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Soo-Hyung Kim and Bert Cregg

specialty crops, coupled with targeted development of adaptation strategies, is urgently needed. Research on environmental stress physiology can provide fundamental knowledge and forms the basis for tools to develop climate adaptation strategies in

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Allan M. Armitage

Minimizing environmental stress in bedding plant and greenhouse and seedling development has occupied many researchers in academia and industry for many years. The dependence on single plant germination units (plugs) for bedding plant production and high value hybrid seed demand high rates of germination and successful seedling establishment. Pre-germinating or priming of seed is an important method of germination enhancement and methods and benefits of “priming” will be discussed. Environmental options to enhance seed germination of non-primed seed include control of vapor pressure deficit (VPD) and temperature.

Enhancement of seedling establishment through growth room and greenhouse technology includes the optimal use of CO2, temperature and light. Carbon dioxide fertilization on seedlings is receiving serious study and will be further elucidated.

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T.K. Hartz

Overcoming environmental stresses during seedling establishment is crucial to successful vegetable production. In the irrigated production areas of the West stress is most often related to unfavorable temperature, soil or water salinity, or poor soil structure; it is frequently difficult to separate the effects of these stresses since they may all be present to some significant degree. Growers use a variety of techniques to ameliorate these conditions. Advances in seed priming and coating have improved seedling establishment under unfavorable temperatures, particularly for lettuce. The use of sprinkler irrigation for stand establishment has become a widespread practice; sprinkling moderates soil temperature, minimizes salinity in the zone of germination, and reduces soil crusting. By modifying bed configuration growers have been able to increase soil temperature to stimulate germination. Modifying furrow irrigation patterns can create zones of lower salinity. Various chemical treatments have proven effective in reducing soil crusting. The use of transplants is expanding for many crops, both as a means to circumvent seedling establishment problems as well as a technique to obtain earliness.

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Kang Mo Ku and John A. Juvik

Aqueous solutions of 250 μM methyl jasmonate (MeJA) were sprayed on aerial plant surfaces 4 days before harvest at commercial maturity of five commercial broccoli (Brassica oleracea L. var. italica) hybrids, ‘Pirate’, ‘Expo’, ‘Imperial’, ‘Gypsy’, and ‘Green Magic’, and two kale cultivars, Red Winter (Brassica napus ssp. pabularia) and Dwarf Blue Curled Vates (Brassica oleracea L. var. acephala DC.) in replicated field trials over 2 years. While having no effect on broccoli floret concentrations, MeJA treatments significantly increased total phenolics in kale cultivars over two seasons by 27% and extract antioxidant activity by 31% using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Partitioning experiment-wide trait variances indicated that the variability in broccoli floret concentrations of total phenolics (74%), quercetin (24%), kaempferol (34%), and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) (66%) and DPPH (62%) antioxidant activity was largely influenced by year-associated environmental factors. In broccoli, the differential accumulation of solar radiation among cultivars resulting from the variation in days to maturity was significantly correlated with total phenolics, ABTS, and DPPH antioxidant activity. Broccoli floret and kale total phenolic, quercetin, and kaempferol concentrations significantly correlated with DPPH and ABTS antioxidant activity. To summarize, total phenolic and flavonoid concentrations and their associated antioxidant activity in broccoli florets were unaffected by MeJA but varied significantly among cultivars and over growing seasons. Apical, compared with basal, leaves in kale were more responsive to MeJA-mediated increases in total phenolics and ABTS and DPPH antioxidant activity.

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Greg Osterhaus and Alice Le Duc

An anatomical study was conducted to determine and compare the internal leaf surface to volume (S/V) ratio of the spongy mesophyll in selected cultivars of Acer saccharum. A low S/V ratio is one of several selectively advantageous characteristics associated with xerophytic plants. It has been proposed that a correlation exists between certain injuries produced by environmental stress and plant leaf anatomy. The taxa included in the study were Acer saccharum cvs. Green Mountain and Legacy, A. saccaharum Caddo and Wichita Mountain (seedlings of Caddo County and Wichita Mountains, Oklahoma relictual populations respectively), and A. saccharum ssp. nigrum (syn. Acer nigrum). Leaf samples were taken from five different representative trees for each of the five cultivars. The results showed that Caddo, which is highly stress tolerant, had a significantly lower internal S/V ratio than the other four cultivars. `Legacy' which is intermediate in stress tolerance had the next lowest S/V ratio. As expected the highly injury-susceptible selections A. saccharum `Green Mountain' and A. saccharum nigrum had high S/V ratios. However, the Wichita Mountain variety which exhibits a stress tolerance similar to Caddo, also had a high S/V ratio. These results suggest that other factors may be involved in determining environmental stress tolerance.

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T.K. Hartz

Overcoming environmental stresses during seedling establishment is crucial to successful vegetable production. In the irrigated production areas of the southwestern United States, stress most often is related to unfavorable temperature, soil or water salinity, or poor soil structure; it is frequently difficult to separate the effects of these stresses, since they may all be present to some significant degree. Growers use a variety of techniques to ameliorate these conditions. The use of sprinkler irrigation for stand establishment has become a widespread practice; sprinkling moderates soil temperature, minimizes salinity in the zone of germination, and reduces soil crusting. By modifying bed configuration, growers have been able to increase soil temperature to stimulate germination. Various chemical and physical treatments have proven effective in reducing soil crusting. The use of transplants has expanded for many crops, both as a means to circumvent seedling establishment problems and as a technique to obtain earliness.

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T.K. Hartz

Overcoming environmental stresses during seedling establishment is crucial to successful vegetable production. In the irrigated production areas of the southwestern United States, stress most often is related to unfavorable temperature, soil or water salinity, or poor soil structure; it is frequently difficult to separate the effects of these stresses because they may all be present to some significant degree. Growers use a variety of techniques to ameliorate these conditions. Advances in seed technology have improved seedling establishment under unfavorable temperatures, particularly for lettuce. The use of sprinkler irrigation for stand establishment has become a widespread practice; sprinkling moderates soil temperature, minimizes salinity in the zone of germination, and reduces soil crusting. By modifying bed configuration, growers have been able to increase soil temperature to stimulate germination. Modifying seed placement and furrow irrigation patterns can create zones of lower salinity. Various chemical and physical treatments have proven effective in reducing soil crusting. The use of transplants-has expanded for many crops, both as a means to circumvent seedling establishment problems, as well as a technique to obtain earliness.

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Christine M. Worthington* and Chad M. Hutchinson

`Atlantic' potatoes (Solanum tuberosum L.) are grown on approximately 8100 hectares with seepage irrigation in Northeast Florida's Tri-County Agricultural Area (St. Johns, Putnam, and Flagler counties). `Atlantic' is preferred for its chipping quality, high specific gravity and yield, but is susceptible to internal heat necrosis (IHN), a physiologic disorder that affects potato tuber quality. The relationships of environmental stressors (growing degree days, GDD and rainfall) to IHN were evaluated on two fields (fields 3 and 4) on a local producer's farm. IHN reduced marketable tuber yield by 100% in the 1995 and 2003 seasons, but not in 2001 and 2002 seasons. From 3 to 6 weeks after planting (WAP), GDD for 1995, 2001, 2002, and 2003 were 470, 325, 386, and 628 (45° F base), respectively. This is the only 4 week period during the 14 week season that GDD accumulation by week was different among treatments. Average rainfalls (cm) for the same periods were 1.60, 1.12, 2.23 and 7.91, respectively. Both warmer/dryer and warmer/wetter early season conditions occurred during seasons with higher rates of IHN. Although circumstantial, higher accumulated heat units and water stress within the first 6 weeks of the growing season resulted in higher percentages of tubers with IHN. These relationships should be evaluated further with other growers.

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David M. Glenn

the proportion of intercellular spaces in the fruit. Therefore, any environmental stress that reduces carbon allocation to the fruit during the cell division phase of fruit development will reduce fruit size, or conversely, any treatment that improves