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  • Author or Editor: Thomas A. Monaco x
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Abstract

Chemical defoliation of cucumber (Cucumis sativus L.) vines was evaluated as a method for rapid screening of breeding lines. Six chemicals (dinoseb, diquat, ethephon, glufosinate, glyphosate, and paraquat) were used at one or 2 rates on one pickling and one fresh-market cucumber cultivar (‘Calypso’ and ‘Poinsett 76’, respectively) in 1983 to determine speed of vine defoliation and amount of fruit damage. Of the chemicals tested, paraquat at 0.6 kg/ha provided the most rapid defoliation (85% to 91% defoliation one day after treatment) but caused some bleaching and chlorosis of the fruit. If the fruit were rolled 180° during evaluation, the damage was not noticeable. Chemical defoliation of vines for simulated once-over harvest provided a rapid, labor-saving method, requiring only 42% of the time to evaluate each plot compared to the conventional method. The chemical defoliation method is especially useful for initial evaluation of populations and breeding lines for fruit yield and other horticultural characteristics.

Open Access

Abstract

Seventeen herbicide treatments used in the production of sweet potato [Ipomea batatas (L.) Lam.] seed roots were evaluated for their influence on transplant production the following season. Number of transplants/root at five harvests, total transplants/root, and transplants/100 g of root were not influenced by the herbicide treatments. Weight/transplant was influenced by the herbicide treatments only at the last harvest. Total transplant weight/root and total transplant weight/100 g of root also were not influenced by the experimental treatments. No visual deleterious effects on transplant production were observed with any of the herbicide treatments.

Open Access

Abstract

Seven vegetation management programs ranging from 100% cover of grass-dominated vegetation to bare soil were created on opposing north and south aspects. Nutrient contents of the herbaceous vegetation and soil were effected significantly by management programs, location in the plot (row and interrow), and time. The presence or absence of vegetation influenced vegetative uptake and leaching losses, resulting in differences among the vegetation management programs. In general, the upper soil (0- to 15-cm depth) with 100% vegetative cover contained more exchangeable Mg and less NO3 and available P than under bare soil. Exchangeable Ca was not affected by the management programs. Differences in growth form (grass or forb), perennial or annual vegetation, and percent bare soil accounted for the majority of differences in the nutrient content of the noncrop vegetation. Aspect did not affect any of the plant and soil parameters measured.

Open Access

Low-quality (i.e., impaired) water sources are commonly used to irrigate warm-season turfgrass landscapes as a result of limited supplies of potable water sources. Currently, there is great need to define the impacts of impaired water sources on turfgrass water consumption, growth, and quality. The objectives of this study were to characterize actual evaporation (ETa), clipping production, and quality of three hybrid bermudagrass varieties [‘TifTuf’, ‘Tifway’, and ‘Midiron’; Cynodon dactylon (L.) Pers. × C. traansvalensis Burtt Davy] grown under three water sources [reverse osmosis (RO), local well, and recycled], each supplied at full irrigation levels (1.0 × ETa) over two 8-week study periods. When pooling across water source and date, TifTuf maintained the highest visual quality and normalized difference vegetation index (NDVI) compared with both Midiron and Tifway. This was accompanied by a greater daily ETa rate, clipping production, and water use efficiency (WUE) compared with Midiron in both studies. When pooling across variety and date, daily ETa of turfgrass receiving recycled water was 5% to 10% less than those receiving the local well or RO water. In addition, turfgrasses receiving local well water held the greatest visual quality and NDVI compared with those receiving either RO water in the summer study. Visual quality and NDVI were also less in turfgrasses receiving RO water compared with those receiving local well or recycled water in the fall. Despite turfgrasses having a lower ETa under recycled water in both study periods, these plants had significantly greater clipping production compared with RO water in the summer. Also, clipping production under recycled water did not differ significantly from the other two sources in the fall study. Furthermoe, in both studies, WUE was similar for turfgrasses receiving recycled water compared with those receiving RO or local well water. Results demonstrated that irrigation water quality influences critical factors for hybrid bermudagrass growth and that considerable variability exists among three commercially available varieties for evapotranspiration rates, quality, and clipping production.

Open Access

Abstract

Seven vegetation management programs ranging from 100% cover of grass-dominated vegetation to bare soil were created on opposing north and south aspects. After 3 years, fraser fir [Abies fraseri (Pursh) Poir.] survival had decreased when grown in bare soil, compared to survival in the other management programs. Norway spruce [Picea abies (L.) Karst.] survival was not affected by the management programs. Maximum stem diameter and root growth of Norway spruce were obtained with a bare row regardless of the interrow vegetation. Root growth in fraser fir was similar to spruce, but bare soil was required for maximum stem diameter growth. Height growth in both species was affected little by treatment. Stem diameter and root growth were negatively correlated with above-ground herbaceous biomass in the row. Forbs interfered less than grasses with fraser fir and Norway spruce diameter growth. Norway spruce growth was not affected by aspect, but fraser fir was larger (height and stem diameter) on the south aspect when grown in bare soil.

Open Access

Shepherdia rotundifolia Parry (roundleaf buffaloberry), a shrub endemic to the U.S. Colorado Plateau high desert, has aesthetic and drought tolerance qualities desirable for low-water urban landscapes. However, slow growth and too often fatal sensitivity to wet or disturbed soil stymies nursery production and urban landscape use. The goal of this study was to create an interspecific hybrid between the evergreen-xeric S. rotundifolia and its widely adapted, fast-growing, deciduous relative Shepherdia argentea (silver buffaloberry) distributed in western North America riparian habitats. Genetics and leaf morphology of the resulting S. argentea × S. rotundifolia hybrid are described and compared with the parents, as well as hybrid gas exchange as a reasonable proxy for growth rate and potential tolerance of poor soil. Hybrid genotypes were heterogenous, but contained an intermediate and equal contribution of alleles from genetically heterogenous parent populations. Leaf morphology traits were also intermediate between both parents. Aesthetic leaf qualities (silver-blue color and revolute margins) sought from S. rotundifolia were conserved in all offspring. However, gas exchange responses varied widely between the two surviving hybrids. Both hybrids showed greater tolerance of wet, fertile substrate—and promise for use in low-water landscapes—than S. rotundifolia. However, one hybrid conserved faster growth, and by inference possibly greater tolerance of wet or disturbed soil, from S. argentea, while the opposite was observed in the second hybrid. Following botanical nomenclature, we named this hybrid Shepherdia ×utahensis.

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