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  • Author or Editor: Barbara L. Goulart x
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An “in the trenches” researcher/coordinator viewpoint of a northeast regional LISA grant which has been funded from 1989-1993 will be presented. The specifics of the logistics of coordinating a multi-state grant in a fledgling granting program will be emphasized, as well as the evolution of the content and focus of the research directions for the grant entitled Evaluation of Alternative Strategies for Small Fruit Production (University of Vermont Agreement No. 92-08-01). This was a project in which five states in the northeastern United States proposed to cooperate on a multi-disciplinary project exploring the biological and economic feasibility of selected production practices for small fruit. These practices were selected because they showed potential for increasing net profit by either reducing purchased inputs or maximizing yield. Information transfer, before, during and after the studies was emphasized, using such diverse means as grower experimental plots, the participation of growers in integrated pest management programs, the development and publication of economic data relevant to the projects, the development of a LISA small fruits newsletter, as well as more traditional means of information dissemination such as grower meetings and trade and scientific publications.

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Abstract

‘Heritage’ and ‘Titan’ tissue-cultured red raspberry (Rubus idaeus L.) plants were treated with paclobutrazol (4 and 100 mg/pot), cycocel (250 and 900 mg/pot), ancymidol (2 and 10 mg/pot), daminozide (1000 and 5000 ppm), and benzyladenine (100 ppm). Paclobutrazol and 5000 ppm daminozide decreased node number and height. Only the ‘Heritage’ cultivar flowered, and only the 5000 ppm daminozide treatment increased inflorescence number. ‘Titan’ had greater dry mass and a higher relative growth rate, predominantly due to greater root growth, while ‘Heritage’ was taller by virtue of increased internode elongation. Chemical names used: β-[(4-chlorophenyI)methyl]-α(1,1-dimethylethy)-1H-l,2,4-triazoIe-1-ethanol (paclobutrazol); α-cydopropyl-α-[4-methyoxy-phenyl]-5-pyrimidinemethanol (ancymidol); (2-chloroethyI)trimethyl ammonium chloride (cycocel); butanedioic acid mono(2,2-dimethylhydrazide) (daminozide); N-(phenylmethyl)-1H-purin-6-amine (benzyladenine, BA).

Open Access

Aluminum (Al) uptake by and root cation exchange capacity (CEC) of mycorrhizal (M) and nonmycorrhizal (NM) blueberry (Vaccinium corymbosum L.) plants were studied. Root CEC was higher in M plants than in NM plants, but total and root Al contents were higher in NM plants. Leaf Al content was higher in NM than in M plants after 1 and 5 hours of exposure. The aurintriboxylic acid stain for Al indicated the presence of Al in the M symbiont. Despite a larger root system and higher root CEC, regression analysis indicated roots of M plants absorbed less Al in the first 5 hours, suggesting that Al sequestration in the M symbiont is responsible for reduced total Al uptake. Differences in dry matter partitioning between M and NM plants were also observed.

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A factorial experiment was conducted to determine the effect of aluminum (0 and 600 μM) and media (sand, and 1:1 sand:soil) on mycorrhizal (M) and non-mycorrhizal (NM) highbush blueberry plantlets. There were no differences in nutrient uptake and total plant dry weight between M and NM plantlets. However, more root growth, as determined by dry weight, was observed in M than NM plantlets. The plantlets growing in sand had more dry weight than did those in the soil medium. Although the root growth and shoot growth were reduced by the 600-μM Al treatment, the direct effect of Al on plantlet growth was not clear due to Al and P interactions. Plant nutrient uptake was reduced by high concentrations of Al, suggesting that high Al concentration limited the ability of roots to acquire most of the nutrients. Mycorrhizal epidermal cell infection levels of 15% to 20% were maintained in the roots in soil medium but decreased to about 5% over the 6 weeks of the experiment in the sand medium. Although M plantlets accumulated more Al in their roots, Al was readily transported to the leaf tissues of M and NM plantlets.

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A field trial was conducted to investigate the effectiveness of soil fumigation on maintaining nonmycorrhizal status and the effect of mycorrhizal inoculation and preplant soil amendment on the growth of tissue-cultured highbush blueberry plants. Soil fumigation using a methyl bromide/chloropicrin (67/33) mixture at the rate of 560 kg·ha-1 was effective in maintaining nonmycorrhizal status for one growing season. Noninoculated control plants became infected during the second growing season. Field inoculation using a native Oidiodendron maius was successful, but plant growth was not significantly affected by mycorrhizal inoculation in either year. Rotted sawdust amendment, however, reduced plant growth in the first year but effects were no longer measurable in the second year. Soil fumigation and field inoculation could be used to establish mycorrhizal plants and nonmycorrhizal controls for future short-term field experiments.

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Aluminum and P interactions were investigated in mycorrhizal (M) and nonmycorrhizal (NM) highbush blueberry plantlets in a factorial experiment. The toxic effects of Al on highbush blueberry were characterized by decreased shoot, root, and total plant dry weight. Many of the negative effects of Al on plant root, shoot, and total dry-matter production were reversed by foliar P and N application, indicating P or N uptake were limited by high Al concentration. However, Al mediated growth reduction in P-stressed plants suggested that the restriction of P uptake by high Al may not have been the only mechanism for Al toxicity in this experiment. Root Al and P concentration were negatively correlated in NM plantlets but not in M plantlets, suggesting mycorrhizal infection may alter P uptake processes. Al uptake also was affected by M infection, with more Al accumulating in M plantlet roots and leaves. Correlations among foliar ion concentrations were also affected by M fungal infection.

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