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F B Salisbury

Publications and source records attributed to F B Salisbury.

At least 55 records · Page 3Linked to original sources
PubMed1985

An evaluation of MES (2(N-Morpholino)ethanesulfonic acid) and Amberlite IRC-50 as pH buffers for nutrient solution studies.

All buffering agents used to stabilize pH in hydroponic research have disadvantages. Inorganic buffers are absorbed and may become phytotoxic. Solid carbonate salts temporarily mitigate decreasing pH but provide almost no protection against increasing pH, and they alter nutrient absorption. Exchange resins are more effective, but we find that they remove magnesium and manganese from solution. We have tested 2(N-Morpholino)ethanesulfonic acid (MES) as a buffering agent at concentrations of 1 and 10 mol m-3 (1 and 10 mM) with beans, corn, lettuce, tomatoes, and wheat. MES appears to be biologically inert and does not interact significantly with other solution ions. Relative growth rates among controls and MES treatments were nearly identical for each species during the trial period. The pH was stabilized by 1 mol m-3 MES. This buffer warrants further consideration in nutrient research.

Alkanesulfonic Acids↗
PubMed1985

Reduced phenylalanine ammonia-lyase and tyrosine ammonia-lyase activities and lignin synthesis in wheat grown under low pressure sodium lamps.

Wheat (Triticum aestivum L. cv Fremont) grown in hydroponic culture under 24-hour continuous irradiation at 560 to 580 micromoles per square meter per second from either metalhalide (MH), high pressure sodium (HPS), or low pressure sodium (LPS) lamps reached maturity in 70 days. Grain yields were similar under all three lamps, although LPS-grown plants lodged at maturity. Phenylalanine ammonia-lyase (PAL) and a tyrosine ammonia lyase (TAL) with lesser activity were detected in all extracts of leaf, inflorescence, and stem. Ammonia-lyase activities increased with age of the plant, and plants grown under the LPS lamp displayed PAL and TAL activities lower than wheat cultured under MH and HPS radiation. Greenhouse solar-grown wheat had the highest PAL and TAL activities. Lignin content of LPS-grown wheat was also significantly reduced from that of plants grown under MH or HPS lamps or in the greenhouse, showing a correlation with the reduced PAL and TAL activities. Ratios of far red-absorbing phytochrome to total phytochrome were similar for all three lamps, but the data do not yet warrant a conclusion about specific wavelengths missing from the LPS lamps that might have induced PAL and TAL activities in plants under the other lamps.

Ammonia-Lyases↗
PubMed1985

Photoperiodism.

Explore the source record for details and available documents.

Biological Clocks↗
PubMed1984

Gravitropism in Higher Plant Shoots : III. Cell Dimensions during Gravitropic Bending; Perception of Gravity.

Cross and longitudinal sections were prepared for light microscopy from vertical control plants (Xanthium strumarium L. Chicago strain), free-bending horizontal stems, plants restrained 48 hours in a horizontal position, and plants restrained 48 hours and then released, bending immediately about 130 degrees . Top cells of free-bending stems shrink or elongate little; bottom cells continue to elongate. In restrained stems, bottom cells elongate some and increase in diameter; top cells elongate about as much but decrease in diameter. Upon release, bottom cells elongate more and decrease in diameter, while top cells shorten and increase in diameter, accounting for the bend. During restraint, bottom cells take up water while tissue pressures increase; top cells fail to take up water although tissue pressures are decreasing.Settling of amyloplasts was observed in cells of the starch sheath.Removal of different amounts of stem (Xanthium; Lycopersicon esculentum Miller, cv Bonny Best; Ricinus communis L. cv Yolo Wonder) showed that perception of gravity occurs in the bending (elongation) zone, although bending of fourth and fifth internodes from the top was less than in uncut controls. Uniform application of 1% indoleacetic acid in lanolin to cut stem surfaces partially restored bending. Reversing the gradient in tension/compression in horizontal stems (top under compression, bottom under tension) did not affect gravitropic bending.

Journal Article↗
PubMed1984

Gravitropism in Higher Plant Shoots : II. Dimensional and Pressure Changes during Stem Bending.

Dimensional changes during gravitropic bending of cocklebur (Xanthium strumarium L.) dicot stems were measured using techniques of stereo photogrammetry. The differential growth is from an increased growth rate on the bottom of the stem and a stopping or contraction of the top.Contraction of the top was especially evident upon release and immediate bending of horizontal stems that had been restrained between stiff wires for 36 hours. The energy for this could have been stored in both the top and bottom, since the bottom elongated, and the top contracted.Forces developed during bending were measured by fastening a stem tip to the end of a bar with attached strain gauges and recording electrical output from the strain gauges. Restrained mature cocklebur stems continued to accumulate potential energy for bending for about 120 hours, after which the recorded force reached a maximum.Pressures within castor bean (Ricinus communis L.) stems were also measured with 3.5-millimeter diameter pressure transducers. As expected, the pressure on the bottom of the restrained plants increased with time; pressures decreased in vertical controls, tops of restrained stems, and bottoms of free-bending stems. Pressures increased in tops of free-bending stems. When restrained plants were released, pressure on the bottom decreased and pressure on the top increased. Results suggest a possible role for cell contraction in the top of stems bending upward in response to gravity.

Journal Article↗
PubMed1984

Achieving maximum plant yield in a weightless, bioregenerative system for a space craft.

Limitations to maximum plant yield are photosynthesis, respiration, and harvest index (edible/total biomass). Our best results with wheat equal 97.5 g total biomass m-2 day-1. Theoretical maximums for our continuous 900 micromoles photons m-2 s-1 = 175 g carbohydrate, so our life-cycle efficiency is about 56%. Mineral nutrition has posed problems, but these are now nearly solved. CO2 levels are about 80 micromoles m-3 (1700 ppm; ambient = 330 ppm). We have grown wheat plants successfully under low-pressure sodium lamps. The main factor promising increased yields is canopy development. About half the life cycle is required to develop a canopy that uses light efficiently. At that point, we achieve 89% of maximum theoretical growth, suggesting that most parameters are nearly optimal. The next important frontier concerns application of these techniques to the microgravity environment of a space craft. There are engineering problems connected with circulation of nutrient solutions, for example. Plant responses to microgravity could decrease or increase yields. Leaves become epinastic, grass nodes elongate, and roots grow out of their medium. We are proposing space experiments to study these problems.

Biomass↗
PubMed1981

Interpreting Plant Responses to Clinostating: I. MECHANICAL STRESSES AND ETHYLENE.

The severe epinasty and other symptoms developed by clinostated leafy plants could be responses to gravity compensation and/or the mechanical stresses of leaf flopping. Epinasty in cocklebur (Xanthium strumarium L.), tomato (Lycopersicon esculentum Mill.), and castor bean (Ricinus communis L.) is delayed by inhibitors of ethylene synthesis and action (aminoethoxyvinylglycine and Ag(+)), confirming the role of ethylene in clinostat epinasty. To test the possibility that clinostat mechanical stresses (leaf flopping) cause ethylene production and, thus, epinasty, vertical plants were stressed with constant, gentle, horizontal, or vertical shaking or with a quick, back-and-forth rotation (twisting). Clinostat leaf flopping was closely approximated but with a minimum of gravity compensation, by turning plants so their stems were horizontal, rotating them quickly about the stem axis, and then returning them to the vertical, repeating the treatment every four minutes (clinostat rotation time). None of these mechanical stresses produced significant epinasties, but vigorous hand-shaking (120 seconds per day) generated minor epinasties, as did Ag(+) applied daily (concentrations high enough to cause leaf browning). Plants gently inverted every 20 minutes developed epinasty at about the same rate and to about the same extent as clinostated plants, but plants inverted every 20 minutes and immediately returned to the upright position did not become epinastic. It is concluded that clinostat epinasty is probably caused by disturbances in the gravity perception mechanism, rather than by leaf flopping.

Journal Article↗
PubMed1981

Gravitropism in Higher Plant Shoots: I. A ROLE FOR ETHYLENE.

It has long been known that applied ethylene can redirect the gravitropic response, but only occasionally has it been suggested that ethylene normally plays a role in gravitropism. Two inhibitors of ethylene synthesis [Co(2+) and aminoethoxyvinylglycine (AVG)] and two inhibitors of ethylene action (Ag(+) and CO(2)) were shown to delay the gravitropic response of cocklebur (Xanthium strumarium L.), tomato (Lycopersicon esculentum Mill.), and castor bean (Ricinus communis L.) stems. Gentle shaking on a mechanical shaker does not inhibit the gravitropic response, but vigorous hand shaking for 120 seconds delays the response somewhat. AVG and Ag(+) further delay the response of mechanically stimulated plants. AVG delays the response of defoliated and of decapitated plants. Plants laid on their side and restricted so that they cannot bend upward store both bending energy and gravitropic stimulus; they bend immediately when released from restriction (stored energy) and continue to bend for some hours after (stored stimulus). AVG retards the storage of bending energy but not of stimulus. In gravitropism, graviperception may first stimulate ethylene evolution, which may then influence bending directly, or responses involving ethylene could be more indirect.

Journal Article↗
PubMed1981

Twilight effect: initiating dark measurement in photoperiodism of xanthium.

Six experiments studied the effects of low levels of red and far-red light upon the initiation of measurement of the dark period in the photoperiodic induction of flowering in Xanthium strumarium L. (cocklebur), a short-day plant, and compared effects with those of comparable light treatments applied for 2 hours during the middle of a 16-hour inductive dark period. Red light, or red plus far-red, at levels that inhibit flowering when applied during the middle of the inductive dark period, either had no effect on the initiation of dark measurement (i.e., were perceived as darkness), or they delayed the initiation of dark measurement by various times up to the full interval of exposure (2 hours). Far-red light alone had virtually no effect either at the beginning or in the middle of the dark period. These results confirm that time measurement in the photoperiodic response of short-day Xanthium plants is not simply the time required for metabolic dark conversion of phytochrome. Results also suggest that the pigment system (phytochrome?) and/or responses to it may be significantly different as they function during twilight (initiation of dark measurement), and as they function during a light break several hours later. Possible mechanisms by which cocklebur plants detect the change from light to darkness are discussed.COMPARING EXPERIMENTAL RESULTS WITH SPECTRAL LIGHT MEASUREMENTS DURING TWILIGHT AND WITH MEASUREMENTS OF LIGHT FROM THE FULL MOON LED TO TWO CONCLUSIONS: First, light levels pass from values perceived by the plant as full light to values perceived as complete darkness in only about 5.5 to 11.5 minutes, although twilight as perceived by the human eye lasts well over 30 minutes. Second, cocklebur plants probably do not respond to light from the full moon, even when most sensitive, 7 to 9 hours after the beginning of darkness.

Journal Article↗
PubMed1972

Aftereffects of low and high temperature pretreatment on leaf resistance, transpiration, and leaf temperature in xanthium.

Leaf resistance for water vapor (total diffusion resistance minus boundary layer resistance), transpiration, and leaf temperature were measured in attached leaves of greenhouse-grown Xanthium strumarium L. plants that had been pretreated for 72 hours with high (40 C day, 35 C night), or low (10 C day, 5 C night) air temperatures. Measurements were made in a wind tunnel at light intensity of 1.15 cal cm(-2) min(-1), air temperatures between 5 and 45 C, and wind speed of 65 cm sec(-1). Leaf resistances in low temperature pretreated plants were higher (8 to 27 sec cm(-1)) than in controls or high temperature pretreated plants (0.5 to 3 sec cm(-1)) at leaf temperatures between 5 and 25 C. Thus, the pretreatment influenced stomatal aperture.

Journal Article↗
PubMed1971

Participation of Long-Day Inhibition in Flowering of Xanthium strumarium L.

Two basic experiments defined a long-day inhibitory effect on Xanthium flowering: the basal half of a single leaf on long day inhibits response of the tip half to a short day; and a long-day leaf inhibits response of a short-day leaf, providing it is between the short-day leaf and a receptive bud (whether above or below the short-day leaf). Five hypotheses were explored with the conclusions that the tip half can synthesize florigen, and inhibition is not due to prevention of florigen synthesis, translocational effects, or a translocatable long-day inhibitor. Inhibition is localized and may be a condition of the leaf or a relatively immobile substance. Studies of critical dark period, light intensity, and interruption of a dark period show that, when the leaf is not producing florigen, it is actively inhibitory. Immature leaves are more inhibitory than older leaves. The effect was found not to pass dead tissue, and iron-deficient tissue will cause inhibition, though it will not cause promotion.

Journal Article↗
PubMed1970

Temperature and transpiration resistances of xanthium leaves as affected by air temperature, humidity, and wind speed.

Transpiration and temperatures of single, attached leaves of Xanthium strumarium L. were measured in high intensity white light (1.2 calories per square centimeter per minute on a surface normal to the radiation), with abundant water supply, at wind speeds of 90, 225, and 450 centimeters per second, and during exposure to moist and dry air. Partitioning of absorbed radiation between transpiration and convection was determined, and transpiration resistances were computed.Leaf resistances decreased with increasing temperature (down to a minimum of 0.36 seconds per centimeter). Silicone rubber replicas of leaf surfaces proved that the decrease was due to increased stomatal apertures. At constant air temperature, leaf resistances were higher in dry than in moist air with the result that transpiration varied less than would have been predicted on the basis of the water-vapor pressure difference between leaf and air.The dependence of stomatal conductance on temperature and moisture content of the air caused the following effects. At air temperatures below 35 C, average leaf temperatures were above air temperature by an amount dependent on wind velocity; increasing wind diminished transpiration. At air temperatures above 35 C, leaf temperatures were below air temperatures, and increasing wind markedly increased transpiration. Leaf temperatures equaled air temperature near 35 C at all wind speeds and in moist as well as in dry air.

Journal Article↗
PubMed1969

Simultaneous reactivation of ultraviolet damage in xanthium leaves.

Experiments on Xanthium leaf discs were carried out to determine whether concomitant photoreactivation could be detected and if so, to compare its effects with photoreactivation due to post-irradiation treatments. Attempts mere made to simulate certain intensities of unfiltered solar radiation. A small but definite amount of simultaneous reactivation was observed. The dose reduction factor averaged 0.57. It was not clear whether the reactivation was due mainly to direct photoreactivation, photoprotection, or to heating effects. A much larger amount of reactivation due to post-irradiation treatments (direct photoreactivation) was noted with the dose reduction factor averaging 0.30.

Journal Article↗
PubMed1967

Aspects of clock resetting in flowering of xanthium.

Flowering is induced in Xanthium strumarium by a single dark period exceeding about 8.3 hours in length (the critical night). To study the mechanism which measures this dark period, plants were placed in growth chambers for about 2 days under constant light and temperature, given a phasing dark period terminated by an intervening light period (1 min to several hrs in duration), and finally a test dark period long enough normally to induce flowering. In some experiments, light interruptions during the test dark period were given to establish the time of maximum sensitivity.If the phasing dark period was less than 5 hours long, its termination by a light flash only broadened the subsequent time of maximum sensitivity to a light flash, but the critical night was delayed. In causing the delay, the end of the intervening light period was acting like the dusk signal which initiated time measurement at the beginning of the phasing dark period.If the phasing dark period was 6 hours or longer, time of maximum sensitivity during the subsequent test dark period was shifted by as much as 10 to 14 hours. In this case the light terminating the phasing dark period acted as a rephaser or a dawn signal.Following a 7.5-hour phasing dark period, intervening light periods of 1 minute to 5 hours did not shift the subsequent time of maximum sensitivity, but with intervening light periods longer than 5 hours, termination of the light acts clearly like a dusk signal. The clock appears to be suspended during intervening light periods longer than 5 to 15 hours. It is restarted by a dusk signal. There is an anomaly with intervening light periods of 10 to 13 hours, following which time of maximum sensitivity is actually less than the usual 8 hours after dusk.Ability of the clock in Xanthium to be rephased, suspended, restarted, or delayed, depending always upon conditions of the experiment, is characteristic of an oscillating timer and may confer upon this plant its ability to respond to a single inductive cycle. It is suggested that phytochrome may influence only the phase of the clock and not other aspects of flowering such as synthesis of flowering hormone.

Journal Article↗