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Seung-Hyun Kim, A.A. De Hertogh, and P.V. Nelson

Two experiments were conducted to determine the effects of applied ancymidol, chlormequat, daminozide, paclobutrazol, and uniconazole on early spring (March) and late (May) spring forcing of Dutch-grown Bleeding Heart [Dicentra spectabilis (L.) Lem.] as a flowering pot plant. Most of the plant growth regulator (PGR) treatments delayed flowering, however, the average time to flower after planting was from 17 to 21 days for untreated plants and delays were only 3 to 6 days with PGR treatments. Thus, the effect is not important commercially. Acceptable plant quality and height control not only at flowering but also 14 days later was obtained with two sprays of 3000 mg·L-1 (ppm) daminozide or two sprays of 50 mg·L-1 paclobutrazol. Uniconazole reduced total plant height, however, because the inflorescence did not elongate, plant quality was greatly reduced. Most ancymidol sprays were phytotoxic producing a chlorosis of the leaf margins. Media drenches of ancymidol or chlormequat did not control total plant height. Sprays and media drenches of ancymidol, daminozide, paclobutrazol, and uniconazole produced plants with a very deep green leaf color, but chlormequat did not. The total number of shoots per tuberous root, the number of shoots with flowers, and stem strength were not significantly affected by PGR treatments. If the tuberous roots have been properly cold treated, they initiate growth rapidly after planting. Thus, the first PGR spray must be applied immediately after shoot growth is initiated, which was 6 to 8 days after planting, followed by a second spray 5 days later. Two applications are necessary because of uneven shoot emergence and growth from the tuberous roots.

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D.H. Willits, P.V. Nelson, M.M. Peet, M.A. Depa, and J.S. Kuehny

The results of six experiments conducted over 3 years were analyzed to develop a relationship between nutrient uptake rate and growth rate in hydroponically grown Dendranthema ×grandiflorum (Ramat.) Kitamura, cv. Fiesta. Plants subjected to two levels of CO, and three levels of irradiance in four greenhouses were periodically analyzed for growth and the internal concentration of 11 mineral elements. The resulting data were used to determine relative accumulation rate and relative growth rate, which were included in linear regression analyses to determine the dependence of uptake on growth. The regression equations were significant, with a slight trend toward nonlinearity in some elements. This nonlinearity seems to be related to the aging of the plant and suggests a process in the plant capable of controlling uptake rate, perhaps as a result of changes in the rate of formation of different types of tissues.

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W.J. Sperry, J.M. Davis, D.C. Sanders, and P.V. Nelson

Fresh-market tomato (Lycopersicon esculentum Mill.) was grown in a growth chamber, hydroponically, and in a field to evaluate the effect of foliar-applied boron (B) and root-applied K on growth, yield, quality, and tissue nutrient levels. Plant and root dry weight, plant height, fruit set, total yields, marketable yields, fruit shelf life, fruit firmness, and fruit crack were positively influenced by B treatments. Boron-treated plants contained more K than plants not treated with B. Plants not treated with B contained less calcium (Ca) than plants treated with B. Leaflets from plants treated with B maintained higher K levels during fruit development than leaflets from plants not treated with B. Roots from plants treated with foliar B had significantly more B than roots from plants not treated with B. Fruit from B-treated plants had significantly more B than fruit from plants not treated with B. This indicates B was translocated from leaves to root and fruit tissues.