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Genhua Niu, Denise S. Rodriguez, and Lissie Aguiniga

were interactive effects of salinity and rootstock on DW of shoots and roots and root to shoot ratio, indicating that plant growth responses to salinity differed among rootstocks. Because most plants did not survive at 9.0 dS·m −1 , this treatment was

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Darren J. Hayes and Bryan J. Peterson

application rate of Osmocote Pro 17–5–11 4-month CRF. Ninety-five percent CIs can be compared across panels to infer differences in substrate EC among taxa. Expt. 2. The main effect of taxon was significant for all variables of plant growth ( Table 4 ). In

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Dean A. Kopsell, J. Scott McElroy, Carl E. Sams, and David E. Kopsell

The family Brassicaceae (Cruciferae) represents a diverse group of plant species commercially important in many parts of the world. The plants produce condiment mustard; leafy, stored, processed, and picked vegetables; seed oils for margarine

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Bernadine C. Strik and David R. Bryla

the following spring (D.R. Bryla and B.C. Strik, unpublished data). Nutrient partitioning varied considerably among elements due to different nutrient concentrations and requirements in each plant part. This difference not only affected the proportion

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Celina Gómez and Cary A. Mitchell

treatments. No significant differences were recorded for k in either experiment (data not shown). Similar to quantum-use efficiency, A max was not different among leaf layers for plants grown with ICL-LED or hybrid SL during winter-to-summer ( Fig. 8

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Yan Wang and Stanley J. Kays

The sweetpotato weevil (SPW) [Cylas formicarius elegantulus (Summers) (Coleoptera: Curculionidae)] is the single most devastating pest of the sweetpotato [Ipomoea batatas (L.) Lam.] worldwide. Attempts to develop host-plant resistance have been only moderately successful due in part to deficiencies in parent and progeny selection methods. Host-plant phytochemicals play critical roles in insect behavior, modulating a cross-section of key behavioral decisions. Thus, identification of the phytochemicals the female weevil uses in decision making could greatly facilitate development of host-plant resistance. The volatile chemistry of the sweetpotato was studied in relation to the host-finding behavior of the female weevil. Critical biologically active volatiles were determined via isolation (Tenax trapping), fractionation (gas chromatography-thermal conductivity detector), identification (gas chromatography and gas chromatography-mass spectroscopy), and bioassay (olfactometry). Differences in volatile chemistry among sweetpotato clones that may relate to differences in resistance or susceptibility to the female SPW were assessed. Volatile extracts from storage roots (site of oviposition) and aerial plant parts were attractive to female SPW, the former being substantially greater. In total, 33 compounds were identified from storage roots and aerial plant parts, including 23 terpenes. Three oxygenated monoterpenes (nerol, Z-citral, and methyl geranate), found in storage roots but not aerial plant parts, were identified as attractants. The sesquiterpene volatile fraction was repellent to female SPW with α-gurjunene, α-humulene, and ylangene active in the concentration range emanating from storage roots. The aerial plant parts emanated a higher composite concentration of sesquiterpenes than storage roots. Differences in the relative attraction among four sweetpotato cultivars to female SPW was inversely correlated with the composite concentration of headspace sesquiterpenes. Selection of clones with decreased volatile attractants and/or increased deterrents using an analytical means of quantification may significantly facilitate developing resistance to the SPW.

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Johnny Carter, Bharat P. Singh, and Young W. Park

In the United States, the common daylily is cultivated as an ornamental. However, in other countries, such as China and Japan, it is an important food crop. With this in mind, a study was conducted to determine the mineral nutrient content of edible parts (flower buds, flowers and tubers) of the daylily plant. Edible parts were analyzed for P, K, Ca, Mg, Mn, Fe, B, Cu, Al, and Na. Results of this study showed that flower buds had significantly higher level of P and Mg than tubers and flowers. The K and B concentration in flower buds were similar to flowers, but significantly greater than in the tubers. The respective Zn concentrations in flowers and flower buds were 32% and 23% greater than those in the tubers. There was no difference in the Mn concentration among the edible parts. Tuber contained significantly higher contents of Ca and Cu than the flowers and flower buds. It also had 10.6-, 14.3-, and 2.8-times greater concentration of Mn, Al, and Na, respectively, than the combined average flower buds and flowers. From this study, daylily appears to have potential as a nutritious food source for human consumption.

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Dean A. Kopsell, Scott McElroy, Carl Sams, and David Kopsell

Vegetable crops can be significant sources of nutritionally important dietary carotenoids and Brassica vegetables are sources that also exhibit antioxidant and anticarcinogenic activity. The family Brassicaceae contains a diverse group of plant species commercially important in many parts of the world. The six economically important Brassica species are closely related genetically. Three diploid species (B. nigra, B. rapa, and B. oleracea) are the natural progenitors of the allotetraploid species (B. juncea, B. napus, and B. carinata). The objective of this study was to characterize the accumulation of important dietary carotenoid pigments among the genetically related Brassica species. The HPLC quantification revealed significant differences in carotenoid and chlorophyll pigment accumulation among the Brassica species. Brassica nigra accumulated the highest concentrations of lutein, 5,6-epoxy lutein, violaxanthin, and neoxanthin. The highest concentrations of beta-carotene and total chlorophyll were found in B. juncea. Brassica rapa accumulated the highest concentrations of zeaxanthin and antheraxanthin. For each of the pigments analyzed, the diploid Brassica species accumulated higher concentrations, on average, than the amphidiploid species. Brassicas convey unique health attributes when consumed in the diet. Identification of genetic relationships among the Brassica species would be beneficial information for improvement programs designed to increase carotenoid values.

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J.G. Williamson, W.S. Castle, and K.E. Koch

Three commercially employed treatments to force scion bud growth were compared using greenhouse-grown `Carrizo' citrange [Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.] seedlings budded with `Hamlin' orange [Citrus sinensis (L.) Osb.]. Scion buds were forced either by 1) cutting off (removing the rootstock shoot above the bud union); 2) lopping (cutting half-way through the rootstock shoot above the bud union and breaking over the rootstock stem); or 3) bending (bending the rootstock shoot to its base and tying it in position). Plants were harvested, dried, and weighed at various times after scion shoot emergence. Plants on which rootstock shoots remained attached (lopping or bending) had the largest scion leaf area and gained the most scion and whole-plant dry weight. Bending rootstock shoots also resulted in a longer scion, more leaves, and higher root dry weight than did removal of rootstock shoots by cutting off. Few differences in overall growth were observed among trees retaining their rootstock shoots after two scion growth flushes. Removal of rootstock shoots after the first scion growth flush reduced leaf area and dry weight gain of the second scion growth flush; however, it did not affect total scion leaf area or dry weight. Analysis of 14C-photosynthate transfer from labeled rootstock leaves showed that bending allowed the greatest movement of labeled assimilates to other plant parts during the 24 hours after 14CO2 fixation. Radiolabeled photosynthates from rootstock leaves were partitioned primarily to shoots during scion growth flushes and to roots during periods between growth flushes.

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J. Naraguma, J.R. Clark, and R.J. Norman

A spring application of 19 g CO(15NH2)2/plant at 2.49% atom percent enrichment was made in Mar. 1995 on 2-year old, field-grown `Arapaho' blackberry plants. Individual plants were harvested during the study at preharvest (late May), postharvest (mid-July), and early dormancy (late October). The following plant parts were separated for analysis: roots, primocanes, floricanes, primocane leaves, floricane leaves, fruits. Soil samples were also taken from within the drip line of the plants at each sample date. Plant tissues were washed, dry weights measured and ground for acid digestion, total N determination and 15N analysis. Samples were measured for 15N atom percent abundance by a isotope ratio spectrometer. The whole-plant dry matter in creased during the season from 53 g in May to 153 g in October. Plants sampled in October had a greater amount of dry matter in roots than in any other tissue. There was a decreased total N content in all vegetative tissues (leaves and canes) from May to October. The maximum fertilizer 15N percent recovery was 43% (October) and the minimum was 12% (May) from the total plant tissues. Compared to other plant tissues, floricane leaves and primocanes recovered significantly more fertilizer 15N in May, while roots and primocane leaves recovered more in October. Floricanes and fruits did not increase in 15N levels during the sampling period. Fertilizer 15N recovered in the soil amounted to 35.5% of the applied with 4.5% found in the inorganic fraction, 31% in the organic fraction. There were no statistical differences in percent recovery of the fertilizer 15N among sample dates in the topsoil. October 15N percent recovery was much lower than May in the subsoil, indicating a downward movement of N by leaching. Averaging all sample dates, 59.5% of the labeled fertilizer was accounted for in the plant and soil, with the remaining portion probably lost via volatilization, leaching, and/or denitrification.