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Biweekly cold hardiness and water content were measured on 1-year-old field cuttings of bearing Concord grapevines at the Horticultural Teaching and Research Center at MSU from Sept. 1998 to Apr. 1999. Cold hardiness index LT50 (temperature at which 50% of the sample was killed) was determined by three viability tests after laboratory controlled sub-freezing treatments. Weather data were obtained from the MSU agricultural weather automatic system. Average maximum and minimum air temperatures of 1, 3, 5, and 7 days prior to each field sampling were regressed against the LT50 of the tissues. Our results suggested that: 1) Tmin1 (minimum air temperature of the preceding 1 day of each sampling) had the most significant correlation with LT50 and cane water content among all air temperatures analyzed. 2) While cane water content was significantly related to its bark water, the water content of periderm and pith did not. 3) When comparing the effects of Tmin1 and bark water content on cane LT50 together, bark water had significant higher coefficient of determination (R 2). This research provided additional information about the mechanisms of plant dormancy and cold hardiness.

Free access

Abstract

Field death of dormant primary buds of Vitis labrusca L. cv. Concord may be effectively simulated by in situ puncture with an aluminum needle super-cooled by liquid N2. This allows the subsequent development of the secondary buds for studies of their growth and productivity.

Open Access

Abstract

Horticulturalists frequently use the analysis of variance (F-test) to determine treatment differences. Many simple non-parametric tests, which require fewer assumptions, are also available. This note presents an example of the modified Friedman test as an alternative analysis for ranked data from a randomized complete-block design.

Open Access

Abstract

Environmental and phenological factors considered potential components of flower bud hardiness of highbush blueberry (Vaccinium australe Small) were regressed against hardiness (T50). Three multiple regression equations were derived from 1 year’s hardiness and component data on 7 commercial highbush cultivars. Factors considered in the models were air temperature, photoperiod, bud dry weight, bud moisture content, bark color, date of leaf drop and pollen tetrad formation in the field and time to 50% flowering. The standard deviations of the estimated T50 values from the actual T50’s were 1°C or less.

Open Access

Abstract

Winter injury to branches of highbush blueberries (Vaccinium australe Small cv. Jersey) resulted when mechanical harvester use caused lesions on the branches during the harvesting process. Of the dead wood collected during 2 years study, more than 99% had such a lesion. The amount of wood lost increased as the vibration rates of the harvester increased and at high rates loss of bearing surface reduced production the following season.

Open Access

Chambers were constructed to measure gas exchange of entire potted grapevines (Vitis vinifera L.). The plant enclosures were constructed from Mylar film, which is nearly transparent to photosynthetically active radiation. Maintaining a slight, positive, internal pressure allowed the Mylar chambers to inflate like balloons and required no other means of support. The whole-plant, gas-exchange chamber design and construction were simple and inexpensive. They were assembled easily, equilibrated quickly, and did not require cooling. They allowed for the measurement of many plants in a relatively short period. This system would enable the researcher to make replicated comparisons of treatment influences on whole-plant CO2 assimilation throughout the growing season. While CO2 measurement was the focus of this project, it would be possible to measure whole-plant transpiration with this system.

Free access

An experiment was conducted to evaluate interrelationships between differing crop loads and water stress on physiology and root dynamics of 3 year old Seyval grapevines grafted to 5-BB, Seyval and Seyval own-rooted stock grown under a rain exclusion shelter. Treatments were: 1) cropping level, either 0 (defruited) or 6 clusters/vine (heavily cropped) and 2) irrigation level, either 2.5 (stress) or 10 liters (control) of water/plant/week. Vines had significantly different root dynamics in regards to crop load, water status and rootstock. Water stressed vines had significantly fewer and smaller leaves (area cm 2 lighter trunk weights (g) and shorter shoot length compared to control vines. Heavily cropped vines had significantly fewer mature nodes, shorter shoot growth and higher bud mortality (winter injury) compared to defruited vines.

Free access

Abstract

Shade treatments giving 36% full sun or less reduced both hardiness and shoot cross-sectional area of one-year-old sour cherry (Prunus cerasus L. cv. Montmorency) and peach [Prunus persica (L.) Batsch cv. Redhaven]. Shade significantly reduced soluble carbohydrate in ‘Redhaven’.

Open Access

Abstract

Early introduction of honey bees into caged ‘Jersey’ blueberries was associated with increased yields and fruit size and suggests that hives be introduced in plantations for pollination not later than 25% of full bloom.

Open Access

Abstract

At last year's W-130 Regional Project meeting in Penticton, B.C., Edward L. Proebsting, Jr., chairman of the meeting, requested that we communicate our interest and discussion in the Oct. 1985 Viewpoint article by Lang, Early, Arroyave, Darnell, Martin, and Stutte concerning dormancy terminology (HortScience 20:809–812).

Open Access