Waterlogged Conditions Research Articles

Effect of Waterlogging on Growth and Productivity of Fruit Crops

Τhe production of fresh fruit as well as olive orchards is increasing around the world, in order to meet the global demand for both fruits and olive products. This results in the spread and establishment of fruit and olive tree cultivation in areas where they were not found before, for example, plains and lowlands prone to waterlogging. Climate change is having a significant impact on the natural environment. Agricultural open-field crops have less growth and yield under these harsh weather conditions. Nowadays, unpredictable rainfall more often exposes field crops to waterlogging on a regular basis. This is a very stressful factor which can cause a reduction in yield and even total crop elimination. In this review, the morphological and physiological parameters affected by waterlogging are developed in order to understand better how olive and other fruit crops respond to waterlogging conditions and how this affects their development and productivity. Having a better understanding of these mechanisms can help us design strategies and approaches to increase fruit crop resistance to waterlogging stress.

Leaf and twig traits predict habitat adaptation and demographic strategies in tropical freshwater swamp forest trees.

Differences in demographic and environmental niches facilitate plant species coexistence in tropical forests. However, the adaptations that enable species to achieve higher demographic rates (e.g. growth or survival) or occupy unique environmental niches (e.g. waterlogged conditions) remain poorly understood. Anatomical traits may better predict plant environmental and demographic strategies because they are direct measurements of structures involved in these adaptations. We collected 18 leaf and twig traits from 29 tree species in a tropical freshwater swamp forest in Singapore. We estimated demographic parameters of the 29 species from growth and survival models, and degree of association toward swamp habitats. We examined pairwise trait-trait, trait-demography and trait-environment links while controlling for phylogeny. Leaf and twig anatomical traits were better predictors of all demographic parameters than other commonly measured leaf and wood traits. Plants with wider vessels had faster growth rates but lower survival rates. Leaf and spongy mesophyll thickness predicted swamp association. These findings demonstrate the utility of anatomical traits as indicators of plant hydraulic strategies and their links to growth-mortality trade-offs and waterlogging stress tolerance that underlie species coexistence mechanisms in tropical forest trees.

Quantifying the fluxes of carbon loss from an undrained tropical peatland ecosystem in Indonesia

Conservation of undrained tropical peatland ecosystems is critical for climate change mitigation as they store a tremendous amount of soil carbon that is preserved under anoxic water-logged conditions. Unfortunately, there are too few measurements of carbon fluxes from these ecosystems to estimate the climate change mitigation potential from such conservation efforts. Here, we measured carbon dioxide (CO2) and methane (CH4) fluxes as well as fluvial organic carbon export over the peat swamp forest within an undrained tropical peatland landscape in East Kalimantan, Indonesia. Our measurements throughout one year (Oct 2022–Sep 2023) showed that despite its water-logged condition, peat and water overlying the swamp forest on average emits 11.02 ± 0.49 MgCO2 ha−1 yr−1 of CO2 and 0.58 ± 0.04 MgCO2e ha−1 yr−1 of CH4. Further, the fluvial organic carbon export contributes to additional carbon loss of 1.68 ± 0.06 MgCO2e ha−1 yr−1. Our results help improve the accuracy of carbon accounting from undrained tropical peatlands, where we estimated a total carbon loss of 13.28 ± 0.50 MgCO2e ha−1 yr−1. Nevertheless, the total carbon loss reported from our sites is about half than what is reported from the drained peatland landscapes in the region and resulted in a larger onsite carbon sink potential estimate compared to other undrained peat swamp forests. Together, these findings indicate that conserving the remaining undrained peatland ecosystems in Indonesia from drainage and degradation is a promising natural climate solution strategy that avoids significant carbon emissions.

Low nitrate under waterlogging triggers exodermal suberization to form a barrier to radial oxygen loss in rice roots.

To acclimate to hypoxic waterlogged conditions, the roots of wetland plants form a radial oxygen loss (ROL) barrier that can promote oxygen diffusion to the root tips. We hypothesized that the low-nitrate concentrations that occur after molecular oxygen is consumed in waterlogged soils are an environmental trigger for ROL barrier formation in rice (Oryza sativa). We previously identified 128 tissue-specific up/downregulated genes during rice ROL barrier formation. The RiceXPro database showed that many of these genes were differentially regulated in response to nitrogen deficiency. Therefore, we assessed changes in the concentrations of ionic species of nitrogen under stagnant conditions, i.e. in a nutrient solution that mimics waterlogged soil conditions, and examined the effects of an increase or decrease of nitrate in the nutrient solution on ROL barrier formation and exodermal suberization. Preventing nitrate deficiency in the stagnant nutrient solution suppressed the formation of an ROL barrier. Conversely, a decrease in nitrate strongly induced ROL barrier formation, even under aerated conditions. In parallel with ROL barrier formation, suberin lamellae formed at the exodermis. Nitrate deficiency also promoted aerenchyma formation and the enlargement of root diameters. These findings suggest that the severe decline of nitrates under waterlogged conditions is an environmental cue for exodermal suberization to form an ROL barrier in rice roots.

Comparison of the Waterlogging Tolerance and Morphological Responses of Five Urochloa spp. Grasses

Periods with high precipitation and temporary waterlogging in the humid tropics are challenging to the production and survival of some grasses of the genus Urochloa. This study aimed to evaluate the tolerance of five types of grass belonging to the genus Urochloa under waterlogging conditions through productive and morphological traits. The grasses [U. arrecta (Tanner), U. arrecta x U. mutica (Brachipará), U. brizantha cv. Marandú, U. hybrid cv. Cayman and U. humidicola cv. Llanero] were planted in pots and kept under field capacity for 33 days; then, half of them were submitted to (i) field capacity (33% humidity retention) and the other half were submitted to (ii) waterlogging conditions (2 cm of water above soil level) for 28 days. In this study, Tanner and Brachipará grasses showed higher dry shoot mass under waterlogging conditions, which were followed by Llanero, Cayman, and Marandú, respectively. Llanero, Tanner, and Brachipará presented higher waterlogging tolerance coefficients, 78.7, 76.5, and 64.5, respectively, being less affected than Cayman and Marandú (41.0 and 23.1, respectively). Brachipará, Tanner, and Cayman presented a higher root volume under waterlogging conditions, while Marandú root volume decreased by 88.77%. The Tanner, Brachipará, and Llanero genotypes were more tolerant to poorly drained or waterlogged soils than Cayman and Marandú genotypes.

The prospects of intercropping of brinjal (Solanum melongena L.) with other vegetables on sorjan system in vulnerable southern coastal saline and non-saline areas of Bangladesh

The demand for food in Bangladesh is increasing due to the increasing population. Land is the primary natural resource that affords habitat and sustenance for living beings. In Bangladesh, the coastal areas cover an area of 47,201 km2 or 32 % of the total land under 19 districts of Bangladesh. The coastal southern saline and non-saline areas are vulnerable to water logging conditions and farmers cannot grow any crops except dry season (rabi). However, in some areas, farmers are trying to use their indigenous technologies to combat natural disasters to ensure food security. For example, floating, sorjan or raised bed systems are potential and farmers are practicing in these areas. Among these techniques, the sorjan bed system is one of the potential techniques that is extensively used in southern Bangladesh, particularly water logging conditions to improve food security. To enhance the production and make land cultivation profitable, the experiments were carried out at the farmers’ fields under the sorjan system in consecutive two growing seasons. The sole crop was brinjal (cv. BARI Begun-12), BARI Lalshak-1 (cv. Red amaranth), BARI Dhania-1 (cv. Coriander leaf), Cauliflower (cv. Cold queen), Cabbage (cv. Equatoria) and Knol Khol were utilized as intercropping with brinjal. The treatments were i) Sole brinjal, ii) Brinjal + Red amaranth, iii) Brinjal + Coriander leaf, iv) Brinjal + Cauliflower, v) Brinjal + Cabbage, and vi) Brinjal +. 24-day-old seedlings of the BARI Begun-12 grown in a nursery bed were transferred to the plots where the seeds of Red amaranth and Coriander leaf were directly sown. However, the seedlings of Cauliflower, Cabbage, and Knol Khol were also transplanted to the field after one week of transplanting brinjal. The results exposed that sole crops had the highest results in terms of days to flowering, days to first fruit set, days to first harvesting, leaf area, fruit length, fruit breadth, single fruit weight, fruits plant−1, fruit yield, TSS %, and dry matter %. In both years, brinjal exhibited the highest yield as the sole crop compared to intercropping. 48.12 t/ha and 46.27 t/ha in the first and second cropping seasons, respectively. In the first cropping season, Red amaranth, Coriander leaf, Cauliflower, Cabbage, and Knol Khol performed with a yield of 10.12, 7.23, 23.14, 22.87, and 9.05 t/ha. During the second cropping season, the same crops exhibited a yield of 10.05, 7.01, 23.09, 22.68, and 9.98 t/ha. The highest land equivalent ratio, gross return, net return, and BCR were obtained from brinjal-cauliflower intercropping, which was 1.74, 1049300 BDT, 553820 BDT, and 2.12, respectively, in the 2021–2022 cropping season and 1.78, 1057900 BDT, 562010 BDT, and 2.13, respectively, in the next season in 2022–2023. This intercropping approach resulted in a higher land equivalent ratio, net return, and benefit-cost ratio of 1.76, 557915 BDT, and 2.125, respectively, over the average of two successive cropping seasons.

Nature’s marvel, Deep water rice

Rice is the most important food crop of India. It is the staple food in most of the North Eastern parts as well as Southern part of India. Therefore, the people of North East India especially Assam is completely dependent on rice cultivation and its production. However, Assam is immensely affected by flood during the monsoon season. During that time of the year, most of the rice varieties are intolerant to water stress by submergence. Therefore, farmers are only able to cultivate deep water rice varieties during this season. Deep water rice shows an incredible tolerance to water-logged condition by escaping or managing to survive during submergence. Due to its fascinating water stress tolerance properties, it has been a major topic of concern. This review aims at encompassing the major studies done to investigate the factors responsible for making the plant tolerant to submergence and to evaluate its phytochemicals and nutritional values. Studying deeper into the plant can help in its biofortification as well as improve its yield through different breeding programs using enhanced varieties and thereby develop its marketing status.

How does water stress affect the bioaccumulation of galanthamine and lycorine, growth performance, phenolic content and defense enzyme activities in summer snowflake (Leucojum aestivum L.)?

Leucojum aestivum L. is an Amaryllidaceae bulbous plant with two alkaloids that have remarkable medicinal potential: galanthamine and lycorine. Although the presence of galanthamine in L. aestivum has commercial value for the pharmaceutical industry and the effect of water stress (WS) applications on secondary metabolite enhancement is well established in a variety of plants, no studies have been carried out to reveal the effectiveness of WS on this beneficial medicinal plant. Objective of the study was to investigate the effects of eight different WS treatments [Control, waterlogging (WL) condition, and drought stress conditions (water deficiency generated by water deficit irrigation-WDI 25%, 50%, and 75%- and polyethylene glycol-PEG 6000 15%, 30%, and 45%-)] on growth parameters, alkaloid levels (galanthamine and lycorine), non-enzymatic antioxidant activities (total phenol-flavonoid content and free radical scavenging activity), and enzymatic antioxidant activities [superoxide dismutase (SOD) and catalase (CAT)] of L. aestivum in a pot experiment. Based on the findings, maximum increases in growth parameters were obtained with PEG-induced WS treatments. Moderate water deficiency (50% WDI) produced the highest levels of galanthamine and lycorine, total phenol-flavonoid content, and antioxidant capacity, along with moderately elevated CAT activity in the bulbs. All WS treatments resulted in increased CAT activity in the bulbs. It was observed that bulbs had higher SOD and CAT activities under WL conditions had lower fresh weights and were close to control in terms of alkaloid levels, total phenol-flavonoid content, and free radical scavenging activity. When all of the outcomes were taken into account, it can be concluded that moderate water-deficit stress (50% WDI) was regarded as the most effective treatment for increasing the pharmaceutical value of L. aestivum.Graphical abstract

Multi-objective optimization of farmland water level and nitrogen fertilization management for winter wheat cultivation under waterlogging conditions based on TOPSIS-Entropy

Aiming at the problems of reduced winter wheat yield and aggravation of nitrogen leaching pollution caused by the waterlogging in the Middle-Lower Yangtze Plain, China, a two-year field experiment with three farmland water levels (W40, W60, W80) and three nitrogen application rates (N150, N225, N300) as well as a non-waterlogged treatment (CK) was carried out, to investigate the coupling effects of farmland water level and nitrogen application rate on the plant growth, grain yield, crop water productivity (WPC) and nitrogen load with waterlogging conditions. Three man-made waterlogging events were applied at winter wheat jointing-booting stage, heading-flowering stage and grain filling stage, respectively. The results indicated that with the farmland water level decreased from −40 cm to −60 cm and the nitrogen application rate increased from 150 kg∙ha−1 to 225 kg∙ha−1, the plant height, aboveground dry matter, leaf area index, spike length, grain yield, effective panicles, grain number per ear, 1000-grain weight and WPC in the waterlogging field increased significantly. However, since the nitrogen application rate exceeded 225 kg∙ha−1 and farmland water level lowered more than −60 cm, the favorable effects of nitrogen application rate and farmland water level for winter wheat growth and production reduced. Additionally, both the nitrogen load and partial factor productivity of nitrogen (PFPN) increased with the decline of farmland water level, while the nitrogen load increased and the PFPN decreased with the increasing nitrogen application rate. The raise of nitrogen rate from 150 kg∙ha−1 to 225 kg∙ha−1 was beneficial to plant growth, however, the increase of nitrogen application resulted in the decrease of PFPN and increase of drainage nitrogen loads. Compared with the water farmland water level of −40 cm and nitrogen application rate of 150 kg∙ha−1, the increase of nitrogen application rate and the decrease of farmland water level in the range of 50%-100% resulted in yield raise by 5.78%-32.29% approximately and the increase of nitrogen load by 36.20%-178.44% approximately. The comprehensive evaluation with TOPSIS-Entropy method for plant growth, grain yield, WPC, PFPN and nitrogen loads suggested that, the appropriate nitrogen application rate for winter wheat in the waterlogging areas of Middle-Lower Yangtze Plain in China was 225 kg∙ha−1, and the proper farmland water level was lowering to −80 cm in wet year and −60 cm in dry year within 3 days after waterlogging.

A multi-technique and multiscale comparative study on the efficiency of conservation methods for the stabilisation of waterlogged archaeological pine

Archaeological wood can be preserved in waterlogged conditions. Due to their degradation in the ground, these archaeological remains are endangered after their discovery, since they decay irretrievably during drying. Conservation measures are used to preserve waterlogged archaeological objects, maintaining their shape and character as much as possible. However, different methods have been developed leading to varying results. This study compares their effectiveness in order to clarify their mode of action. The methods including alcohol-ether resin, lactitol/trehalose, melamine formaldehyde, polyethylene glycol impregnation prior to freeze–drying, saccharose and silicone oil were assessed by analysing mass changes and volume stability using structured-light 3D scanning. The state of the conserved wood samples including the spatial distribution of the conservation agent was examined using synchrotron micro-computed tomography. Raman spectroscopy was used to observe the agent´s spatial distribution within the cells. The findings demonstrated that melamine formaldehyde stabilises the degraded cell walls. The lumens are void, as in the case with alcohol-ether resin, while polyethylene glycol, silicone oil, saccharose and lactitol/trehalose also occupy the lumens. It is assumed that the drying method has an effect on the distribution of the solidifying agent. The knowledge gained affords insights into the mechanism of conservation methods, which in turn accounts for the varied outcomes. It also allows conclusions to be drawn about the condition and stability of conserved museum objects and serves as a starting point for the further development of conservation methods.

Modelling the paleopedological development of loess/palaeosol sections using discriminant function analysis of compositional geoscience data, case study in Eastern Croatia

Previous studies on the mineralogical differentiation of Pleistocene loess/palaeosol sections focused on the description and source material of four loess/palaeosol sections located on the eastern border of Croatia along the Danube: Zmajevac, Zmajevac I, Erdut and Šarengrad. The authors demonstrated the decreasing influence of the Danube and the increasing influence of the rivers draining the Central Bosnian Mountains of the Dinaric Ophiolite Zone both important source areas for aeolian sediments at the southern edge of the Carpathian Basin that transport material from the Central Bosnian Mountains. The aim of this research is to identify the palaeoclimatic factors that influenced the pedogenetic development of the studied palaeosols. The model was created based on the research results of the same four loess/palaeosol sequences in Eastern Croatia. This model can also be applied in other locations to determine the influence of certain climatic factors on the degree of pedogenetic development of individual palaeosols. The loess/palaeosol sequences were divided into eight comprehensive groups (horizons) based on their genesis, degree of pedological development and/or position in the soil profiles. The explanation of the typical patterns occurring between the studied horizons is based on the construction of a Discriminant Function Model (DFM) resulting from the analysis of the compositional data (CoDa) of the geochemical (major and trace elements) and granulometric (grain size) data of the loess/palaeosols in combination with external variables such as weathering coefficients and chemical soil properties. In the final phase, the DFM was transformed from structural (mathematical) to functional (process) terms. This revealed that three main themes dominate the formation of Pleistocene loess/palaeosol sequences: 1) the separation of well-developed palaeosols from parent material; 2) the separation of automorphic palaeosols from hydromorphic soils exposed to post-pedogenic waterlogging conditions; and 3) the differentiation of horizons (soils and alluvium) formed by the redeposition (by water or mudflows) of previously deposited aeolian material, regardless of whether and to what extent it was exposed to post-sedimentary pedogenesis.

Comparative Morpho-Physiological, Biochemical, and Gene Expressional Analyses Uncover Mechanisms of Waterlogging Tolerance in Two Soybean Introgression Lines.

Waterlogging is one of the key abiotic factors that severely impedes the growth and productivity of soybeans on a global scale. To develop soybean cultivars that are tolerant to waterlogging, it is a prerequisite to unravel the mechanisms governing soybean responses to waterlogging. Hence, we explored the morphological, physiological, biochemical, and transcriptional changes in two contrasting soybean introgression lines, A192 (waterlogging tolerant, WT) and A186 (waterlogging sensitive, WS), under waterlogging. In comparison to the WT line, waterlogging drastically decreased the root length (RL), shoot length (ShL), root fresh weight (RFW), shoot fresh weight (ShFW), root dry weight (RDW), and shoot dry weight (ShDW) of the WS line. Similarly, waterlogging inhibited soybean plant growth by suppressing the plant's photosynthetic capacity, enhancing oxidative damage from reactive oxygen species, and decreasing the chlorophyll content in the WS line but not in the WT line. To counteract the oxidative damage and lipid peroxidation, the WT line exhibited increased activity of antioxidant enzymes such as peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT), as well as higher levels of proline content than the WS line. In addition, the expression of antioxidant enzyme genes (POD1, POD2, FeSOD, Cu/ZnSOD, CAT1, and CAT2) and ethylene-related genes (such as ACO1, ACO2, ACS1, and ACS2) were found to be up-regulated in WT line under waterlogging stress conditions. In contrast, these genes showed a down-regulation in their expression levels in the stressed WS line. The integration of morpho-physiological, biochemical, and gene expression analyses provide a comprehensive understanding of the responses of WT and WS lines to waterlogging conditions. These findings would be beneficial for the future development of soybean cultivars that can withstand waterlogging.

A statistical model predicts N mineralization of various organic amendments for paddy fields

ABSTRACT To predict the mineralization of nitrogen(N) in organic amendments in paddy fields, we applied data obtained from incubation experiments under waterlogged conditions by a hierarchical Bayesian model using acid-detergent-soluble organic N (ADSON) as a model input. Each of 20 organic amendments (6 cattle manure composts, 3 swine manure composts, 3 poultry manure composts, 2 oil cakes, 2 rice brans, 1 fish meal, 1 sludge fertilizer, and 2 mixed commercial organic fertilizers) was mixed with paddy soil, and the N mineralization curves obtained after 1, 2, 4, 8, and 12 weeks of waterlogging were incorporated into the model to obtain values of the model parameters k i , α1, and Q 10. All model parameters converged with a mean absolute error (MAE) of 0.044 g N kg−1, a root mean square error (RMSE) of 0.060 g N kg−1, and a model efficiency (EF) of 0.96. These values were comparable to or slightly better than those of a previous model for upland soil conditions. Most of the observed values were within the 95% Bayesian prediction interval, indicating that the model performed well with the observed data. Although it is generally believed that livestock manure composts decompose more slowly than organic fertilizers such as oil cake, the livestock manure composts had a large value of the rate constant k i , presumably because of the initial rapid decomposition of the small amounts of organic N present in them. In paddy fields, the soil conditions are aerobic between the application of organic amendments and water entry. In such a case, we propose the use of the upland field model to predict the mineralization of organic N during the period of aerobic soil conditions and of this study’s model during the period of waterlogging, subtracting the amount of already mineralized N from the parameters N in and ADSON. The model devised here is expected to be useful for fertilization design in organic agriculture and in the reduction of the use of inorganic fertilizer.

Will the beneficial properties of plant-growth promoting bacteria be affected by waterlogging predicted in the wake of climate change: A model study

The agricultural sector today is faced with climate change that amplifies extreme climatic events. The use of plant growth promoting bacteria (PGPB) could provide a new approach to increase crop production under these new conditions. In this study, PGPB were isolated from a 5-week pot experiment conducted under greenhouse conditions using cabbage (Brassica oleracea L. var. capitata f. alba) as a model plant. Plants were exposed to either one or two long-term waterlogging events at two different stages of plant development. The results clearly showed that waterlogging leads to changes in the soil microbial community affecting both its overall structure (culturable bacterial fraction) as well as the plant growth promotion (PGP) function provided by the beneficial bacteria to the plant. In general, “the core” of the bacterial community (Bacillus, Pseudomonas, Stenotrophomonas and Peribacillus populations) remained preserved under waterlogged conditions, but shifts in their abundance were observed, with Bacillus, and Pseudomonas proliferating under these conditions. The key to adaptation to waterlogging may lie in “rare” bacterial populations isolated only under certain waterlogging conditions. In our study we identified 11 different genera that can be termed as waterlogging-tolerant. Waterlogging was also shown to induce shifts in the PGP potential, as well as on the structure of a population exhibiting a particular trait, which could eventually lead to either promotion or reduction of plant growth. While the abundances of populations promoting nutrient availability to plants were found to increase after waterlogging, biocontrol protease activity proved to be the trait most sensitive to waterlogging. Enterobacter and Pantoea species were identified as main players in biofilm formation under waterlogging conditions. Waterlogging also appears to trigger the emergence of extremophilic and acidophilic bacteria, aspect important for potential adaptation of soil bacteria to future climate projections, with Bacillus and Pseudomonas showing best potential. Based on all PGP characteristics studied, we selected 11 bacterial isolates belonging to genera Enterobacter, Bacillus, Pseudomonas, Stenotrophomonas, and Pantoea designating them as the most promising bacterial bioinoculants i.e. strains with good potential for future applications in potential waterstress recover of the soil and plants.

Development of sustainable hydromorphic Technosols within artificial wetlands in mining landscapes: the effects of wastewater and hydrothermal geological materials

PurposeThe Buenavista del Cobre mine is in a semiarid environment in NW Mexico. A part of the mine tailings dam has been flooded with wastewater from Cananea, generating an artificial wetland. The main objectives of this work were to evaluate the effect of wastewater on the pedogenesis of wetland Technosols developed on mine tailings and to compare them with the soil of non-irrigated tailings and with a natural soil profile.Materials and methodsThree profiles were studied inside the dam as follows: a profile under waterlogging conditions, a profile under conditions of periodic sewage saturation, and a profile with no waterlogging conditions. Laboratory methods included the micromorphological analysis of the soil structure and pedo-features, fertility properties, identification of clay minerals, and analysis of bulk chemical composition.Results and discussionIt was found that the biogenic structure and voids associated with organic materials were the main micromorphological features of the studied wetland Technosols. Primary sulfides remained unaltered in the Technosols irrigated with wastewater, whereas incipient sulfide oxidation was observed in the non-irrigated tailings. Chlorite and smectite were detected in the Technosols. Such mineral assemblage was found to be mostly generated by hydrothermal processes.ConclusionIrrigation of tailings with wastewater supported the biological aggregation and porosity formation within the soil matrix, supplied plant nutrients, and enhanced the ecological soil quality of the studied hydromorphic Technosols. Saturation with wastewater hampered the oxidation of primary sulfides in the hydromorphic Technosols, preventing soil acidification and the mobilization of heavy metal contaminants.

Root system architecture change in response to waterlogging stress in a 448 global collection of rapeseeds (Brassica napus L.).

A novel image-based screening method for precisely identifying genotypic variations in rapeseed RSA under waterlogging stress was developed. Five key root traits were confirmed as good indicators of waterlogging and might be employed in breeding, particularly when using the MFVW approach. Waterlogging is a vital environmental factor that has detrimental effects on the growth and development of rapeseed (Brassica napus L.). Plant roots suffer from hypoxia under waterlogging, which ultimately confers yield penalty. Therefore, it is crucially important to understand the genetic variation of root system architecture (RSA) in response to waterlogging stress to guide the selection of new tolerant cultivars with favorable roots. This research was conducted to investigate RSA traits using image-based screening techniques to better understand how RSA changes over time during waterlogging at the seedling stage. First, we performed a t-test by comparing the relative root trait value between four tolerant and four sensitive accessions. The most important root characteristics associated with waterlogging tolerance at 12 h are total root length (TRL), total root surface area (TRSA), total root volume (TRV), total number of tips (TNT), and total number of forks (TNF). The root structures of 448 rapeseed accessions with or without waterlogging showed notable genetic diversity, and all traits were generally restrained under waterlogging conditions, except for the total root average diameter. Additionally, according to the evaluation and integration analysis of 448 accessions, we identified that five traits, TRL, TRSA, TRV, TNT, and TNF, were the most reliable traits for screening waterlogging-tolerant accessions. Using analysis of the membership function value (MFVW) and D-value of the five selected traits, 25 extremely waterlogging-tolerant materials were screened out. Waterlogging significantly reduced RSA, inhibiting root growth compared to the control. Additionally, waterlogging increased lipid peroxidation, accompanied by a decrease in the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). This study effectively improves our understanding of the response of RSA to waterlogging. The image-based screening method developed in this study provides a new scientific guidance for quickly examining the basic RSA changes and precisely predicting waterlogging-tolerant rapeseed germplasms, thus expanding the genetic diversity of waterlogging-tolerant rapeseed germplasm available for breeding.

Silicon promotes biomass accumulation in Phragmites australis under waterlogged conditions in coastal wetland

Silicon promotes biomass accumulation in Phragmites australis under waterlogged conditions in coastal wetland

Exogenous abscisic acid induces the formation of a suberized barrier to radial oxygen loss in adventitious roots of barley (Hordeum vulgare).

Internal root aeration is essential for root growth in waterlogged conditions. Aerenchyma provides a path for oxygen to diffuse to the roots. In most wetland species, including rice, a barrier to radial oxygen loss (ROL) allows more of the oxygen to diffuse to the root tip, enabling root growth into anoxic soil. Most dryland crops, including barley, do not form a root ROL barrier. We previously found that abscisic acid (ABA) signalling is involved in the induction of ROL barrier formation in rice during waterlogging. Although rice typically does not form a tight ROL barrier in roots in aerated conditions, an ROL barrier with suberized exodermis was induced by application of exogenous ABA. Therefore, we hypothesized that ABA application could also trigger root ROL barrier formation with hypodermal suberization in barley. Formation of an ROL barrier was examined in roots in different exogenous ABA concentrations and at different time points using cylindrical electrodes and Methylene Blue staining. Additionally, we evaluated root porosity and observed suberin and lignin modification. Suberin, lignin and Casparian strips in the cell walls were observed by histochemical staining. We also evaluated the permeability of the apoplast to a tracer. Application of ABA induced suberization and ROL barrier formation in the adventitious roots of barley. The hypodermis also formed lignin-containing Casparian strips and a barrier to the infiltration of an apoplastic tracer (periodic acid). However, ABA application did not affect root porosity. Our results show that in artificial conditions, barley can induce the formation of ROL and apoplastic barriers in the outer part of roots if ABA is applied exogenously. The difference in ROL barrier inducibility between barley (an upland species) and rice (a wetland species) might be attributable to differences in ABA signalling in roots in response to waterlogging conditions.

Integrated transcriptomics and metabolomics analysis provide insights into the alleviation of waterlogging stress in maize by exogenous spermidine application

Waterlogging stress has been found to have adverse impacts on plant growth, subsequently reducing crop yields. Spermidine (Spd), a second messenger, positively affects the growth of plants under waterlogging stress. However, the molecular mechanisms of exogenous Spd application alleviating waterlogging stress remained unclear. In this study, we performed physiological analysis and multi-omics to underlying the effect of Spd application on waterlogging stress. Spd application increased genes expression level of light-harvesting complex (LHC) and photosynthesis-related and starch-related pathway, inhibited chlorophyll degradation and maintained higher photosynthetic rate, thus increased biomass accumulation under waterlogging stress. The activation of genes related trehalose and Spd biosynthesis would result in high accumulation of trehalose and endogenous Spd. Inhibiting 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase (ACO,) expression contributed to reduced ethylene emission. All those changes increased maize resistance to waterlogging. After Spd sparying, auxin-related genes up-regulated and IAA content was increased, those favor cell elongation in maize and thus keep normal growth after Spd application under waterlogging stress. Most of genes involved in lipids were up-regulated and thus increased lipids content and protected cell membranes in maize after Spd application under waterlogging conditions. All those changes contributed to increasing the resistance to waterlogging stress. These findings broaden our understanding of the regulatory roles of Spd in alleviating waterlogging damage and will provide evidence for breeding waterlogging-tolerant maize varieties.

Progress towards adopting low-carbon agriculture on peatlands for sustainable development in Indonesia

Indonesia, progressing towards sustainable development, faces the complex task of transitioning to low-carbon agriculture in peatlands, an essential part of broader sustainable objectives. Under the Paris Agreement, it targets a conditional 41% emission reduction, focusing on minimizing emissions from peat decomposition and fires within agricultural practices in peatlands. This paper explores the complexities and progress of low-carbon agriculture in peatlands, underscoring its significance in the larger sustainable development agenda. Our study reveals that current strategies to reduce carbon emissions in peatlands aim at restoring their natural waterlogged conditions. Yet, progress is hindered mainly due to an inadequate understanding of greenhouse gas emissions from peatlands and overlooking their unique features, which leads to overestimated emissions from agricultural use. For improved strategies, it’s important to analyze successful existing sustainable practices and enhance understanding of peatland ecology. Techniques like the “Water Management Trinity,” implemented since 1986, and eco-management emphasize the importance of using permanent water gates to maintain water levels optimal for both peat preservation and crop production. Over time, these practices modify peatland attributes, making emissions comparable to those from mineral soil, thus rendering low-carbon agriculture attainable. It’s vital for stakeholders to assess emissions with updated data, incorporating detailed information on peatland characteristics and emissions. The journey towards low-carbon agriculture in Indonesia’s peatlands is a complex endeavor necessitating the amalgamation of scientific research, sustainable practices, and socio-economic development. Adopting a holistic approach can strike a balance between agricultural productivity, peatland conservation, and climate change mitigation, fulfilling sustainable development goals in Indonesia and globally.