and groundwater pollution ( Dukes et al., 2003 ; Skaggs et al., 2010 ). Nonetheless, more frequent and short-duration (pulsed) irrigation events have been shown to better match plant water uptake by improving soil water distribution ( Assouline et al
Laurence Gendron, Guillaume Létourneau, Julien Cormier, Claire Depardieu, Carole Boily, Raymond Levallois, and Jean Caron
D. Sean Moody, Steven E. Newman, and Douglas A. Hopper
Three irrigation strategies [10% leaching, 0% leaching (pulse), and ebb-and-flood] and two constant liquid feed fertilizer treatments, 150 and 300 ppm N, were applied to poinsettias, `Freedom Red' and `V-17 Angelika Red', with a harvest date of November 25, 1995. There were no differences in plant dry weights among the three irrigation strategies at the 150 ppm N treatment. At 300 ppm N, 10% leaching irrigation grew plants with the greatest dry weights, followed by the ebb-and-flood treatment and the pulse treatment, respectively. The 10% leaching and ebb-and-flood plants had the greatest growth index, while the pulse treatment growth index was lower. Growth index was greatest for the 10% leaching strategy for `Freedom Red', while ebb-and-flood had the lowest index. The growth index was greater at 150 ppm N for `Freedom Red' compared to 300 ppm N. `V-17 Angelika Red' was not influenced by fertility level. Pulse irrigation grew marketable poinsettia plants at lower fertility levels.
Juan Carlos Melgar, Arnold W. Schumann, and James P. Syvertsen
-month-old seedlings were arranged randomly in three groups of 10 plants each and one of three irrigation frequencies was applied to each group: 1) 15 mL per day applied in 10 1.5-mL pulses applied each hour for 10 h beginning at 0900 hr ; 2) 15 mL per
Susan S. Han
Sucrose addition to the vase solution improved the postharvest qualities of cut liatris by increasing the length of inflorescences showing color and by prolonging the vase life of the spikes. The main effect of sucrose was on the development and opening of the flower heads with minimal effect on their longevity. Pulsing with concentrations of sucrose ≥10% for 20 hours prolonged the vase life of the spikes. Responses of spikes to the pulsed treatment varied greatly due to the differences in their degree of leafiness, thus limiting its commercial application. A continuous supply of 2.5% or 5% sucrose in the vase solution allowed most of the flower heads on the spikes to develop and doubled the vase life of the spikes.
Horst W. Caspari, M. Hossein Behhoudian, David J. Chalmers, and A. Richard Renquist
similar commercial products. We gratefully acknowledge the support of W.R.N. Edwards for the installation and maintenance of the heat-pulse equipment. H.W.C.`s research was supported by a grant from Gottlieb Daimler-und Karl Benz-Stiftung, Ladenburg
George C. Elliott
A schematic diagram and parts list is presented for a simple and inexpensive system for pulsed subirrigation (commerically referred to as ebb and flow or flood and drain). The system can be readily modified for flowing solution culture. It has proven useful in teaching and research applications. It can be assembled from readily available parts using hand tools.
Iftikhar Ahmad, John M. Dole, and Bruno T. Favero
-h pulse at 25 mg·L −1 controlled leaf chlorosis of cut oriental and asiatic lilies. However, continuous application enhanced bud blasting ( Han, 2001 ). Similarly, mode and time of application of PGR also affected leaf chlorosis of lilies and
Richard C. Beeson Jr.
Pulsing consists of applying subvolumes of a normal daily irrigation volume several times per day. Previous studies have shown splitting overhead irrigation into two subapplications increased growth of container-grown landscape ornamentals in the southeastern U.S. In Florida, water restrictions prohibit overhead irrigation during the critical mid-afternoon when irrigation is most beneficial. Using individual microirrigation spray stakes, only 25% of the water required for overhead irrigation per bed area was necessary to produce similar plants if irrigated once per day. When the same daily volume was pulsed as 2 or 3 subvolumes, tree growth was significantly increased. Data suggest 2 pulses are sufficient for trees with a xeric nature while mesic trees prefer 3 pulses per day. Root:shoot ratios were unchanged by pulsing. Lower cumulative diurnal water stress was measured on pulsed trees.
Motoaki Doi and Michael S. Reid
Regardless of their maturity at harvest, the vase life of cut inflorescences of the hybrid Limonium `Fantasia' placed in deionized water was 4 to 5 days. A vase solution containing Physan (a quaternary ammonium disinfectant solution) at 200 μl·liter–1 and 20 g sucrose/liter not only prolonged the longevity of individual florets but also promoted bud opening so that the vase life of cut inflorescences extended to 17 days. Pulse treatment with 100 g sucrose/liter in combination with Physan at 200 μl·liter–1 for 12 hours partially substituted for a continuous supply of sucrose. Including 30 mg gibberellic acid/liter in the vase solution was without benefit.
B.K. Behe and T.S. Krentz
Research shows differences among flowering species in ethylene sensitivity in response to ethylene inhibitors, including silver thiosulfate. Buddleia sp. is an arching shrub with spike-shaped inlforescences in a wide range of colors, including pink, purple, yellow, and white. The objective of this study was to determine optimal pulsing time of silver thiosulfate to maximize the postharvest life of five cultivars of Buddleia sp.: `Empire Blue', `Lochinch', `Nanho Blue', `Pink Delight', `Royal Red', and `Sungold'. Flower stems harvested at 1/3 to 2/3 development were transported to a simulated consumer environment. Stems were recut under water and pulsed for 0, 30, 60, and 120 min prior to placing them in a solution of deionized water and Floralife at 10 3 g·liter–1. No silver thiosulfate treatment was more effective than the control at extending vaselife, increasing floret development, or increasing stem fresh weight.