scholarly journals DIFFUSIVE RESISTANCE, TRANSPIRATION, AND PHOTOSYNTHESIS IN SINGLE LEAVES OF CORN AND SORGHUM IN RELATION TO LEAF WATER POTENTIAL

1973 ◽  
Vol 53 (3) ◽  
pp. 537-544 ◽  
Author(s):  
C. L. BEADLE ◽  
K. R. STEVENSON ◽  
H. H. NEUMANN ◽  
G. W. THURTELL ◽  
K. M. KING
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Zea Mays L ◽  
Narrow Range ◽  
Light Flux ◽  
Leaf Water ◽  
Diffusive Resistance ◽  
Chamber Studies ◽  
Growth Chamber Studies ◽  
Mesophyll Resistance

Growth chamber studies were conducted to determine the relationships between leaf water potential and diffusive resistance, transpiration rate, and photosynthesis in corn (Zea mays L.) and sorghum (Sorghum vulgare L.). Few differences were apparent between species in response to leaf water potentials above −8 to −6 bars at all light flux densities used. At lower potentials their ability to withstand water stress differed. Rapid increases in both total resistance to water vapor and mesophyll resistance to carbon dioxide within a narrow range of water potential were observed in corn with simultaneous decreases in transpiration and photosynthesis. More gradual changes occurred in sorghum, with little increase in mesophyll resistance except at the highest light flux density. Photosynthetic rate of sorghum was still 25% of maximum at −11.5 bars whereas corn was severely wilted and photosynthesis had ceased at a similar water potential.

COMPARISON BETWEEN TWO INBRED CORN LINES FOR DIFFUSIVE RESISTANCES, PHOTOSYNTHESIS AND TRANSPIRATION AS A FUNCTION OF LEAF WATER POTENTIAL

1974 ◽  
Vol 54 (4) ◽  
pp. 765-770 ◽  
Author(s):  
P. A. DUBÉ ◽  
K. R. STEVENSON ◽  
G. W. THURTELL
Keyword(s):  
Water Vapor ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Zea Mays L ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Water Potentials ◽  
Diffusive Resistance ◽  
Response To Water ◽  
Mesophyll Resistance

Relationships between (1) photosynthesis (2) transpiration (3) total diffusive resistance to water vapor and (4) mesophyll resistance and leaf water potential were examined in two lines of corn (Zea mays L.) differing in phenotypic response to water stress. One line (Q-188) was a wilting inbred and the other (DR-1) was an inbred known to have at least some heat and drought resistance under field conditions. No differences were found between inbred lines in net photosynthetic rate, transpiration rate and total diffusive resistance to water vapor at high or low leaf water potentials in the light. In both lines, stomatal closure began to occur between − 8.5 to − 9.5 bars. Similarly, rapid increases in both total resistance to water vapor diffusion and mesophyll resistance to carbon dioxide diffusion occurred within a narrow range of water potentials. However, leaf water potential, and thus all other parameters, differed markedly between lines when considered on a time scale. The early wilting of Q-188 suggested that high resistances to water flow were present in the xylem system.

Anomalous Water Relations in Copper-Deficient Wheat Plants

1976 ◽  
Vol 3 (2) ◽  
pp. 229 ◽  
Author(s):  
RD Graham
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Leaf Water Potential ◽  
Copper Deficiency ◽  
Water Status ◽  
Specific Effect ◽  
Water Levels ◽  
Leaf Water ◽  
Diffusive Resistance ◽  
Effect Of Copper

Leaf water potential, diffusive resistance, relative water content, weekly water use, yields and head bending were measured on wheat plants subjected to four copper levels (0, 0.4, 0.8 or 4.0 mg Cu per pot) and two water levels (6 or 12% soil water content). Severe copper deficiency (Cu 0) resulted in no grain yield, wilting, increased leaf diffusive resistance and, at the same time, increased leaf water potential relative to plants receiving 4.0 mg Cu (Cu 4.0). Water supply effects were observed but there was no interaction between copper and water treatments. Mild copper deficiency (Cu 0.4, Cu 0.8) resulted in small yield decreases, relative to Cu 4.0, and increased head bending towards maturity. It is concluded that wilting, characteristic of copper-deficient plants, is due to structural weakness (decreased lignification) and not to the water status of the plants; also, increased leaf diffusive resistance is due to a specific effect of copper deficiency on guard cells and not to decreased leaf water potential.

NET CO2 EXCHANGE RATE AS A SENSITIVE INDICATOR OF PLANT WATER STATUS IN CORN (Zea mays L.)

1988 ◽  
Vol 68 (3) ◽  
pp. 597-606 ◽  
Author(s):  
R. CEULEMANS ◽  
I. IMPENS ◽  
M. C. LAKER ◽  
F. M. G. VAN ASSCHE ◽  
R. MOTTRAM
Keyword(s):  
Zea Mays ◽  
Exchange Rate ◽  
Water Stress ◽  
Water Potential ◽  
Soil Water ◽  
Leaf Water Potential ◽  
Zea Mays L ◽  
Leaf Water ◽  
Water Capacity ◽  
Available Water Capacity

With the objective to evaluate and compare different physiological plant parameters as indicators of water stress, net CO2 exchange rate (NCER), leaf temperature, predawn and daytime leaf water potential were monitored diurnally on last fully expanded leaves of corn (Zea mays L.) plants under two different soil water treatments (stressed and nonstressed) during a 10-d period at anthesis in a semi-arid region in South Africa. Profile available water capacity (PAWC) was used to express the soil water contents during the experiments. A significant decrease in NCER was noticed as soon as 30% of PAWC was extracted, i.e. 2 or 3 d after irrigation. Although the results were limited to a short, well-defined measuring period, NCER, and especially NCER at noon, seemed to be a more sensitive and more reliable indicator of corn water stress than, for example, predawn or daytime leaf water potential, at least under the conditions studied here. This reduction in NCER might have a significant impact on total biomass, rooting density, flower and ear formation.Key words: Corn, irrigation scheduling, photosynthesis, leaf water potential, profile available water capacity, soil water content

EFFECTS OF WATER STRESS ON LEAF RESPIRATION, TRANSPIRATION RATES IN THE DARK AND CUTICULAR RESISTANCE TO WATER VAPOR DIFFUSION OF TWO CORN INBREDS

1975 ◽  
Vol 55 (2) ◽  
pp. 565-572 ◽  
Author(s):  
P. A. DUBÉ ◽  
K. R. STEVENSON ◽  
G. W. THURTELL ◽  
R. B. HUNTER
Keyword(s):  
Water Vapor ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Inbred Line ◽  
Leaf Water ◽  
Leaf Respiration ◽  
Vapor Diffusion ◽  
Water Vapor Diffusion ◽  
Growth Chamber Studies ◽  
Cuticular Resistance

Growth chamber studies were undertaken to determine relationships between leaf respiration and transpiration in the dark, and leaf water potential. Leaf cuticular resistances were calculated. Two lines of corn (Zea mays L.), one a wilting inbred line, Q188, and the other, DR1, an inbred line known to have at least some heat and drought tolerance under field conditions were used in this study. Differences were found in dark transpiration and the magnitude of cuticular resistances to water vapor diffusion between these lines. Dark transpiration occurred at a greater rate in Q188 than in DR1. Both lines showed decreased transpiration as leaf water potentials decreased and were not significantly different in this respect. Cuticular resistance to water vapor diffusion was higher initially in DR1 than in Q188 and also increased at a faster rate in DR1 as the drying cycle progressed. Incomplete recovery in leaf water potential was observed in both lines upon watering after severe desiccation. No differences were found in leaf respiration rates between the inbreds.

Emerging effects of selected rhizosphere properties on transpiration and leaf water potential of two Zea mays L. genotypes in semi-arid environments

2020 ◽  
Author(s):  
Tina Köhler ◽  
Daniel-Sebastian Moser ◽  
Ákos Botezatu ◽  
Jana Kholova ◽  
Andrea Carminati ◽  
...  
Keyword(s):  
Zea Mays ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Zea Mays L ◽  
Root Hairs ◽  
Leaf Water ◽  
Soil Drying ◽  
Wild Type ◽  
Stomatal Regulation ◽  
Semi Arid

<p>Understanding the mechanisms that control water use of plants exposed to soil drying and increasing vapour pressure deficit (VPD) has important implications for crop growth in semi-arid regions with low-input agriculture. In particular, the effect of belowground processes on transpiration and stomatal regulation remains controversial. Objective of this study was to understand the role of soil properties and root hairs (as an example of rhizosphere traits) on transpiration and leaf water potential. We hypothesize that root hairs facilitate the water extraction from drying soils, particularly at high VPD, and that this impacts the relation between transpiration rate and leaf water potential. We further hypothesize that stomatal regulation attenuates the drop in leaf water potential when the soil water flow cannot match the transpiration demand and thus emphasizes the importance of root hairs on transpiration rates during soil drying.</p><p>We compared maize (Zea mays L.) with (wild-type) and without (mutant) root hairs in three different soil substrates (Alfisol, Vertisol and Sandy Soil). Transpiration and leaf water potential were monitored at varying VPD and soil moistures during soil drying. The hairless mutant showed a higher transpiration in wet soils but declined transpiration at greater water contents as compared to the wild-type. Under well-watered conditions, both genotypes had the highest transpiration rates in Vertisol. In Vertisol, both genotypes closed their stomata at relatively higher water content levels. The relation between transpiration and soil moisture strongly varied between soils. No obvious differences between the genotypes were visible in the relationship between leaf water potential and transpiration. This is explained by the prompt closure of stomata. This study provides experimental evidence of the strong link between stomatal regulation and soil-root hydraulic properties.</p>

scholarly journals IDENTIFICATION OF ROOT (WILT) DISEASED COCONUT PALMS BEFORE VISUAL SYMPTOM EXPRESSION

CORD ◽  
1989 ◽  
Vol 5 (02) ◽  
pp. 34
Author(s):  
V. Rajagoval ◽  
B. Sumathykuttyamma
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Cocos Nucifera ◽  
Stomatal Resistance ◽  
Leaf Water ◽  
Symptom Expression ◽  
Diffusive Resistance ◽  
Cocos Nucifera L ◽  
Apparently Healthy

Determination of stomatal resistance (rs) and leaf water potential (ψ) were employed as techniques to distinguish coconut palms (Cocos nucifera L.) devoid of foliar symptoms ('apparently healthy') from those with symptorns of wilt disease viz. flaccidity, yellowing and necrosis ('wilt diseased'). Infected palms are characterized by low stomatal diffusive resistance and reduction in leaf water potential. Among the apparently healthy palms, some exhibited high rs and high ψ, characteristic of truly healthy palms, while others had the trend similar to the 'wilt' diseased palms. The latter group of palms was considered as disease 'suspects' and was closely monitored for the symptom expression. In about 10 to 14 months, all the palms 'suspected' to be diseased had the visual symptoms of the disease.

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