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Raul I. Cabrera and Diana R. Devereaux

Containerized crape myrtle (Lagerstroemia indica L. × Lagerstroemia fauriei Koehne `Tonto') plants were grown for 9 months under various nitrogen fertility regimes, and then transplanted to a sandy loam soil with minimal management to evaluate their landscape establishment and growth performance. During the nursery phase plants were irrigated, except over an overwintering period, with complete nutrient solutions differing in applied N concentration, ranging from 15 to 300 mg·L-1. By 16 weeks after transplanting (WAT) into the landscape soil, plant biomass was significantly higher in the plants that had been grown with higher N supplies and had been among the smallest at transplant. Such plant growth response was linearly and positively correlated to plant N status at transplant. Plant shoot to root ratio and tissue N, Ca, S, and Fe concentrations, which had been significantly affected by the N fertilization regime in the nursery, equalized over time after transplant, with no significant differences observed among treatments by 16 WAT. Flowering response in the landscape was delayed in plants originally grown with the higher N supplies. Plant survival and establishment per se were not affected by treatments; no plants were lost, and aside from the differences in size and flower timing, all plants were considered aesthetically similar.

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S. Jiménez and M.T. Lao

The plant quality in function of the ratio nitrate:ammonium has been studied. The experiment was carried out in a recicling system in a Buried Solar Greenhouse. Dieffenbachia amoena `Tropic Snow' was cultivated in expanded clay substrate. The parameters considered to evaluate the quality have been plant height, leaf area index (LAI), leaf area ratio (LAR), leaf weight ratio (LWR), biomass, shoot to root ratio, number of buds, number of leaves, leaf length and width, leaf color, variegation, and ornamental visual quality evaluated by a group of experts and consumers. The rehearsed NO3-:NH4 + ratios has been 100:0, 50:50, and 0:100. The amoniacal form improves the following productive parameters: plant height, LAI, biomass, number of leaves, number of buds and color of the leaf, as well as the visual quality as much for experts as for consumers.

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Erin Alvarez, S.M. Scheiber, Richard C. Beeson Jr, and David R. Sandrock

total root biomass gain. Average initial root dry weight in the root ball and total root biomass gain were summed to obtain an estimated total root dry weight for calculation of shoot-to-root ratios. Shoot biomass gain was calculated as the difference

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Paongpetch Phimchan, Suchila Techawongstien, Saksit Chanthai, and Paul W. Bosland

and their capsaicinoid levels were analyzed, whereas the shoot-to-root ratio was recorded at the final harvest. Capsaicinoid was extracted from the dried fruit and quantified with high-performance liquid chromatography (HPLC) using a modification of

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S.M. Scheiber, Richard C. Beeson Jr, and Sudeep Vyapari

harvest on 12 Dec. 2003. The experiment was conducted for 100 d. To calculate shoot-to-root ratios, shoots were severed at the soil line and dried at 65 °C until constant dry weight was obtained. To obtain root dry weight, each lysimeter was subsampled

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James C. Locke, James E. Altland, and Deanna M. Bobak

in hydroponic solution in plastic buckets. z Shoot-to-root ratio was unaffected by N treatment at 8 DAT. The number of treatments with reduced shoot-to-root ratio increased with time. At 16 DAT, only plants grown without N for 12 d or longer had

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S.M. Scheiber and Richard C. Beeson, Jr

calculate shoot-to-root ratios, shoots were severed at the soil line and dried at 149 °F until constant dry weight was obtained. Coleus initiated flowering during the final month of the experiment, but only sparingly and uniformly across treatments

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Marc W. van Iersel and Jong-Goo Kang

To determine the effect of fertilizer concentration on plant growth and physiology, whole-plant C exchange rates of pansies (Viola ×wittrockiana Gams.) subirrigated with one of four fertilizer concentrations were measured over 30 days. Plants were watered with fertilizer solutions with an electrical conductivity (EC) of 0.15, 1.0, 2.0, or 3.0 dS·m-1 (N at 0, 135, 290, or 440 mg·L-1, respectively). Plants watered with a fertilizer solution with an EC of 2 dS·m-1 had the highest shoot dry weight (DW), shoot to root ratio, leaf area, leaf area ratio (LAR), and cumulative C gain at the end of the experiment compared to those watered with a solution with a higher or lower EC. Shoot tissue concentrations of N, P, K, S, Ca, Fe, Na, and Zn increased linearly with increasing fertilizer concentration. A close correlation between final DW of the plants and the measured cumulative C gain (CCG) (r2 = 0.98) indicated that the C exchange rates were good indicators of plant growth. There were quadratic relationships between fertilizer EC and gross photosynthesis, net photosynthesis, and dark respiration, starting at 13, 12, and 6 days after transplanting, respectively. Although plants fertilized with a fertilizer solution with an EC of 2 dS·m-1 had the highest C exchange rates, the final differences in shoot DW and CCG among ECs of 1.0, 2.0, and 3.0 dS·m-1 were small and it appears that pansies can be grown successfully with a wide range of fertilizer concentrations. Plants with a high LAR also had higher DW, suggesting that increased growth was caused largely by increased light interception. A detrimental effect of high fertilizer concentrations was that it resulted in a decrease in root DW and a large increase in shoot to root ratio.

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Catherine Neal

Bare-root, 4-ft whips of green ash (Fraxinus pennsylvanica `Marshall's Seedless') were planted in June 2001 in a randomized complete-block design with three trees per plot. An incomplete factorial design was used to test whether annual fertilizer rate and/or application dates affected growth. Treatments were fertilized from 0 to 4 times per year in mid-April, mid-June, mid-August, and/or mid-October. A rate of 1 lb of nitrogen (N)/1000 sq ft was used whenever fertilizer was applied to a plot. Each treatment received 0, 2, 3, or 4 lbs N/1000 sq ft/year depending on the number of applications. Caliper, height, and terminal growth were measured annually for three growing seasons. At the end of seasons 2 and 3, one plant per plot was destructively harvested and processed to obtain dry weights of shoots and roots, and the shoot to root ratio was calculated. Data were analyzed by analysis of variance with least square means contrasts. Treatment effects on top weights, root weights, and shoot to root ratios were nonsignificant. There were significant treatment differences for caliper and terminal growth in years 1 and 2, but not 3. A set of orthogonal contrasts was used to determine that the effect was due primarily to growth differences in plants receiving 2 vs. 3 or 4 lbs N/1000 sq ft/year, but that 3 vs. 4 lbs made no difference. Another set of planned, but nonorthogonal contrasts was used to compare application date effects. Plants fertilized in June were greater in caliper and terminal growth in the first 2 years than plants not fertilized in June. There were nonsignificant effects of fertilizing vs. not fertilizing in late fall or early spring.

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José A. Franco and Daniel I. Leskovar

Containerized `Lavi' muskmelon [Cucumis melo L. (Reticulatus Group)] transplants were grown in a nursery with two irrigation systems: overhead irrigation (OI) and flotation irrigation (FI). Initially, root development was monitored during a 36-day nursery period. Thereafter, seedling root growth was monitored either in transparent containers inside a growth chamber, or through minirhizotrons placed in the field. During the nursery period, OI promoted increased early basal root growth, whereas FI promoted greater basal root elongation between 25 and 36 days after seeding (DAS). At 36 DAS leaf area, shoot fresh weight (FW) and dry weight (DW), and shoot to root ratio were greater for OI than for FI transplants, while root length and FWs and DWs were nearly the same. Total root elongation in the growth chamber was greater for FI than for OI transplants between 4 and 14 days after transplanting. Similarly, the minirhizotron measurements in the field showed a greater root length density in the uppermost layer of the soil profile for FI than for OI transplants. Overall, muskmelon transplants had greater root development initially when subjected to overhead compared to flotation irrigation in the nursery. However, during late development FI transplants appeared to have a greater capacity to regenerate roots, thus providing an adaptive mechanism to enhance postplanting root development and to withstand transplant shock in field conditions. At harvest, root length density and yield were closely similar for the plants in the two transplant irrigation treatments.