Including soil water stress in process-based ecosystem models by scaling down maximum carboxylation rate using accumulated soil water deficit

Mitigating climate change requires the identification of tree species that can tolerate water stress with fewer negative impacts on plant productivity. Therefore, the study aimed to evaluate the water stress tolerance of young saplings of C. erectus and M. alba under three soil water deficit treatments (control, CK, 90% field capacity, FC, medium stress MS, 60% FC and high stress, HS, 30% FC) under controlled conditions. Results showed that leaf and stem dry weight decreased significantly in both species under MS and HS. However, root dry weight and root/shoot ratio increased, and total dry weight remained similar to CK under MS in C. erectus saplings. Stomatal conductance, CO2 assimilation rate decreased, and intrinsic water use efficiency increased significantly in both species under MS and HS treatments. The concentration of hydrogen peroxide, superoxide radical, malondialdehyde and electrolyte leakage increased in both the species under soil water deficit but was highest in M. alba. The concentration of antioxidative enzymes like superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase also increased in both species under MS and HS but was highest in C. erectus. Therefore, results suggest that C. erectus saplings depicted a better tolerance to MS due to an effective antioxidative enzyme system.

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Foliar Application of Salicylic Acid Improves Water Stress Tolerance in Conocarpus erectus L. and Populus deltoides L. Saplings: Evidence from Morphological, Physiological and Biochemical Changes

Plants ◽

10.3390/plants10061242 ◽

2021 ◽

Vol 10 (6) ◽

pp. 1242

Author(s):

Zikria Zafar ◽

Fahad Rasheed ◽

Rana Muhammad Atif ◽

Muhammad Asif Javed ◽

Muhammad Maqsood ◽

...

Keyword(s):

Water Stress ◽

Stress Tolerance ◽

Soil Water ◽

Water Deficit ◽

Populus Deltoides ◽

Foliar Application ◽

Leaf Gas Exchange ◽

Soil Water Deficit ◽

Water Stress Tolerance ◽

Conocarpus Erectus

Reforestation efforts are being challenged as water stress is hampering the sapling growth and survival in arid to semiarid regions. A controlled experiment was conducted to evaluate the effect of foliar application of salicylic acid (SA) on water stress tolerance of Conocarpus erectus and Populus deltoides. Saplings were watered at 90%, 60%, and 30% of field capacity (FC), and half of the saplings under 60% and 30% FC were sprayed with 1.0 mM SA. Results indicated that dry weight production decreased significantly in Populus deltoides under both water deficit conditions, and leaf gas exchange parameters decreased significantly in both the species under both soil water deficit conditions. Foliar application of SA resulted in a significant increase in leaf gas exchange parameters, and compatible solutes, thereby increasing the dry weight production in both of the species under soil water deficit. Oxidative stress (hydrogen peroxide and superoxide anions) increased under soil water deficit and decreased after the foliar application of SA and was parallel to the increased antioxidant enzymes activity (superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase). Therefore, it can be concluded that foliar application of 1.0 mM SA can significantly improve the water stress tolerance in both species, however, positive impacts of SA application were higher in Conocarpus erectus due to improved photosynthetic capacity and increased antioxidant enzyme activity.

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Salicylic Acid-Induced Morpho-Physiological and Biochemical Changes Triggered Water Deficit Tolerance in Syzygium cumini L. Saplings

Forests ◽

10.3390/f12040491 ◽

2021 ◽

Vol 12 (4) ◽

pp. 491

Author(s):

Zikria Zafar ◽

Fahad Rasheed ◽

Rana Muhammad Atif ◽

Muhammad Maqsood ◽

Oliver Gailing

Keyword(s):

Salicylic Acid ◽

Water Stress ◽

Gas Exchange ◽

Soil Water ◽

Water Deficit ◽

Foliar Application ◽

Leaf Gas Exchange ◽

Dry Weight ◽

Soil Water Deficit ◽

Water Stress Tolerance

Fruit tree culture is at the brink of disaster in arid to semi-arid regions due to low water availability. A pot experiment was carried out to analyze whether foliar application of salicylic acid (SA) can improve water stress tolerance in Syzygiumcumini. Saplings were subjected to control (CK, 90% of field capacity, FC), medium stress (MS, 60% of FC) and high stress (HS, 30% of FC) along with foliar application of 0.5 and 1.0 mM of SA. Results showed that soil water deficit significantly decreased leaf, stem and total dry weight, leaf gas exchange attributes and chlorophyll a, b. However, root dry weight and root/shoot ratio increased under MS and HS, respectively. Contrarily, foliar application of SA significantly improved chlorophyll a, b, leaf gas exchange attributes, and dry weight production under soil water deficit. Concentration of oxidants like hydrogen peroxide and superoxide radicals, along with malondialdehyde and electrolyte leakage increased under soil water deficit; however, decreased in plants sprayed with SA due to the increase in the concentration of antioxidant enzymes like superoxide dismutase, peroxidase, catalase and ascorbate peroxidase. Results suggest that the foliar application of SA can help improve water stress tolerance in Syzygiumcumini saplings; however, validation of the results under field conditions is necessary.

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Developing a climate-driven root zone water stress function for different climates and ecosystems

10.5194/egusphere-egu21-3480 ◽

2021 ◽

Author(s):

Rodolfo Nóbrega ◽

Iain Colin Prentice

Keyword(s):

Water Stress ◽

Soil Water ◽

Water Deficit ◽

Root Zone ◽

Data Availability ◽

Data Uncertainty ◽

Soil Water Stress ◽

Stress Functions ◽

Soil Information ◽

Zone Water

Plant roots have less water available when soils have low moisture content and, consequently, limit their root-to-leaf water potential gradient to protect their xylem, which reduces H2O and CO2 exchanges with the atmosphere. In vegetation, hydrological and land-surface models, plant responses to reduced available water in the soil have been implemented in various ways depending on data availability, type of ecosystem, and modelling assumptions. Most models use soil water stress functions &#8211; commonly known as beta functions &#8211; to reduce transpiration and carbon assimilation, by applying a factor that reflects the soil water availability for plants. These functions usually produce reasonably satisfactory results, but rely on the information on soil properties (e.g. wilting point and field capacity) that are not widely available. On a global level, soil information is mediocre, and data uncertainty is compensated by tuning parameters that rarely represent a physiological process. We propose instead the use of a beta function derived from a mass-balance approach focused on the root zone water capacity. This method quantifies the root zone water storage by calculating the accumulated water deficit based on the balance between water influxes and effluxes, and it does not require land-cover or soil information. We assessed how our approach performs compared to those other soil water stress functions. We used global datasets, including WDFE5 and PMLv2, to extract precipitation and evapotranspiration and compute water deficit. For most vegetation types and climates our approach yielded promising results. Worst results were found for some (semi-)arid sites due to the overestimation of the water deficit. We aim to deliver an approach that can be easily applied on global scales.

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Effects of soil water deficit on leaf nitrogen, chlorophylls and spad chlorphyll meter reading on growth stages of soybean

Bangladesh Journal of Botany ◽

10.3329/bjb.v40i2.9773 ◽

1970 ◽

Vol 40 (2) ◽

pp. 171-175 ◽

Cited By ~ 2

Author(s):

Shakil Uddin Ahmed

Keyword(s):

Water Stress ◽

Grain Yield ◽

Soil Water ◽

Water Deficit ◽

Leaf Nitrogen ◽

Growth Stages ◽

Soil Water Deficit ◽

Flowering Stage ◽

Soybean Leaf ◽

Response To Water

Soybean leaf Nitrogen (N) status correlated linearly with the amount of chlorophylls and SCMR at flowering stage in response to water deficit levels. In addition, SCMR showed significant positive correlation with chlorophylls at flowering stage. Grain yield significantly correlated to the leaf nitrogen as well as to the chlorophylls and SCMR at flowering stage in response to water deficit levels. These relationships indicated that the water stress decreased leaf nitrogen, chlorophylls and SCMR which in turn caused decreased grain yield of soybean. The results from the study suggest that, flowering stage is the best time for prediction on the adverse effects of water stress on leaf nitrogen assimilation, chlorophylls and SCMR on potential yielding ability of soybean.Key words: Soil water deficit; Leaf nitrogen; Chlorophyll (a+b); Growth stages; Soybean DOI: http://dx.doi.org/10.3329/bjb.v40i2.9773 Bangladesh J. Bot. 40(2): 171-175, 2011 (December)

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Soil water deficit as a tool to measure water stress and inform silvicultural management in the Cape Forest Regions, South Africa

iForest - Biogeosciences and Forestry ◽

10.3832/ifor3059-013 ◽

2020 ◽

Vol 13 (6) ◽

pp. 473-481

Author(s):

GP Scheepers ◽

B Du Toit

Keyword(s):

South Africa ◽

Water Stress ◽

Soil Water ◽

Water Deficit ◽

Soil Water Deficit ◽

Silvicultural Management ◽

Forest Regions

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Potassium Application Positively Modulates Physiological Responses of Cocoa Seedlings to Drought Stress

Agronomy ◽

10.3390/agronomy11030563 ◽

2021 ◽

Vol 11 (3) ◽

pp. 563

Author(s):

Esther Anokye ◽

Samuel T. Lowor ◽

Jerome A. Dogbatse ◽

Francis K. Padi

Keyword(s):

Water Stress ◽

Soil Water ◽

Chlorophyll Content ◽

Electrolyte Leakage ◽

Seedling Survival ◽

Biomass Accumulation ◽

Biomass Partitioning ◽

Chlorophyll Content And Fluorescence ◽

Physiological Functions ◽

Soil Water Stress

With increasing frequency and intensity of dry spells in the cocoa production zones of West Africa, strategies for mitigating impact of water stress on cocoa seedling survival are urgently required. We investigated the effects of applied potassium on biomass accumulation, physiological processes and survival of cocoa varieties subjected to water stress in pot experiments in a gauzehouse facility. Four levels of potassium (0, 1, 2, or 3 g/plant as muriate of potash) were used. Soil water stress reduced plant biomass accumulation (shoot and roots), relative water content (RWC), chlorophyll content and fluorescence. Leaf phenol and proline contents were increased under water stress. Additionally, compared to the well-watered conditions, soils under water stress treatments had higher contents of exchangeable potassium and available phosphorus at the end of the experimental period. Potassium applied under well-watered conditions reduced leaf chlorophyll content and fluorescence and increased leaf electrolyte leakage, but improved the growth and integrity of physiological functions under soil water stress. Potassium addition increased biomass partitioning to roots, improved RWC and leaf membrane stability, and significantly improved cocoa seedling survival under water stress. Under water stress, the variety with the highest seedling mortality accumulated the highest contents of phenol and proline. A significant effect of variety on plant physiological functions was observed. Generally, varieties with PA 7 parentage had higher biomass partitioning to roots and better seedling survival under soil moisture stress. Proportion of biomass partitioned to roots, RWC, chlorophyll fluorescence and leaf electrolyte leakage appear to be the most reliable indicators of cocoa seedling tolerance to drought.

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