A Gene Controlling Differences in Osmoregulation in Wheat

1991 ◽  
Vol 18 (3) ◽  
pp. 249 ◽  
Author(s):  
JM Morgan
Keyword(s):  
Water Content ◽  
Osmotic Potential ◽  
Relative Water Content ◽  
Flag Leaf ◽  
Single Gene ◽  
Recessive Gene ◽  
Single Chromosome ◽  
Relative Water ◽  
Environment Chamber ◽  
Response To Water

Evidence is presented for a single gene controlling differences in osmoregulation in wheat in response to water stress, confirming earlier results. Analyses of osmoregulation were made on the flag leaves of wheat plants which were grown in pots in the glasshouse and stressed in a controlled environment chamber by withholding water after the flag leaf had fully emerged. Osmoregulation was derived from responses of osmotic potential to relative water content or from responses of relative water content and osmotic potential to water potential. Usable estimates of osmoregulation were obtained for 67 F2 lines derived from contrasting parents, to test for gene number, and for one substitution series with contrasting parents, to determine chromosomal location. The F2 frequency response, which consisted of two overlapping distributions, was compatible with a single recessive gene, the estimated ratio being 2.79 : 1 (low: high osmoregulation). This confirmed previous measurements made on F1s and F4s Results for the substitution series were also compatible with these results in indicating a single chromosome, 7A, which had an identical response to the low osmoregulation parent, Red Egyptian. The effects of the gene were confined to solute accumulations at water potentials above, but not below, zero turgor.

Osmoregulation as a selection criterion for drought tolerance in wheat

1983 ◽  
Vol 34 (6) ◽  
pp. 607 ◽  
Author(s):  
JM Morgan
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Water Deficit ◽  
Relative Water Content ◽  
Flag Leaf ◽  
Single Gene ◽  
Selection Criterion ◽  
Breeding Lines ◽  
Intermediate Group ◽  
Relative Water

A method is described in which measurements of osmoregulation made on glasshouse-grown wheat plants may be used to select lines which yield higher under conditions of water deficit in the field. The procedure involved growing F4 breeding lines in pots in a semi-controlled glasshouse. When the plants reached booting stage, they were transferred to a controlled environment chamber and droughted by withholding water. During the water deficit cycle approximately 10 flag leaf samples from each line were taken, and measurements were made of relative water content, osmotic potential and water potential. The lines were evaluated using estimates of the relative water content at either osmotic or water potential values of -2.5 MPa, after relationships between these measurements and relative water content had been established. The distribution of data into two main groups with a smaller intermediate group indicated possible single gene control. Under drought conditions in the field, lines selected from the high osmoregulating group maintained turgor to lower water potentials and gave grain yields which were 1.6 and 1.5 times greater than those selected from the low group at the F4 and F6 stages respectively.

scholarly journals Correlation and Path Coefficient Analysis in Bread Wheat (Triticum aestivum L.) Genotypes for Morpho-physiological Traits along with Grain Fe and Zn Content

2020 ◽  
pp. 130-140
Author(s):  
Mainak Barman ◽  
Vinay Kumar Choudhary ◽  
Satish Kumar Singh ◽  
Rabiya Parveen ◽  
Abhishek K. Gowda
Keyword(s):  
Triticum Aestivum ◽  
Grain Yield ◽  
Water Content ◽  
Leaf Area ◽  
Relative Water Content ◽  
Flag Leaf ◽  
Triticum Aestivum L ◽  
Path Coefficient ◽  
Path Coefficient Analysis ◽  
Relative Water

Character association studies help in assessing the relationship among yield and its components to enhance the selection utility. In view of this, the present research was carried out for assessing correlation and path coefficients among 30 bread wheat (Triticum aestivum L.) genotypes using fifteen quantitative parameters. Correlation analysis demonstrated a noteworthy positive relationship of days to fifty per cent flowering, number of tillers/plant, flag leaf area, spike length, plant height, chlorophyll content, relative water content, number of grains/ ear, thousand-grain weight, days to maturity and harvest index, with grain yield per plant at both the phenotypic and genotypic level except canopy temperature which showed a significant negative relationship. Path coefficient analysis revealed that plant height, flag leaf area, relative water content and grain per ear had the maximum positive direct effect on grain yield. Hence, the present investigation can be helpful in executing a reliable selection of parental lines based on these above mentioned traits in addition to developing high-yielding varieties for further breeding programme.

Genotypic variation for drought stress response traits in soybean. I. Variation in soybean and wild Glycine spp. for epidermal conductance, osmotic potential, and relative water content

2008 ◽  
Vol 59 (7) ◽  
pp. 656 ◽  
Author(s):  
A. T. James ◽  
R. J. Lawn ◽  
M. Cooper
Keyword(s):  
Water Content ◽  
Wild Species ◽  
Osmotic Potential ◽  
Relative Water Content ◽  
Stomatal Closure ◽  
Genotypic Variation ◽  
Soil Water Potential ◽  
Genotypic Differences ◽  
Relative Water ◽  
Soybean Genotypes

Studies were undertaken to assess genotypic variation in soybean and related wild species for traits with putative effects on leaf turgor maintenance in droughted plants. Traits of interest were (i) epidermal conductance (ge) which influences the rate of water loss from stressed leaves after stomatal closure; (ii) osmotic adjustment (OA) as indicated by tissue osmotic potential (π), which potentially affects the capacity to withdraw water at low soil water potential; and (iii) relative water content (RWC) at incipient leaf death (critical relative water content, RWCC), which is a measure of the dehydration tolerance of leaf tissue. The germplasm comprised a diverse set of 58 soybean genotypes, 2 genotypes of the annual wild species G. soja and 9 genotypes representing 6 perennial wild Glycine spp. indigenous/endemic to Australia. Seedling plants were grown in soil-filled beds in the glasshouse and exposed to terminal water deficit stress from the second trifoliolate leaflet stage (21 days after sowing). Measurements were made on well watered plants, moderately stressed plants, and at incipient plant death, in 2 separate studies. In both studies, there were significant genotypic differences in all 3 traits in the stressed plants. However, across the 3 sample times, ge decreased and the absolute magnitude of π increased, indicating that the expression of these traits changed as the plants acclimated to the stress. RWC was therefore used as a covariate to adjust the genotypic values of π and ge in order to facilitate comparison at a consistent plant water status of 70% RWC. There was statistically significant genotypic variation for the adjusted values, ge70 and π70, in both studies, and genotypic correlations between the 2 studies were significant (P < 0.05) and positive for all 3 traits: ge70 (r = 0.48), π70 (r = 0.50), and RWCC (r = 0.53). Among the soybean genotypes, there was at least a 2-fold range in ge70, a 0.7 MPa range in π70, and a 12 percentage point range in RWCC. Some of the perennial wild genotypes exhibited lower values of ge and RWCC and greater OA than soybean and G. soja, consistent with adaptation to drier environments. While the repeatability of measurement between experiments was variable among genotypes, the studies confirmed the existence of genotypic differences for ge, OA, and RWCC in cultivated soybean, with a wider range among the wild germplasm.

scholarly journals Genetic control and combining ability of flag leaf area and relative water content traits of bread wheat cultivars under drought stress condition

Genetika ◽  
2013 ◽  
Vol 45 (2) ◽  
pp. 351-360 ◽  
Author(s):  
Ahmad Golparvar
Keyword(s):  
Drought Stress ◽  
Water Content ◽  
Leaf Area ◽  
Genetic Control ◽  
Bread Wheat ◽  
Combining Ability ◽  
Relative Water Content ◽  
Flag Leaf ◽  
Mean Square ◽  
Relative Water

In order to compare mode of inheritance, combining ability, heterosis and gene action in genetic control of traits flag leaf area, relative water content and grain filling rate of bread wheat under drought stress, a study was conducted on 8 cultivars using of Griffing?s method2 in fixed model. Mean square of general combining ability was significant also for all traits and mean square of specific combining ability was significant also for all traits except relative water content of leaf which show importance of both additive and dominant effects of genes in heredity of these traits under stress. GCA to SCA mean square ratio was significant for none of traits. Results of this study showed that non additive effects of genes were more important than additive effect for all traits. According to results we can understand that genetic improvement of mentioned traits will have low genetic efficiency by selection from the best crosses of early generations. Then it is better to delay selection until advanced generations and increase in heritability of these traits.

Genotypic variation for drought stress response traits in soybean. III. Broad-sense heritability of epidermal conductance, osmotic potential, and relative water content

2008 ◽  
Vol 59 (7) ◽  
pp. 679 ◽  
Author(s):  
A. T. James ◽  
R. J. Lawn ◽  
M. Cooper
Keyword(s):  
Water Content ◽  
Osmotic Potential ◽  
Relative Water Content ◽  
Genotypic Variation ◽  
Broad Sense ◽  
Broad Sense Heritability ◽  
Relative Water ◽  
Rainout Shelter ◽  
Additive Gene ◽  
Leaf Survival

The broad-sense heritability of 3 traits related to leaf survival in severely stressed plants was studied in several hybrid soybean populations. The 3 traits were epidermal conductance (ge), osmotic potential (π), and relative water content (RWC). The populations were generated by hybridising unrelated parental genotypes previously shown to differ in the 3 traits. ge (mm/s) was measured on well watered plants from 10 populations involving all combinations of 5 parental lines, grown in soil-filled beds in the glasshouse. π (MPa) and RWC (%) were measured on severely stressed plants of 3 populations involving all combinations of 3 different parents, growing into a terminal water deficit under a rainout shelter in the field. Broad-sense heritability for ge was significantly different from zero (P < 0.05) in all 10 populations and ranged from 60% to 93%. Heritability estimates for π70 (the tissue osmotic potential at 70% RWC) ranged from 33% to 71%. Only two estimates were statistically significant (P < 0.05) because of large standard errors and the fact that parental differences were smaller than previously observed. Broad-sense heritability for RWC of severely stressed plants ranged from 40% to 74%, and was statistically significant (P < 0.05) for 2 of the 3 populations. For all 3 traits, F2 progeny distributions were consistent with quantitative inheritance with a high degree of additive gene action. It was concluded that capacity exists to breed varieties with low ge, low π70, and high RWC in stressed plants. However, in the case of osmotic potential, genotypes with lower π70 combined with greater precision of measurement would be needed than proved possible in these studies. Further, specific strategies would be needed to select for the critical RWC, the minimal RWC at which leaf tissues die and which provides a measure of tissue dehydration tolerance. More research is also needed to characterise the dynamic relations between ge, π, and RWC in influencing leaf survival in soybean, before they could be confidently used in a breeding program to improve drought tolerance.

Genotypic variation for drought stress response traits in soybean. II. Inter-relations between epidermal conductance, osmotic potential, relative water content, and plant survival

2008 ◽  
Vol 59 (7) ◽  
pp. 670 ◽  
Author(s):  
A. T. James ◽  
R. J. Lawn ◽  
M. Cooper
Keyword(s):  
Drought Stress ◽  
Water Content ◽  
Osmotic Potential ◽  
Relative Water Content ◽  
Genotypic Variation ◽  
Genotypic Differences ◽  
Plant Survival ◽  
Turgor Maintenance ◽  
Relative Water ◽  
Rate Of Decline

As part of a project exploring the potential for using leaf physiological traits to improve drought tolerance in soybean, studies were conducted to explore whether epidermal conductance (ge), osmotic potential (π), and relative water content (RWC) influenced turgor maintenance and ultimately the survival of droughted plants. In a glasshouse study, plants of 8 soybean genotypes that showed different expression of the traits were grown in well watered soil-filled beds for 21 days and then exposed to terminal water deficit stress. The trends in each trait were then monitored periodically until plant death. Genotypic differences were observed in the rate of decline in RWC as the soil dried, in the temporal patterns of change in ge and π, in the duration of survival after watering ceased, and in the critical relative water content (RWCC) at which plants died. In general, ge became smaller and π became more negative as RWC declined and plants acclimated to the increasing stress. Genotypic differences in ge remained broadly consistent as RWC declined. In contrast, the genotypic rankings for π in stressed plants were poorly correlated with those for well watered plants, indicating differential genotypic capacity for osmotic adjustment (OA) in response to stress. Survival times among genotypes after stress commenced ranged from 27 to 41 days, while RWCC ranged from 49% down to 41%. The differences in survival time among the genotypes were able to be explained by genotypic differences in the rate of decline in RWC and in the RWCC, using a multiple linear regression relationship (R 2 = 0.94**). In turn, genotypic differences in the rate of decline in RWC were positively correlated (r = 0.75*) with ge at 70% RWC, and with OA over the drying period (r = 0.98**). In a second study in a controlled environment facility, leaf area retention at 90% soil water extraction was greatest in the one genotype that combined low ge, high OA, and low RWCC. Overall, the responses from the two studies were consistent with the hypothesis that turgor maintenance and ultimately leaf and plant survival of different genotypes during advanced stages of drought stress are enhanced by low ge, high OA capacity, and low RWCC.

Some Aspects of the Water Relations of the Lichen Parmotrema Tinctorum Measured Using Thermocouple Psychrometry

1996 ◽  
Vol 28 (3) ◽  
pp. 257-266 ◽  
Author(s):  
R. P. Beckett
Keyword(s):  
Bulk Modulus ◽  
Water Potential ◽  
Water Content ◽  
Water Relations ◽  
Osmotic Potential ◽  
Relative Water Content ◽  
Thermocouple Psychrometer ◽  
Relative Water ◽  
Parmotrema Tinctorum

AbstractThe thermocouple psychrometer was used to determine water potential, Ψ and its components in the lichen Parmotrema tinctorum. Data suggested that using conventional pressure-volume curves to study the water relations of lichens may give anomalous results, possibly because lichens may contain appreciable amounts of intercellular water. A way of correcting pressure-volume curves to remove the effect of intercellular water is discussed. Parmotrema tinctorum had a very low osmotic potential at full turgor (c. −2.5 MPa), and a low bulk modulus of elasticit (c. 2.1 MPa). As a result, P. tinctorum lost turgor only when the relative water content dropped below 0.47. Likely benefits of this for the lichen are discussed.

The Method of Plant Water Status Measurement in Sweet Potato (Ipomoea Batatas (L) Lam.)

2010 ◽  
Vol 7 (1) ◽  
Author(s):  
Saraswati Prabawardani
Keyword(s):  
Water Content ◽  
Sweet Potato ◽  
Relative Water Content ◽  
Water Status ◽  
Plant Water Status ◽  
Equilibration Time ◽  
Plant Water ◽  
Font Size ◽  
Potato Leaf ◽  
Relative Water

<!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning /> <w:ValidateAgainstSchemas /> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables /> <w:SnapToGridInCell /> <w:WrapTextWithPunct /> <w:UseAsianBreakRules /> <w:DontGrowAutofit /> <w:UseFELayout /> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--> <!--[if gte mso 10]> <mce:style><! /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} --> <!--[endif]--> <p class="MsoNormal" style="text-align: justify;"><span style="font-size: 10pt;">The measurement of plant water status such as leaf water potential (LWP) and leaf relative water content (RWC) is important part of understanding plant physiology and biomass production. Preliminary study was made to determine the optimum amount of leaf abrasion and equilibration time of sweet potato leaf inside the thermocouple psychrometer chambers. Based on the trial, the standard equilibration time curve of a Peltier thermocouple for sweet potato leaf was between 2 and 3 hours. To increase the water vapour conductance across the leaf epidermis the waxy leaf cuticle should be removed or broken by abrasion. The result showed that 4 times leaf rubbings was accepted as the most effective way to increase leaf vapour conductance of sweet potato in the psychrometer chambers. In calculating the leaf relative water content, unstressed water of sweet potato leaves require 4 hours imbibition, whereas water stressed of sweet potato leaves require 5 to 6 hours to reach the saturation time. Either leaf water potential or relative water content can be used as a parameter for plant water status in sweet potato.</span><span style="font-size: 10pt;"> </span></p>

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