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- Author or Editor: D. Scott NeSmith x
During 1997 through 1999 mature `Southland' muscadine grapes were grown in Griffin, Ga., with different rates of daily irrigation. Irrigation rates were 0, 15, 22.5, and 30 L·d–1, supplied to individual plants through two emitters. Substantial water deficit occurred during August 1997, May and June 1998, and July and August 1999. The greatest yield response to irrigation was observed during 1998. No significant response to irrigation was observed during 1999, even though soil water was greatly depleted in the upper 30 cm late in the season for control plants. The 3-year average response of total yield indicated a significant response to irrigation, with the greatest yield occurring at the 22.5-L·d–1 rate. Together these data suggest that muscadine grapes respond to irrigation, especially when water deficits during the early to midseason are prevalent. With single trellis vines, 22.5 L·d–1 should provide adequate water in warm, humid regions similar to the southeastern U.S.
Regionalization is a contemporary issue facing those of us involved in research, teaching and extension in the area of agricultural and environmental sciences. Primarily, regionalization involves sharing of intellectual resources (i.e., scientists, specialists) across institutional boundaries to accomplish common objectives. While at times it seems that regionalization is simply a euphemism for down-sizing, the issue can actually be broader reaching than that. Given our increased ability for virtual technology transfer, the global market our clientele face, and the ever decreasing budgets for agriculture, regionalization may well be a key to meeting the needs of those we serve in the most cost efficient way. Hopefully, as we regionalize, the efforts will be synergistic. There also has to be awareness that personal contact with our constituents is still highly desirable for many. The purpose of this forum is to gain perspectives, both pros and cons, from those involved in regional efforts. These perspectives will include an administrator, a regional faculty, and an extension specialist/agent. Also, there will be two examples of regional efforts that are underway: the USDA–ARS Southern Horticultural Laboratory and the Southern Region Small Fruit Consortium.
During 1997 through 1999 mature `Southland' muscadine grapes were grown in Griffin, Ga., with different rates of daily irrigation. Irrigation rates were 0, 15, 22.5, and 30 L·d–1 (LPD), supplied to individual plants through 2 emitters. In 1997, substantial water deficit occurred during August, in 1998 during May and June, and in 1999 during July and August. The greatest yield response to irrigation was observed during 1998. No significant response to irrigation was observed during 1999, even though soil water was greatly depleted in the upper 30 cm late in the season for control plants. The 3-year average response of total yield indicated a significant response to irrigation, with the greatest yield occurring at the 22.5 LPD rate. Together these data suggest that muscadine grapes respond to irrigation, especially when water deficits during the early to mid season are prevalent. With single trellis vines, 22.5 LPD should provide adequate water in warm, humid regions similar to the southeastern U.S.
Different planting dates were used to study the influence of thermal time on leaf appearance rate of four summer squash (Cucurbita pepo L.) cultivars. During the first year (1991), thermal time or growing degree days (GDD) were calculated using a base temperature of 8C and a ceiling temperature of 32C for several planting dates. Leaf numbers per plant were determined every 2 to 3 days. Leaves that were beginning to unfold with a width of 2 cm or greater were included in the counts. The relationship between leaf number and GDD was established from the initial data set, and data from subsequent years were used for model validation. Results indicated that single equation could be used to predict leaf appearance of all four cultivars in response to thermal time. The response of leaf appearance to GDD was curvilinear, with a lag over the first five leaves. After five leaves, the increase in leaf number per plant was linear with increased GDD. Segmented regression with two linear functions also fit the data well. With this approach, leaf 5 was the node, and a separate linear function was used to predict the leaf number below five leaves and above five leaves. The results of this model should prove to be useful in developing a model of leaf area development, and eventually a crop growth model, for summer squash.
Experiments were conducted during 1999 and 2000 at Griffin, Ga., with rabbiteye blueberries (Vaccinium ashei Reade) to determine how the growth regulator CPPU affected fruit set, berry size, and yield. CPPU (applied at two different timings) was used alone, and in conjunction with GA3 on mature, field-grown `Tifblue' plants. A control treatment without either growth regulator was also included. The CPPU concentration used was 10 mg·L-1 (a single application per treatment), and the GA3 concentration used was 200 mg·L-1 (two applications per treatment). Results from both years showed a positive benefit of CPPU with respect to fruit set and berry size, especially in the absence of GA3. Depending on timing, berry number per plant was increased by more than 200% in 1999 using CPPU. Berry size increases of more than 30% occurred in 2000 when CPPU alone was applied at 17 d after flowering (DAF). CPPU did not increase berry size of GA3-treated plants in either year. Total yield per plant during 2000 was 5.0, 7.1, and 8.3 kg for control, CPPU applied 7 DAF, and CPPU applied 17 DAF treatments, respectively, without GA3. While CPPU did substantially increase fruit set, berry size, and yield of `Tifblue', there was a notable delay in fruit ripening. These results suggest that CPPU may be useful for increasing yield of rabbiteye blueberries under conditions of inadequate fruit set (such as occurs in much of the Southeast), but a delay in ripening will likely result. Chemical names used: N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU); gibberellic acid (GA3).