Duration Of Waterlogging Research Articles

Rational reduction of planting density and enhancement of NUE were effective methods to mitigate maize yield loss due to excessive rainfall

The impact of excessive rainfall or waterlogging on maize growth and yield have been widely studied, but the effects of planting density and N management under waterlogging remain unknown. We observed the changes in maize yield caused by excessive rainfall via a short-term experiment (2017 to present) in Changchun (125°14.231′–125°14.914′ E, 43°56.603′–43°57.274′ N), China. The experiment was conducted at four planting densities (45,000, 60,000, 75,000 and 90,000 plants/ha) and three nitrogen (N) rates (120, 180, and 240 kg/ha). The objective was to explore the effect of excessive precipitation on maize yield through changes in maize growing conditions, and the uptake, allocation, and utilization of N under different planting densities and N rates from 2019 to 2022. The precipitation during the whole growth period of maize in 2019 (542.9 mm) and 2020 (560.0 mm) was normal, while it was excessive in 2021 (829.10 mm) and 2022 (953.56 mm), especially during the vegetative stage from V12 to VT (355.60–482.10 mm). Excessive rainfall negatively affected the growth, photosynthetic characteristics (Pn: −20.00 %, SPAD: −50.50 %), absorption (−56.86 %), distribution (−15.83 %), N utilization efficiency (NUE: −29.69 %), and grain yield (−44.67 %) of maize. Our results indicate that yield loss was minimized (−22.88 %) when the planting density was appropriately reduced (from 75,000 to 60,000 plants/ha) and the N rate was increased from 180 to 240 kg/ha. The effect of different waterlogging durations on yield exhibited a significantly negative linear relation (R2 > 0.80). This study revealed the physiological mechanism of the sustained effects of excessive rainfall on maize growth and yield. Waterlogging significantly affected the SPAD of maize (p < 0.01, R2 = 0.04), resulting in insufficient kernel N content (p < 0.001, R2 = 0.16) and decreased NUE (p < 0.001, R2 = 0.48). These factors significantly affected yield and exerted a significant negative correlation with planting density (p < 0.05). Our findings improved understanding of planting density and N management for growth and yield of maize under excessive rainfall conditions in mid-high latitude agriculture areas of the world.

Effect of Transient Waterlogging Stress on Growth, Physiology and Yield of Cowpea (Vigna unguiculata L.) in Semi-Arid Region

Cowpea cultivation during rainy season is highly affected by the waterlogging stress due to unpredicted high-intensity rains. The studies on assessment of waterlogging effect on different growth stages of cowpea are necessary for planning mitigation strategies. Hence study was conducted during kharif (June to September) 2022 under factorial randomized block design (FRCBD) set up. The first factor consisted of seven waterlogging durations (3 to 15 days), and second factor was three growth stages of cowpea (15 DAE; Days after emergence, 25 DAE and at 50% flowering). The results revealed that regardless of growth stages, growth and yield attributes were drastically decreased with increased duration of waterlogging. The highest plant height (25.07 cm), number of branches plant–1 (5.33) and leaf area (205.27 cm2 plant–1), and number of pods plant–1 (4.27), pod length (15.24 cm), number of seeds pod–1 (14.27), grain (6.27 g plant–1) and haulm yield (15.62 g plant–1) were recorded with 3 days of waterlogging, whereas lowest values were reported with 15 days of waterlogging. Regarding growth stages, highest growth, and yield attributes were recorded with waterlogging during 50% flowering, followed by 25 DAE and 15 DAE. Moreover, the correlation study indicated that physiological parameters such as leaf protein content (r = 0.95) and Normalized Difference Vegetation Index NDVI (r = 0.97) were positively related to grain yield. It was found that, cowpea is sensitive to high-intensity waterlogging (beyond 3–5 days) especially during the early growth stage (15 DAE).

Assessment of cyclone induced flood using microwave Synthetic Aperture Radar (SAR) data in four blocks of East Midnapore district, India

East Midnapore district is one of the flood prone regions of West Bengal, India. Geomorphological character, topographic nature and geographical location are the main causes of such kind of flood extensiveness in this region. Four most flood prone blocks of East Midnapore district are considered in this study to analyse, monitor and estimate the flood consequences. Flood intensity, duration of water logging, frequency, interval of flood and measurement of the vulnerability are the important parameters to assess the flood risk. Synthetic Aperture Radar (SAR) data has its distinct character to collect the data at the flood time even in bad weather and it can also penetrate the cloud cover and can avoid weather caused signal attenuation. European Space Agency’s (ESA) Sentinel-1 SAR before and after flood data (2021) of Vertical transmit and Vertical receives (VV) polarization has been used to monitor and detect the flood extension and assess the inundated areas. The decibel (dB) value is mentioned and speckle noise correction is applied before and after both images. By applying the threshold dB values on both images, the flood inundated areas are detected and extracted from the natural water bodies. A village wise water logged condition of this region was observed for a long time and the study reveals that total 11612.28 ha. areas are submerged due to flood inundation. For the development of the agriculture and aquaculture in terms of the local economy a special care should be taken in this low land flood, affected region.

Molecular mechanism of salinity and waterlogging tolerance in mangrove Kandelia obovata.

Mangrove forests are colloquially referred to as "Earth's kidneys" and serve many important ecological and commercial functions. Salinity and waterlogging stress are the most important abiotic stressors restricting the growth and development of mangroves. Kandelia obovata (K. obovata) is the greatest latitudinally-distributed salt mangrove species in China.Here, morphology and transcriptomics were used to study the response of K. obovata to salt and waterlogging stress. In addition, weighted gene co-expression network analysis of the combined gene expression and phenotypic datasets was used to identify core salinity- and waterlogging-responsive modules. In this study, we observed that both high salinity and waterlogging significantly inhibited growth and development in K. obovata. Notably, growth was negatively correlated with salt concentration and positively correlated with waterlogging duration, and high salinity was significantly more inhibitive than waterlogging. A total of 7, 591 salt-responsive and 228 waterlogging-responsive differentially expressed genes were identified by RNA sequencing. Long-term salt stress was highly correlated with the measured physiological parameters while long-term waterlogging was poorly correlated with these traits. At the same time, 45 salinity-responsive and 16 waterlogging-responsive core genes were identified. All 61 core genes were mainly involved in metabolic and biosynthesis of secondary metabolites pathways. This study provides valuable insight into the molecular mechanisms of salinity and waterlogging tolerance in K. obovata, as well as a useful genetic resource for the improvement of mangrove stress tolerance using molecular breeding techniques.

Exogenous melatonin application helps late-sown durum wheat to cope with waterlogging under Mediterranean environmental conditions.

In Mediterranean countries, late-sown durum wheat (Triticum turgidum L. subsp. durum) may face waterlogging (WL) at early stages. As mitigation of waterlogging by melatonin (MT) has been poorly explored, we analyzed the effects of exogenous MT foliar application to WL-stressed durum wheat on its ecophysiological performance, growth and biomass production. Late-sown plants of a relatively tolerant cultivar (i.e., Emilio-Lepido) were subjected to two WL durations (i.e., 14 and 35 days of WL; DOW) at tillering, with or without exogenous MT application (i.e., 0 and 100 μM). Prolonged WL reduced shoot biomass (-43%), but the application of MT mitigated this detrimental effect. Waterlogging impaired photosynthesis, reducing leaf CO2 assimilation and chlorophyll content (-61 and - 57%, at 14 and 35 DOW). In control, MT increased the photosynthetic pigments (+48%), whereas it exacerbated the decrease in photosynthesis under both WL conditions (-72%, on average). Conversely, MT reduced WL-induced oxidative damage in both shoots and roots (-25% hydrogen peroxide production), facilitating osmotic adjustments and mitigating oxidative stress. The accumulation of osmotic regulators in MT + WL plants (+140 and + 42%, in shoots and roots at 35 DOW; respectively) and mineral solutes (+140 and + 104%, on average, in shoots and roots at 14 DOW) likely mitigated WL stress, limiting the impact of oxidative stress and promoting biomass accumulation. Our results highlight the potential of MT as a bioactive compound in mitigating the adverse effects of WL on late-sown durum wheat and the importance of the complex interactions between physiological responses and environmental stressors.

Tolerance of &lt;i&gt;Capsicum frutescens&lt;/i&gt; L. (Solanales: Solanaceae) to the duration of waterlogging and impact on the post-waterlogging and recovery periods

Waterlogging is a shallow flooding in the area of the root and in some parts of the shoot. It is one of the most common types of flooding in agricultural areas. The duration of waterlogging affects plant growth and yield in response to stress by interacting with their ability to adapt. Plant adaptability during waterlogging affects their resilience to post-waterlogging and recovery conditions. In this research, we examined the tolerance of Capsicum frutescens to short (1 day), medium (3 days) and long (10 days) duration of waterlogging, as well as its implications on post-waterlogging, recovery, reproductive phase and harvest. Adaptability and growth rates were used to determine plant tolerance to waterlogging stress. The percentage of wilting, root damage, survival, stomatal response, formation of hypertrophic lenticels, adventitious roots, photosynthetic pigment content, height, leaf number, plant biomass, flower number, and fruit fresh weight were used to measure adaptability and growth. The results showed that a longer duration of waterlogging increased root damage and decreased plant growth, affecting photosynthetic pigment content, leaf number, root and shoot biomass. The ability to regulate the stomata opening, the formation of hypertrophic lenticels and adventitious roots enabled plants not to wilt permanently, surviving post-waterlogging conditions and during recovery, growing during reproductive phase and producing yields. The critical duration of waterlogging at the beginning of the vegetative phase occurred at 10 days, and pepper suffered a drastic reduction in vegetative and reproductive growth and yields. The maintenance of the root system and the development of adaptive mechanisms increased plant survival, thereby affecting yield.

Developing functional relationships between waterlogging and cotton growth and physiology-towards waterlogging modeling.

Cotton crop is known to be poorly adapted to waterlogging, especially during the early growth stages. Developing functional relationships between crop growth and development parameters and the duration of waterlogging is essential to develop or improve existing cotton crop models for simulating the impact of waterlogging. However, there are only limited experimental studies conducted on cotton specifically aimed at developing the necessary functional relationships required for waterlogging modeling. Further research is needed to understand the effects of waterlogging on cotton crops and improve modeling capabilities in this area. The current study aimed to conduct waterlogging experiments and develop functional relationships between waterlogging and cotton growth and physiology. The experiments were conducted in pots, and the waterlogging was initiated by plugging the drain hole at the bottom of the pot using a wooden peg. In the experiments, eight waterlogging treatments, including the control treatment, were imposed at the vegetative growth stage (15 days after sowing). Control treatment had zero days of water-logged condition; other treatments had 2, 4, 6, 8, 10, 12, and 14 days of waterlogging. It took five days to reach zero oxygen levels and one to two days to return to control after the treatment. After a total treatment duration of 14 days (30 days after sowing), the growth, physiological, reproductive, and nutrient analysis was conducted. All physiological parameters decreased with the number of days of waterlogging. Flavonoid and anthocyanin index increased with increased duration of waterlogging. Photosynthesis and whole plant dry weight in continuously waterlogged conditions were 75% and 78% less compared to 0, and 2-day water-logged plants. Plant height, stem diameter, number of main stem leaves, leaf area, and leaf length also decreased with waterlogging duration. When waterlogging duration increased, leaf, stem, and root macronutrients decreased, while micronutrients showed mixed trends. Based on the experimental study, functional relationships (linear, quadratic, and exponential decay) and waterlogging stress response indices are developed between growth and development parameters and the duration of waterlogging. This can serve as a base for developing or improving process-based cotton models to simulate the impact of waterlogging.

Waterlogging Effects on Soybean Physiology and Hyperspectral Reflectance during the Reproductive Stage

In humid climates, waterlogging from excessive rainfalls can be a major limiting factor for soybean production, particularly during the reproductive stage. However, there is a limited understanding of how soybean growth and physiology respond to waterlogging during this critical stage. Here, we investigated the effects of waterlogging and subsequent reoxygenation on the growth, physiology, yields, and leaf hyperspectral reflectance traits of the soybean cultivar ‘Asgrow AG5332’. The crop was grown to stage R1 (initial flowering) in outdoor pot culture conditions, and then waterlogged for 16 days. The flooded pots were drained and continuously monitored for recovery for an additional 16 days. The results showed that soil oxygen levels declined rapidly to zero in about 5 days after waterlogging, and slowly recovered in about 5–16 days. However, it did not reach the same level as the control plants, which maintained an oxygen concentration of 18%. Increasing waterlogging duration negatively affected leaf chlorophyll index, water potential, and stomatal conductance, with a consequent decline in the photosynthetic rate. Further, decreased photosynthetic rate, leaf area, and mineral nutrients resulted in lower biomass and seed yield. Pod dry weight and leaf number were the most and least sensitive parameters, respectively, decreasing by 81% and 15% after 16 days of waterlogging. Waterlogged plants also had higher reflectance in the PAR, blue, green, and red regions, and lower reflectance in the near-infrared, tissue, and water band regions, indicating changes in chemistry and pigment content. The current study reveals that the soybean crop is susceptible to waterlogging during the reproductive stage, due to poor recovery of soil oxygen levels and physiological parameters. Understanding and integrating the growth, physiology, and hyperspectral reflectance data from this study could be used to develop improved cultivars to ensure the stability of soybean production in waterlogging-prone areas.

Effect of Reproductive Stage-Waterlogging on the Growth and Yield of Upland Cotton (Gossypium hirsutum)

The reproductive stage of cotton (Gossypium sp.) is highly sensitive to waterlogging. The identification of potential elite upland cotton (Gossypium hirsutum) cultivar(s) having higher waterlogging tolerance is crucial to expanding cotton cultivation in the low-lying areas. The present study was designed to investigate the effect of waterlogging on the reproductive development of four elite upland cotton cultivars, namely, Rupali-1, CB-12, CB-13, and DM-3, against four waterlogging durations (e.g., 0, 3, 6, and 9-day). Waterlogging stress significantly impacted morpho-physiological, biochemical, and yield attributes of cotton. Two cotton cultivars, e.g., CB-12 and Rupali-1, showed the lowest reduction in plant height (6 and 9%, respectively) and boll weight (8 and 5%, respectively) at the highest waterlogging duration of 9 days. Physiological and biochemical data revealed that higher leaf chlorophyll, proline, and relative water contents, and lower malondialdehyde contents, particularly in CB-12 and Rupali-1, were positively correlated with yield. Notably, CB-12 and Rupali-1 had higher seed cotton weight (90.34 and 83.10 g, respectively), lint weight (40.12 and 39.32 g, respectively), and seed weight (49.47 and 43.78 g, respectively) per plant than CB-13 and DM-3 in response to the highest duration of waterlogging of 9 days. Moreover, extensive multivariate analyses like Spearman correlation and the principle component analysis revealed that CB-12 and Rupali-1 had greater coefficients in yield and physiological attributes at 9-day waterlogging, whereas CB-13 and DM-3 were sensitive cultivars in response to the same levels of waterlogging. Thus, CB-12 and Rupali-1 might be well adapted to the low-lying waterlogging-prone areas for high and sustained yield.

Economic loss of urban waterlogging based on an integrated drainage model and network environ analyses

In this study, an economic loss assessment framework was proposed to evaluate the economic losses of urban waterlogging based on the integrated catchment management (ICM) model and information-based network environ analysis (NEA). First, the urban waterlogging model was constructed based on the ICM model to simulate the submerged depth, inundated area and duration of waterlogging. Second, the initial waterlogging risk of different economic sectors was combined with the submerged depth-disaster loss rate curve. Last, the information-based NEA was employed to quantify the distributed control relationships among different economic sectors. The results of a case study of Beijing showed that direct economic loss can reach 16.3 billion yuan in a recurrence period of once in 50 years. Forty percent of the waterlogging risk was transferred to the downstream regions or sectors via the national supply chain. The proposed economic loss assessment framework may help promote waterlogging prevention strategies.

Silver lining to a climate crisis in multiple prospects for alleviating crop waterlogging under future climates

Extreme weather events threaten food security, yet global assessments of impacts caused by crop waterlogging are rare. Here we first develop a paradigm that distils common stress patterns across environments, genotypes and climate horizons. Second, we embed improved process-based understanding into a farming systems model to discern changes in global crop waterlogging under future climates. Third, we develop avenues for adapting cropping systems to waterlogging contextualised by environment. We find that yield penalties caused by waterlogging increase from 3–11% historically to 10–20% by 2080, with penalties reflecting a trade-off between the duration of waterlogging and the timing of waterlogging relative to crop stage. We document greater potential for waterlogging-tolerant genotypes in environments with longer temperate growing seasons (e.g., UK, France, Russia, China), compared with environments with higher annualised ratios of evapotranspiration to precipitation (e.g., Australia). Under future climates, altering sowing time and adoption of waterlogging-tolerant genotypes reduces yield penalties by 18%, while earlier sowing of winter genotypes alleviates waterlogging by 8%. We highlight the serendipitous outcome wherein waterlogging stress patterns under present conditions are likely to be similar to those in the future, suggesting that adaptations for future climates could be designed using stress patterns realised today.

Effects and Recovery of Maize (Zea mays Linn) to Waterlogging Imposed at Early Seedling Stage

Background: This study aimed to determine the effects of different waterlogging duration imposed at the V2 leaf stage and assess the impact of waterlogging on maize growth during the recovery period, identify susceptible and tolerant lines and traits conferring tolerance to waterlogging at the early seedling stage. Methods: The study was arranged in a Split-plot RCBD and replicated three times. Intercharacter and waterlogging durations to maize growth parameters were correlated to determine the degree of the linear relationship using Pearson’s product moments correlation and simple linear regression analysis. Result: The result shows that the different waterlogging durations negatively influenced the maize growth parameters regarding plant height and root length. These parameters became shorter and did not recover after waterlogging stress was removed. Therefore, plant height and root length are traits sensitive to waterlogging stress. The USM Var 10, BRK and T. Monkayo obtained a high degree of leaf greenness, heaviest shoot and root dry matter compared to other evaluated maize lines. Maize with greener leaves, taller plant height, longer root length and high total dry matter accumulation could be a good criterion in selecting a parent material in the maize waterlogging breeding program.

Effect of waterlogging stress on grain nutritional quality and pod yield of peanut (Arachis hypogaea L.)

AbstractTo investigate the effects of waterlogging stress on grain nutritional quality and pod yield, peanut plants were waterlogged for 3 and 6 days at 7, 14, 21, 28, 35, 42, 49, 56 and 63 days after gynophores touched the ground in 2019 and 2020. Results revealed that compared with the control treatment, the oil and starch content in grain increased, while crude protein and soluble sugar content decreased under waterlogging. Waterlogging stress increased the unsaturated fatty acids content but decreased the saturated fatty acids, essential amino acids, non‐essential amino acids and total amino acids content. In addition, waterlogging stress decreased the total pod number per plant by 6.78%–49.33%, 100‐pod weight by 1.11%–14.08% and 100‐grain weight by 1.85%–16.41%, which caused a 34.33%–55.90% reduction in pod yield per plant. After the gynophore touched the ground for 7 days, waterlogging had a greater negative effect on grain nutritional quality, and longer waterlogging duration led to greater yield reduction. In summary, waterlogging stress caused peanut yield reduction and grain quality deterioration.

Soil physico-chemical changes half a century after drainage and cultivation of the former Antela lake (Galicia, NW Spain)

Wetlands in Mediterranean climates undergo large fluctuations in water levels that lead to wet-dry cycles in lake beds, with important effects on sediments and water biogeochemistry. Thus, wetland drainage and ploughing have different effects on soil properties that depend on previous waterlogging periods. However, current knowledge of this topic remains scarce. Fifty-six years after drainage of the Antela lake (Galicia, NW Spain) and characterisation of the main soil properties, in 2019 a stratified sampling - using elevation as proxy for waterlogging length - was done. We checked three hypotheses: a) that changes in the soil pH and organic C were higher in the lake core (permanently waterlogged) than in sediment samples representing four different periods of waterlogging; b) that 13C and 15N signatures are useful for tracing differences in the soil C and N dynamics related to the prior duration of waterlogging; and c) that land subsidence in the area previously occupied by peat was higher than predicted immediately after drainage. As hypothesized, we found that drainage and ploughing triggered acidification and C mineralization processes, which were more intense in the previously most waterlogged soils (-0.8 pHH2O units; −0.5 pHKCl units; 20–70% of C lost). In the 2019 samples: a) the highest soil N content (values up to 4-fold higher) and lowest C/N ratio (up to 4 units lower) were recorded in the area that was previously permanently waterlogged; b) soil δ15N increased significantly (around 3‰) with elevation (i.e. shorter waterlogging period), while soil δ13C did not vary; and c) peat subsidence ranged from 17 to 32 cm (3.0–5.7 mm y−1). The main consequence of draining the Antela lake and cultivating the reclaimed land was the opening of water and nutrient cycles, drainage effects being greater than the cultivation ones, and land subsidence 6–8 times higher than initially predicted.

Potassium application promote cotton acclimation to soil waterlogging stress by regulating endogenous protective enzymes activities and hormones contents

To investigate the effect of potassium application on cotton damage mitigation after waterlogging stress, experiments were conducted under two potassium application levels (0 and 150 kg K2O hm−2) with three types of soil waterlogging treatments (0d, 3d and 6d) during cotton flowering stage. The results showed that: (a) under simple soil waterlogging stress, the increments of endogenous hormones contents of IAA, GA3 and ZR in cotton leaves were decreased as days of soil waterlogging. On the contrary, the soluble protein, MDA and ABA contents were significantly increased, while ZR/ABA, IAA/ABA and GA3/ABA were decreased. CAT and POD enzyme activities were increased although SOD activity decreased with the duration of soil waterlogging. (b) Potassium application combined with soil waterlogging significantly affected the antioxidant enzymes activity and endogenous hormones balance compared with soil waterlogging alone, leading to a significant increase in soluble protein and a pronounced decrease in H2O2 content, O2− generation rate, and MDA content, a significant increase in IAA, GA3 and ZR contents while a decrease in ABA content. Besides, it also kept higher SOD, CAT activities and slowly increased POD activity. (c) There was an obvious compensatory effect in cotton after 3d soil waterlogging under potassium application, which promoted rapidly recovery of physiological enzymes activities and ABA content. However, 6d soil waterlogging required a longer time for recovery. These findings were expected to provide a scientific and theoretical basis for reducing flood damage and improving cotton yield.

Post-flowering Soil Waterlogging Curtails Grain Yield Formation by Restricting Assimilates Supplies to Developing Grains.

Soil waterlogging is among the major factors limiting the grain yield of winter wheat crops in many parts of the world, including the middle and lower reaches of the Yangtze River China. In a field study, we investigated the relationship between leaf physiology and grain development under a varying duration of post-flowering waterlogging. A winter wheat cultivar Ningmai 13 was exposed to soil waterlogging for 0 (W0), 3 (W3), 6 (W6), and 9 d (W9) at anthesis. Increasing waterlogging duration significantly reduced flag leaf SPAD (soil plant analysis development) values and net photosynthetic rate (Pn). There was a linear reduction in flag leaf Pn and SPAD as plant growth progressed under all treatments; however, the speed of damage was greater in the waterlogged leaves. For example, compared with their respective control (W0), flag leaves of W9 treatment have experienced 46% more reduction in Pn at 21 d after anthesis (DAA) than at 7 DAA. Increasing waterlogging duration also induced oxidative damage in flag leaves, measured as malondialdehyde (MDA) contents. The capacity to overcome this oxidative damage was limited by the poor performance of antioxidant enzymes in wheat leaves. Inhibited leaf Pn and capacity to sustain assimilate synthesis under waterlogged environments reduced grain development. Compared with W0, W6 and W9 plants experienced a 20 and 22% reduction in thousand grain weight (TGW) in response to W6 and W9, respectively at 7 DAA and 11 and 19%, respectively at 28 DAA. Sustained waterlogging also significantly reduced grain number per spike and final grain yield. Averaged across two years of study, W9 plants produced 28% lesser final grain yield than W0 plants. Our study suggested that wheat crops are highly sensitive to soil waterlogging during reproductive and grain filling phases due to their poor capacity to recover from oxidative injury to photosynthesis. Management strategies such as planting time, fertilization and genotype selection should be considered for the areas experiencing frequent waterlogging problems.

A quantitative revision of the waterlogging tolerance of perennial forage grasses

Waterlogging tolerance of eight C4 and seven C3 perennial forage grasses was reviewed. The median waterlogging duration was similar between species’ type, ranging between 18 and 21 days. Inter- and intra-species variability was found in shoot and root biomass in response to waterlogging. Urochloa brizantha (C4), Brachiaria hybrid (C4) and Dactylis glomerata (C3) were the less tolerant species to waterlogging (shoot biomass median of 45%, 53% and 80% of controls), while U. humidicola (C4), Paspalum dilatatum (C4), Festuca arundinacea (C3) and Lolium perenne (C3) were the most tolerant (shoot biomass median of 97%, 101%, 87% and 94% of controls). A similar ranking of responses was found among species for root biomass. The formation of aerenchyma/root porosity (a key trait for waterlogging tolerance) was evaluated mainly in U. humidicola and P. dilatatum (C4 waterlogging-tolerant species), which showed considerable constitutive porosity (13% and 32%) and final values of 30% and 41% under waterlogging. Net photosynthesis and stomatal conductance as typical leaf physiological responses matched species’ waterlogging tolerance, with the impact of hypoxia higher in C3 than in C4 species. Gaps in knowledge about waterlogging tolerance in forage grasses are: (i) additional studies on C3 perennial grasses for temperate pasture areas prone to waterlogging, (ii) identification of traits and responses aiding plant recovery after waterlogging (and also during the stress), (iii) reassessment of waterlogging tolerance considering plant developmental stage (e.g. adult vs young plants), and (iv) evaluation of sequential (i.e. waterlogging − drought) and combined (i.e. waterlogging + salinity) stresses, which often co-occur in pasture lands.

CHỌN LỌC GIỐNG SẮN TIỀM NĂNG CHỐNG CHỊU ĐIỀU KIỆN NGẬP ÚNG THÔNG QUA SỰ BIỂU HIỆN HÌNH THÁI - SINH LÍ

The experiment screening of potential cassava varieties for good tolerance to artificial waterlogging was evaluated on 17 varieties of cassava in vitro at 3 months of age after planting in potting soil for 12 days through physiological parameters: number of leaves\plant, number of yellow leaves, number of wilted plants and chlorophyll content. The results showed that cassava varieties had different tolerance to waterlogging: some varieties showed physiological symptoms only after 3 days of growth on waterlogging conditions such as the number of leaves\plant decreasing to 83.93 %. 93.75 %, 93.81 %, 95.88 % and 96.48 % in cassava varieties C86, C23, Hanoi3, C84 and C31, respectively. After 6 days of waterlogging, the percentage of yellow leaves in some varieties of cassava had been increased, attained up to 40 % of the total leaves\plant turned yellow such as C71 (44.68 %) or C13 (53.12 %) varieties while other cassava varieties wilted and die 100 % such as Hanoi3, C10, C13, C34, C42, C66, C71, C84 and C86; along with the symtoms of morphological and growth of cassava varieties on waterlogging conditions, the total of chlorophyll content also decreased. After 9 days of waterlogging, only C60 variety remained chlorophyll content with 77.38 % but in other cassava varieties, the chlorophyll content was not more than 50 %. We founded that the longer the duration of waterlogging, the more tolerant response of the studied cassava varieties was revealed. After 12 days of experiment, we initially determined that the C60 variety was the best flood tolerance among the 17 studied varieties and this was a good source of materials on selecting the variety of flood tolerant cassava.

Carbohydrate Assimilation and Translocation Regulate Grain Yield Formation in Wheat Crops (Triticum aestivum L.) under Post-Flowering Waterlogging

In a two-year field study, we quantified the impact of post-flowering soil waterlogging on carbon assimilation and grain yield formation in wheat crops. At anthesis, wheat cultivars YangMai 18 (YM18) and YanNong 19 (YN19) were waterlogged for different durations, i.e., 0 (W0), 3 (W3), 6 (W6) and 9 (W9) days using artificial structures. Changes in leaf physiology, carbon assimilation and biomass production were quantified at 0, 7, 14, and 21 days after anthesis under all treatments. Short-term (W3) waterlogging had no significant effect on wheat crops but W6 and W9 significantly reduced the net photosynthetic rate (Pn), leaf SPAD value, and grain weight of the tested cultivars. Increasing waterlogging duration significantly increased dry matter accumulation in the spike-axis + glumes but reduced dry matter accumulation in grain. Further, the tested cultivars responded significantly variably to W6 and W9. Averaged across two years, YM 18 performed relatively superior to YN19 in response to long-term waterlogging. For example, at 14 days after anthesis, W9 plants of YM18 and YN19 experienced a 17.4% and 23.2% reduction in SPAD and 25.3% and 30.8% reduction in Pn, respectively, compared with their W0 plants. Consequently, YM18 suffered a relatively smaller grain yield loss (i.e., 16.0%) than YN19 (23.4%) under W9. Our study suggests that wheat cultivar YM18 could protect grain development from waterlogging injury by sustaining assimilates supplies to grain under waterlogged environments.

Developing Functional Relationships between Soil Waterlogging and Corn Shoot and Root Growth and Development.

Short- and long-term waterlogging conditions impact crop growth and development, preventing crops from reaching their true genetic potential. Two experiments were conducted using a pot-culture facility to better understand soil waterlogging impacts on corn growth and development. Two corn hybrids were grown in 2017 and 2018 under ambient sunlight and temperature conditions. Waterlogging durations of 0, 2, 4, 6, 8, 10, 12, and 14 days were imposed at the V2 growth stage. Morphological (growth and development) and pigment estimation data were collected 15 days after treatments were imposed, 23 days after sowing. As waterlogging was imposed, soil oxygen rapidly decreased until reaching zero in about 8–10 days; upon the termination of the treatments, the oxygen levels recovered to the level of the 0 days treatment within 2 days. Whole-plant dry weight declined as the waterlogging duration increased, and after 2 days of waterlogging, a 44% and 27% decline was observed in experiments 1 and 2, respectively. Leaf area and root volume showed an exponential decay similar to the leaf and root dry weight. Leaf number and plant height were the least sensitive measured parameters and decreased linearly in both experiments. Root forks were the most sensitive parameter after 14 days of waterlogging in both experiments, declining by 83% and 80% in experiments 1 and 2, respectively. The data from this study improve our understanding of how corn plants react to increasing durations of waterlogging. In addition, the functional relationships generated from this study could enhance current corn simulation models for field applications.