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S.E. Garrison, J.M. Williams and J.A. Barden

A greenhouse experiment was conducted to determine the effects of shade treatments (0, 30, 47 and 63%) on photosynthetic and growth responses of `Redchief' strawberries. Net photosynthesis (Pn) measured on plants under shade decreased as % shade increased. Pn of plants grown under shade but measured under saturating light intensities decreased after 30% shade. Light saturation curves of leaves allowed to expand in full sun and then placed under shade indicated a decrease in the saturation rate and point under 63% shade. Leaves which expanded under shade had decreased saturation rates and points at all levels. Specific leaf weight and total plant dry weight decreased linearly as % shade increased.

A field study in which plants were either shaded in the fall or in the fall and spring demonstrated a decreasing trend in berry number for plots which were shaded in the fall and spring. Berry number decreased in fall-shaded plants after 30% shade. In both cases, berry weight decreased with increasing shade.

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M. Aneja, T.J. Gianfagna, S.A. Garrison and E.F. Durner

Precocious flowering can be induced in asparagus (Asparagus officinalis L.) seedlings with N-phenylcarbamate herbicides, such as n-propyl N-(3,4-dichlorophenyl) carbamate (NPC); however, only ≈50% of the treated seeds produce flowering plants because these compounds inhibit germination and seedling emergence. We have improved the treatment method by determining the environmental conditions, timing, dose, and duration needed to maximize the percentage of germination, emergence, and flowering. Imbibing seeds in water for 5 days, and then treating germinated seeds with 0.4 mm NPC for 5 days after radicle emergence, with seedling aeration in the light, resulted in the production of flowering seedlings from >90% of the treated seeds. For freshly harvested seeds, in which germination rates are more variable than aged seeds, individual seedlings must be transferred to NPC within 1 day after radicle emergence to produce a high percentage of flowering plants. For seven male asparagus cultivars, chemical induction of flowering in seedlings with NPC produced a sex ratio similar to that of field-grown plants, demonstrating that NPC induces flowering without altering floral differentiation or sex expression. This method can be used for rapidly and accurately identifying the percentage of females in “male” cultivars.

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A.J. Both, E. Reiss, J.F. Sudal, K.E. Holmstrom, C.A. Wyenandt, W.L. Kline and S.A. Garrison

The impact of a manually operated energy curtain on the recorded nighttime inside air and soil temperatures, relative humidity (RH), and daily light integrals during early-season high tunnel tomato (Lycopersicon esculentum) production in central and southern New Jersey were examined. Environmental data (air and soil temperatures, RH, and photosynthetically active radiation) were collected from late March through mid-May at two New Jersey locations for the 2004 and 2005 growing seasons. The continued impact of the early use of an energy curtain was further evaluated by collecting light, temperature, and marketable fruit yield data for the remainder of both growing seasons for one of the two experimental sites. Results showed that although the use of the curtain modestly increased early season nighttime inside air and soil temperatures and RH, the curtain reduced accumulated light integral during the first 7 weeks after transplanting and resulted in a marginal early yield increase. The main benefit of the energy curtain occurred on cold nights when an early season crop might otherwise be exposed to potentially damaging low temperatures.

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E.W. Stover, P.J. Stoffella, S.A. Garrison, D.I. Leskovar, D.C. Sanders and C.S. Vavrina

A commercial mixture of 1-naphthaleneacetamide and 1-naphthaleneacetic acid (Amcotone) was applied to tomato (Lycopersicon esculentum Mill.) and pepper (Capsicum annuum L.) at various timings from early bloom through early fruit development to evaluate effects on fruit size and both early and total marketable yield. Amcotone was applied at rates from 10 to 40 mg·L-1, at three sites for each of the species studied. Measured yield response variables in tomato did not differ between the control and Amcotone treatments, regardless of location. Amcotone treatments did not affect yields or fruit size for pepper at the New Jersey or Texas sites. However, at Ft. Pierce, Fla., early marketable yield of pepper was increased in plots receiving three Amcotone applications at 10 mg·L-1, but total marketable yield was significantly reduced in all plots receiving more than two Amcotone sprays, and mean fruit weight was reduced by all Amcotone treatments. Early and total marketable yield of pepper at Ft. Pierce were markedly reduced in plots receiving four applications of 40 mg·L-1, which was a high rate used to assess potential phytotoxicity. While minimal benefit from auxin application was observed in this study, earlier studies suggest that these results may have been influenced by favorable environmental conditions for fruit development or negative effects on unopened flowers during all Amcotone spray applications.

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K.S. Lewers, J.M. Enns, S.Y. Wang, J.L. Maas, G.J. Galletta, S.C. Hokanson, J.R. Clark, K. Demchak, R.C. Funt, S.A. Garrison, G.L. Jelenkovic, G.R. Nonnecke, P.R. Probasco, B.J. Smith, B.R. Smith and C.A. Weber