Differences among Merino strains in resistance to fleece-rot

1958 ◽  
Vol 9 (2) ◽  
pp. 260 ◽  
Author(s):  
AA Dunlop ◽  
RH Hayman
Keyword(s):  
Field Conditions ◽  
Merino Sheep ◽  
High Incidence

The incidence of fleece-rot was observed in a number of strains of Merino sheep distributed variously over fire sets of field conditions. In three locations rainfall was sufficiently high to cause moderate to high incidence of fleece-rot among susceptible sheep. In two other locations conditions were such that its occurrence in susceptible sheep was either negligible or absent. In two of the former localities South Australian strong-wool Merinos proved to be highly susceptible, while in two medium-wool Peppin strains the susceptibility varied from moderate to high. In a medium-wool non-Peppin strain the incidence was less than in the Peppin and South Australian strains; in a fine non-Peppin strain the incidence was moderate to low; while in a flock of Camden Park fine-wools the incidence was low.

Selection schemes for improving both reproduction rate and clean wool weight in the Australian Merino under field conditions

1965 ◽  
Vol 16 (5) ◽  
pp. 863 ◽  
Author(s):  
SY Young ◽  
Turner H Newton
Keyword(s):  
Theoretical Consideration ◽  
Relative Efficiency ◽  
Selection Pressure ◽  
Field Conditions ◽  
Reproduction Rate ◽  
Optimal Method ◽  
Merino Sheep ◽  
Selection Of ◽  
Australian Merino

Theoretical consideration has been given to 28 selection schemes which might readily be applied for the improvement of both number of lambs born and clean wool weight per head in Australian Merino sheep under field conditions. Two sets of relative weights were used, one lamb being considered equivalent to 5 or 10 lb of clean wool, and when both characters were selected in one sex, equal selection pressure was applied to each. Quality of wool is assumed to be safeguarded by preliminary culling of off-types. The schemes were investigated at two levels of twinning (15 and 30%). At both levels, the optimal method of ram selection was to select on clean wool weight among twin-born rams. At the lower level, the optimal method of ewe selection was to save twin-born ewes and to make up numbers by selecting on clean wool weight among those born as singles. At the higher level, this scheme was slightly exceeded in total genetic gain by one involving selection of ewes on their own 3-year-old reproduction rate. After 10 years of selection under the optimal scheme, an increase of about 40 lambs born per 100 ewes joined would be expected in reproduction rate, and about 1.2 lb clean wool in the cut per head. The gain in wool weight will be less (about 1 lb) if more rigorous culling on crimp is practiced, but the relative efficiency of the schemes near the optimum will not be changed. The tables presented could be used in flocks of any breed in which clean wool weight and reproduction rate were uncorrelated and to which approximately the same estimates of heritability, variances, and relative weights of lamb and wool could be applied.

Studies in controlled artificial insemination of Merino sheep

1958 ◽  
Vol 9 (5) ◽  
pp. 693 ◽  
Author(s):  
TJ Robinson
Keyword(s):  
Artificial Insemination ◽  
Treatment Effects ◽  
Factorial Experiment ◽  
Merino Sheep ◽  
High Incidence ◽  
Lambing Rate

A total number of 507 ewes were inseminated at the rate of approximately 100 per day for 5 days, in a factorial experiment with variables: rams (5), treatments (5), days of insemination (5), volume of semen (2). Treatments were: (1) control; (2) progesterone daily for 16 days, PMS on 17th, inseminated on teasing; (3) progesterone every 2 days, PMS on 17th, inseminated on teasing; (4) as for (2), but inseminated 2 days after PMS; (5) as for (3), but inseminated 2 days after PMS. The overall lambing rate was low (31-6 per cent.). There were significant differences between rams, treatments, and day of insemination. Relative infertility of one ram was related to high incidence of sperm with curled tails. Treatment effects were: (1) 40.8 per cent. of ewes lambed; (2) 33.7 per cent.; (3) 32.9 per cent.; (4) 30.2 per cent.; (5) 15.0 per cent. Insemination was less efficient on the first day. Volume of undiluted semen used (0.05 or 0.1 ml) had no effect.

scholarly journals Incidence of ‘Candidatus Liberibacter asiaticus’-Infected Plants Among Citrandarins as Rootstock and Scion Under Field Conditions

2015 ◽  
Vol 105 (4) ◽  
pp. 518-524 ◽  
Author(s):  
Leonardo Pires Boava ◽  
Cíntia Helena Duarte Sagawa ◽  
Mariângela Cristofani-Yaly ◽  
Marcos Antonio Machado
Keyword(s):  
Quantitative Polymerase Chain Reaction ◽  
Genetic Resistance ◽  
Poncirus Trifoliata ◽  
Field Conditions ◽  
Economic Losses ◽  
Rangpur Lime ◽  
Hybrid Plants ◽  
High Incidence ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus

Huanglongbing (HLB), caused by the bacterium ‘Candidatus Liberibacter’ spp., is currently one of the most serious diseases of citrus plants and has caused substantial economic losses. Thus far, there is no source of genetic resistance to HLB in the genus Citrus or its relatives. However, several studies have reported Poncirus trifoliata and some of its hybrids to be more tolerant to the disease. The main objective of this study was to report differences in the incidence of ‘Ca. L. asiaticus’ infection in citrandarin plants, hybrids from Sunki mandarin (Citrus sunki (Hayata) hort. ex Tanaka), and trifoliate orange Rubidoux (P. trifoliata (L.) Raf.)), after conducting an extensive survey under field conditions. These hybrid plants were established for approximately 7 years in an area with a high incidence of ‘Ca. L. asiaticus’-infected plants. We selected two experimental areas (area A and area B), located approximately 10 m apart. Area A consists of Pera sweet orange (C. sinensis (L.) Osb.) grafted onto 56 different citrandarin rootstocks. Area B consists of citrandarin scions grafted onto Rangpur lime (C. limonia Osb.) rootstock. Bacteria in the leaves and roots were detected using real-time quantitative polymerase chain reaction. The incidence of ‘Ca. L. asiaticus’-infected plants was 92% in area A and 14% in area B. Because infected plants occurred in both areas, we examined whether the P. trifoliata hybrid rootstock influenced HLB development and also determined the distribution of ‘Ca. L. asiaticus’ in Citrus tree tissues. Although this survey does not present evidence regarding the resistance of P. trifoliata and its hybrids in relation to bacteria or psyllids, future investigation, mainly using the most promising hybrids for response to ‘Ca. L. asiaticus’, will help us to understand the probable mechanism of defense or identifying compounds in P. trifoliata and its hybrids that are very important as strategy to combat HLB. Details of these results are presented and discussed in this article.

scholarly journals Evaluation of Cucumber Hybrids for Yield and Quality Under Plastic House and Open Field Conditions

2021 ◽  
Vol 15 ◽  
pp. 52-63
Author(s):  
Ishwori Prasad Gautam ◽  
Navin Gopal Pradhan ◽  
Sujan Subedi ◽  
Manis Kumar Thakur
Keyword(s):  
Open Field ◽  
Agricultural Research ◽  
Block Design ◽  
Field Conditions ◽  
Female Ratio ◽  
Yield And Quality ◽  
Significant Difference ◽  
High Incidence ◽  
Male To Female ◽  
Double Yield

Low yield of off-season cucumber due to use of open-pollinated varieties with high male to female ration, long gestation period and high incidence of diseases are the major problems of cucumber production in Nepal. The use of imported hybrids varieties during the off-season and plastic film technology has shown to lead to enhanced growth and higher yield in recent years. However, there is a little work on hybrid cucumber research and their testing in Nepal.  Therefore, experiments were conducted at the National Horticulture Research Center (NHRC), Directorate of Agricultural Research (DoAR), Tarahara and Farmer's field in Dhankuta district accordingly to select best hybrids. Sixteen genotypes including best Indian hybrid Dynasty and 3 open-pollinated check genotypes were evaluated at NHRC, Khumaltar during the years 2018 and 2019 in Randomized Complete Block Design (RCBD) with three replications under the plastic house. Previously selected seven genotypes were evaluated in DoAR, Tarahara in 3 replications and best hybrid was compared with farmers' varieties in Dhankuta at open field conditions. Tested genotypes showed a significant difference in yield and other parameters like male to female ratio, early flowering, vine length, disease scoring etc. both under the plastic house and open field conditions. The new hybrids HRD CUM 009 x 003 (107.05 mt/ha), HRD CUM 006 x 003 (91.55 mt/ha) and HRD CUM 004 x 001(88. 10 mt/ha) were promising due to higher yield, earlier to 50% female and male flowering, a greater number of female flowers, short vine length, higher number of fruits per plants and earliness harvesting than other cultivated varieties. Most of the tested hybrids produced more than double yield than open-pollinated genotypes.

Self-cure of Haemonchus contortus infections under field conditions

Parasitology ◽  
1973 ◽  
Vol 66 (1) ◽  
pp. 43-53 ◽  
Author(s):  
E. W. Allonby ◽  
G. M. Urquhart
Keyword(s):  
Adult Worm ◽  
East Africa ◽  
Haemonchus Contortus ◽  
Field Conditions ◽  
Aetiological Factor ◽  
Sheep Grazing ◽  
Natural Conditions ◽  
Merino Sheep ◽  
Before And After ◽  
Dramatic Fall

The phenomenon of self-cure, as it occurred under field conditions in East Africa, was studied in Merino sheep infected with Haemonchus contortus. The onset of self-cure, as judged by a dramatic fall in faecal egg counts, was found to be simultaneous in sheep grazing on infected pasture and in sheep grazing on parasite-free pasture. Furthermore the results of autopsies carried out before and after self-cure showed that a marked and equal loss of adult worm burdens had also occurred. These results indicate that self-cure of H. contortus infections under natural conditions occurs in the absence of reinfection and is apparently non-immunological in origin. Since the phenomenon was always associated with a period of significant rainfall, it is suggested that new growth of pasture may be a significant aetiological factor.

The observation of defects on (100) CdTe surfaces by chemical etching

1992 ◽  
Vol 50 (2) ◽  
pp. 1424-1425
Author(s):  
M.E. Lee
Keyword(s):  
Single Crystal ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Chemical Etching ◽  
Crystalline Perfection ◽  
Crystalline Defects ◽  
High Incidence ◽  
Crystallographic Defects ◽  
Cdznte Substrates ◽  
Device Technology

The crystalline perfection of bulk CdTe substrates plays an important role in their use in infrared device technology. The application of chemical etchants to determine crystal polarity or the density and distribution of crystallographic defects in (100) CdTe is not well understood. The lack of data on (100) CdTe surfaces is a result of the apparent difficulty in growing (100) CdTe single crystal substrates which is caused by a high incidence of twinning. Many etchants have been reported to predict polarity on one or both (111) CdTe planes but are considered to be unsuitable as defect etchants. An etchant reported recently has been considered to be a true defect etchant for CdTe, MCT and CdZnTe substrates. This etchant has been reported to reveal crystalline defects such as dislocations, grain boundaries and inclusions in (110) and (111) CdTe. In this study the effect of this new etchant on (100) CdTe surfaces is investigated.The single crystals used in this study were (100) CdTe as-cut slices (1mm thickness) from Bridgman-grown ingots.

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