Search Results

You are looking at 41 - 50 of 666 items for :

  • All content x
Clear All
Free access

Bhaskar Bondada

alluring organoleptic and nutritional communicative traits, in effect, intended for reproductive success, also appeal intuitively to their sense of aesthetics and liking, for instance berries of grapevine, grapes as fresh and dry fruit, and wine. Among all

Free access

Peter Cousins*

The grapevine shoot consists of nodes without clusters (inflorescences) basal to a zone in which leaf-opposed clusters are found at the nodes. Beyond the cluster zone leaf-opposed tendrils are borne at the nodes. The numbers and possible relationship of basal nodes and clusters are important in grapevine breeding and improvement. Basal node number influences cluster placement within the canopy, which relates to light penetration to the fruit and fruit maturation and to application of cultural practices, including harvest and cluster treatments. Cluster number is a primary yield component. Basal node and clusters numbers were counted on ten primary shoots each of forty grapevine (Vitis) accessions. The accessions analyzed are cultivars and wild species collections held in the United States National Plant Germplasm System. The correlation coefficient of the number of basal nodes and number of clusters was calculated using the means of the ten observations per accession. Basal node and clusters numbers were negatively correlated; the correlation coefficient was -0.763, which is significant (P <0.001). The negative correlation of basal node and cluster number has implications for grapevine improvement.

Free access

Edna Tanne, N. Shlamovitz, and P. Spiegel-Roy

Grapevine (Vitis vinifera L.) explant shoots indexed forcorky-bark and rootstocks from healthy LN33 indicator plants were sterilized and maintained in vitro. When infected shoot tips were micrografted onto LN33 shoots, typical corky-bark symptoms appeared in 8 to 12 weeks. We suggest developing this method further to replace the regular, 2-year indexing procedure.

Free access

Thomas J. Zabadal, Gary R. VanEe, Thomas W. Dittmer, and Richard L. Ledebuhr

Growing conditions in Michigan can threaten the yield and acceptable fruit quality of `Chardonnay' grapevines. Three grapevine training systems, mid-wire cordon (MWC), umbrella kniffin (UK), and a combination of the two (MWC-UK) were evaluated under Michigan growing conditions to determine their influence on yield, fruit quality, cluster compactness, incidence and severity of Botrytis bunch rot, and trellis fill. Vines were grown on C3309 rootstock and pruned to 44 nodes per kilogram of cane prunings. The MWC-UK treatment had an additional 30 nodes per vine retained, and the crop level on these nodes was removed after fruitset. Over a 2-year period, UK and MWC-UK trained vines had fruit soluble solids about 1 °Brix higher and yields were 48% and 63% higher than MWC trained vines, respectively. MWC-UK trained vines consistently out-performed MWC trained vines for all variables measured, while UK-trained vines provided an intermediate response.

Free access

Peter Cousins

The grapevine shoot has a zone in which leaf-opposed clusters are found at the nodes. Beyond the cluster zone, leaf-opposed tendrils are borne at the nodes in a patterned distribution. Cluster number is a primary yield component and selection programs for increasing yield in grapevine frequently consider cluster number. However, selection for increased cluster number requires direct observation, which is only possible once the vine matures. Clusters and tendrils are developmentally related, so it may be that tendril density (tendrils per node) reflects cluster number. In contrast to cluster number, tendril density can be observed on plants of all ages. The hypothesis that tendril density is related to cluster number was tested here. Cluster numbers and tendril density were assessed on 10 primary shoots each of 180 grapevine (Vitis) accessions. The accessions analyzed are cultivars and wild species collections held in the United States National Plant Germplasm System. The correlation coefficient of the number of clusters and tendril density was calculated using the means of 10 observations per accession. Tendril density was determined by calculating the mean number of tendrils per node in the nodes beyond the cluster zone. Cluster number and tendril density were positively correlated; the correlation coefficient was 0.35. This implies that vines with more tendrils per node also tend to have more clusters. The positive correlation of cluster number and tendril density has implications for grapevine improvement, pointing to the possibility of indirect selection for higher cluster number through selection for higher tendril density. Correlation between juvenile tendril density and mature cluster number is yet to be tested.

Free access

E. Peterlunger and B. Marangoni

ABA implication in root signals of water stress has been suggested by several authors. To verify this hypothesis in grapevines, this experiment has been carried out. One-year-old own rooted cuttings of grapevine cultivar Cabernet Sauvignon were exposed to water stress. After three months of growth, water was completely withdrawn for nine days, till the plants reached the wilting point. The plants were then rewatered. During the whole period, root hydraulic conductivity was measured with a pressure bomb; xylem sap samples were collected, as well as leaf and root samples. ABA concentration in these samples was measured using Radio Immuno Assay with DBPA1, a monoclonal antibody for ABA. The concentration of xylem sap ABA was 68.2 mg m-3 at the start of the experiment. After eight days of stress it was 1863.6 mg m-3, 27 × higher. On the ninth day the plants were rewatered, and the xylem sap ABA decreased at 100.2 mg m-3, keeping this level for eight more days. Leaf ABA showed high levels of this inhibitor, with a peak in correspondence with the maximum stress. A similar behaviour was attained by roots. In grapevine, ABA seems to be involved in a water stress root signal directed to the canopy.

Free access

Da-Peng Zhang, Zi-Lian Zhang, Jia Chen, and Jiang Lu

The abscisic acid (ABA) has a key role in the regulation of grapevine fruit ripening, but the cellular and molecular biological mechanism of the hormone action in the fruit ripening remains unknown. By means of differential centrifugation, microsomes were prepared from Kyoho grapevine (Vitis vinifera L. × V. Labrusca L.) berries, and using the microsomes, we have obtained evidence for the occurrence of specific ABA-binding sites on the membranes with the microvolume radio-ligand binding assay. The binding sites had saturability, high affinity, and low capacity. The results of trypsin and dithiothreitol treatments to the microsomes suggested that ABA binding sites had the properties of proteins that might have disulfide group located at or near the binding site. The binding maximum amount of ABA in the microsomes was at pH 6.0 and the activity of ABA binding proteins was higher at 25 than at 0°C (temperature). The amount of ABA bound reached 54% of the ABA binding maximum (Bmax) for 10 minutes of incubation and Bmax reached for 30 minutes. The dissociation constant (Ka) and Bmax of ABA binding proteins in the microsomes were 17.5 nmol/L and 98.4 fmol/mg protein, respectively.

Free access

Terence R. Bates, Richard M. Dunst, Theodore Taft, and Michael Vercant

One- and 2-year-old 'Concord' (Vitis labruscana L.) grapevines were used to study the effect of soil pH on vegetative growth and nutrition. Ninety-eight, own-rooted, 'Concord' grapevines were planted in 94.6-L pots containing vineyard soil adjusted to seven soil pH levels ranging from 3.5 to 7.5. After the first growing season, seven vines from each soil pH treatment were randomly selected, destructively harvested, and measured for root and shoot growth. The remaining 49 vines over-wintered in the pots, were defruited in year two, and were destructively harvested at the end of the second growing season. There was a reduction in root biomass below soil pH of 4.5 and a greater reduction in shoot biomass leading to a higher root: shoot ratio. There were no significant differences in vegetative growth of young 'Concord' vines from a soil pH of 5.0-7.5. However, there was a trend toward lower shoot biomass and higher root: shoot ratio at the highest soil pH level. Phylloxera nodosities on roots were present in equal densities at all soil pH values. However, the negative impact of phylloxera on vine dry mass was greater on vines under nutrient stress at the highest and lowest pH treatments than on those with adequate nutrition at the mid-range soil pH values.

Free access

Bhaskar R. Bondada

shoot growth, but also flowering and fruit set, for instance in grapevine ( Al-Khatib et al., 1993 ). Once drifted to these locations, leaves readily absorb and translocate the particles and volatiles of 2,4-D ( Bovey, 1971 ). In most woody perennials

Free access

David G. Himelrick, Robert M. Pool, and Philip J. McInnis

Several cryoprotectant chemicals were tested for their ability to increase the freeze resistance of grapevine (Vitis labruscana Bailey) leaf and dormant bud tissue. DuPont Surfactant WK, ethylene glycol, and BRIJ 35 were effective in lowering the low-temperature exotherm (LTE) in `Concord' grape buds below controls by 5.4, 5.1, and 3.9C, respectively, in March. Measurements taken in April showed BRIJ 35 and Surfactant WK to be notably superior to the other products, giving LTEs 14.1 and 12.2C below controls, respectively. Ethylene glycol, Frostguard, and Frost Free were less effective. LTEs were also significantly decreased in grape leaf disks 4.1C by BRIJ 35, 2.1C by Frostguard, and 0.4C by Frost Free treatments. Chemical name used: trimethylnonylpolyethoxyethanol (DuPont Surfactant WK).