Root biomass in the upper layer of the soil profile is related to the stomatal response of wheat as the soil dries

2016 ◽  
Vol 43 (1) ◽  
pp. 62 ◽  
Author(s):  
Renu Saradadevi ◽  
Helen Bramley ◽  
Jairo A. Palta ◽  
Everard Edwards ◽  
Kadambot H. M. Siddique
Keyword(s):  
Stomatal Conductance ◽  
Soil Water ◽  
Soil Profile ◽  
Root Biomass ◽  
Stomatal Closure ◽  
Wheat Yield ◽  
Grain Filling ◽  
Potential Yield ◽  
Aba Metabolism ◽  
Terminal Drought

Terminal drought is a common abiotic stress affecting wheat yield in Mediterranean-type environments. As terminal drought develops, top layers of the soil profile dry, exposing the upper part of the root system to soil water deficit while deeper roots can still access soil water. Since open stomata rapidly exhausts available soil water, reducing stomatal conductance to prolong availability of soil water during grain filling may improve wheat yields in water-limited environments. It was hypothesised that genotypes with more root biomass in the drying upper layer of the soil profile accumulate more abscisic acid in the leaf and initiate stomatal closure to regulate water use under terminal drought. The wheat cultivar Drysdale and the breeding line IGW-3262 were grown in pots horizontally split into two segments by a wax-coated layer that hydraulically isolated the top and bottom segments, but allowed roots to grow into the bottom segment. Terminal drought was induced from anthesis by withholding water from (i) the top segment only (DW) and (ii) the top and bottom segments (DD) while both segments in well-watered pots (WW) were maintained at 90% pot soil water capacity. Drysdale, initiated stomatal closure earlier than IGW-3262, possibly due to higher signal strength generated in its relatively larger proportion of roots in the drying top segment. The relationship between leaf ABA and stomatal conductance was strong in Drysdale but weak in IGW-3262. Analysis of ABA metabolites suggests possible differences in ABA metabolism between these two genotypes. A higher capability of deeper roots to extract available water is also important in reducing the gap between actual and potential yield.

Stomatal behaviour under terminal drought affects post-anthesis water use in wheat

2017 ◽  
Vol 44 (3) ◽  
pp. 279 ◽  
Author(s):  
Renu Saradadevi ◽  
Helen Bramley ◽  
Jairo A. Palta ◽  
Kadambot H. M. Siddique
Keyword(s):  
Grain Yield ◽  
Water Use ◽  
Soil Profile ◽  
Stomatal Closure ◽  
Grain Filling ◽  
Ww Ii ◽  
Terminal Drought ◽  
Stomatal Behaviour ◽  
Top Soil ◽  
Use Efficiency

Post-anthesis water use is important for grain yield in wheat under drought because this water is immediately used for grain filling. The aim of this study was to determine whether root capacity for water uptake from deeper layers in the soil profile differed between two genotypes with contrasting stomatal behaviour under terminal drought. The wheat cultivar Drysdale and the breeding line IGW-3262 were grown in 1 m deep pots in a glasshouse under well-watered conditions until anthesis, when three watering treatments were imposed: (i) watering maintained at 90% pot soil water capacity (WW), (ii) watering withheld but supplementary watering supplied to the bottom 30 cm of the pot to keep this layer of the soil profile wet until physiological maturity (WB) and (iii) watering completely withheld (WS). Stomatal conductance, post-anthesis water use and water use efficiency, and grain yield were measured. Post-anthesis water use in Drysdale was similar in the WB and WW treatments, while in IGW-3262 it was 30% less in the WB treatment than in the WW treatment. In the WB treatment as the top soil dried, stomatal closure was faster in IGW-3262 than in Drysdale, which may have affected the capacity of roots to uptake available water at depth. The reduction in post-anthesis water use in IGW-3262 resulted in a decline in grain yield.

A modelling framework to predict transpiration reductions during drought based on soil hydraulics 

2021 ◽  
Author(s):  
Andrea Carminati ◽  
Mathieu Javaux
Keyword(s):  
Hydraulic Conductivity ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Soil Water ◽  
Stomatal Closure ◽  
Soil Water Potential ◽  
Soil Drying ◽  
Soil Hydraulic Conductivity ◽  
Plant Hydraulics ◽  
Soil Hydraulic

<p>There is increasing need for mechanistic and predictive models of transpiration and stomatal response to drought. Global measurements of transpiration showed that the decrease in soil moisture is a primary constrain on transpiration. Additionally, a recent meta-analysis indicated that stomatal closure is explained by the loss in soil hydraulic conductivity, more than that of the xylem. Despite these evidences on the role of soil drying as a key driver of transpiration reduction, the mechanisms by which soil drying impacts transpiration, including the effect of different soil hydraulic properties, are not fully understood.</p><p>Here, we propose that stomata regulate transpiration in such a way that the relation between transpiration and the difference in water potential between soil and leaves remains linear during soil drying and increasing vapor pressure deficit (VPD). The onset of hydraulic nonlinearity sets the maximum stomatal conductance at a given soil water potential and VPD. The resulting trajectory of the stomatal conductance for varying soil water potentials and VPD depends on soil and plant hydraulics, with the soil hydraulic conductivity and root length being the most sensitive parameters.</p><p>From this hydraulic framework it follows that stomatal closure is not simply a function of soil moisture, soil water potential or leaf water potential. Instead, it depends on transpiration demand and soil-plant hydraulics in a predictable way. The proposed concept allows to predict transpiration reductions during drought with a limited number of parameters: transpiration demand, plant hydraulic conductivity, soil hydraulic conductivity and active root length. In conclusion, this framework highlights the role of the soil hydraulic conductivity as primary constrain on transpiration, and thus on stomatal conductance and photosynthesis.</p>

scholarly journals Effect of Water Stress during Grain Filling on Yield, Quality and Physiological Traits of Illpa and Rainbow Quinoa (Chenopodium quinoa Willd.) Cultivars

Plants ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 173 ◽  
Author(s):  
Angie L. Gámez ◽  
David Soba ◽  
Ángel M. Zamarreño ◽  
José M. García-Mina ◽  
Iker Aranjuelo ◽  
...  
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Deficit ◽  
Stomatal Closure ◽  
Chenopodium Quinoa ◽  
Grain Filling ◽  
Quality Parameters ◽  
Stomatal Opening ◽  
Climate Change Scenarios ◽  
Yield And Quality

The total area under quinoa (Chenopodium quinoa Willd.) cultivation and the consumption of its grain have increased in recent years because of its nutritional properties and ability to grow under adverse conditions, such as drought. Climate change scenarios predict extended periods of drought and this has emphasized the need for new crops that are tolerant to these conditions. The main goal of this work was to evaluate crop yield and quality parameters and to characterize the physiology of two varieties of quinoa grown under water deficit in greenhouse conditions. Two varieties of quinoa from the Chilean coast (Rainbow) and altiplano (Illpa) were used, grown under full irrigation or two different levels of water deficit applied during the grain filling period. There were no marked differences in yield and quality parameters between treatments, but the root biomass was higher in plants grown under severe water deficit conditions compared to control. Photosynthesis, transpiration and stomatal conductance decreased with increased water stress in both cultivars, but the coastal variety showed higher water use efficiency and less discrimination of 13C under water deficit. This response was associated with greater root development and a better stomatal opening adjustment, especially in the case of Rainbow. The capacity of Rainbow to increase its osmoregulant content (compounds such as proline, glutamine, glutamate, K and Na) could enable a potential osmotic adjustment in this variety. Moreover, the lower stomatal opening and transpiration rates were also associated with higher leaf ABA concentration values detected in Rainbow. We found negative logarithmic relationships between stomatal conductance and leaf ABA concentration in both varieties, with significant R2 values of 0.50 and 0.22 in Rainbow and Illpa, respectively. These moderate-to-medium values suggest that, in addition to ABA signaling, other causes for stomatal closure in quinoa under drought such as hydraulic regulation may play a role. In conclusion, this work showed that two quinoa cultivars use different strategies in the face of water deficit stress, and these prevent decreases in grain yield and quality under drought conditions.

scholarly journals Biochemical and Molecular Effects Induced by Triacontanol in Acquired Tolerance of Rice to Drought Stress

Genes ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1119
Author(s):  
Basmah M. Alharbi ◽  
Awatif Mahfouz Abdulmajeed ◽  
Heba Hassan
Keyword(s):  
Drought Stress ◽  
Stomatal Conductance ◽  
Oryza Sativa L ◽  
Water Status ◽  
Stomatal Closure ◽  
Photochemical Efficiency ◽  
Seed Priming ◽  
Plant Tolerance ◽  
Photochemical Efficiency Of Psii ◽  
Aba Metabolism

To assess the effect of triacontanol (TRIA) on rice plants grown under normal or drought conditions, rice seeds were presoaked in TRIA (35 ppm) for two hours. After 20 days of sowing, rice seedlings developed from TRIA-treated or untreated seeds were subjected to drought stress. After 10 days of plant exposure to drought stress, data of major growth attributes and the content of photosynthetic pigments were recorded. Moreover, the effect of drought stress on stomatal conductance and the photochemical efficiency of PSII (Fv/Fm) were followed. The data obtained indicated that the species of rice (Oryza sativa L.) cultivar Giza 177 under investigation was sensitive to drought stress where there were significant decreases in the fresh and dry weights of shoots and roots and in stomatal conductance, as well as in the content of chlorophyll a, chlorophyll b, and carotenoids. Seed priming with TRIA enhanced both growth and acquired plant tolerance to drought stress. Thus, TRIA via the enhancement of stomatal conductance through the regulation of stomatal closure, the rate of water loss, ABA metabolism, the accumulation of osmolytes, and the regulation of aquaporins genes improved the water status of plants grown under water scarcity. Moreover, TRIA via increasing the content of free amino acids and sugars under drought stress may increase the chance of plant tissues to retain more water under scarcity conditions.

Photosynthesis and Stomatal-Conductance Responses of Johnsongrass (Sorghum halepense) to Water Stress

Weed Science ◽  
1985 ◽  
Vol 33 (5) ◽  
pp. 635-639 ◽  
Author(s):  
Bryan L. Stuart ◽  
Daniel R. Krieg ◽  
John R. Abernathy
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Osmotic Potential ◽  
Grain Filling ◽  
Leaf Temperature ◽  
Sorghum Halepense

The influence of water stress on johnsongrass [Sorghum halepense(L.) Pers. ♯ SORHA] physiology was evaluated in a semiarid environment. Stomatal conductance of johnsongrass responded to more negative leaf water potential and increasing leaf temperature. The sensitivity of the leaf temperature effect was dependent on the soil water content. At low soil water content, conductance was limited by low water potential, and increasing leaf temperature had little effect. Conductance of CO2was related to net photosynthesis in a curvilinear manner, with conductance levels greater than 0.3 mol·m-2· s-1being in excess of that necessary for maximum photosynthesis. At both high conductance levels and low levels associated with increased water stress, intercellular CO2concentration increased, indicating nonstomatal limitations to photosynthesis. Decreased osmotic potential provided the highest correlation with the linear decline of photosynthetic rate as stress intensified. The expression of osmotic adjustment in johnsongrass is reported during grain filling. Plants in the milkdough stage of grain filling had approximately 0.3 MPa lower osmotic potential at any relative water content than those at anthesis.

Physiological trade-offs of stomatal closure under high evaporative gradients in field grown soybean

2016 ◽  
Vol 43 (1) ◽  
pp. 40 ◽  
Author(s):  
Viviana Medina ◽  
Matthew E. Gilbert
Keyword(s):  
Stomatal Conductance ◽  
Soil Water ◽  
Water Deficit ◽  
Agricultural Research ◽  
Stomatal Closure ◽  
Photochemical Efficiency ◽  
Vapour Pressure Deficit ◽  
Soil Water Deficit ◽  
Night Time ◽  
Trade Offs

Limited rainfall is the main constraint to agriculture, making agricultural research to understand plant behaviour that leads to avoidance of soil water deficit a matter of priority. One focus has screened for crop varieties that decrease stomatal conductance under high vapour pressure deficit (VPD), a proxy for the leaf evaporative gradient. However, the link between stomatal closure and physiological consequences in field environments is not yet clear. A field experiment on soybeans demonstrated that considerable variation in leaf temperature relative to air temperature occurred, leading to evaporative gradients differing substantially from VPD. Thus, transpiration is decreased by stomatal closure at high VPD, but to compensate, transpiration is somewhat increased due to higher leaf temperatures. Soil water deficit led to lower stomatal conductance, particularly under low evaporative conditions, not just under hot conditions. Non-stomatal photosynthetic limitations were observed due to combined occurrence of stomatal closure and high temperature under high VPD. Although leaves reached temperatures higher than the threshold for a decrease in maximum photochemical efficiency, and displayed non-stomatal photosynthetic limitations, no photoinhibition or damage was observed by night-time. The results demonstrate that more understanding of physiological strategies for achieving altered water use is needed to avoid trade-offs and heat stress.

Effects of deep ripping and liming on soil water deficits, sorptivity and penetrometer resistance

1987 ◽  
Vol 27 (5) ◽  
pp. 701 ◽  
Author(s):  
GR Steed ◽  
TG Reeves ◽  
ST Willatt
Keyword(s):  
Soil Water ◽  
Water Use ◽  
Soil Profile ◽  
Wheat Yield ◽  
Major Effect ◽  
Water Extraction ◽  
Soil Resistance ◽  
Wet Season ◽  
Penetrometer Resistance ◽  
Yield Responses

A field experiment was conducted at Rutherglen, in north-eastern Victoria, to determine the effects of liming and deep ripping on soil water extraction by wheat, sorptivity of water into the soil profile and soil resistance to a penetrometer. The site was typical of many cropping paddocks in the region. In the unmodified state the top 20 cm of the soil profile was acid (pH 4.80) and there was a dense hardpan between 7.5 and 17.5 cm depth. Deep ripping increased water extraction by wheat by an average of 8 mm during a drought season (1982), but had no effect on water use in a wet season (1983). The major effect of ripping was to increase the water use in winter from below the ripped zone (40 cm) compared with the unripped treatment. Lime, either with or without ripping, had no significant effect on crop water extraction. Sorptivity, a measure of infiltration, was increased by ripping alone and by ripping plus lime. Soil resistance to a penetrometer was reduced by deep ripping; an effect which had persisted at least 30 months after the last ripping operation. Economic wheat yield responses were obtained by using deep ripping and liming to improve soil physical properties at this site.

scholarly journals Sustaining productivity of a Vertosol at Warra, Queensland, with fertilisers, no-tillage or legumes. 8. Effect of duration of lucerne ley on soil nitrogen and water, wheat yield and protein

2004 ◽  
Vol 44 (10) ◽  
pp. 1013 ◽  
Author(s):  
R. C. Dalal ◽  
E. J. Weston ◽  
W. M. Strong ◽  
M. E. Probert ◽  
K. J. Lehane ◽  
...  
Keyword(s):  
Soil Water ◽  
Soil Nitrogen ◽  
Soil Profile ◽  
Phase 1 ◽  
Wheat Yield ◽  
Soil N ◽  
N Supply ◽  
Long Duration ◽  
Moisture Deficit ◽  
Fertiliser Application

Soil nitrogen (N) supply in the Vertosols of southern Queensland, Australia has steadily declined as a result of long-term cereal cropping without N fertiliser application or rotations with legumes. Nitrogen-fixing legumes such as lucerne may enhance soil N supply and therefore could be used in lucerne–wheat rotations. However, lucerne leys in this subtropical environment can create a soil moisture deficit, which may persist for a number of seasons. Therefore, we evaluated the effect of varying the duration of a lucerne ley (for up to 4 years) on soil N increase, N supply to wheat, soil water changes, wheat yields and wheat protein on a fertility-depleted Vertosol in a field experiment between 1989 and 1996 at Warra (26°47′S, 150°53′E), southern Queensland. The experiment consisted of a wheat–wheat rotation, and 8 treatments of lucerne leys starting in 1989 (phase 1) or 1990 (phase 2) for 1, 2, 3 or 4 years duration, followed by wheat cropping. Lucerne DM yield and N yield increased with increasing duration of lucerne leys. Soil N increased over time following 2 years of lucerne but there was no further significant increase after 3 or 4 years of lucerne ley. Soil nitrate concentrations increased significantly with all lucerne leys and moved progressively downward in the soil profile from 1992 to 1995. Soil water, especially at 0.9–1.2 m depth, remained significantly lower for the next 3 years after the termination of the 4-year lucerne ley than under continuous wheat. No significant increase in wheat yields was observed from 1992 to 1995, irrespective of the lucerne ley. However, wheat grain protein concentrations were significantly higher under lucerne–wheat than under wheat–wheat rotations for 3–5 years. The lucerne yield and soil water and nitrate-N concentrations were satisfactorily simulated with the APSIM model. Although significant N accretion occurred in the soil following lucerne leys, in drier seasons, recharge of the drier soil profile following long duration lucerne occurred after 3 years. Consequently, 3- and 4-year lucerne–wheat rotations resulted in more variable wheat yields than wheat–wheat rotations in this region. The remaining challenge in using lucerne–wheat rotations is balancing the N accretion benefits with plant-available water deficits, which are most likely to occur in the highly variable rainfall conditions of this region.

Leaf Gas Exchange and Water Relations of Lupins and Wheat. I. Shoot Responses to Soil Water Deficits

1989 ◽  
Vol 16 (5) ◽  
pp. 401 ◽  
Author(s):  
IE Henson ◽  
CR Jensen ◽  
NC Turner
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Leaf Water Potential ◽  
Stomatal Closure ◽  
Turgor Pressure ◽  
Leaf Conductance ◽  
Leaf Water

The effects of a progressive increase in soil water deficit on the leaf conductance and gas exchange of lupin (Lupinus cosentinii) and wheat (Triticum aestivum) were investigated in pot experiments in a temperature-regulated glasshouse, using a coarse, sandy soil characteristic of the Western Australian wheatbelt. Transpiration rates decreased rapidly in both species after water was withheld, mainly as a result of stomatal closure. Photosynthesis declined also, but to a lesser extent than conductance. Leaf extension in lupin was equally as sensitive to a decrease in leaf water potential and soil water potential as stomatal conductance. Stomatal closure served to maintain the water potential of lupin leaves to within 0.1 MPa of that of control (watered) plants as the soil water content decreased from 0.14 to 0.06 m3 m-3 and as the leaf conductance and the relative transpiration rate fell to less than 50% of control values. Maintenance of leaf water potential with decreasing soil water content and stomatal conductance was less evident in wheat. In both lupin and wheat, leaf conductance decreased linearly with soil water content and curvilinearly with bulk soil matric potential, indicating that water uptake was restricted at similar water contents and matric potentials in both species. Diurnal measurements on lupin indicated a substantial reduction in stomatal conductance after water was withheld, even when the leaf water potential at midday was reduced by only 0.1 MPa and no change could be detected in the bulk leaf turgor pressure. Conductance in lupin was reduced even though the soil matric potential decreased in only part of the rooting zone. This, together with the absence of any significant change in the leaf water potential, turgor pressure, or relative water content in lupin during the initial stages of stomatal closure, suggests that a soil or root factor initiates the reduction in leaf conductance - and hence regulates the shoot water status - in response to soil drying.

Wheat yield losses in India due to ozone and aerosol pollution and their alleviation: A critical review

2019 ◽  
Vol 48 (3) ◽  
pp. 181-189 ◽  
Author(s):  
Tony Fischer
Keyword(s):  
Stomatal Conductance ◽  
Solar Radiation ◽  
Wheat Yield ◽  
Diffuse Radiation ◽  
Total Solar Radiation ◽  
Yield Losses ◽  
Potential Yield ◽  
Pollution Damage ◽  
Aerosol Pollution ◽  
Genetic Tolerance

This review examines estimations made over the last two decades of the wheat yield losses in India due to elevated tropospheric ozone (O3) and to aerosol pollution. Notwithstanding the poor record of O3 and solar radiation measurement in wheat regions, a reasonable estimate can be made yield losses around 2010. From an average of the more credible studies, this is around 30% compared to the yield which would have been achieved with 1970 solar radiation and O3 assumed to be <40 ppb (parts per billion by volume). The results suggest that O3 causes two-thirds of the loss and reduced total solar radiation due to aerosols (but corrected for increased diffuse radiation) one-third. Ozone, in particular, appears to be still increasing. It is likely that increased stomatal conductance (e.g. due to more irrigation (97% of production now irrigated) and the unwitting consequence of breeding for increased potential yield) has added to current O3 losses. Much is known about the physiology of O3 damage in the wheat leaf and plant. What is lacking is a thorough search for genetic tolerance independent of stomatal conductance and potential yield penalties, and this requires, at least initially, many chamber and/or FACE (free-air CO2 enhancement) experiments under typical Indian field conditions. Genetic engineering could offer a solution for O3 but only in the long term. Other solutions to pollution damage are very limited, but earlier planting should help wheat escape the rising O3 level in the spring. The 40 million tonnes of wheat currently foregone annually by India due to these two pollutants, even if an overestimate, far exceeds estimates of wheat yield loss to date due to climate change and demands concerted action to reduce the sources of this pollution, bringing added direct advantages for other crops and for human health.

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