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Osamu Kawabata and Richard A. Criley

An aqueous solution of dikegulac-sodium at 0, 2000, 4000, 6000, or 8000 mg a.i./liter was sprayed on a mature Murraya paniculata hedge as the first leaves expanded on newly developing lateral shoots after trimming. The lateral shoots from each 0.09-m2 hedge surface elongated less and the coefficient of variation (cv) decreased as the growth regulator concentration increased. Application of dikegulac-sodium at 4000 mg a.i./liter to the most distal leaf on topped, single-leader seedlings inhibited the elongation of distal shoots while it enhanced proximal shoot growth. Dikegulac-sodium spray between 4000 and 6000 mg a.i./liter to the hedge decreased apical dominance among lateral shoots and enhanced uniform regrowth without causing visible damages. The cv reduction was attributed to the growth regulator-induced weakening of apical dominance. Chemical name used: sodium salt of 2,3:4,6-bis-O-(1-methylethylidene)-α-l-xylo-2-hexulofuranosonic acid (dikegulac-sodium).

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Johnny Carter and Sauveur Mahotiere

Effects of BA, Promalin and Dikegulac-sodium on frond number and overall growth in Boston Fern (Nephrolepis exaltata L.) were studies. Four weeks after transplanting, fern liners were sprayed with aqueous solutions of BA, Promalin and dikegulac-sodium. Chemical concentrations of BA and promalin ranged from 0 to 150 mg. liter-1 at 50 mg. liter-1 increments. Chemical concentrations of dikegulac-sodium ranged for 0 to 750 mg.liter-1 at 250 mg.liter-1 increments. Chemical treatments were arranged in a randomized complete block design with 6 replications. BA and Promalin significantly increased the number of fronds, average frond length, leaf area and dry weight as the concentration of the chemicals increased. In contrast, dikegulac-sodium significantly suppressed the average frond length, leaf area and dry weight when compared to the control. Similarly to BA and Promalin, dikegulac-sodium increased the number of fronds as the concentration of the chemical increased.

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Janice Coons and Sandra Baumgartner

Navy (Phaseolus vulgaris L.) and tepary (P. acutifolius Gray) beans were grown hydroponically in a growth chamber with no NaCl or -0.25 MPa NaCl for 9 days beginning 22 days after planting. Chloride and sodium distribution in leaves and roots as well as percent ion leakage as an indication of membrane integrity in leaves were determined. Chloride and sodium levels in NaCl treated plants were significantly higher than in controls. Chloride distribution was not significantly different between plant parts or between plant species. Sodium distribution was significantly different between roots of the two species, but not between leaves of the two species. The navy root tissues contained twice as much sodium as the leaves, whereas, in tepary sodium levels were similar in roots and leaves. Percent ion leakage showed no notable trends relative to plant species or to NaCl treatments, but a significant difference was observed between younger and older leaves on the same plant.

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M. Benlloch, F. Arboleda, D. Barranco, and R. Fernández-Escobar

The influence of sodium and boron excess in the irrigation water on shoot growth and on the distribution of these elements within various leaf types was studied on rooted olive cuttings (Olea europaea L.). `Lechín de Granada' was more tolerant than `Manzanillo' to sodium excess, as indicated by greater shoot growth and lower accumulation of sodium, especially in the young leaves. `Picual' was more tolerant to boron than `Manzanillo', with less accumulation in adult leaves. The results suggest the avoidance of toxicity by an ionic exclusion mechanism that is more effective in some cultivars than others. Also, the results reveal cultivar differences in the tolerance of olive to sodium and boron excess in the culture medium.

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Judy A. Thies, Richard F. Davis, John D. Mueller, Richard L. Fery, David B. Langston, and Gilbert Miller

Root-knot nematode-resistant `Charleston Belle' bell pepper (Capsicum annuum L. var. annuum) and metam sodium treatment were evaluated for managing the southern root-knot nematode [Meloidogyne incognita (Chitwood) Kofoid and White] in fall-cropped cucumber (Cucumis sativus L.). `Charleston Belle' and its susceptible recurrent parent, `Keystone Resistant Giant', were planted as spring crops at Blackville, S.C., and Tifton, Ga. `Charleston Belle' exhibited high resistance and `Keystone Resistant Giant' was susceptible at both locations. After termination of the bell pepper crop, one-half of the plots were treated with metam sodium delivered through the drip irrigation system. Cucumber yields and numbers of fruit were highest for cucumber grown in plots treated with metam sodium following either `Charleston Belle' or `Keystone Resistant Giant'; however, root gall severity and numbers of M. incognita eggs in the roots were lowest for cucumber grown in plots treated with metam sodium following `Charleston Belle'. Conversely, root gall severity and nematode reproduction were highest for cucumber grown in plots following `Keystone Resistant Giant' without metam sodium treatment. Application of metam sodium through the drip irrigation system following a spring crop of root-knot nematode-resistant bell pepper should reduce severity of root galling and reproduction of M. incognita as well as increase fruit yield of fall-cropped cucumber.

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Luis A. Valdez-Aguilar, David William Reed, and John A. Cornell

Publishing New York, NY Campbell, S.A. Nishio, J.N. 2000 Iron deficiency studies of sugar beet using an improved sodium bicarbonate-buffered hydroponic growth system J. Plant Nutr. 23 741 757 Cornell

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Warren E. Copes, Haibo Zhang, Patricia A. Richardson, Bruk E. Belayneh, Andrew Ristvey, John Lea-Cox, and Chuanxue Hong

analysis of monthly samples consisted of the determination of NO 3 − -N, NH 4 + -N, PO 4 -P, T-P, potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), aluminum (Al), B, Cu, Fe, manganese (Mn), Zn, pH, T-Alk, EC, and sodium (Na), and were performed by

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Steve Kovach, James Brown, Walter Hogue, Larry Curtis, and William S. Gazaway

Drip-irrigated tomato (`Sunny') plants were treated with five levels of fumigant in combination with three levels of mulch. Fumigants were metham sodium at two rates, 475 and 950 L/ha, a 67% methyl bromide + 33% chloropicrin formulation (164.5 kg/ha, and a 98% methyl bromide + 2% chloropicrin formulation (329 kg/ha). Mulching levels were 1.25 mil silver on black polyethylene (plastic), blue-black latex mulch sprayed over the plant beds, and no mulch. Plants treated with metham sodium (950 L/ha) had a significantly higher number of marketable fruit than plants treated with no fumigant or the 98% methyl bromide + 2% chloropicrin formulation. Marketable fruit weight was not significantly affected by the five fumigation levels. Plants grown with black plastic mulch had a significantly higher marketable yield than plants grown with no mulch, 58,100 kg/ha vs. 50,800 kg/ha, respectively. The level of mulching did not significantly affect the marketable number of fruit.

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Douglas A. Hopper

One-year-old plants of four cut rose (Rosa hybrida L.) cultivars were grown under either natural or supplemental irradiance for 4 months during the winter in Colorado. Supplemental irradiance with high-pressure sodium (HPS) lamps was supplied at 100 μmol·m–2·s–1 for 10 h each night during off-peak electrical use periods. Total cut flower yield, stem length, and fresh weight of individual flowers were recorded. The number of flowers produced and fresh weight increased for all cultivars under the supplemental irradiance treatment. Flower count, stem length, and fresh weight showed significant differences among the four 4-week production periods; production differences were promoted through pinches of two stems per plant to time for holiday peaks. When production was highest, stem length and fresh weight were lower, most likely due to redistribution of the limited carbohydrate pool during the winter.

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Glenn L. Roberts and M. J. Tsujita

An experiment was conducted to determine whether the high R:FR ratio in high pressure sodium (HPS) lamps contributes to lateral bud breaking in roses. Rosa hybrida cv. `Samantha' plants were grown under HPS lamps, HPS lamps fitted with blue gel filters to reduce the R:FR ratio or metal halide lamps. Spectral graphs showed R:FR ratios of 1.05, 0.5 and 3.8 for HPS, filtered HPS and metal halide respectively. Although the R:FR ratio in metal halide was notably higher than in HPS the total energy in this range was much lower. At a 24hr supplemental PPF level of 70-75uEm-2s-1 more flowering shoots were produced under HPS and metal halide lighting than under filtered HPS. There were more dormant shoots under the filtered HPS. No differences in quality were found among flowers from any treatment.