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

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.

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

Australian Journal of Agricultural Research ◽

10.1071/ar07160 ◽

2008 ◽

Vol 59 (7) ◽

pp. 670 ◽

Cited By ~ 22

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.

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

Australian Journal of Agricultural Research ◽

10.1071/ar07161 ◽

2008 ◽

Vol 59 (7) ◽

pp. 679 ◽

Cited By ~ 8

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.

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EFEITOS DO DÉFICIT HÍDRICO EM PARÂMETROS FISIOLÓGICOS DE FOLHAS DE SORGO (Sorghum bicolor, L.)

Irriga ◽

10.15809/irriga.1998v3n3p81-88 ◽

1998 ◽

Vol 3 (3) ◽

pp. 81-88

Author(s):

Carlos Augusto Lima Porto ◽

Antonio Evaldo Klar ◽

José Vicente Vasconcelos

Keyword(s):

Water Stress ◽

Sorghum Bicolor ◽

Water Potential ◽

Water Content ◽

Relative Water Content ◽

Water Status ◽

Soil Water Potential ◽

Relative Water ◽

Conductivity Water ◽

Sorghum Bicolor L

EFEITOS DO DÉFICIT HÍDRICO EM PARÂMETROS FISIOLÓGICOS DE FOLHAS DE SORGO (Sorghum bicolor, L.) Carlos Augusto Lima PortoAntonio Evaldo Klar(2)José Vicente VasconcelosDepartamento de Engenharia Rural – Faculdade de Ciências Agronômicas – UNESPFone: (014) 821-3883 Fax: (014) 821-343818603-97’ – Botucatu - SP 1 RESUMO O experimento foi conduzido em casa de vegetação no Departamento de Engenharia Rural da Faculdade de Ciências Agronômicas - UNESP/Botucatu, SP, com delineamento experimental inteiramente casualizado, com 12 repetições. A cultura do sorgo (Sorghum bicolor, L.) foi plantada em vasos que continham 8,0 kg de solo (base em peso de solo seco), pertencente ao grande grupo Terra Roxa Estruturada para os dois tratamentos: a) plantas submetidas a défices hídricos, sendo irrigadas quando o potencial de água no solo chegava a -1,5 MPa, elevando-o às imediações de -0,01 MPa), e b) plantas irrigadas constantemente por capilaridade. Todas as plantas foram irrigadas aos 55 dias após a emergência e os parâmetros avaliados foram: condutância estomática, potencial de água e teor relativo de água nas folhas mais novas totalmente expandidas, com determinações diárias entre as onze e treze horas, até que o potencial de água no solo atingisse valores em torno de -1,5 MPa. Da análise geral dos dados obtidos, pode-se inferir que a variação no status de água na folha observado através do potencial e do teor relativo de água nas folhas pode ser utilizado para indicar o momento de irrigar; ainda estas medições podem ser indicativas das plantas ou cultivares de sorgo que se mostram mais tolerantes à seca e que o mecanismo de adaptação é o “avoidance”. UNITERMOS: Condutividade estomática, potencial de água na folha, teor relativo de água na folha, tolerância à seca. PORTO, C. A . L.., KLAR, A. E. , VASCONCELLOS, V. J. Water deficit on physiological parameters of soybean leaves (Sorghum bicolor L). 2 ABSTRACT A study was carried out at Agricultural Engineering Department, UNESP, Botucatu - SP, with a sorghum crop (Sorghum bicolor, L.) in order to physiologically evaluate the crop response to drought. A completely random design with twelve replications were used. Pots with 8 kg of a medium texture soil (dry weight basis) were used in order to test the influence of the two treatments: a) plants being submitted to a water stress, where irrigation were done when the water potential in the soil (s) were -1,5 MPa, raising it to about -0,01 MPa, and b) plants being always irrigated by capillary. The parameters evaluated were water vapor stomata conductivity, water potential and relative water content in the leaves. All plants were irrigated at 55 days after emergency, with daily determinations from eleven AM to thirteen PM, until soil water potential reaches around -1,5MPa. From the general data analysis, it can be inferred that there was a significant variation in the water status in the leaves by determinations of water potential and relative water content in the leaves, indicating that the method may be used to indicate the moment of irrigation and the plants and cultivars more tolerant to drought. Sorghum plants showed adaptation to water stress under avoidance mechanism. KEYWORDS: Stomata conductivity, water potential in the leaves, relative water content, drought tolerance.

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Midday Drop of Relative Leaf Water Content to Drought Tolerance in Soybean

Bangladesh Agronomy Journal ◽

10.3329/baj.v18i2.28901 ◽

2016 ◽

Vol 18 (2) ◽

pp. 31-38

Author(s):

JA Chowdhury ◽

MA Karim ◽

QA Khaliq ◽

MSA Khan ◽

SK Paul ◽

...

Keyword(s):

Water Stress ◽

Drought Tolerance ◽

Water Content ◽

Seed Yield ◽

Relative Water Content ◽

Growth Stages ◽

Water Stress Condition ◽

Relative Water ◽

Soybean Genotypes ◽

And Control

An experiment was conducted in a Venylhouse of Bangabandhu Sheikh Mujibur Rahman Agricultural University during September to December 2012 to determine the effect of midday drop of relative water content (RWC) on drought tolerance of soybean genotypes. Four soybean genotypes viz. Shohag, BARI Soybean-6, BD2331 and BGM2026 were used in the study. Plants were grown in pots under stress and control condition. A marked difference in RWC between morning and midday was observed both in stressed and control plants. BARI Soybean-6 showed higher RWC than rest of the genotypes and BGM2026 showed the lowest at all growth stages. The reduced RWC of BARI Soybean-6 under water stress at vegetative, flowering and pod developing stages were 11.35, 13.52 and 15.04% at 1.00 PM as compared to control, respectively. The reduced RWC of BGM2026 at vegetative, flowering and pod developing stages were 18.99, 20.64 and 23.05% at 1.00 PM, respectively. In stressed plants, midday drop of relative water content was minimal in BARI Soybean-6 (8.97%) and maximum in BGM2026 (17.89%) at 1.00 PM. Under water stress condition BARI Soybean-6 gave the highest seed yield (5.23 g plant-1) and BGM2026 the lowest (3.21 g plant-1) which might be attributed to the drastic reduction in 100-seed weight of RWC in the variety BGM2026 due to the significant reduction in RWC in this variety. Considering the midday drop of RWC and seed yield, it may be concluded that BGM2026 is susceptible and BARI Soybean-6 is drought tolerant among the genotypes.Bangladesh Agron. J. 2015, 18(2): 31-38

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A Gene Controlling Differences in Osmoregulation in Wheat

Functional Plant Biology ◽

10.1071/pp9910249 ◽

1991 ◽

Vol 18 (3) ◽

pp. 249 ◽

Cited By ~ 48

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.

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Changes in Water Relations Associated With Infection by Phytophthora cinnamomi

Australian Journal of Botany ◽

10.1071/bt9820393 ◽

1982 ◽

Vol 30 (4) ◽

pp. 393 ◽

Cited By ~ 13

Author(s):

P Dawson ◽

G Weste

Keyword(s):

Water Potential ◽

Water Content ◽

Water Relations ◽

Relative Water Content ◽

Phytophthora Cinnamomi ◽

Stomatal Closure ◽

Leaf Conductance ◽

Eucalyptus Species ◽

Significant Difference ◽

Relative Water

Changes in water relations associated with infection by Phytophthora cinnamomi were measured for three native species from the Brisbane Ranges forest. Measurements included leaf conductance, stomatal aperture, transpiration, water potential and relative water content in container-grown plants of Isopogon ceratophyllus (highly susceptible), Eucalyptus macrorhyncha (field-susceptible) and E. goniocalyx (field-resistant) maintained in a glasshouse. I. Ceratophyllus showed a large and highly significant difference in water relations between infected and control plants. Infection was associated with stomatal closure, reduced transpiration, reduced relative water content and leaf water potential. These reactions to infection were not observed for either of the glasshouse-reared Eucalyptus species. In the forest diseased E. macrorhyncha showed significant differences in leaf conductance compared with healthy trees, whereas E. goniocalyx forest trees showed less infection-associated variation. This variation in leaf conductance was not associated with water stress.

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Studies on the Impact of Water Deficit on Plant Height, Relative Water Content, Total Chlorophyll, Osmotic Potential and Yield of Banana (Musa spp.,) Cultivars and Hybrids

International Journal of Horticulture ◽

10.5376/ijh.2013.03.0011 ◽

2013 ◽

Cited By ~ 1

Author(s):

K. Krishna Surendar ◽

D. Durga Devi ◽

I. Ravi ◽

P. Jeyakumar ◽

S. Ramesh Kumar ◽

...

Keyword(s):

Water Content ◽

Plant Height ◽

Water Deficit ◽

Osmotic Potential ◽

Relative Water Content ◽

Total Chlorophyll ◽

Relative Water ◽

The Impact

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

The Lichenologist ◽

10.1006/lich.1996.0023 ◽

1996 ◽

Vol 28 (3) ◽

pp. 257-266 ◽

Cited By ~ 8

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.

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Apoplastic water fraction and rehydration techniques introduce significant errors in measurements of relative water content and osmotic potential in plant leaves

Physiologia Plantarum ◽

10.1111/ppl.12380 ◽

2015 ◽

Vol 155 (4) ◽

pp. 355-368 ◽

Cited By ~ 26

Author(s):

Stefan K. Arndt ◽

Andi Irawan ◽

Gregor J. Sanders

Keyword(s):

Water Content ◽

Osmotic Potential ◽

Relative Water Content ◽

Plant Leaves ◽

Water Fraction ◽

Relative Water

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

Beccariana Botanical Research Bulletin ◽

10.30862/bbrp.v7i1.274 ◽

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

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.

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