Control of cambial activity and dormancy in Picea sitchensis by indol-3-ylacetic and abscisic acids

1981 ◽  
Vol 59 (8) ◽  
pp. 1480-1493 ◽  
Author(s):  
C. H. A. Little ◽  
P. F. Wareing
Keyword(s):  
Water Stress ◽  
Seasonal Changes ◽  
Cambial Activity ◽  
Picea Sitchensis ◽  
Gas Chromatography Mass Spectrometry ◽  
Short Day ◽  
Internal Water ◽  
Tracheid Production ◽  
Cambial Dormancy ◽  
Exogenous Iaa

The combined gas chromatography – mass spectrometry (GCMS) technique of single-ion current monitoring was used to measure indol-3-ylacetic acid (IAA) and abscisic acid (ABA) levels in diffusible, acidic, and conjugated fractions obtained from the cambial region of Sitka spruce (1) during the annual cycle of cambial activity and dormancy in trees reared under natural and controlled environmental conditions, and (2) after debudding, girdling, defoliating, applying exogenous IAA, droughting, or changing the photoperiod. Seasonal changes occurred in the level of IAA and ABA in each fraction, but not obviously and consistently in conjunction with specific changes in cambial activity and dormancy. Debudding and girdling halted tracheid production, decreased the radial enlargement of the last-formed tracheids, and abruptly reduced the content of IAA and ABA in the diffusible and acidic fractions without affecting the ABA level in the conjugated fraction. Applying exogenous IAA to debudded shoots maintained tracheid production and differentiation, and largely prevented the decrease in IAA and ABA content. Elevating the internal water stress inhibited apical and cambial growth, increased the contents of diffusible, acidic, and conjugated ABA, and decreased diffusible and acidic IAA levels; the foliar concentrations of acidic IAA, acidic ABA, and conjugated ABA were similarly altered. Short-day photoperiod induced apical and cambial dormancy and reduced the levels of diffusible and acidic IAA and diffusible, acidic, and conjugated ABA; the decline in hormone content occurred mainly after the cambium ceased activity. Exogenous IAA could not prevent the cambium from ceasing activity under natural field conditions or short-day photoperiod. It is concluded that (1) there is an intrinsic seasonal pattern of change in IAA and ABA levels in the cambial region, governed primarily by seasonal changes in foliar hormone production; (2) this pattern is readily and variously perturbed by changes in the environment, particularly by factors affecting the internal water stress; (3) the evidence accumulated to date casts doubt on a role for ABA in controlling cambial dormancy; (4) cambial activity and the completion of the springtime transition from quiescence to activity depend on a continuous supply of basipetally transported IAA; (5) the changeover from activity to rest at the end of the cambial growing period is due to the development of an inability to respond to IAA, not to a deficiency in IAA supply; and (6) the transition from rest to quiescence during the cambial dormant period involves regaining the ability to respond to IAA.

Inhibition of cambial activity in Abies balsamea by internal water stress: role of abscisic acid

1975 ◽  
Vol 53 (24) ◽  
pp. 3041-3050 ◽  
Author(s):  
C. H. A. Little
Keyword(s):  
Abscisic Acid ◽  
Water Stress ◽  
Indoleacetic Acid ◽  
Stomatal Closure ◽  
Abies Balsamea ◽  
Cambial Activity ◽  
Inhibitory Effect ◽  
Internal Water ◽  
Endogenous Aba

In experiments with attached and detached shoots of balsam fir, Abies balsamea L., synthetic (±)abscisic acid (ABA) (1) reduced photosynthesis and transpiration by inducing stomatal closure, (2) inhibited indoleacetic acid (IAA) - induced cambial activity in photosynthesizing and non-photosynthesizing shoots, and (3) inhibited the basipetal movement of [14C]IAA. Neither gibberellic acid nor kinetin counteracted the inhibitory effect of (±)ABA on IAA-induced cambial activity. In addition it was demonstrated that increasing the internal water stress increased the level of endogenous ABA in the phloem–cambial region of bark peelings and decreased the basipetal movement of [14C]IAA through branch sections. On the basis of these findings it is proposed that internal water stress inhibits cambial activity, partly through increasing the level of ABA; the ABA acts to decrease the provision of carbohydrates and auxin that are required for cambial growth.

Seasonal Variations in Endogenous Indole-3-Acetic Acid and Abscisic Acid in the Cambial Region of Pinus densiflora Sieb. et Zucc. Stems in Relation to Earlywood-Latewood Transition and Cessation of Tracheid Production

Holzforschung ◽  
2001 ◽  
Vol 55 (2) ◽  
pp. 128-134 ◽  
Author(s):  
R. Funada ◽  
T. Kubo ◽  
M. Tabuchi ◽  
T. Sugiyama ◽  
M. Fushitani
Keyword(s):  
Acetic Acid ◽  
Abscisic Acid ◽  
Seasonal Changes ◽  
Pinus Densiflora ◽  
Growing Season ◽  
Cambial Activity ◽  
Early Summer ◽  
Indole 3 Acetic Acid ◽  
Lower Stem ◽  
Tracheid Production

Summary Seasonal changes in the total amount (measured as ng cm−2) of endogenous indole-3-acetic acid (IAA) and abscisic acid (ABA) in the cambial region of Pinus densiflora Sieb. et Zucc. trees with crowns of different sizes were determined at different stem heights. The total amount of IAA varied seasonally in all trees and at all stem positions, being maximal in early summer (May or July). In a tree with a large crown, the total amount of IAA remained high after peaking and declined in autumn, whereas in a tree with small crown it decreased rapidly after peaking, in particular in the lower stem. The transition from earlywood to latewood occurred concurrently with the decrease in the total amount of IAA after it had peaked, suggesting the involvement of IAA in the control of latewood formation. Cessation of the production of tracheids also paralleled the decline in the total amount of IAA early in the growing season in the lower stem of the tree with a small crown, but not in the tree with a large crown. Thus, other factors in addition to declining IAA seem to be involved in halting the production of the tracheids. The total amount of ABA was lower than that of IAA in all trees and at all stem heights, and changes were not correlated with specific changes during the annual cycle of cambial activity and dormancy.

scholarly journals The sensitivity of stand-scale photosynthesis and transpiration to changes in atmospheric CO2 concentration and climate

1999 ◽  
Vol 3 (1) ◽  
pp. 55-69 ◽  
Author(s):  
B. Kruijt ◽  
C. Barton ◽  
A. Rey ◽  
P. G. Jarvis
Keyword(s):  
Water Stress ◽  
Nitrogen Content ◽  
Leaf Area ◽  
Water Use ◽  
N Uptake ◽  
Co2 Concentration ◽  
Picea Sitchensis ◽  
Atmospheric Co2 ◽  
Atmospheric Co2 Concentration ◽  
Needle Longevity

Abstract. The 3-dimensional forest model MAESTRO was used to simulate daily and annual photosynthesis and transpiration fluxes of forest stands and the sensitivity of these fluxes to potential changes in atmospheric CO2 concentration ([CO2]), temperature, water stress and phenology. The effects of possible feed-backs from increased leaf area and limitations to leaf nutrition were simulated by imposing changes in leaf area and nitrogen content. Two different tree species were considered: Picea sitchensis (Bong.) Carr., a conifer with long needle longevity and large leaf area, and Betula pendula Roth., a broad-leaved deciduous species with an open canopy and small leaf area. Canopy photosynthetic production in trees was predicted to increase with atmospheric [CO2] and length of the growing season and to decrease with increased water stress. Associated increases in leaf area increased production further only in the B. pendula canopy, where the original leaf area was relatively small. Assumed limitations in N uptake affected B. pendula more than P. sitchensis. The effect of increased temperature was shown to depend on leaf area and nitrogen content. The different sensitivities of the two species were related to their very different canopy structure. Increased [CO2] reduced transpiration, but larger leaf area, early leaf growth, and higher temperature all led to increased water use. These effects were limited by feedbacks from soil water stress. The simulations suggest that, with the projected climate change, there is some increase in stand annual `water use efficiency', but the actual water losses to the atmosphere may not always decrease.

Effect of cambial dormancy state on the transport of [1-14C]indol-3-ylacetic acid in Abies balsamea shoots

1981 ◽  
Vol 59 (3) ◽  
pp. 342-348 ◽  
Author(s):  
C. H. A. Little
Keyword(s):  
Abies Balsamea ◽  
Cambial Activity ◽  
Controlled Environment ◽  
Long Distance ◽  
Dormant Period ◽  
Cambial Zone ◽  
Time Required ◽  
Ylacetic Acid ◽  
Exogenous Iaa

Dormant attached or detached shoots of balsam fir were naturally or artificially chilled to induce different states along the rest–quiescence continuum. At the end of the chilling pretreatment, the shoots either were left intact or were debudded and treated with indol-3-ylacetic acid (IAA). The shoots were placed under controlled-environment conditions favorable for growth, and at intervals thereafter, a pulse of [1-14C]IAA was applied to the shoot apex. Measured at the end of the chilling pretreatment, [14C]IAA velocity and flux decreased with increasing duration of chilling (i.e., as rest graded into quiescence). The time required to commence cambial growth and to attain maximum rates of cambial activity and [14C]IAA transport also decreased as rest changed to quiescence. Transport in actively growing shoots exceeded that in quiescent shoots, but was similar to that in resting shoots. The [14C]IAA pulse moved basipetally as unchanged IAA, was blocked by a bark + cambium girdle, and was inhibited by abscisic acid and long-term application of exogenous IAA. The results indicate that: (1) the long-distance, cambium-located, IAA transport system demonstrated in dicotyledonous species also operates in conifers, (2) during the dormant period changes occur in [14C]IAA transport and in the cambial response to exogenous IAA, (3) the change in [14C]IAA transport is the result of change in the transporting capability of cells in the cambial zone, and (4) the change in [14C]IAA transport is not the cause of the differential response of quiescent and resting cambia to exogenous IAA.

Daily and Seasonal Response of Huisache and Macartney Rose to Herbicides

Weed Science ◽  
1972 ◽  
Vol 20 (6) ◽  
pp. 577-580 ◽  
Author(s):  
R. W. Bovey ◽  
R. H. Haas ◽  
R. E. Meyer
Keyword(s):  
Acetic Acid ◽  
Water Stress ◽  
Application Rate ◽  
Effective Control ◽  
Acacia Farnesiana ◽  
Internal Water

Triethylamine salts of 4-amino-3,5,6-trichloropicolinic acid (picloram) plus (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) (1:1) sprays were more effective for the control of huisache(Acacia farnesiana(L.) Willd.) than for the control of Macartney rose(Rosa bracteataWendl.) at 13 dates of application in 1969 and 1970. Both species were more controlled effectively with the application rate of 1.12 than 0.56 kg/ha. Most effective control of huisache was obtained June 18, 1970, although other summer treatments in 1970 were effective. The herbicide was, on the average, more effective on huisache and Macartney rose when applied in the evening than morning or midday. Macartney rose was most effectively controlled by treatments applied in September and October of both years. Poorest control of the two species occurred when internal water stress was highest.

Seasonal changes in concentrations of plasma hormones in the male ring dove (Streptopelia risoria)

1986 ◽  
Vol 108 (3) ◽  
pp. 385-391 ◽  
Author(s):  
R. W. Lea ◽  
P. J. Sharp ◽  
H. Klandorf ◽  
S. Harvey ◽  
I. C. Dunn ◽  
...  
Keyword(s):  
Seasonal Changes ◽  
Plasma Corticosterone ◽  
Early Spring ◽  
Energy Requirements ◽  
Breeding Cycle ◽  
Plasma Prolactin ◽  
Winter Solstice ◽  
Natural Lighting ◽  
Short Day ◽  
Ring Dove

ABSTRACT Seasonal changes in concentrations of plasma LH, prolactin, thyroxine (T4), GH and corticosterone were measured in captive male ring doves exposed to natural lighting at latitude 56 °N. Plasma LH levels decreased steeply in autumn when the daylength fell below about 12·5 h but increased in November as the birds became short-day refractory. In comparison with plasma LH concentrations in a group of short-day refractory birds exposed to 6 h light/day from the winter solstice, plasma LH levels in birds exposed to natural lighting increased further in spring after the natural daylength reached about 12·5 h. There were no seasonal changes in plasma prolactin concentrations and plasma T4 concentrations were at their highest during December, January and February, the coldest months of the year. The seasonal fall in plasma LH levels in September was associated with a transitory increase in plasma T4, a transitory decrease in plasma corticosterone and a sustained increase in plasma GH. It is suggested that in the ring dove, short-day refractoriness develops rapidly in November to allow the bird to breed when the opportunity arises, during the winter and early spring. The annual breeding cycle is synchronized by a short-day induced regression of the reproductive system in the autumn, the primary function of which may be to enable the birds to meet the energy requirements for the annual moult. The changes in plasma T4, corticosterone and especially of GH at this time of year are probably concerned with the control of moult or the associated changes in energy requirements. J. Endocr. (1986) 108, 385–391

De-coupling seasonal changes in water content and dry matter to predict live conifer foliar moisture content

2014 ◽  
Vol 23 (4) ◽  
pp. 480 ◽  
Author(s):  
W. Matt Jolly ◽  
Ann M. Hadlow ◽  
Kathleen Huguet
Keyword(s):  
Water Stress ◽  
Moisture Content ◽  
Water Content ◽  
Seasonal Variations ◽  
Seasonal Changes ◽  
Dry Matter ◽  
Water Mass ◽  
Water Status ◽  
Dry Mass ◽  
Dry Matter Partitioning

Live foliar moisture content (LFMC) significantly influences wildland fire behaviour. However, characterising variations in LFMC is difficult because both foliar mass and dry mass can change throughout the season. Here we quantify the seasonal changes in both plant water status and dry matter partitioning. We collected new and old foliar samples from Pinus contorta for two growing seasons and quantified their LFMC, relative water content (RWC) and dry matter chemistry. LFMC quantifies the amount of water per unit fuel dry weight whereas RWC quantifies the amount of water in the fuel relative to how much water the fuel can hold at saturation. RWC is generally a better indicator of water stress than is LFMC. We separated water mass from dry mass for each sample and we attempted to best explain the seasonal variations in each using our measured physiochemical variables. We found that RWC explained 59% of variation in foliar water mass. Additionally, foliar starch, sugar and crude fat content explained 87% of the variation in seasonal dry mass changes. These two models combined explained 85% of the seasonal variations in LFMC. These results demonstrate that changes to dry matter exert a stronger control on seasonal LFMC dynamics than actual changes in water content, and they challenge the assumption that LFMC variations are strongly related to water stress. This methodology could be applied across a range of plant functional types to better understand the factors that drive seasonal changes in LFMC and live fuel flammability.

Seasonal Changes in Water Potential and Turgor Maintenance in Sorghum and Maize under Water Stress

1978 ◽  
Vol 44 (3) ◽  
pp. 261-267 ◽  
Author(s):  
E. FERERES ◽  
E. ACEVEDO ◽  
D. W. HENDERSON ◽  
T. C. HSIAO
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Seasonal Changes ◽  
Turgor Maintenance
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