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  • Author or Editor: Paul E. Read x
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Abstract

‘Northblue’ blueberry (Vaccinium corymbosum L.) plants propagated by tissue culture (TC) have a branching pattern and growth rate different from plants propagated by leaf-bud cuttings. Two to 3 times more basal branches were formed on tissue culture-derived plants by the time they were 27 to 34 weeks old. These basal branches were maintained on older plants in the field, where lateral branching was also twice as high. The growth rate of the young TC-derived plants was 3 times the rate of young leaf-bud, cutting-propagated (ST) plants. However, lateral branch length of older plants in the field was similar for both groups of plants, indicating a reduction in the growth rate of TC-derived plants from 34 to 82 weeks after propagation. Pruning and chilling methods reduced basal branch length and the number of lateral branches produced in the field, while enhancing the length of lateral branches and total buds per lateral branch. Although TC-derived blueberry plants had numbers of total flower buds and total buds per lateral branch similar to ST-derived plants, they produced more flower buds per plant. The enhanced branching framework of TC-derived plants, composed of rapidly forming basal and lateral branches, may increase photosynthesis at an early age and hasten fruit production.

Open Access

Abstract

Experiments on the design of plot applicators for use in irrigation research were conducted, with 4 units constructed and successfully used on the University of Minnesota Sand Plain Experimental Field, of such applicators permits uniform application and precise measurement of the water applied. With minor adjustments, plot application areas up to 1, 250 ft2 (25 × 50 ft) can be accommodated.

Those units where the sprinkler arm was driven hydraulically by the available water pressure had less down-time and were more easily maintained, as compared to those which were driven by chain from a small gasoline engine. With hydraulically driven models, operating at pressures of 30 psi or less, it is recommended that cylinder diam of 1½-inch (or larger) be used.

Balloon-type tires are recommended for greater maneuverability between plots. The supporting beam of the applicator should be at the minimum heights permissible, as determined by the maximum anticipated height of the crop being grown.

Open Access

Abstract

Foliar sprays of succinic acid-2,2 dtmethylhydrazide (SADH) at 2500 ppm and (2-chlorethyl)trimethylammonium chloride (chlormequat) at 1500 ppm increased no. and size of tuberous roots of dahlias under short-day conditions. Root wt were frequently tripled, both in cultivars which normally form tuberous roots readily, and those which generally form slender, poor-quality roots. Plants grown from roots of treated plants were of excellent size, color, and quality. Similar treatments under long-day conditions caused formation of tuberous roots where untreated cuttings produced only fibrous roots.

Open Access

Cultures of several orchid species [Barlia robertiana (Loisel.), Dactylorhiza fúchsii Soó, D. incarnata (L.) Soó, D. maculata (L.) Soó, D. majalis (Rchb.), D. saccifera (Brong) Soó, D. sambucina (L.) Soó, Gymnadenia conopsea (L.) R.Br., Himantoglossurn hircinum (L.) Spreng., Ophris sphegodes Mill., Orchis coriophora ssp. fragrans L., Orchis laxiflora ssp. palustris Lam., Orchis mascula L., Orchis morio L., Platanthera bifolia (L.) Rich., Spiranthes aestivalis (Poir.) Rich.] were initiated with fresh ripe seeds from desiccated fruit and 4-month-old in vitro seedlings. The medium used for both germination and seedling culture was a modified FAST medium. Samples for the scanning electron microscope (SEM) surveys were taken from the in vitro cultures and some plant materials were collected from their native habit. Samples were observed with a Tesla BS 300 SEM. Seeds ranged from 300 to 450 μm in length and were flask-shaped. The first germination step is opening of the seedcoat, when the first few white cells will be visible. After a few weeks, the apical meristem appears. The young protocorm is covered with numerous translucent rhizoids. In the last stage of germination, the first root and the first true leaf start to develop. After 2 years, they are suitable for transfer ex vitro. Structure of the mature organs and tissues can be examined at this stage.

Free access

Abstract

Rapid clonal propagation of Alnus glutinosa was achieved in vitro using lateral buds excised from greenhouse grown, juvenile stock plants. Multiple shoot development occurred in 50% of the cultures after the first subculture (7–8 weeks after initial explanting) using a low salt, woody plant medium containing 1 μM 6-benzylaminopurine (BA). Microshoots were removed from pro-liferating tissues and rooted in a conventional potting medium under high humidity prior to establishment in the greenhouse.

Open Access

Abstract

Multiple shoots of Chinese chestnut (Castanea mollissima Blume), produced in vitro from axillary buds of juvenile shoots, were successfully rooted and transplanted to the greenhouse. Benzyladenine (BA) at 0.44 μM promoted the proliferation of axillary shoots, but 4.44 μM and 44.4 μM of BA inhibited buds from sprouting and promoted callus growth. Zeatin at 4.56 μM, induced longer and more vigorous shoots than BA, but did not promote the multiplication of axillary shoots. Rooting was achieved by a 1 sec basal dip of excised microshoots in 9.8 mM or 14.8 mM indolebutyric acid (IBA) solution. The treated shoots were transferred to a plant growth regulator-free medium in flasks or to plastic flats containing sand under high humidity. Roots developed within 30 days in both rooting regimes.

Open Access

The role of sucrose alone and in combination with different cytokinin-like compounds on the microtuberization of potato, Solanum tuberosum `Atlantic', was investigated. Single nodal segments were placed in Magenta boxes containing Murashige & Skoog medium supplemented with one of 15 treatments in a 3 × 5 factorial. Treatment factors were sucrose at 3%, 6%, or 9%, and cytokinin-like compounds at five levels [cytokinin-free; 2 mg kinetin/L; 0.1 mg thidiazuron (TDZ)/L; 1.0 mg AC 243,654/L; 0.1 mg AC 239,604/L]. Except in a few cases in kinetin and TDZ treatments, nearly all cytokinin treatments failed to induce tuberization at the 3% sucrose, noninductive level. However, all cytokinin treatments induced tuberization in the presence of 6% sucrose. By raising the sucrose level from 6% to 9%, more and larger microtubers were obtained in the cytokinin-free medium. At the 9% sucrose level, even though more tubers per box were produced by TDZ and AC 243,654 treatments, less total fresh weight of tubers per box resulted from kinetin, TDZ and AC 243,654 treatments because tubers formed were smaller. Higher sucrose concentrations (9%) favored tuberization in the cytokinin-free medium, whereas 6% sucrose was optimum for the medium containing cytokinins. Sucrose might produce a strong tuberization signal that might either change endogenous hormone levels affecting tuberization or activate a number of genes coding tuber proteins and enzymes related to starch synthesis.

Free access

Phenolic levels have been analyzed in several grape cultivars that are suited for growing in southeastern Nebraska. The phenolic levels of these cultivars are not known to have been previously published. The polyphenol content of fruits and fruit products such as wine have been shown to be directly correlated to the antioxidant potential of the product. Antioxidants help to prevent the effects of aging and age-associated diseases. The grape cultivars in the study are grown primarily for wine production, but also as fresh table grapes and for making juice and jellies. The total phenolic content is being analyzed by the Folin-Ciocalteu method. Of the red grapes, `St. Croix' and `Frontenac' have the highest levels of polyphenols, followed by `Chambourcin' and `deChaunac', with levels varying from 1.4–4.9 mg·g-1 (polyphenols/grape), measured as gallic acid equivalents (GAE). The white grapes `Vignoles' and `LaCrosse' have total phenolic levels of 1.4 to 2.2 mg·g-1 (polyphenols/grape), also measured as gallic acid equivalents (GAE).

Free access

Plants of `Northblue' blueberry, propagated in tissue culture (TC) or from softwood, single-node cuttings (ST), were evaluated in field plantings established in 1984 at Becker and Grand Rapids, in central and northern Minnesota, respectively. Plantings were observed from 1987 through 1994 to determine the persistence of such effects as increased vigor, more spreading growth habit, and higher yield observed for TC plants during the initial 3 years after planting. TC plants had significantly higher yields at Grand Rapids in 1989 and 1994. At Grand Rapids, the consistently greater plant spread (bearing area) of TC plants resulted in higher yields of TC plants over all years combined. At Becker, TC and ST plants did not differ for plant height or spread after 10 years and, in 2 of 5 years, ST plants had heavier average berry weights. At Grand Rapids, TC plants did not differ consistently in height, or subjective ratings of the amount of bloom or crop. The effects of propagation method on yield and growth habit of `Northblue' are limited to early years in warmer locations, but can be of longer-term significance in colder areas with shorter growing seasons and lower winter temperatures, where plant spread is a more important factor than plant height in determining yield.

Free access

Phenolic compounds contribute greatly to the sensory attributes of wine and have a wide range of human health benefits as well. In this study, four trellis/training systems were evaluated for effects on fruit-zone light environment, fruit chemical composition (including phenol and flavonoid concentrations), and yield of ‘Frontenac’ grapes (Vitis sp. MN 1047) grown in southeastern Nebraska over two growing seasons. Photosynthetically active radiation (PAR) was measured above the canopy and within the fruiting zone at berry set, veraison, and harvest. Point quadrat canopy analysis was performed at veraison. Both bound and free (unbound) flavonoid and total phenolic contents were determined for the skins and seeds of fruit samples in 2008. At all sampling dates in 2008, vines grown on Geneva double curtain (GDC) and high cordon (HC) had higher midday percentage PAR transmittances than vines grown on Smart-Dyson (SD) and vertical shoot positioned (VSP) training systems. In 2009, transmittance relationships between trellises were not consistent throughout the season. In both years, leaf layer number (LLN) was lower for GDC and HC than for SD and VSP. Flavonoid and total phenol concentrations of the bound seed and bound skin extracts did not differ among trellises. Within the free extracts, VSP had higher total phenol concentration than SD (GDC and HC were intermediate) and there were no differences in flavonoid concentration. In 2008, GDC had higher pH than other trellises and higher soluble solids than SD and VSP; titratable acidity (TA) was lower in GDC and HC than in SD and VSP. In 2009, SD and VSP had the highest soluble solids concentrations; HC had lower pH than SD and VSP and there were no differences in TA. Results were inconclusive regarding light environment effects on fruit chemical composition.

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