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

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.

2007 ◽  
Vol 29 (2) ◽  
pp. 355-358 ◽  
Author(s):  
José Moacir Pinheiro Lima Filho

The experiment was carried out at the Embrapa Semi-Árido, Petrolina-PE, Brazil, in order to study the physiological responses of umbu plants propagated by seeds and by stem cuttings under water stress conditions, based on leaf water potential and gas exchange measurements. Data were collected in one-year plants established in pots containing 30 kg of a sandy soil and submitted to twenty-day progressive soil water deficit. The evaluations were based on leaf water potential and gas exchange data collection using psychrometric chambers and a portable infra-red gas analyzer, respectively. Plants propagated by seeds maintained a significantly higher water potential, stomatal conductance, transpiration and photosynthesis under decreasing soil water availability. However, plants propagated by stem cuttings were unable to maintain a favorable internal water balance, reflecting negatively on stomatal conductance and leaf gas exchange. This fact is probably because umbu plants propagated by stem cuttings are not prone to formation of root tubers which are reservoirs for water and solutes. Thus, the establishing of umbu plants propagated by stem cuttings must be avoided in areas subjected to soil water deficit.


1998 ◽  
Vol 25 (6) ◽  
pp. 645 ◽  
Author(s):  
Júlio Osório ◽  
M. Leonor Osório ◽  
M. Manuela Chaves ◽  
João S. Pereira

Potted cuttings of three Eucalyptus globulus Labill. clones (AR3, CN44, MP11) were grown over 6 months in a greenhouse under three watering regimes: well watered (HW), moderate soil water deficit (MS) and severe soil water deficit (SS). Transpiration efficiency (W = total dry matter/water transpired) and leaf intrinsic gas exchange efficiency (A/gs = carbon assimilation rate/stomatal conductance) increased under water stress and were positively correlated with the stable carbon isotope composition of leaf tissue (δ13C). The clones did not vary significantly with respect to A/gs and W. However, statistically significant differences were detected among clones in δ13C, A and biomass. W did not differ between the MS and SS regimes, probably due to plant acclimation to increasing soil water deficits. The increase in W with soil water deficits relative to the well watered control was primarily associated with stomatal closure, but was also influenced by differences in respiratory carbon losses (?c) and variation in the leaf-to-air water vapour difference (v). Variance in ?c and v may explain partially why the two levels of soil water deficit were different in regard to δ13C but not in terms of W.


1998 ◽  
Vol 26 (3) ◽  
pp. 289-296
Author(s):  
M. Jurišić ◽  
Ž. Vidaček ◽  
Ž. Bukvić ◽  
D. Brkić ◽  
R. Emert

1984 ◽  
Vol 103 (1) ◽  
pp. 189-199 ◽  
Author(s):  
M. J. Goss ◽  
K. R. Howse ◽  
Judith M. Vaughan-Williams ◽  
M. A. Ward ◽  
W. Jenkins

SummaryIn each of the years from September 1977 to July 1982 winter wheat was grown on one or more of three clay soil sites (clay content 35–55%) in Oxfordshire where the climate is close to the average for the area of England growing winter cereals.The effects on crop water use of different soil management practices, including ploughing, direct drilling and subsoil drainage, are compared. Cultivation treatment had little effect on the maximum depth of water extraction, which on average in these clay soils was 1·54 m below the soil surface. Maximum soil water deficit was also little affected by cultivation; the maximum recorded value was 186±7·6 mm. Subsoil drainage increased the maximum depth of water extraction by approximately 15 cm and the maximum soil water deficit by about 17 mm.Generally soil management had little effect on either total water use by the crop which was found to be close to the potential evaporation estimated by the method of Penman, or water use efficiency which for these crops was about 52 kg/ha par mm water used.Results are discussed in relation to limitations to potential yield.


1997 ◽  
Vol 24 (1) ◽  
pp. 19-24 ◽  
Author(s):  
P. J. Sexton ◽  
J. M. Bennett ◽  
K. J. Boote

Abstract Peanut (Arachis hypogaea L.) fruit growth is sensitive to surface soil (0-5 cm) conditions due to its subterranean fruiting habit. This study was conducted to determine the effect of soil water content in the pegging zone (0-5 cm) on peanut pod growth rate and development. A pegging-pan-root-tube apparatus was used to separately control soil water content in the pegging and root zone for greenhouse trials. A field study also was conducted using portable rainout shelters to create a soil water deficit. Pod phenology, pod and seed growth rates, and final pod and seed dry weights were determined. In greenhouse studies, dry pegging zone soil delayed pod and seed development. In the field, soil water deficits in the pegging and root zone decreased pod and seed growth rates by approximately 30% and decreased weight per seed from 563 to 428 mg. Pegs initiating growth during drought stress demonstrated an ability to suspend development during the period of soil water deficit and to re-initiate pod development after the drought stress was relieved.


2012 ◽  
Vol 39 (1) ◽  
pp. 53-61 ◽  
Author(s):  
Maria Balota ◽  
Steve McGrath ◽  
Thomas G. Isleib ◽  
Shyam Tallury

Abstract Water deficit, i.e., rainfall amounts and distribution, is the most common abiotic stress that limits peanut production worldwide. Even though extensive research efforts have been made to improve drought tolerance in peanut, performance of genotypes largely depends upon the environment in which they grow. Based on greenhouse experiments, it has been hypothesized that stomata closure under high vapor pressure deficit (VPD) is a mechanism of soil water conservation and it has been shown that genotypic variation for the response of transpiration rate to VPD in peanut exists. The objective of this study was to determine the relationship between stomatal conductance (gs) and VPD for field grown peanut in Virginia-Carolina (VC) rainfed environments. In 2009, thirty virginia-type peanut cultivars and advanced breeding lines were evaluated for gs at several times before and after rain events, including a moisture stress episode. In 2010, eighteen genotypes were evaluated for gs under soil water deficit. In 2009, VPD ranged from 1.3 to 4.2 kPa and in 2010 from 1.78 to 3.57 kPa. Under water deficit, genotype and year showed a significant effect on gs (P  =  0.0001), but the genotype × year interaction did not. During the water deficit episodes while recorded gs values were relatively high, gs was negatively related to VPD (R2  =  0.57, n  =  180 in 2009; R2  =  0.47, n  =  108 in 2010), suggesting that stomata closure is indeed a water conservation mechanism for field grown peanut. However, a wide range of slopes among genotype were observed in both years. Genotypes with significant negative relationships of gs and VPD under water deficit in both years were Florida Fancy, Gregory, N04074FCT, NC-V11, and VA-98R. While Florida Fancy, Gregory, and NC-V11 are known to be high yielding cultivars, VA-98R and line N04074FCT are not. The benefit of stomatal closure during drought episodes in the VC environments is further discussed in this paper.


2013 ◽  
Vol 41 (2) ◽  
pp. 524 ◽  
Author(s):  
Qiu-Dan NI ◽  
Ying-Ning ZOU ◽  
Qiang-Sheng WU ◽  
Yong-Ming HUANG

Arbuscular mycorrhizal fungi (AMF) can enhance tolerance of plants to soil water deficit, whereas morphological observations of reactive oxygen species and antioxidant enzyme system are poorly studied. The present study thereby evaluated temporal variations of the antioxidant enzyme system in citrus (Citrus tangerina) seedlings colonized by Glomus etunicatum and G. mosseae over a 12-day period of soil drying. Root colonization by G. etunicatum and G. mosseae decreased with soil drying days from 32.0 to 1.0% and 50.1 to 4.5% in 0-day to 12-day, respectively. Compared to the non-AM controls, the AMF colonized plants had significantly lower tissue (both leaves and roots) hydrogen peroxide (H2O2) and superoxide anion radical (O2•–) concentrations during soil water deficit, whereas 1.03–1.92, 1.25–1.84 and 1.18–1.69 times higher enzyme activity in superoxide dismutase, peroxidase (POD) and catalase. In situ leaf H2O2 and root POD location also showed that AM seedlings had less leaf H2O2 but higher root POD accumulation. Furthermore, significantly higher root infection and antioxidant enzymatic activities in plants colonized with G. mosseae expressed than with G. etunicatum during the soil drying. These results demonstrated that the AMs could confer greater tolerance of citrus seedlings to soil water deficit through an enhancement in their antioxidant enzyme defence system whilst an decrease level in H2O2 and O2•–.


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