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Christopher J. Currey and Roberto G. Lopez

), and 73% (373.5 μmol·m −2 ·s −1 PPF ) on 2, 8, and 14 DAT, respectively. Alternatively, starch concentrations consistently increased linearly with DLI from 5 DAT onward. Discussion For all three species, biomass accumulation in roots, stems, and

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Sandra R. Menasha* and Milton E. Tignor

Sweet corn (Zea mays L.) is difficult to transplant due to poor root regeneration. Despite reduced yields, growers are transplanting sweet corn to hasten maturity time to target profitable early markets in the Northeast. Researchers have ascribed the negative impacts on yield to restricted rooting volume. Therefore, the impacts plug cell volume had on sweet corn transplant root architecture and biomass accumulation were investigated. `Temptation' sweet corn was sown in volumes of 15, 19, 14, and 29 mL correlating to transplant plug trays with plug counts of 200, 162, 128, and 72 plugs per tray. Plug cells were exposed to three substrate environments; a dairy manure based organic compost media, a commercial soil-less germination mix, and the soil-less media supplemented 2X with 200 ppm soluble 3-3-3 organic fertilizer. A 4 × 3 factorial randomized complete-block experimental design with two blocks and five replicates per treatment was repeated twice in the greenhouse. For each experiment a total of three center cells were harvested from each replicate for analysis using the WinRhizo Pro root scanning system (Regent Instruments Inc., Montreal). Three cells per treatment were also transplanted into 8-inch pots to stimulate field transplanting. Based on mean separation tests (n = 30), increased cell volume before transplanting significantly increased root surface area, average diameter, and root volume after transplanting (n = 18). Mean root surface area for a 29-mL cell was 30% greater than a 15-mL cell before transplanting and 22% greater after transplanting. Plug cell volume also significantly impacted shoot and root biomass (P <0.0001). A 14-mL increase in cell volume resulted in a root and shoot dry weight increase of about 15%.

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Fan Li, Shenchong Li, and Qinli Shan

biomass accumulation in Gerbera hybrida ( Fig. 2 ). Compared with other cultivars, the plant weight of cultivar Autumn was less sensitive to temperature changes, whereas cultivar Yellow Storm showed a dramatic change in plant weight, and cultivar Pretty

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Yun Kong and Youbin Zheng

cultivation, when external Na + concentrations increased from 75 to 300 m m , Na + accumulation in fresh shoots increased from around 300 to 400 m m ( Yang et al., 2008 ). However, salt tolerance, Na + uptake, and biomass accumulation in plants can be

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Roberto G. Lopez and Erik S. Runkle

of propagation on shoot and root biomass accumulation and the effects on subsequent development of vegetatively propagated bedding crops. Petunia ( Petunia × hybrida hort. Vilm.-Andr.) and New Guinea impatiens ( Impatiens hawkeri Bull.) are two of

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Yun Kong and Youbin Zheng

). Consequently, comparisons of sodium removal and biomass accumulation between green- and golden-leafed purslane genotypes are needed under moderate NaCl concentrations (≈6 to 10 m m ). Determining how growth stage affects purslane biomass accumulation and sodium

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Clyde Wilson, Xuan Liu, Scott M. Lesch, and Donald L. Suarez

Over the last several years, there has been increasing interest in amending the soil using cover crops, especially in desert agriculture. One cover crop of interest in the desert Coachella Valley of California is cowpea [Vigna unguiculata (L.) Walp.]. Cowpea is particularly useful in that as an excellent cover crop, fixing abundant amounts of nitrogen which can reduce fertilizer costs. However, soil salinity problems are of increasing concern in the Coachella Valley of California where the Colorado River water is a major source of irrigation water. Unfortunately, little information is available on the response of cowpea growth to salt stress. Thus, we investigated the growth response of 12 major cowpea cultivars (`CB5', `CB27', `CB46', `IT89KD-288', `IT93K-503-1', `Iron Clay', `Speckled Purple Hall', `UCR 134', `UCR 671', `UCR 730', `8517', and `7964') to increasing salinity levels. The experiment was set up as a standard Split Plot design. Seven salinity levels ranging from 2.6 to 20.1 dS·m–1 were constructed, based on Colorado River water salt composition, to have NaCl, CaCl2 and MgSO4 as the salinization salts. The osmotic potential ranged from –0.075 to –0.82 MPa. Salt stress began 7 days after planting by adding the salts into irrigating nutrient solution and ended after 5 consecutive days. The plants were harvested during flowering period for biomass measurement (53 days after planting). Data analysis using SAS analysis of variance indicated that the salinity in the range between 2.6 and 20.1 dS·m–1 significantly reduced leaf area, leaf dry weight, stem dry weight and root dry weight (P ≤ 0.05). We applied the data to a salt-tolerance model, log(Y) = a1 + a2X + a3X2, where Y represents biomass, a1, a2 and a3 are empirical constants, and X represents salinity, and found that the model accounted for 99%, 97%, 96%, 99%, and 96% of salt effect for cowpea shoot, leaf area, leaf dry weight, stem dry weight and root dry weight, respectively. We also found significant differences (P ≤ 0.05) of each biomass parameter among the 12 cultivars and obtained different sets of the empirical constants to quantitatively describe the response of each biomass parameter to salinity for individual cowpea cultivars. Since a significant salt × cultivar interaction effect (P ≤ 0.05) was found on leaf area and leaf dry weight, we concluded that salt tolerance differences exist among the tested cultivars.

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Hector R. Valenzuela, Osamu Kawabata, and Harry Yamamoto

Methanol sprays reportedly increased yields of several crops in Arizona by 50 to 100 percent (Nonomura and Benson PNAS 89:9794(1992). Reports from other parts of the country have shown conflicting results with regards to the effect of methanol sprays on yields of horticultural crops. Several greenhouse and growth chamber (controlled temperature. day length, and photosynthetic photon flux) experiments were conducted to evaluate the effect of methanol sprays on the growth and productivity of several vegetable crops in Hawaii. Treatment spray solutions consisted of 20-25% methanol, 0.5% low biuret urea. 0.001% chelated iron, and 0.02% surfactant. Control sprays only contained urea, chelated iron, and surfactant. Each experiment consisted of at least 5 weekly methanol sprays. Flowering cabbage, Brassica campestris var. parachinensis, had greater biomass production when sprayed with methanol in the late summer months. Similar results were obtained with choi sum in a 2 by 2 factorial experiment with methanol and water stress treatments. However, choi sum did not respond to methanol treatments in follow-up greenhouse trials. perhaps attributable to the shorter and Overcast days experienced in the fall and winter. Okra, chili pepper, and eggplant showed no response to methanol sprays. Okra showed a trend toward increase yields in response to methanol sprays, but differences were not significant. Follow-up studies in the greenhouse and in the field, which include evaluation of photosynthetic efficiency through chlorophyll fluorescence determinations will be presented.

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Yun Kong and Youbin Zheng

little phenotypic response to salinity gradient ( Dagar, 2005 ; Jaradat and Shahid, 2012 ). Also, the plants of this species have not shown significant differences in the growth rate and biomass accumulation at a salinity between 0.5 and 10 ppt (≈9 and

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Ariana P. Torres and Roberto G. Lopez

−1 ( PPF between 200 and 400 μmol·m −2 ·s −1 under a 12-h photoperiod) to promote fully rooted cuttings and optimal shoot and root biomass accumulation ( Dole and Hamrick, 2006 ; Lopez and Runkle, 2008 ). Pramuk and Runkle (2005) suggest that