Estimates of genetic variability and heritability for vegetative and reproductive characters of kiwifruit (Actinidia deliciosa)

The results of this study indicated a great deal of genetic variation in a number of characters of horticultural interest in kiwifruit seedling populations, and therefore, a potential to improve kiwifruit by vine selection. High narrow sense heritability was shown for pedicel length(0.62) and flowering duration (0.50) in male vines, and pedicel length (0.67),floral shoot percentage (0.54), leaf length-width ratio (0.64), fruit elongation (0.64) and fruit weight (0.52) in female vines. For these traits, selection of superior seedlings should lead to rapid genetic improvement in these populations. This revised version was published online in August 2006 with corrections to the Cover Date.     

Detection of QTL for forage yield,lodging resistance and spring vigor traits in alfalfa (Medicago sativa L.)

Alfalfa (Medicago sativa L.) is an internationally significant forage crop. Forage yield, lodging resistance and spring vigor are important agronomic traits conditioned by quantitative genetic and environmental effects. The objective of this study was to identify quantitative trait loci (QTL) and molecular markers associated with increased forage yield, resistance to lodging, and spring vigor. A backcross population composed of 128 progeny was developed by crossing the breeding parents DW000577 (lodging susceptible) and NL002724 (lodging-resistant) and back-crossing an individual F₁ plant to the maternal parent (i.e. DW000577). A linkage map of NL002724 was developed based upon the segregation of 236 AFLP, SRAP, and SSR markers among the backcross progeny. The markers were distributed among 14 linkage groups, covering an estimated recombination distance of 1497.6 centiMorgans (cM). Replicated clones of both parents and backcross progeny were evaluated in the field for estimated forage yield, lodging, and spring vigor in Washington and Wisconsin during 2007 and 2008. Significant QTL were found for all three traits. In particular, two QTL for lodging resistance were identified that explained ≥14 % of trait variation, and were significant in all years and locations. Major QTL explaining over 25 % of trait variation for forage yield were detected in multiple environments at two separate locations on chromosome III. Several QTL for spring vigor were located in the same or similar positions as QTL for forage yield, possibly explaining the significant correlation between these traits. Molecular markers associated with the aforementioned QTL were also identified.     

From wine to pepper: rotundone, an obscure sesquiterpene, is a potent spicy aroma compound

An obscure sesquiterpene, rotundone, has been identified as a hitherto unrecognized important aroma impact compound with a strong spicy, peppercorn aroma. Excellent correlations were observed between the concentration of rotundone and the mean 'black pepper' aroma intensity rated by sensory panels for both grape and wine samples, indicating that rotundone is a major contributor to peppery characters in Shiraz grapes and wine (and to a lesser extent in wine of other varieties). Approximately 80% of a sensory panel were very sensitive to the aroma of rotundone (aroma detection threshold levels of 16 ng/L in red wine and 8 ng/L in water). Above these concentrations, these panelists described the spiked samples as more 'peppery' and 'spicy'. However, approximately 20% of panelists could not detect this compound at the highest concentration tested (4000 ng/L), even in water. Thus, the sensory experiences of two consumers enjoying the same glass of Shiraz wine might be very different. Rotundone was found in much higher amounts in other common herbs and spices, especially black and white peppercorns, where it was present at approximately 10000 times the level found in very 'peppery' wine. Rotundone is the first compound found in black or white peppercorns that has a distinctive peppery aroma. Rotundone has an odor activity value in pepper on the order of 50000-250000 and is, on this criterion, by far the most powerful aroma compound yet found in that most important spice.     

Genomic Relationships of Triticum sharonense with Other S-Genome Diploid Triticum Species

Triticum sharonense was hybridized with autotetra-ploid T. speltoides, T. longissimum and T. bicorne. Meiotic analysis of these hybrids showed that T. sharonense is almost equally related to both T. speltoidcs and T. longissimum, while it is comparatively distant from T. bicorne. Therefore, this study does not support treating T. sharonense as a subspeies or variety of T. lottgissimum.     

Use of spectral radiance for correcting nitrogen deficiencies and estimating soil test variability in an established bermudagrass pasture

The use of variable rate technology has become increasingly popular for applying plant nutrient elements. The most widely used method for determining variable fertilizer rates is presently based on soil testing and yield mapping. Three field studies (Bumeyville 1995, Burneyville 1996, and Ardmore 1996) were initiated in established Midland bermudagrass [Cynodon dacrylon (L) Pers.] pastures to determine the relationship between spectral radiance at specific wavelengths with forage nitrogen (N) removal and biomass, and to determine field variability of soil test parameters. Variable N (applied to 1.5 × 2.4 m subplots within 2.4 × 45.7 m main plots), fixed N and check treatments were evaluated at each location. Spectral radiance readings were taken in the red (671±6 nm), green (570±6 nm), and near infrared (NIR) (780±6 nm) wavelengths. The normalized difference vegetation index (NDVI) was calculated as NIR‐red/NIR+red. Variable N rates were applied based on NDVI. The highest fixed variable N rate was set at 224, 336, and 672 kg N ha^‐1 for Burneyville, 1995, 1996, and Ardmore, 1996, respectively. At Bumeyville, soil samples were collected in all variable rate plots (1.5 × 2.4 m) and analyzed for various soil test characteristics. NDVI, red, green, and NIR spectral radiance readings were correlated with bermudagrass forage N removal and yield. Correlation of forage yield and N removal with red, NIR, and NDVI were best with maximum forage production, however, when forage production levels were low correlation decreased dramatically for the red wavelength compared with NIR and NDVI. Forage yield and forage N removal in variable rate treatments increased when compared to the check while being equal to the half‐fixed and fixed rates where higher N rates were applied. Also, variability about the mean in variable rate plots was significantly lower than half‐fixed and fixed rates which supports adjusting N rates based on indirect NDVI measurements. Variable N rate plots reduced fertilizer inputs by 60% and produced the same yield as fixed rate plots, while fixed and half‐fixed rates did not increase N content in the forage over that of the variable rate treatment. Soil sample data collected from small consecutive plots (<4 m²) was extremely variable indicating that intense sampling would be needed if variable fertilizer application were to be based on soil test results.     

The exploitation of genetic resources of Brassica oleracea in breeding for resistance to clubroot (Plasmodiophora brassicae)

Summary About 1000 Brassica oleracea accessions were evaluated in glasshouse tests for response to Plasmodiophora brassicae (clubroot). Resistance was confirmed in some north and west European kales and cabbage. A new source of resistance in cabbage, from Eire, is reported. Most other accessions were highly susceptible but lower levels of susceptibility were observed in open pollinated Brussels sprouts and forms of south European cabbage, cauliflower and broccoli. Modern breeding (as in the production of hybrid cultivars) appears to have resulted in increased susceptibility in several crop types. The implications of these results for the exploitation of germplasm are discussed.     

Over-canopy saline sprinkler irrigation of grapevines during different growth stages

Wetting plant foliage with saline irrigation increases the uptake of toxic ions Na⁺ and Cl⁻. Over three consecutive seasons, Colombard vines grafted on Ramsey rootstock were irrigated with saline water (EC 3.5 dS/m) by over-canopy sprinklers during any one of the first three of the four annual growth stages: bud burst to full bloom (treatment BB-FB), full bloom to veraison (treatment FB-V), and veraison to harvest (treatment V-H). At other times, vines received non-saline water (EC 0.5 dS/m) as did the control. Seasonal average soil salinities remained relatively constant over the trial. In contrast, the concentrations of Na⁺ and Cl⁻ in one-year old wood and grape juice more than doubled. In treatments FB-V and V-H the average yield over the three seasons was reduced by up to 15%. Results were compared with those obtained in an earlier study which was undertaken in the same vineyard with the same treatments applied via dripper. With drippers, the maximum reduction in the average yield over three seasons was 2%. Saline sprinkling caused rises in Na⁺ and Cl⁻ concentrations of fruit, leaf lamina and one-year-old wood that were at least 7-fold, 5-fold and 2-fold greater, respectively, than the rises caused by application of the same treatments with drip. Progressive seasonal rises in the concentrations of Na⁺ and Cl⁻ in these tissues were due in part to carryover of salt added in previous seasons; with saline sprinkling the magnitude of these carryovers was 4-fold greater than those with saline drip irrigation. With saline water, vignerons can reduce losses by using irrigation systems which do not wet the foliage.     

Landowner perceptions and the adoption of agroforestry practices in southern Ontario,Canada

A mail-out survey questionnaire was developed by the Agroforestry group at the University of Guelph to determine the level of awareness and interest in the adoption of agroforestry systems by landusers from four townships in Wellington County, Ontario. The questionnaire investigated: (1) the current level of knowledge regarding windbreaks, woodlots and plantations, intereropping, riparian plantations and silvipasture, (2) the present level of participation in each of these systems on-farm, (3) the perceived benefits and/or drawbacks of each of these initiatives with respect to total farm income, income diversity, land rehabilitation, land value/equity, soil/water conservation, labour intensity, overhead and return on the term of investment.The majority of respondents were familiar with conventional agroforestry systems such as windbreaks and woodlots/plantations (80%, 62% respectively), therefore the level of interest in the adoption of these practices was significant (74%, 66% respectively). Response rates were lower for silvipasture, riparian plantations and intercropping, most likely as result of the low level of familiarity with these practices (20%, 32%, 4% respectively). Respondents commented that agroforestry systems would have a neutral effect on farm income, and would increase land stewardship. In some cases, interested landusers indicated a willingness to participate in agroforestry systems even though they anticipated increases in overhead and labour intensity; however, this was only true if they held land stewardship as a priority. Landusers were more concerned with the economic aspects of agroforestry, as a determinant to the future adoptability of particular practices. Age, gender, farm operation and farm size were not correlated with the adoption of agroforestry systems.The success of agroforestry programs on farms in the study area is largely dependent on the attitudes and willingness of landusers to participate in non-traditional agricultural systems.