Root Signals Mediate Coordination of Stomatal and Hydraulic Conductance in Growing Sugarcane

1991 ◽  
Vol 18 (4) ◽  
pp. 329 ◽  
Author(s):  
FC Meinzer ◽  
DA Grantz ◽  
B Smit
Keyword(s):  
Stomatal Conductance ◽  
Leaf Area ◽  
Xylem Sap ◽  
Plant Size ◽  
Hydraulic Conductance ◽  
Zeatin Riboside ◽  
Donor Plant ◽  
Developmental Patterns ◽  
Unit Leaf ◽  
Stomatal Complexes

Root hydraulic conductance and total stomatal conductance on a per plant basis changed in parallel during growth of sugarcane. Changes in root system water and solute transport properties were evaluated to determine the role of changes in root xylem sap composition in this coordination of vapour and liquid phase conductances. Stomatal conductance of excised leaf strips supplied with root exudate declined with increasing leaf area of the exudate donor plants. Leaf strips from plants of different sizes responded similarly to exudate from each donor plant, indicating that there were no inherent differences in leaf stomatal properties. The effect of xylem sap from plants of increasing size paralleled the decline in stomatal conductance of intact plants of similarly increasing plant size. Delivery rates per unit leaf area of K+, Ca2+, abscisic acid, and zeatin riboside (ZR) in xylem sap declined with increasing plant size. Patterns of delivery of ZR and K+ were consistent with a role in the plant size-dependent regulation of stomatal conductance, although additional xylem constituents are likely to be involved. Developmental patterns of stomatal conductance in intact sugarcane plants may be linked to plant hydraulic properties by the composition and flux of xylem sap arriving at the stomatal complexes in leaves.

Stomatal Development During Leaf Expansion in Tobacco and Sunflower

1975 ◽  
Vol 23 (2) ◽  
pp. 253 ◽  
Author(s):  
HM Rawson ◽  
CL Craven
Keyword(s):  
Leaf Area ◽  
Stomatal Density ◽  
Stomatal Development ◽  
Developmental Patterns ◽  
Full Size ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Wide Range ◽  
Young Leaves ◽  
Different Levels

Changes in stomatal density and size were followed in tobacco and sunflower leaves expanding from 10% of final area (10% Amax) to Amax under different levels of radiation. Lower radiation increased final leaf area, reduced stomatal densities, and increased area per stoma but had little effect on stomatal area per unit leaf area at Amax. In very young leaves (20% Amax) there was a wide range in the sizes of individual stomata, some stomata being close to full size, but by Amax differences were small. The possible relationship between the developmental patterns described and photosynthesis is briefly discussed.

Water transfer in a mature oak stand (Quercuspetraea): seasonal evolution and effects of a severe drought

1993 ◽  
Vol 23 (6) ◽  
pp. 1136-1143 ◽  
Author(s):  
N. Bréda ◽  
H. Cochard ◽  
E. Dreyer ◽  
A. Granier
Keyword(s):  
Stomatal Conductance ◽  
Potential Evapotranspiration ◽  
Stomatal Closure ◽  
Time Lag ◽  
Xylem Sap ◽  
Water Shortage ◽  
Hydraulic Conductance ◽  
Canopy Conductance ◽  
Severe Drought ◽  
Order Of Magnitude

The reactions of sessile oak (Quercuspetraea (Mattuschka) Liebl.) to drought were studied under natural conditions in a 32-year-old stand near Nancy (northeastern France) during the summers of 1989 (strongly rain deficient) and 1990. A plot of five trees was subjected to imposed water shortage, while a group of irrigated trees was used as a control. Measurements of xylem sap flows and water potential enabled the computation of plot transpiration, canopy conductance, and specific hydraulic conductance in the soil–tree continuum. Stomatal conductance was measured directly with a porometer. Specific hydraulic conductance of our oaks was of the same order of magnitude as that reported for other species. It decreased significantly during spring because of a time lag between cambial growth and leaf area expansion. Measured transpiration was close to potential evapotranspiration, except during days with high vapor pressure deficits, which promoted stomatal closure in the absence of soil water deficits. Imposed drought caused predawn leaf water potentials to reach values as low as −2.0 MPa and a progressive decline in hydraulic conductance, which was probably attributable to modifications in hydraulic properties at the soil–root interface. This gradual decline in conductance was attributed to their deep rooting (1.40 m). This study revealed that Q. petraea may be considered as drought tolerant because of adaptations like deep rooting, efficient and safe xylem sap transport, maintenance of significant stomatal conductance, and significant transpiration, even during strong drought stress.

Growth Analysis of the Effect of Phosphorus Nutrition on Seedings of Eucalyptus grandis

1992 ◽  
Vol 19 (1) ◽  
pp. 55 ◽  
Author(s):  
MUF Kirschbaum ◽  
DW Bellingham ◽  
RN Cromer
Keyword(s):  
Leaf Area ◽  
Specific Leaf Area ◽  
Carbon Fixation ◽  
Eucalyptus Grandis ◽  
Dry Weight ◽  
Plant Size ◽  
Phosphorus Concentration ◽  
Fixation Rate ◽  
Unit Leaf ◽  
Addition Rate

Eucalyptus grandis seedlings were grown in growth units in which plant roots were suspended in air while continuously being sprayed with nutrient solution (aeroponic system). Phosphorus was added to nutrient solutions in exponentially increasing amounts which determined plant growth. Phosphorus was added at five different relative addition rates. The proportion of dry matter in stems increased with plant size, but was independent of plant internal phosphorus concentration. In contrast, the ratio of root to leaf dry weight decreased almost 2-fold with increasing phosphorus concentration but changed little with plant size, and specific leaf area more than doubled with increasing phosphorus concentration. Carbon fixation rate per unit plant dry weight increased about 5-fold with increasing nutrient addition rate over the range of addition rates used. That increase was due to a doubling in specific leaf area and a doubling in assimilation rate per unit leaf area, while leaf weight as a fraction of total plant dry weight increased by about 20%.

Interaction of Single Tobacco Plants With Direct-Beam Light

1980 ◽  
Vol 7 (4) ◽  
pp. 435 ◽  
Author(s):  
DM Whitfield ◽  
DJ Connor
Keyword(s):  
Leaf Area ◽  
Zenith Angle ◽  
Three Dimensional ◽  
Plant Size ◽  
Structural Features ◽  
Beam Angle ◽  
Unit Leaf Area ◽  
Direct Beam ◽  
Unit Leaf ◽  
Orientation Distributions

The interaction of single plants of tobacco with direct-beam light was investigated using coordinate data describing the three-dimensional display of foliage. The projection of unit leaf area of single plants showed little variation with either plant size or azimuth angle of sight but showed a major dependence on the zenith angle. In contrast, the beam-lit area of foliage varied with each of these factors. Zenith angle also had the largest effects on the distribution of beam-lit foliage area with respect to the leaf-beam angle. These variables were also estimated with a model which took account of the basic structural features of the plants. The assumption of a uniform distribution of the leaf projections on the plane normal to the beam led to systematic errors in estimates of the proportion of beam-lit foliage. These deviations were used for estimates of an empirical index of the dispersion of the projections of the elements of foliage. The index varied with plant size and zenith angle of sight. Satisfactory estimates of the projections of unit leaf area and of distributions of the beam-lit foliage with respect to the leaf-beam angle were obtained from the model orientation distributions and assuming that foliage intercepts light in proportion to its frequency in the orientation distributions. Results are discussed in terms of changes in the structure of the plant associated with growth and development.

scholarly journals Irrigation Frequency and Shading Influences on Water Relations and Growth of Container-Grown Euonymus japonica ‘Aureo-marginata’

1988 ◽  
Vol 6 (3) ◽  
pp. 96-100 ◽  
Author(s):  
S.E. Newman ◽  
M.W. Follett
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Leaf Area ◽  
Water Relations ◽  
Dry Weight ◽  
Trickle Irrigation ◽  
Irrigation Frequency ◽  
Irrigation Level ◽  
Once Daily ◽  
Unit Leaf

Trickle irrigation frequency, shading, water relations, and plant growth of container-grown Euonymus japonica Thunb. ‘Aureomarginata’ was investigated. Plants were grown under a combination of 3 irrigation frequencies and 2 shade levels. Stomatal conductance (gs) was reduced when plants were irrigated 3 times per week compared to irrigation daily and twice daily after week 4 under full sun and after week 8 under shade. Few differences were detected in predawn shoot water potential (Ψshoot) under shade at any irrigation level. The predawn shoot water potential (Ψshoot) was reduced (rnore negative) for plants irrigated 3 times per week compared to irrigation daily and twice daily after week 8 for plants grown under full sun and week 10 for plants grown under shade. These values remained lower for the duration of the study. Plants grown under shade and irrigated once daily had greater plant dry weight and leaf area compared to plants irrigated either twice daily or 3 times per week. They were also larger than all plants grown under full sun. Plants grown under shade had greater chlorophyll levels per unit leaf area. Under shade, plant quality was not affected by irrigation rates. However, only plants grown under shade were of salable quality.

scholarly journals Why are tropical conifers disadvantaged in fertile soils? Comparison of Podocarpus guatemalensis with an angiosperm pioneer, Ficus insipida

2020 ◽  
Vol 40 (6) ◽  
pp. 810-821 ◽  
Author(s):  
Ana C Palma ◽  
Klaus Winter ◽  
Jorge Aranda ◽  
James W Dalling ◽  
Alexander W Cheesman ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Leaf Area ◽  
Nitrogen Availability ◽  
Dry Mass ◽  
Area Ratio ◽  
Leaf Area Ratio ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Fertilized Soil ◽  
Whole Plant

Abstract Conifers are, for the most part, competitively excluded from tropical rainforests by angiosperms. Where they do occur, conifers often occupy sites that are relatively infertile. To gain insight into the physiological mechanisms by which angiosperms outcompete conifers in more productive sites, we grew seedlings of a tropical conifer (Podocarpus guatemalensis Standley) and an angiosperm pioneer (Ficus insipida Willd.) with and without added nutrients, supplied in the form of a slow-release fertilizer. At the conclusion of the experiment, the dry mass of P. guatemalensis seedlings in fertilized soil was approximately twofold larger than that of seedlings in unfertilized soil; on the other hand, the dry mass of F. insipida seedlings in fertilized soil was ~20-fold larger than seedlings in unfertilized soil. The higher relative growth rate of F. insipida was associated with a larger leaf area ratio and a higher photosynthetic rate per unit leaf area. Higher overall photosynthetic rates in F. insipida were associated with an approximately fivefold larger stomatal conductance than in P. guatemalensis. We surmise that a higher whole-plant hydraulic conductance in the vessel bearing angiosperm F. insipida enabled higher leaf area ratio and higher stomatal conductance per unit leaf area than in the tracheid bearing P. guatemalensis, which enabled F. insipida to capitalize on increased photosynthetic capacity driven by higher nitrogen availability in fertilized soil.

scholarly journals Water Relations and Growth of Vinca Following Chemical Growth Regulation

1995 ◽  
Vol 13 (1) ◽  
pp. 19-21
Author(s):  
Kim P. Fuller ◽  
Jayne M. Zajicek
Keyword(s):  
Stomatal Conductance ◽  
Leaf Area ◽  
Water Use ◽  
Growth Regulation ◽  
Foliar Spray ◽  
Dry Weight ◽  
Plant Size ◽  
Plant Water Use ◽  
Chemically Treated ◽  
Leaf Dry Weight

Abstract Growth of vinca (Vinca major (L.)) was limited by either a medium drench application of uniconazole of 2 or 4 mg a.i. per pot or a foliar spray application of 2, 4, or 6.25 mg a.i. per plant, both applied in 25 ml (0.75 fl oz) of water. Shoot length, leaf number, leaf area, leaf dry weight and stem dry weight averaged over uniconazole treatments were 51%, 45%, 32%, 33%, and 38% less than control plants, respectively. When compared to control plants, water use of chemically treated plants was reduced by 35% due to the reduction of leaf area and also lower stomatal conductance readings. Stomatal conductance readings of chemically treated plants were 2 to 5 times less than control plants indicating the plant size was not the only factor affecting plant water use.

Abscisic Acid and Cytokinins as Possible Root-to-Shoot Signals in Xylem Sap of Rice Plants in Drying Soil

1993 ◽  
Vol 20 (1) ◽  
pp. 109 ◽  
Author(s):  
A Bano ◽  
K Dorffling ◽  
D Bettin ◽  
H Hahn
Keyword(s):  
Abscisic Acid ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Root System ◽  
Nutrient Solution ◽  
Xylem Sap ◽  
Zeatin Riboside ◽  
Stem Water Potential ◽  
Rice Plants ◽  
Stem Water

Seedlings of rice cv. IR 36 were grown in soil in small pots with a horizontally divided root system: after 6-7 weeks, about 20% of the entire root system had protruded through the holes at the base of the pots and was kept in contact with nutrient solution. At this stage the plants were exposed to three different treatments: (a) the soil was kept watered and the protruding free roots were dried in air; (b) the free roots were kept moist and the soil left unwatered; (c) both soil and protruding roots were left unwatered for 30 h and then rewatered. During the first hours of treatment a and b, a decline in stomatal conductance was observed, whereas the stem water potential remained unchanged. The concentration of abscisic acid (ABA) in the xylem, however, increased. At later stages of treatment a and b, the stem water potential began to decrease with a parallel further increase of xylem ABA. Xylem sap contained considerable amounts of bound ABA, the level of which increased during total root drying and decreased again after rewatering. Level of cytokinins, zeatin (t-Z)+zeatin riboside (t-ZR) and isopentenyladenine (2iP) + isopentenyladenosine (2iPA), on the contrary, decreased during root drying and increased again after rewatering. The results are discussed with regard to a possible function of ABA and cytokinins as root-to-shoot signals.

scholarly journals Trajectories: how functional traits influence plant growth and shade tolerance across the life-cycle

2016 ◽  
Author(s):  
Daniel S. Falster ◽  
Remko A. Duursma ◽  
Richard G. FitzJohn
Keyword(s):  
Growth Rate ◽  
Plant Growth ◽  
Leaf Area ◽  
Functional Traits ◽  
Shade Tolerance ◽  
Seed Mass ◽  
Plant Size ◽  
Light Environment ◽  
Unit Leaf Area ◽  
Unit Leaf

AbstractPlant species differ in many functional traits that drive differences in rates of photosynthesis, biomass allocation, and tissue turnover. Yet, it remains unclear how – and even if – such traits influence whole-plant growth, with the simple linear relationships predicted by existing theory often lacking empirical support. Here we present a new theoretical framework for understanding the effect of diverse functional traits on plant growth and shade-tolerance, extending a widely-used theoretical model that links growth rate in seedlings with a single leaf trait to explicitly include influences of size, light environment, and five other prominent traits: seed mass, height at maturation, leaf mass per unit leaf area, leaf nitrogen per unit leaf area, and wood density. Based on biomass production and allocation, this framework explains why the influence of prominent traits on growth rate and shade tolerance often varies with plant size and why the impact of size on growth varies among traits. Considering growth rate in height, we find the influence of: i) leaf mass per unit leaf area is strong in small plants but weakens with size, ii) leaf nitrogen per unit leaf area does not change with size, iii) wood density is present across sizes but is strongest at intermediate sizes, iv) height at maturation strengthens with size, and v) seed mass decreases with size. Moreover, we show how traits moderate plant responses to light environment and also determine shade tolerance, supporting diverse empirical results. By disentangling the effects of plant size, light environment and traits on growth rates, our results provide a solid theoretical foundation for trait ecology and thus provide a platform for understanding growth across diverse species around the world.

scholarly journals A Canopy Transpiration Model Based on Scaling Up Stomatal Conductance and Radiation Interception as Affected by Leaf Area Index

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 252
Author(s):  
Muhammad Shahinur Alam ◽  
David William Lamb ◽  
Nigel W. M. Warwick
Keyword(s):  
Stomatal Conductance ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Festuca Arundinacea ◽  
Radiation Energy ◽  
Scaling Up ◽  
Controlled Environment ◽  
Canopy Conductance ◽  
Individual Layer ◽  
Area Index

Estimating transpiration as an individual component of canopy evapotranspiration using a theoretical approach is extremely useful as it eliminates the complexity involved in partitioning evapotranspiration. A model to predict transpiration based on radiation intercepted at various levels of canopy leaf area index (LAI) was developed in a controlled environment using a pasture species, tall fescue (Festuca arundinacea var. Demeter). The canopy was assumed to be a composite of two indistinct layers defined as sunlit and shaded; the proportion of which was calculated by utilizing a weighted model (W model). The radiation energy utilized by each layer was calculated from the PAR at the top of the canopy and the fraction of absorbed photosynthetically active radiation (fAPAR) corresponding to the LAI of the sunlit and shaded layers. A relationship between LAI and fAPAR was also established for this specific canopy to aid the calculation of energy interception. Canopy conductance was estimated from scaling up of stomatal conductance measured at the individual leaf level. Other environmental factors that drive transpiration were monitored accordingly for each individual layer. The Penman–Monteith and Jarvis evapotranspiration models were used as the basis to construct a modified transpiration model suitable for controlled environment conditions. Specially, constructed self-watering tubs were used to measure actual transpiration to validate the model output. The model provided good agreement of measured transpiration (actual transpiration = 0.96 × calculated transpiration, R2 = 0.98; p < 0.001) with the predicted values. This was particularly so at lower LAIs. Probable reasons for the discrepancy at higher LAI are explained. Both the predicted and experimental transpiration varied from 0.21 to 0.56 mm h−1 for the range of available LAIs. The physical proportion of the shaded layer exceeded that of the sunlit layer near LAI of 3.0, however, the contribution of the sunlit layer to the total transpiration remains higher throughout the entire growing season.

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