Reproductive Development in Loblolly Pine. Ii. The Effect of Age, Gibberellin Plus Water Stress and Out‐of‐phase Dormancy on Long Shoot Growth Behavior

Greenwood, Michael S.

doi:10.1002/j.1537-2197.1981.tb07824.x

Cited by 20 publications

(14 citation statements)

References 14 publications

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“…Thus, it may also be true that changes of endogenous GA's in intact stressed plants and detached stressed plants parts could be different . In any case the effects of drough stress on GA metabolism maybe very complex (Greenwood 1981) . A number of studies following the earlier report of El-Beltagy and Hall (1974) (see Wright, 1980) found more ethylene in water and osmotically stressed than unstressed tissue .…”

Section: Discussionmentioning

confidence: 99%

The effect of drought on levels of abscisic acid, cytokinins, gibberellins and ethylene in aeroponically-grown sunflower plants

1986

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Abscisic acid (ABA), cytokinins and gibberellin-like substances (GAs) were extracted from the roots and shoots of 17-day-old sunflower seedlings which had been droughted or were unstressed . Plants were grown in an aeroponic chamber which allowed for good control over degree of water stress and easy access to roots . Following methanolic extraction of lyophilized material, cytokinins were separated from the acidic growthregulators on a cellulose PO, cationic exchange column . The cytokinins were analysed by paper chromatography and HPLC and the soybean hypocotyl section assay . Semipurified acidic regulators were chromatographed on SiO 2 columns and HPLC and aliquots assayed with the dwarf rice cv . Tan-ginbozu bioassay for GAs . Fractions known to contain ABA were purified by sequential reverse-phase HPLC of the acid and then of the methyl ester forms followed by quantitation as Me-ABA on GLC-EC . ABA losses were measured by using an internal standard ['H]-ABA) . Ethylene production was also monitored in stressed and unstressed seedlings .The effect of drought on GAs and ethylene was minimal . The ABA levels were markedly higher in droughted plants . Stressed roots had 32 times more ABA than controls . The levels of cytokinins in the shoots of droughted plants were about half those in unstressed shoots, and qualitative differences occurred in the roots . Under stress a large peak of activity was present similar to zeatin glucoside which was not present in the unstressed condition . The results are discussed in relation to droughteffects on metabolism .

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Section: Discussionmentioning

confidence: 99%

The effect of drought on levels of abscisic acid, cytokinins, gibberellins and ethylene in aeroponically-grown sunflower plants

1986

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“…On the other hand, treatment with GA 4/ alone has only promoted female flowering in P . taeda, regardless of age o7f trees, cultural conditions or timing and application dosage (42)(43)(44)112).…”

Section: 2 Gibberellinsmentioning

confidence: 99%

“…Greenwood (40,42) has shown that when potted grafts of Pinus taeda which have overwintered in a greenhouse under continuous light are then exposed to naturally SD in spring, female flowering is dramatically enhanced .…”

Section: Role Of Photoperiod and Temperaturementioning

confidence: 99%

3. Control of sex expression in conifers

Ross

Pharis

1987

Plant Growth Regul

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Despite considerable progress in recent years in the promotion of flowering in conifers, relatively little is known about the endogenous control of sex expression or its practical manipulation to aid pollen and crop management in seed orchards. Well defined patterns of sexual zonation exist within the tree crown and shoot, and these appear to be associated with hormonal and possibly nutritional gradients . No firm conclusions, however, are possible regarding the specific role(s) of different PGRs in sex expression, this being as much as a problem of lack of critical study as the complexity of the process itself. Whether a PGR such as gibberellins or auxins, or a cultural treatment that itself may influence endogenous hormone levels, primarily promotes female or male flowering often depends on the position within the crown of the shoot being treated, and its timing in relation to stage of primordia development . Photoperiod also may be involved--short days favoring females and long days males, at least in some species--although its role in controlling sex expression is by no means clear . Practical manipulation of sex expression may be possible through selective crown pruning, different PGR combinations, treatment timing and/or photoperiod control, but the development of such techniques for operational use will require a better basic understanding of the endogenous regulatory mechanisms involved .

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“…Water deficits have caused flowering in species of the Cupressaceae, Pinaceae and Taxodiaceae families (24,69) and have been successfully employed to culturally induce flowering in trees . Although the mechanism is not known, flower initiation is related to decreased vegetative growth and increased levels of less polar gibberellins such as GA4 and GA7 (25,58) .…”

Section: Introductionmentioning

confidence: 99%

“…Water deficits apparently retard growth, leading to a shift in GA metabolism from polar to less polar GAs (58) . The elevated levels of less polar GAs then induce strobilus primordia initiation in the quiescent buds (24,25) . Timing of the water stress has been observed to influence the sex of the strobili produced in loblolly pine (25) .…”

Section: Introductionmentioning

confidence: 99%

9. Stress physiology of forest trees: The role of plant growth regulators

Johnson

1987

Plant Growth Regul

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Abiotic and biotic stresses elicit changes in normal physiology of trees . Plant growth regulators (PGR) are involved in the stress response and appear to have two roles : 1) to minimize the impact of the stress on the tree and ; 2) to trigger stress resistance mechanisms . In the latter case the PGR-induced changes appear to enhance resistance to subsequent stress . This cross-adaptation to stress is important in trees .The role of PGRs in the physiological response to the abiotic stresses of water deficit, water excess, temperature, nutrition and mechanical perturbation is discussed along with cross-adaptation in the interactions of these stresses . Disease response and defense, and plant-plant communications involve PGRs and are topics covered with respect to biotic stress . Stress leads to early senescence and abscission in trees . These processes are controlled by PGRs and are briefly discussed .

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Reproductive Development in Loblolly Pine. Ii. The Effect of Age, Gibberellin Plus Water Stress and Out‐of‐phase Dormancy on Long Shoot Growth Behavior

Cited by 20 publications

References 14 publications

The effect of drought on levels of abscisic acid, cytokinins, gibberellins and ethylene in aeroponically-grown sunflower plants

The effect of drought on levels of abscisic acid, cytokinins, gibberellins and ethylene in aeroponically-grown sunflower plants

3. Control of sex expression in conifers

9. Stress physiology of forest trees: The role of plant growth regulators

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