrients (g kg−1) for white clover appeared to be about 2.0 for P, 10·15 for K and 20 for Ca. Herbage production and nutrient contents of ryegrass and white clover grown on a deep peat in the field suggests that critical concentrations may possibly help to diagnose the need fur maintenance fertilizer dressin

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1985.tb01754.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractA model of the ensilage process is presented which can be used to predict silage quality in lactate silages. The model simulates the major microbial and biochemical processes during ensilage, including aerobic respiration, hydrolysis of hemicellulose. growth and death of lactic acid bacteria and their production of lactic and acetic acids, reduction in pH, change in soluble sugar content, increase in osmotic potential, and proteolysis. The model is designed to operate on mixtures of grasses, legumes, or whole‐plant corn. Parameters for the model are developed from published silage experiments and pure‐culture bacterial studies. The model gives reasonably accurate predictions of key silage quality parameters, but further experimental work is needed on growth of lactic acid bacteria and on plant‐enzyme proteolysis. Predicted final pH depends primarily on the pH at which bacterial growth and death rates are equal. Initial bacterial concentration affects the time to rapid pH change, while maximum bacterial growth rate affects the rate of decline there

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1985.tb01755.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractThe addition of nitrogenous fertilizer to a newly cut, N‐deficient ryegrass sward resulted in an increased photosynthetic capacity in the next leaf to expand, showing that greater photosynthesis per unit leaf area as well as greater leaf area contributes to the increased growth of fertilized swards. Later in the 4‐week growth period there was little difference in photosynthetic capacity between fertilized and unfertilized swa

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1985.tb01756.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractInfection ofDactyls glomeratawith cocksfoot mottle virus (Cf MV) and ofCynosurus cristatuswith cynosurus mottle virus (CyMV) is frequently lethal. However, varieties of each species differ in the proportion of genotypes which survive, and in the damage suffered by these surviving plains. Infected plants of the CfMV‐resistant cocksfoot, cv. Cambria, were generally much more aggressive in the competitive environment of the sward than were infected plants of the susceptible cv. S37. Thus, Cambria populations outyielded comparable populations of S37 by only 7% when healthy, but by 40% when infected with CfMV. A few genotypes in the infected Cambria population apparently recovered from the disease, became virus‐free and were immune to further infection Resistance to CyMV inC. cristatustakes the form of resistance to systemic spread. A few symptomless and apparently virus‐free tillers grow up from the bases of infected tillers. However, these tillers are susceptible to further infection. It is suggested that, in resistant genotypes, CfMV and CyMV trigger the production of antiviral agent(s) which block or restrict virus replication. There is some evidence that CfMV resistance is virus isolate specific, and this could present problems when breeding for durable resis

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1985.tb01757.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryThe objective of this study was to compare thein vitrodry matter digestibility (IVDMD) and chemical composition at various cutting dates of autumn‐accumulated tall fescue and orchard‐grass. The effect of time on the digestibility and chemical composition of accumulated red clover was also studied.Tall fescue had significantly higher (P<0.01) IVDMD and total non‐structural carbohydrate (TNC) levels and lower crude protein (CP), acid‐detergent fibre (ADF). lignin (LIG) and cellulose (CEL) levels throughout autumn and winter than orchardgrass. The effects of accumulation period were similar on both grasses; TNC concentrations increased up to November but then declined, with a large drop in levels after December while IVDMD decreased slowly in autumn and fell rapidly in December. Overall there was a significant (P<0.01) increase with advancing time in ADF and CEL levels in both grasses, but LIG levels declined with age in tall fescue between 15 September and 15 November, whilst there was a general increase in LIG in orchardgrass.In both tall fescue and orchardgrass IVDMD and TNC levels were higher (P<0.001) and CP, ADF and CEL levels lower (P<0.001) in the stem than in the leaf. LIG concentrations were higher in orchardgrass leaves than in the stem but the levels were similar in both fractions in tall fescue.Similar patterns of change in IVDMD and composition were evident in red clover but the legume had completely senesced by early

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1985.tb01758.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractProductivity, seasonal growth and persistence of 10 perennial ryegrass (Lolium perenneL.) varieties were assessed al an upland (305 m) and lowland (30 m) site in mid‐Wales. Averaged over 3 harvest years (1979–81), mean dry matter (DM) production at 8.8 t ha−1was 22% lower in the upland environment, with spring (April and May) growth showing greatest contrast varying from only 6% of that in the lowland in 1979, after a severe winter, to 113% in 1981.Relative ranking of varieties differed considerably between the two environments and no correlation was found between DM production at the two sites (r= 0.5945). Early heading varieties performed better in the spring than late types at the upland site. A comparison of the results with those published from official variety testing trials gave a positive relationship under lowland conditions (r= 0.7162*) but no correlation with those from the upland centre (r= 0.1969).The findings of the study show that relative productivity of varieties, but not persistency, differs between upland and lowland environ

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1985.tb01759.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractA sensor which detects the presence of green vegetation against a brown background was used to monitor the establishment of plots ofLolium perenneandPoa trivialis, either hand weeded or unweeded. The spectral assessments obtained by the meter were very closely related to the proportion of ground cover, assessed photographically, and harvested dry weight of the two species, at least up to 100 days (approx. 50% ground cover) from sowing, Such spectral assessments therefore provide a rapid, non‐destructive method of monitoring changes in green‐leaf biomass of establishing grasses. In a complementary investigation the meter provided accurate and objective assessments of scorch damage to grasses caused by various herbici

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1985.tb01760.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractResults from two trials with normal and brown midrib‐3 (bm3) types of LG11, Inra 188, Inra 240 and Inra 258 showed the bm3mutant gene delayed silking by an average of 3 days, decreased whole plant dry matter (DM) concentration by 20 g kg−1and the proportion of ear by 4·6 percentage units. Comparable yields of DM were obtained from normal and bm3crops. The organic matter digestibility and yield of digestible organic matter of the bm3plants was 0.06 units and 14% higher respectively than their normal counterparts.Measurement of the physical strength and resistance to lodging of normal and bm3plants showed the bm3gene reduced stem strength, which was highly correlated to stem diameter, stem weight and rind thickness. However, the major difference in plant lodging was between genotypes with Inra 240 plants less resistant to lodging than other genotypes. These results show that although the bm3gene slightly increased lodging, genotype susceptibility is the major contributing factor to plant lod

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1985.tb01761.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY