Days Of Waterlogging Research Articles

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).

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.

Effect of waterlogging on photosynthesis and growth of finger millet (Eleusine coracana)

AbstractFinger millet (Eleusine coracana (L.) Gaertn.) is an important cereal crop grown in most parts of Asia and Africa owing to its ability to adapt to stressful environments. The objective of this study was to examine the effect of waterlogging on photosynthesis and growth of finger millet. Plants were subjected to waterlogging by keeping pots filled with water from June 16 (transplanting) until November 12 (harvesting) in 2021 in Tokyo. After being subject to 13 days of waterlogging, net photosynthetic rate (Pn) decreased by 10.1% due to reduced stomatal conductance (gs), transpiration rate, and relative chlorophyll content (SPAD). From July to September, long‐term waterlogging increased Pn in the range of 4.9%–26.3%. The alleviation of high temperature, increase in SPAD and gs, and other nonstomatal components were implicated as the cause of increased Pn in summer. These findings suggest that the effect of waterlogging on photosynthesis varies with the duration of waterlogging or the growing season. Plant height was significantly reduced by 27.9% during the first 13 days of waterlogging and remained lower throughout the waterlogging treatment than in irrigated conditions. Waterlogging also caused other morphological changes, such as a significant increase in the number of tillers (63.2%) and a 16.7% increase in the number of panicles. Grain yield decreased by 13.6%, but the reduction was not significant. Overall, finger millet has the potential to tolerate waterlogging and is a promising crop for both paddy and field farming.

Identification of the Effect of Water Stress on Yield Production and Evaluation of the Nutrient Content of Garut Tubers and Flour

Arrowroot tubers (Maranta Arundinace L.) are a tuber plant that has potential as a source of carbohydrates. Arrowroot tuber plants have the potential to adapt well to various environmental conditions including water stress. The aim of this research was to identify the effect of water stress on yield production (number, weight, length and diameter) and evaluate the nutritional content of arrowroot tubers. This research used a Completely Randomized Design (CRD) with 7 water stress treatments, namely (P1) 15 days of waterlogging, (P2) 10 days of waterlogging, (P3) 5 days of waterlogging, (P4) daily watering, (P5) watering every 5 days, (P6) watering every 10 days, and (P7) watering every 15 days which was repeated in 2 experimental repetitions and 2 measurement repetitions. The results of the research showed that there was no decrease in yield in treatments P1 to P3, however in treatments P6 and P7 there was a difference in the yield of lower tuber weight compared to the daily watering treatment (P4) and the once every 5 days watering treatment (P5). Treatment The results of proximate analysis of arrowroot tubers with the best yield production (P5) showed that the water, ash, fat, protein and carbohydrate content of fresh tubers were respectively 69.82%, 1.47%, 0.21%, 0, 45% and 28.15%, while arrowroot flour is 2.28%, 4.77%, 0.33%, 1.47% and 91.16%. The results of this research provide information that arrowroot plants can be planted on land that has the potential to be flooded during the arrowroot growing season, but arrowroot plants require sufficient water to optimize their production. The high carbohydrate content of arrowroot tubers reflects its potential as an alternative food source to replace wheat and rice.

Using stomatal conductance capacity during water stress as a tool for tree species selection for urban stormwater control systems

Improving our understanding of how different tree species function in urban stormwater management systems is important, as tree pits may provide a temporary reservoir for stormwater and as trees have the potential to actively reduce stormwater runoff by transpiration. While urban tree planting pits are increasingly used for short-term water storage during stormwater runoff events, this storage can have negative effects on both tree vitality and water removal capacity, since stress from waterlogging result in stomatal closure. However, sensitivity to water stress varies by species. It is therefore important to determine which tree species can maintain long-term vitality and continued transpiration even under water stress, and thus are suitable for such locations. Here, we studied how nine different tree species, varying in expected tolerance to water stress, were affected by short-term and seasonal waterlogging, in a greenhouse experiment. The seedlings (Magnolia x loebneri, Tilia tomentosa, and Sorbus torminalis – low water logging tolerance; Cercidiphyllum japonicum, Rhamnus cathartica, and Fraxinus ornus – medium water logging tolerance; Quercus palustris, Acer saccharinum, and Fraxinus pennsylvanica – high water logging tolerance) were exposed to two days, five days and seasonal waterlogging. The treatments reflected best practice (optimal), suboptimal and total lack of tree pit drainage, using Swedish standards. Stomatal conductance and leaf water potential were determined regularly over a period of 71 days, and morphological adjustments were registered. Four of the species were affected already after two days of waterlogging, with reduced stomatal conductance either during the waterlogging or immediately after, and only the most waterlogging tolerant species were unaffected by the five-day treatment. However, all plants survived waterlogging for almost 30 days before the estimated permanent wilting was reached in some plants. We suggest that tree species selection for stormwater management systems should consider the species’ capacity to maintain high stomatal conductance during waterlogging, as there were clear differences between species. The effectiveness of the selected species could have an important impact on the stormwater management capacity of cities, as well as on other aspects of ecosystem service delivery from urban trees.

Waterlogging Response of Lentil Cultivars Grown in Greenhouse Throughout The Early Vegetative and Recovery Period

Under conditions of global climate change, the frequency of climate anomalies is predicted to increase. One of these issues is the problem of waterlogging in agricultural areas as a direct result of the unexpected and severe rainfall that has occurred over the last decades. In this study, the morphological responses to waterlogging stress and the recovery capacity of the lentil cultivars were investigated. A waterlogging stress study was conducted in small water pools with four different lentil varieties (Çağıl, Fırat 87, Kafkas and Kayı). Lentil cultivars were exposed to waterlogging stress for 7 and 14 days in the same greenhouse conditions. Measurements were taken at the end of 7 and 14 days of waterlogging (W-7 and W-14) and during the recovery period after flowering (R-7 and R-14). Lentil cultivars and plant traits were negatively affected by waterlogging stress applications (W-7 and W-14). According to the study, 14-day waterlogging had a greater impact on lentil cultivars than 7-day waterlogging. Total biomass measured after flowering at R-7 and R-14 waterlogging decreased by about 31.5% and 49.3%, respectively. Çağıl cultivar had a tolerance to waterlogging stress, but Kafkas cultivar was sensitive to waterlogging stress.

Physiological Mechanism of Waterlogging Stress on Yield of Waxy Maize at the Jointing Stage.

In the main agricultural area for waxy maize production in China, waterlogging occurs frequently during the waxy maize jointing stage, and this causes significant yield reduction. It is very important to understand the physiological mechanism of waterlogging stress in waxy maize during the jointing stage to develop strategies against waterlogging stress. Therefore, this study set waterlogging treatments in the field for 0, 2, 4, 6, 8, and 10 days during the waxy maize jointing stage, and were labelled CK, WS2, WS4, WS6, WS8 and WS10, respectively. By analyzing the effect of waterlogging on the source, sink, and transport of photoassimilates, the physiological mechanism of waterlogging stress in the jointing stage was clarified. The results show that PEPC and POD activities and Pro content decreased significantly under WS2 compared to CK. Except for these three indicators, the Pn, GS, leaf area, kernel number, yield, and puncture strength of stems were significantly decreased under the WS4. Under the WS6, the content of MDA began to increase significantly, while almost all other physiological indices decreased significantly. Moreover, the structure of stem epidermal cells and the vascular bundle were deformed after 6 days of waterlogging. Therefore, the threshold value of waterlogging stress occured at 4 to 6 days in the jointing stage of waxy maize. Moreover, waterlogging stress at the jointing stage mainly reduces the yield by reducing the number of kernels; specifically, the kernel number decreased by 6.7-15.5% in 4-10 days of waterlogging, resulting in a decrease of 9.9-20.2% in the final yield. Thus, we have shown that waterlogging stress at the jointing stage results in the decrease of potential waxy maize kernel numbers and yield when the synthesis of sources was limited and the transport of photoassimilates was restricted.

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 in Adventitious Roots, Tillering and Yield of Bread Wheat Germplasm

In the context of climate changes, expected increases in intensity, frequency, and unpredictability of waterlogging events will aggravate wheat yield losses, currently estimated to range between 20-50%. Wheat production must fulfill ca. 20% of the population’s energy and protein requirements. Evaluating germplasm with different backgrounds may reveal variability for waterlogging tolerance, allowing a better selection of genotypes with desirable traits for wheat breeding programs. In this work, the effect of waterlogging on adventitious root emission, tiller survival and yield was evaluated. Five studied germplasm groups (Portuguese Landraces; Varieties with introduced Italian germplasm; Post-Green Revolution varieties with introduced CYMMIT germplasm; Advanced Lines from the Portuguese Cereal Breeding Program; Australian varieties) were studied. Groups exhibited intra and intervariability in all parameters in response to waterlogging imposed in climatized growth chambers. After 14 days of waterlogging, the number of adventitious roots ranged from 0 to 7.6 plant-1, with 4 Portuguese Landraces depicting the highest number. The number of living tillers at the end of the stress was highly variable, ranging from reductions of 100% to increases up to 35%. At harvest, the number of productive tillers significantly differed among genotypes, with reductions reaching 100% in some cases and increases up to 138% in others. The existence of variability and the identification of key traits underlying waterlogging tolerance will contribute to develop more adapted wheat plants and to improve wheat yield.

Waterlogging stress alters the structure of sugar beet rhizosphere microbial community structure and recruiting potentially beneficial bacterial

Waterlogging has been shown to have a significant inhibitory effect on plant growth. However, the response mechanisms of the soil environment of sugar beet seedlings under waterlogging conditions still need to be fully understood. This study aimed to investigate the effects of waterlogging treatments on the content of effective nutrients and the microbial communities in the rhizosphere and non-rhizosphere using high-throughput sequencing. We set up waterlogging and non-waterlogging treatments, sampled sugar beet seedlings after 10 days of waterlogging, determined the effective soil nutrients in the rhizosphere and non-rhizosphere of the plants, and analyzed the differences in microbial diversity at ten days of waterlogging. The results showed that waterlogging significantly affected available potassium (AK) content. The Ak content of waterlogged soil was significantly higher than that of non-waterlogged soil. Waterlogging caused no significant difference in available nitrogen (AN) content and pH. Moreover, the plant growth-promoting bacteria Pseudomonas was significantly enriched in sugar beet waterlogged rhizospheres compared with the non-waterlogged ones. Similarly, the harmful fungi Gibellulopsis and Alternaria were enriched in sugar beet non-waterlogged rhizosphere. The network analysis revealed that waterlogging built a less complex root-microbial network than non-waterlogging. These findings implied that sugar beets subjected to waterlogging stress were enriched with beneficial microorganisms in the rhizosphere, potentially alleviating the stress.

Transcriptomic and metabolomic analyses reveal the potential mechanism of waterlogging resistance in cotton (Gossypium hirsutum L.).

Cotton (Gossypium hirsutum L.) is susceptible to long-term waterlogging stress; however, genomic information of cotton response mechanisms toward long days of waterlogging is quite elusive. Here, we combined the transcriptome and metabolome expression level changes in cotton roots after 10 and 20 days of waterlogging stress treatment pertaining to potential resistance mechanisms in two cotton genotypes. Numerous adventitious roots and hypertrophic lenticels were induced in CJ1831056 and CJ1831072. Transcriptome analysis revealed 101,599 differentially expressed genes in cotton roots with higher gene expression after 20 days of stress. Reactive oxygen species (ROS) generating genes, antioxidant enzyme genes, and transcription factor genes (AP2, MYB, WRKY, and bZIP) were highly responsive to waterlogging stress among the two genotypes. Metabolomics results showed higher expressions of stress-resistant metabolites sinapyl alcohol, L-glutamic acid, galactaric acid, glucose 1-phosphate, L-valine, L-asparagine, and melibiose in CJ1831056 than CJ1831072. Differentially expressed metabolites (adenosine, galactaric acid, sinapyl alcohol, L-valine, L-asparagine, and melibiose) significantly correlated with the differentially expressed PRX52, PER1, PER64, and BGLU11 transcripts. This investigation reveals genes for targeted genetic engineering to improve waterlogging stress resistance to enhance abiotic stress regulatory mechanisms in cotton at the transcript and metabolic levels of study.

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.

Diferenças fisiológicas e anatômicas entre gramíneas subtropicais crescidas em solo alcalino-sódico alagado

Abstract The objective of this work was to evaluate the effects of 26 days of waterlogging, compared with field capacity, on different traits of the forage plants 'Finecut' Chloris gayana, 'Klein Verde' Panicum coloratum, and 'Shawnee' Panicum virgatum, grown in alkaline-sodic soil. Shoot and root dry mass, leaf greenness index, electrolyte leakage, and root histology were evaluated. The histological analysis was performed along the mid-portion of adventitious roots with a 2.0 mm diameter. Waterlogging inhibited the growth of P. coloratum, in addition to decreasing the leaf greenness index and causing injuries in the cell membrane of C. gayana and P. coloratum. At field capacity, only C. gayana and P. coloratum had aerenchyma; however, waterlogging induced the development and increased the area of the aerenchyma in P. virgatum and C. gayana, respectively. Waterlogging also thickened the exodermis and endodermis of all three genotypes, inducing a greater number of exodermis cell rows and a thicker internal tangential cell wall of the endodermis in C. gayana and P. virgatum. Although P. coloratum growth is more sensitive to waterlogging, there are radial oxygen loss barriers in the roots of the three evaluated genotypes.

Waterlogging during the reproductive growth stage causes physiological and biochemical modifications in the leaves of cowpea (Vigna unguiculata L.) genotypes with contrasting tolerance

Waterlogging causes various metabolic, physiological, and morphological changes in crops, resulting in yield loss of most legumes in rainfed and irrigated agriculture. However, research on cowpea genotypes using physiological and biochemical traits as a measure of tolerance to waterlogging stress is limited. We evaluated the impacts of 7 days of waterlogging (DOW) and 7 days of recovery (DOR) on the physiology and biochemistry of two cowpea (Vigna unguiculata (L.) Walp) genotypes (UCR 369 and EpicSelect.4) with contrasting waterlogging tolerance. Cowpea genotypes were grown in a controlled environment until the R2 stage and then subjected to 7 DOW. Later, the waterlogged plants were reoxygenated for an additional 7 DOR. Overall, cowpea genotypes had a contrasting response to waterlogging using different mechanisms. Compared to the control, the photosynthetic parameters of both cowpea genotypes were impaired under 7 DOW and could not recover at 7 DOR, with a larger decline in EpicSelect.4.7 DOW caused significant loss in the chlorophyll and carotenoid content of both genotypes. However, only waterlogged UCR 369 was not photo-inhibited and able to restore the levels of chlorophyll and carotenoids at 7 DOR. In addition, 7 DOW induced intense stress in UCR 369 with increased zeaxanthin, sucrose, and flavonoid content, while these metabolites were decreased in EpicSelect.4. On the other hand, glucose, fructose, and phenolic content were increased in EpicSelect.4 but decreased in UCR 369 at 7 DOR. In summary, compared to EpicSelect.4, UCR 369 restored their photosynthetic pigments and metabolites to the control levels at 7 DOR, indicating a likely tolerance to waterlogging stress.

Short waterlogging events differently affect morphology and photosynthesis of two cucumber (Cucumis sativus L.) cultivars.

Waterlogging induces growth and developmental changes in sensitive crops such as cucumber (Cucumis sativus L.) during early plant development. However, information on the physiological mechanisms underpinning the response of cucumber plants to waterlogging conditions is limited. Here, we investigated the effects of 10-day waterlogging stress on the morphology, photosynthesis, and chlorophyll fluorescence parameters in two cultivars of cucumber seedlings. Waterlogging stress hampered cultivars’ growth, biomass accumulation, and photosynthetic capacity. Both cultivars also developed adventitious roots (ARs) after 10 days of waterlogging (DOW). We observed differential responses in the light- and carbon-dependent reactions of photosynthesis, with an increase in light-dependent reactions. At the same time, carbon assimilation was considerably inhibited by waterlogging. Specifically, the CO2 assimilation rate (A) in leaves was significantly reduced and was caused by a corresponding decrease in stomatal conductance (gs). The downregulation of the maximum rate of Rubisco efficiency (Vcmax) and the maximum rate of photosynthetic electron transport (Jmax) were non-stomatal limiting factors contributing to A reduction. Exposure of cucumber to 10 DOW affected the PSII photochemistry by downregulating the PSII quantum yield (ΦPSII). The redox state of the primary quinone acceptor in the lake model (1-qL), a measure of the regulatory balance of the light reactions, became more oxidized after 10 DOW, indicating enhanced electron sink capacity despite a reduced A. Overall, the results suggest that waterlogging induces alterations in the photochemical apparatus efficiency of cucumber. Thus, developing cultivars that resist inhibition of PSII photochemistry while maintaining carbon metabolism is a potential approach for increasing crops’ tolerance to waterlogged environments.

Photosynthetic and Morphological Responses of Sacha Inchi (Plukenetia volubilis L.) to Waterlogging Stress.

Sacha inchi (Plukenetia volubilis L.) is an important oilseed crop that is rich in fatty acids and protein. Climate-change-related stresses, such as chilling, high temperature, and waterlogging can cause severe production loss in this crop. In this study, we investigated the photosynthetic responses of sacha inchi seedlings to short-term waterlogging and their morphological changes after long-term waterlogging stress. Sacha inchi CO2 uptake, stomatal conductance, and transpiration rate are affected by temperature and light intensity. The seedlings had a high CO2 uptake (>10 μmol m−2s−1) during the daytime (08:00 to 15:00), and at 32 and 36 °C. At 32 °C, CO2 uptake peaked at irradiations of 1000 and 1500 µmol m−2s−1, and plants could still perform photosynthesis at high-intensity radiation of 2000–3000 µmol m−2s−1. However, after 5 days of waterlogging (5 DAF) sacha inchi seedlings significantly reduced their photosynthetic ability. The CO2 uptake, stomatal conductance, Fv/Fm, ETR, and qP, etc., of the susceptible genotypes, were significantly decreased and their wilting percentage was higher than 50% at 5 DAF. This led to a higher wilting percentage at 7 days post-recovery. Among the four lines assessed, Line 27 had a high photosynthetic capability and showed the best waterlogging tolerance. We screened many seedlings for long-term waterlogging tolerance and discovered that some seedlings can produce adventitious roots (AR) and survive after two weeks of waterlogging. Hence, AR could be a critical morphological adaptation to waterlogging in this crop. In summary, these results suggest that improvement in waterlogging tolerance has considerable potential for increasing the sustainable production of sacha inchi.

Aerenchyma Formation in Adventitious Roots of Tall Fescue and Cocksfoot under Waterlogged Conditions

The formation of aerenchyma in adventitious roots is one of the most crucial adaptive traits for waterlogging tolerance in plants. Pasture grasses, like other crops, can be affected by waterlogging, and there is scope to improve tolerance through breeding. In this study, two summer-active cocksfoot (Dactylis glomerata L.) cultivars, Lazuly and Porto, and two summer-active tall fescue (Lolium arundinaceum Schreb., syn. Festuca arundinacea Schreb.) cultivars, Hummer and Quantum II MaxP, were selected to investigate the effects of waterlogging on root growth and morphological change. Cultivars were subjected to four periods of waterlogging treatments (7, 14, 21 and 28 days), while comparable plants were kept under free drained control conditions. The experiment was arranged as a split–split plot design, with waterlogging treatments (waterlogged, control) considered as main plots, time periods (days of waterlogging) as subplots and cultivars as sub-subplots. Plants began to show signs of waterlogging stress 14–21 days after the onset of waterlogging treatments. There were no significant differences in shoot biomass between the waterlogged and control plants of any cultivar. However, waterlogging significantly reduced root dry matter in all cultivars, with greater reduction in cocksfoot (56%) than in tall fescue (38%). Waterlogging also led to increased adventitious root and aerenchyma formation in both species. Cocksfoot cultivars showed a greater increase in adventitious roots, while tall fescue cultivars had a greater proportion of aerenchyma. Both cultivars within each species showed similar responses to waterlogging treatments. However, an extended screening program is needed to identify whether there are varietal differences within species, which could be used to discover genes related to aerenchyma or adventitious root formation (waterlogging tolerance) for use in breeding programs.

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.

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.

Effect of Waterlogging Duration on Germination, Physiological Characteristics, and Yield of Mungbean (Vigna radiata L.)

The study was conducted to evaluate the germination, physiological responses, yield-related traits, and seed yield of three mungbean varieties, viz. DXVN7, DXVN5, and DX11, under waterlogging coditions in the 2019 Summer. In experiment 1, the seeds of the three mungbean varieties were immersed in distilled water in Petri dishes for 12, 24, 36, 48, and 72h. Afterwards, water was removed and the percentage of germinated seeds was calculated at 84h after sowing. In experiment 2, plants were waterlogged at the seedling stage (25 days after germination) for 3, 6, and 9 days. Waterlogging depth was maintained at 3cm above the soil surface. Physiological traits were determined at the recovery period after termination of waterlogging (45 days after germination). The results showed that waterlogging significantly decreased germination percentages, plant height, root dry weight, leaf relative water content (RWC), SPAD value, Fv/Fm index, leaf photosynthesis, total dry weight, and seed yield of all varieties. Germination percentages at 12 and 24h of waterlogging were not significantly affected, whereas germination was significantly reduced at up to 36h of waterlogging. Seventy-two hours of waterlogging caused failure in germination. Nine days of waterlogging at the seedling stage adversely affected the physiological traits and seed yield of the mungbean varieties with 31% of yield reduction. Meanwhile, plants grew better at 3 days of waterlogging. Among the three varieties, DXVN7 showed the best adaptability under waterlogging conditions, attaining the highest seed germination and yield.