J. M. Peacock

International Center for Agricultural Research in the Dry Areas

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Trends

Author Order

Document Type

Co-Authors

P. Soman

Jain Irrigation Systems (India)

Robin Matthews

Kingston University

L. van Rensburg

University of the Free State

S.N. Azam-Ali

University of Nottingham Malaysia Campus

A. J. PARKER

University of Manchester

J. A. Hockey

University of Manchester

P. G. Ashmore

British Columbia Children's Hospital

P. S. Raju

Defence Research Laboratory

F. R. Bidinger

International Crops Research Institute for the Semi-Arid Tropics

D.J. Flower

International Crops Research Institute for the Semi-Arid Tropics

Cooperative Institutions

International Crops Research Institute for the Semi-Arid Tropics

International Center for Agricultural Research in the Dry Areas

Oregon State University

Centre National de la Recherche Scientifique

University of Bern

Utrecht University

Centro Internacional de Mejoramiento de Maíz Y Trigo

University of British Columbia

Agricultural Research Service

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Field

Determination of Epidermal Transpiration in Four Cultivars ofNicotiana TabacumL. Using Epidermal Strips in a Quasi-Steady State System

Biotechnic & Histochemistry (1998)

L. van Rensburg J. M. Peacock

A quasi-steady state method is presented for quantifying epidermal transpiration of epidermal strips where simple relations between transmembrane fluxes and parameters of diffusibility of penetrating compounds hold. Contrary to most permeability studies, we did not use astomatous, enzymatically isolated, or dried cuticular membranes, because these procedures are largely responsible for the problems cited in the literature. Instead, we used freshly harvested stomatous epidermal strips, thus avoiding the sorption of lipids by the cuticular membranes during enzymatic isolation. Our approach allowed estimation of amounts and composition of intracuticular soluble lipids. Diffusion coefficients (D-values) were calculated with smaller associated standard deviations and an order of magnitude lower than previously reported; the fresh material sorption of the diffusing compound by the membrane and hydration of the cuticular pores was greatly reduced. In the present study the hold-up time (te) ranged from 66.2 ± 0.3 to 110.3 ± 0.9sec. Furthermore, 0.1 μm thick membranes were used, contrary to previous studies of water permeability that used cuticles more than 2 μm thick. Because a small but constant flow of penetrant could be detected during the first half of the steady flow to te, small holes probably did not influence the reported permeability. Permeability coefficients (Pd) in the order of 0.65 × 10−9 ms−1 were calculated. Pd values in the order of 5.68 × 10−3 ms−1 were calculated when incomplete stomatal closure occurred, while when areas of mass flow were detected, Pd values in the order of 1.26 × 10−2 ms−1 were calculated. The degree of contamination of the epidermal strips by cellular debris was quantified and expressed as the total chlorphyll content per exposed surface area of the epidermal strip, and an average of 8.7% contamination was observed compared to the total leaf chlorophyll content. Leakage from the system was calculated to be approximately 0.18 × 10−10 ms−1, which represents an average 2.7% experimental variability. These results are discussed in terms of the limitations associated with using composite membranes that are stomatous and have trichomes, for possible application in drought tolerance selection.

10.3109/10520299809140513

Cite

Citations (1)

Canopy Photosynthesis and Crop Growth Rate of Eight Temperate Forage Grasses

Journal of Experimental Botany (1975)

J. E. SHEEHY J. M. Peacock

The rates of canopy and individual leaf photosynthesis, rates of growth of shoots and roots, and the extinction coefficient for light of eight temperate forage grasses were determined in the field during early autumn. Canopy gross photosynthesis was calculated as net photosynthesis plus dark respiration adjusted for temperature using a Q10 = 2. The relationships between canopy gross photosynthesis and light intensity were hyperbolic, and the initial slopes of these curves indicated that light was being utilized efficiently at low light intensities. The initial slope depended on the distribution of light in the canopy and the quantum efficiency of the individual leaves. The maximum rate of canopy gross photosynthesis reflected the maximum rate of individual leaf photosynthesis. Although the maximum rate of canopy gross photosynthesis was correlated with crop growth rate, there was no significant relationship between daily gross photosynthesis and crop growth rate. Indeed, daily gross photosynthesis varied by only 22 per cent, whereas the daily growth of shoots and roots varied by 120 per cent. This poor correlation is influenced by a negative correlation (P < 0.01) between the maximum rate of canopy gross photosynthesis and the initial slope of the curve relating canopy gross photosynthesis and light intensity. Difficulties in the interpretation of measurements of dark respiration appeared to confound attempts to relate daily net photosynthesis to crop growth rate, individual leaf photosynthesis, and the extinction coefficient for light.

Light intensity

10.1093/jxb/26.5.679

Cite

Citations (33)

Conservation through utilization: a case study of the indigenous forage grasses of the Arabian Peninsula

Journal of Arid Environments (2003)

J. M. Peacock Morag Ferguson Ghaleb Alhadrami I. McCann A.Al Hajoj

Overgrazing

Fodder

Peninsula

10.1006/jare.2001.0895

Cite

Citations (33)

Breeding for low-nutrient environments: Is it sustainable?

Springer eBooks (2002)

J. M. Peacock

Soil nutrients

10.1007/978-94-017-1570-6_6

Cite

Citations (0)

A phytocentric perspective of Asterolecanium quercicola Bouché infestation on Quercus robur L. trees along an urbanization gradient

South African Journal of Botany (1997)

L. van Rensburg G.H.J. Krüger B. Ubbink M.C. Scholes J. M. Peacock

Diurnal courses in gas exchange, photochemical efficiency and water relations were monitored during two late summers in three groups of adult Quercus robur L. trees, planted along an urbanization gradient that correlated positively with the degree of die-back exhibited by the trees. Leaf carbon:nitrogen ratios, proline and polyphenol levels were monitored to explain why the intermediate group of trees were more severely infested (p ≤ 0.01) with Asterolecanium quercicola (Bouché). All three groups of trees showed a significant correlation of net photosynthesis with photon flux density (PPFD), but A correlated more positively with the pre-dawn leaf water potential ψpd of the moderately (trees of group b, i.e. at the edge of town) and severely (trees of group c, i.e. urban) water-stressed trees. A of the rural trees and stomatal conductance (g) of the three groups of trees showed little correlation ψpd values. Possibly due to the long-term effect of stress, g, as reflected by changes in the transpiration rate (E), showed a significantly (p ≤ 0.01) higher sensitivity to relative ambient humidity (RH) in the trees of groups b and c. Photochemically, a close coupling was found to exist between A, ψpd, RH, the time needed to reach the maximum fluorescence level, i.e. FTm, and S, i.e. the complementary area normalized to the variable fluorescence, indicating that the trees were also affected at this level of organization. Proline accumulation occurred in the trees of group c but not in the trees of group b, as opposed to the polyphenolic concentrations which were significantly (p ≤ 0.05) higher in the trees of group b than in the trees of group c. A possible explanation for the higher infestation of A. quercicola on the trees in group b is given in terms of their host specificity and changes in these trees' nitrogen levels.

Quercus robur

Stomatal Conductance

Positive correlation

10.1016/s0254-6299(15)30688-8

Cite

Citations (6)

High Temperature Effects on Seedling Emergence and Embryo Protein Synthesis of Sorghum

Crop Science (1988)

Helen Ougham J. M. Peacock J. L. Stoddart P. Soman

High soil temperatures (>45°C) inhibit the field emergence of sorghum [ Sorghum bicolor (L.) Moench] in the semiarid tropics. The objective of this study is to demonstrate that the measurement of embryo protein synthesis (EPS) is convenient an d rapid technique for the assessment of sorghum emergence at high soil temperatures. Two experiments were conducted, one using four landrace accessions and another using 14 commercially available lines. Seedling emergence was measured in a large water bath containing a series of soil‐filled clay pots. The temperature of the soil in the pots could be regulated (35–50°C) using infrared lamps. Protein synthesis was measured by incubating embryo‐containing half‐seeds with 14 C‐labeled amino acids at different temperatures (35–40°C); the resulting labeled proteins were extracted for counting. The relative rankings of the landraces with respect to EPS and emergence demonstrated that the EPS technique clearly distinguished between lines that were able or unable to emerge at 50°C. However, with the commercially available lines, despite the agreement between the ranking of EPS and emergence, two lines diverged from this relationship, which is attributed to the greater complexity of the overall emergence process.

Sorghum bicolor

10.2135/cropsci1988.0011183x002800020014x

Cite

Citations (14)

Temperature and Leaf Growth in Lolium perenne. III. Factors Affecting Seasonal Differences

Journal of Applied Ecology (1975)

J. M. Peacock

Lolium

10.2307/2402182

Cite

Citations (69)

Temperature and Leaf Growth in Lolium perenne. II. The Site of Temperature Perception

Journal of Applied Ecology (1975)

J. M. Peacock

Lolium

10.2307/2401721

Cite

Citations (154)

Assessment of genotypic differences in sorghum root characteristics.

N. Seetharama D.J. Flower R. Jayachandran K. Rama Krishna J. M. Peacock

Representative data on genotypic differences in sorghum root characteristics are examined for prospective use in applied breeding programmes. Significant genotype differences in root characteristics observed are: root-length density at lower depths when the crop 15 grown on stored. soil moisture. root-shoot ratios early establishment of nodal Roots In seedlings, and microbial associations of roots. Four-fold genotypic differences root-shoot ratio were found at the seedling stage, but high ontogenic shifts negated these differences at later stages. Hence . sorghum breeding for efficient root systems should be confined to well- defined target environments with specific objectives.

Root (linguistics)

Root system

Source

Cite

Citations (6)

Some apparent partial molal volumes of salts in ethylenediamine solutions

Proceedings of the Indiana Academy of Science (1955)

R. E. Davis J. M. Peacock Frederic C. Schmidt Ward B. Schaap

Molality

Ethylene diamine

Source

Cite

Citations (0)