Characterization of core collection of lentil germplasm for phenology, morphology, seed and straw yields
Increasing and maintaining crop residues in predominantly cereal-based rotations of the US Pacific Northwest is critical to controlling soil erosion. The core collection of lentil (Lens culinaris Medik.) germplasm comprising 287 accessions was evaluated for variation in phenological, morphological and growth parameters including seed yields and residue amounts over a two-year period under conventional tillage and no-till conditions. The objectives of this study were (i) assess lentil genetic variation in germplasm for variation in biomass production and seed yield, (ii) assess the relationship of phenological and morphological traits with biomass and seed yield and (iii) identify high biomass producing germplasm for use as parents in the breeding program. Days to flowering and days to maturity ranged from 31 to 78 and from 71 to 106 days, respectively. Time to flowering in terms of cumulative heat units was a more efficient measurement than days to flowering. Plant height and plant canopy width had a significant association with total biomass, seed yield and residue amounts. Total biomass ranged from 788–6389 kg ha−1 under conventional tillage, while the range under no-till conditions was 1045–6195 kg ha−1. Most of the lines with higher biomass also produced the highest seed yields and residue amounts. Overall, only one accession produced more residue than `Laird'. In the more favorable environment of 1997, six accessions exceeded the control cultivars, `Laird' and `Indianhead', for residue amounts, and seven and twenty-four accessions exceeded control cultivars, `Pardina' and `Brewer', for seed yield. Results indicated that plant height, canopy width at maturity and seed yield explained most of the variation in biomass and residue production. Large seeded germplasm consistently had a longer reproductive growth period than small seeded accessions and had 17%, 7% and 21% more biomass, seed yield and residue, respectively. Our data indicated significant variation in lentil germplasm for biomass, seed yield and residue amounts to warrant their use in the breeding program.
Genetic Variation for Biomass and Residue Production in Lentil: II. Factors Determining Seed and Straw Yield
Understanding the influence of vegetative and reproductive traits in lentil (Lens culinaris Medik.) on biomass production and seed yield would facilitate cultivar improvement. The objectives of this study were (i) identify and evaluate the morphological changes that have taken place during past cultivar improvement efforts, and (ii) quantify the effect of rainfall on seed and straw production. Seven breeding lines and three checks were evaluated at Pullman and Farmington, WA, and Genesee, ID, from 1993 to 1995 for vegetative growth period (VGP), generative growth period (GGP), crop growth rate (CGR), seed growth rate (Sd.GR), straw growth rate (St.GR), and partitioning coefficients for seed (p) and straw (q). Results indicated that past cultivar improvement efforts have achieved higher seed yields by (i) shorter generative and vegetative growth periods, (ii) greater rates of crop and seed growth, (iii) higher seed partitioning coefficients, and (iv) a moderate response to rainfall. Greater straw yields have been achieved by (i) longer generative and vegetative growth periods, (ii) greater crop and straw growth rates, (iii) a higher straw partitioning coefficient, and (iv) a greater response to rainfall. Simultaneous improvement of straw and seed yields is possible within existing lentil germplasm.
Genotypic diversity in field isolates of Babesia bovis from cattle with babesiosis after vaccination.
OBJECTIVE
To determine whether particular genotypes of Babesia bovis were common to field isolates obtained from cattle properties in Queensland where the B bovis vaccine had apparently failed.


DESIGN
A comparative study of polymerase chain reaction genotypes in different populations of B bovis.


PROCEDURE
Two polymerase chain reaction assays were applied to analyse DNA extracts of B bovis vaccine (K, T and Dixie strains) and 27 field isolates from 24 properties where disease outbreaks had occurred despite the use of the vaccine. To evaluate the stability of the genotypes identified, 11 of the field isolates were inoculated into experimental cattle that had either been previously vaccinated with T strain or not vaccinated.


RESULTS
No particular genotype of B bovis was responsible for the problems observed in previously vaccinated herds. None of the isolates had genotypes identical to the vaccine strains used. No geographic trends among the genotypes were observed. Isolates that originated from the same property also had different genotypes. Blood passage of the 11 field isolates in either previously vaccinated or nonvaccinated cattle did not alter the original genotype.


CONCLUSION
No particular genotypes identified by the Bv80 and BvVA1 polymerase chain reaction assays could be associated with vaccine failures.