Sufficient Water Supply Research Articles

Between drought and deluge: A history of water provision to Beaufort West, ca. 1858-1955

Beaufort West was the first rural town in South Africa to receive municipal status as early as 1837. Situated in the arid interior of the country, the town has struggled with water provision and sufficient water supplies since its inception to the present day. In addition, the town is flanked by two rivers, which, in times of high rainfall or cloudbursts in the catchment areas, have caused severe flood damage since earliest times. Therefore, throughout its history Beaufort West has been trapped periodically between drought and deluge. The municipal council was challenged in its efforts to provide water to the needs of its growing population. Two outstanding events in this regard were the extension of the colonial railways to the town in 1880 and the outbreak of the South African War in 1899. In this article the quest for water to Beaufort West’s inhabitants is investigated since ca. 1858 until the completion of the Gamka Dam (1955) in the Nieuweveld Mountains some kilometres from Beaufort West. Besides the extraction of potable water from springs, weirs, boreholes, water mains, dams and reservoirs, the paper also highlights state involvement and the collision of national with local interests in the water procurement process. Although the centenary publication of WGH Vivier and S Vivier in 1969 on Beaufort West highlighted some aspects of the town’s water infrastructure developments, this study focuses in more detail on its water vulnerability especially in time of drought and the constant search for adequate alternative water sources.

Pathogenic organisms on spring barley in the eastern forest-steppe of Ukraine

Purpose. To detect harmful organisms on spring barley and their variability under the influence of hydrothermal conditions during the crop vegetation period in the Eastern Forest-Steppe of Ukraine and to improve methods of pathogen detecting on plants and grains.Material and methods. The prevalence of diseases and pests was determined by conventional and special methods in accordance with the existing assessment scales and by methods modified by us in the course of work. We improved methods for determining pathogenic species on spring barley upon spring (optimal) and autumn (simulation of wet conditions) sowing followed by evaluating the disease signs during the tillering phase of plants and selecting nutrient medium for phytoexamination of grain and assessment of its infection rate.Results and discussion. The 2009–2020 assessments of the prevalence of diseases and pests on spring barley plants from seeds sown on different dates (autumn and spring) showed that the autumn sowing was more effective for barley net blotch manifestation on spring barley compared to the conventional method of spring sowing, since the autumn conditions are favorable for development of this fungus. Pathogens on spring barley were mainly represented by head smut (Ustilago hordei), barley leaf stripe disease, root rots and corn flies. The greatest prevalence of head smut (up to 67.0%) was observed in the years when the weather was excessively humid during the growing period (HTC =1.7 in 2020) or slightly arid (HTC =1.1 in 2015). The greatest spread of barley net blotch (100%) was observed on sufficient water supply in 2014 (HTC = 1.4). The numbers of frit flies during the study period were significant (up to 100%), only in 2016 there was a decline to 39%. The pathogen species that develop on spring barley seeds were determined. Alternaria contamination of grain ranged 9.0 to 77.0% from year to year; Drechslera contamination - 4.0 to 55.0%, Fusarium contamination - 0.0 to 12.4%.Conclusions. Head smut (Ustilago hordei (Pers. Lagerh.)) and Drechslera fungi causing leaf blotch and root rot (Drechslera teres Ito, D. graminea (Rabenh.) Shoemaker, D. sorokiniana Subram) were found to be the most common diseases of spring barley in the Eastern Forest-Steppe of Ukraine. Of pests, frit flies (Oscinella frit Linnaeus and O. pusilla Meigen) were most common. Major diseases of spring barley seeds are of fungal etiology (genera Drechslera spp., Fusarium Link. and Altenararia Fries). Two new methods of phytopathological analysis of the prevalence of diseases on spring barley crops have been developed: one of them is carried out by autumn sowing of seeds and evaluating plant damage during the tillering phase; the second method is phytoexamination of seeds for pathogens via germination of caryopses in sucrose solution

Firefighting in Vulnerable Areas Based on the Connection between Fire Hydrants and Fire Brigade

A sufficient supply of water for firefighting is critical for effective responses to urban fires, thus reducing fire hazards. The aim of this study was the development of an analysis method for vulnerable areas with respect to firefighting activities that require the use of fire hydrants. In particular, a method was proposed for the determination of the operational range of firefighting activities based on the distribution of the fire hydrants and the roads that allow for the passage of firefighting vehicles. The proposed method, which employs a geographic information system (GIS), was applied to Buk-gu, Daegu City, South Korea. The research results revealed that the operational range of firefighting activities and vulnerable areas can be determined by studying the connection between the fire hydrant locations and the fire brigade in the analysis of the accessible areas. This study contributes to the development of GIS analysis methods for comprehensive vulnerability analyses of firefighting activities, including accessibility to fire hydrants.

Quantitative Lasting Effects of Drought Stress at a Growth Stage on Soybean Evapotranspiration and Aboveground BIOMASS

Quantifying the lasting effects of drought stress on crop growth is a theoretical basis for revealing agricultural drought risk mechanism and formulating adaptive irrigation strategies. Based on two-season pot experiments of soybean in the Huaibei Plain, quantitative responses of plant evapotranspiration and aboveground biomass at each growth stage from a drought were carried out. The results showed that drought stress at a certain stage of soybean not only significantly reduced the current evapotranspiration and aboveground biomass accumulation during this stage, compared with full irrigation, but also generated the after-effects, which resulted in the reductions of evapotranspiration and biomass accumulation at the subsequent periods. Furthermore, the damaged transpiration and growth mechanism caused by drought gradually recovered through the rewatering later, and the compensation phenomenon even occurred. Nevertheless, the specific recovery effect was decided by both the degree and period of drought before. It is practical to implement deficit irrigation at the seedling and branching stages, but the degree should be controlled. Meanwhile, it is crucial to ensure sufficient water supply during the reproductive growth phase, especially at the flowering and pod-enlargement stage, to guarantee a normal transpiration function and a high biomass yield for soybeans in the Huaibei Plain.

EFFECT OF MgO POWDER ON PHYSICAL AND MECHANICAL PROPERTIES OF POLYOLEFIN FIBER REINFORCED CONCRT

Expansive additives are widely used to compensate the drying shrinkage of cement-based materials to avoid cracking. However, the expansion of conventional expansive additive depends strongly on wet curing and is mainly generated at early age, and hence it may not work well in concretes without sufficient water supply or exhibit long-term shrinkage. MgO-based expansive additive, for which less water is needed for the formation of Mg(OH)2 in comparison to other expansive additives.For the purpose this paper proposed a new kind of cement concrete overlay material comprised of polyolefin fiber and MgO powder. An experimental test procedure including density, compressive strength and flexural strength in this article was investigated. The results showed improvement of all the properties of the concrete mixes. Obvious compound effect of polyolefin fiber and MgO powder on concrete properties was noticed.

The Influences of Different Irrigation Water on Spatial Distribution of Cotton Bolls and Yields

Takeing the jujube orchard intercropping cotton as experimental material In southern Xinjiang to study the influences of different irrigation water on spatial distribution of cotton bolls and yields. Setting the moderate water stress W1 (250 m3/667m2), mild water stress W2(300 m3/667m2), the appropriate moisture W3(350 m3/667m2), the sufficient water supply W4(400 m3/667m2), in total four different irrigation water processing. The results show that : (1) The cotton boll’ shedding rate in different water processing in order W4 > W1 > W3 > W2,the shedding rate of upper and lower is much higher than the middle fruit spur.(2)the effective boll of cotton are mainly in the middle part. (3)The total boll weight of cotton middle fruit spur greater than the total boll weight of fruit spur in the upper and lower. And the lower part’ weight is slightly higher than the upper.(4) The boll weight of upper fruit spur have bigger fluctuations than the lower,each part of the cotton boll weight as W2 > W3 > W4 > W1. (5) Four water treatment have a little effect on lint percent, seed cotton and ginned cotton showed the same trend as W2 > W3 > W4 > W1. Comprehensive consideration in many aspects, the drop irrigation amount 300-350m3/667m2 could as the reference standard of this locality jujube orchard intercropping.

Acceptance and Adequacy of Water Supply Among Flood Victims at the Temporary Evacuation Centres in Kuala Krai, Kelantan, Malaysia

This article discusses the analysis of water supply acceptance and adequacy among flood victims at the Kuala Krai Temporary Evacuation Centres (TECs) in Kelantan, Malaysia. This study applied a quantitative approach using questionnaire. A total of 300 flood victims were randomly selected. The aspects being measured were the types of water resource acceptance as well as the adequacy of water supply according to four main types of domestic activities at the TECs, namely drinking, cooking, bathing and washing. The analysis used was descriptive analysis, a cross-tabulation test to assess the relation of water supply adequacy to respondents' profile and the selected TECs. The findings showed that the bottled/mineral water acceptance by the flood victims was insufficient for drinking and cooking purposes, while the acceptance of rainwater as a water supply for bathing and washing was sufficient. The findings also show that the water supply was insufficient for drinking (84.96%), cooking (85.84%), bathing (61.06%) and washing (53.10%) for female compared to male. Similarly with the married respondents who claimed that water supply was inadequate for all types of domestic activities such as for drinking (74.29%), cooking (66.29%), bathing (53.71%) and washing (50.29%), compared to the unmarried and widowed. Based on TECs, more attention should be given to the water supply at SMK Laloh and SK Kuala Gris as the majority of respondents (>52.17%) stated that the water supply was insufficient for carrying out all domestic activities, compared to SMK Sultan Yahya Petra 2 and SMK Manek Urai Lama. Therefore, water supply management during flood disasters is urgently needed to deal with insufficient water supply issues by increasing the efficiency of water supply distribution so that the Kuala Krai flood victims can get sufficient water supplies at the TECs despite being hit by major floods.

Tuning the wettability of solar absorbers towards high-efficiency solar vapor generation

As an environmentally-friendly fresh water production method, solar water evaporation plays an important role in solving the shortage of fresh water. Recently, various kinds of solar absorbers have been developed. However, most of solar absorbers are hydrophilic for the sufficient water supply, and less attention has been paid to the effect of absorber’s wettability on the evaporation performance. Herein, the effect of wettability of photo-thermal films on the evaporation rates was investigated. The evaporation of the full-wetting film (0.99 kg m−2 h−1) increased by 5.3% compared to the semi-wetting film (0.94 kg m−2 h−1) at 1 kW m−2. Conversely, the evaporation of the full-wetting film (8.77 kg m−2 h−1) decreased by 8.5% compared to the semi-wetting film (9.58 kg m−2 h−1) at 13 kW m−2. The systematic test indicated that the full-wetting film exhibited high evaporation performance at low optical power densities (1–5 kW m−2), and the performance of the semi-wetting film was better at high optical power densities (9–13 kW m−2). This work provides a new avenue to achieve high evaporation performance by tuning the wettability at different application environments.

Sustainable high yields can be achieved in drylands on the Loess Plateau by changing water use patterns through integrated agronomic management

Low yields of winter wheat are common throughout the Loess Plateau due to the region's erratic precipitation and the mismatch between the rainy season and the winter wheat growing season. In order to achieve sustainable high yields of winter wheat in this area, we set 6,000 kg hm−2 as our yield goal and investigated the effects of four types of management systems, including a conventional farmers’ management system and three integrated management systems, on winter wheat production over five consecutive years. The management practices varied in terms of seeding rates, nitrogen (N) application strategies, and application of manure or biochar. Our five-year study revealed that the average winter wheat yield under a manure integrated system (MIS) or a biochar integrated system (BIS) could achieve nearly 6,000 kg hm−2 while also enhancing water use efficiency (WUE) to 1.63–1.69 kg m−3. The high yields under MIS and BIS were mainly due to the large plant population that these systems permitted during the whole growing season, which was supported by favorable soil N levels (NO3−–N content) and sufficient water supply. The high WUE under both systems was mainly due to decreased loss of precipitation (i.e., increased storage in the soil) during early growth stages (from sowing time to regreening stage) and increased use of subsoil water (100–300 cm) during late growth stages (from regreening to harvest time) by the large root system. In addition, the annual evapotranspiration under MIS and BIS was much lower than the annual precipitation in this area. Therefore, MIS and BIS are likely to be useful integrated management systems enabling sustainable high yields of winter wheat in the Loess Plateau through the regulation of water use patterns in both spatial and temporal terms.

Mixed Cropping as Affected by Phosphorus and Water Supply

In a future exposed to threats of climate change, sustainable biomass production will be crucial. Maize (Zea mays) and sorghum (Sorghum sp.) are important crops for human and animal nutrition, as well as for bioenergy. The aim of this study was to investigate maize and sorghum in mixed cropping with soybean (Glycine max) and faba bean (Vicia faba) regarding biomass yield, drought tolerance, phosphorus (P) availability, and enzyme activity in soil as affected by the single and combined effects of water and P supply in two outdoor pot trials with rainout shelters. Maize had the highest biomass under sufficient water supply (80% water holding capacity, WHC), but a sharp decrease of its biomass of about 60% was measured when water was limited (30% WHC). In the mixtures, drought induced reduction of biomass was less than 40%. For mixed cropping usually higher contents of labile P fractions in soil than for sole cropped monocots were found. This was especially true for the combined stress of water and P deficit and can be partly explained by a higher activity of the acid phosphatase in the soil of the mixtures. A higher yield stability of the crop mixtures makes them a suitable agronomic alternative to sole cropped maize or sorghum under suboptimal conditions of water and P shortage.

Xeromorphic Features of the Leaves of Liriodendron Tulipifera L. (Magnoliaceae) in the Arid Climate of Central Asia

High irradiance of a habitat in arid areas is usually associated with high temperature and dry air, which can cause water deficiency in plants. The Tulip tree (Liriodendron tulipifera) is a light-loving mesophytic species. This study showed that L. tulipifera forms shade or sun leaves depending on the light conditions. Some xeromorphic features were found in leaves of the trees in illuminated habitats. These sun leaves are smaller, denser, and thicker, with smaller epidermal cells and a thick cuticle; the spongy parenchyma consists of a larger number of rows of small cells; the cells of the columnar parenchyma are larger than the shade leaves. The sun leaf contains more total chlorophyll (by 20–30%), and the guard cells of the stomata of the sun leaf contain chloroplasts. The increased concentration of chlorophyll probably maintains the energy balance in the conditions of inhibited photosynthesis under high illumination and temperature. Decreased sizes of the sun leaf and epidermis cells, thickening of the cuticle and cell wall of epidermal cells, sunken stomata, compact mesophyll with small intercellular spaces, and multirow spongy parenchyma protect from overheating and passive loss of water and can be considered as xeromorphic features. Large numerous stomata and vascular bundles contribute to effective cooling of the surface by transpiration at high temperatures under sufficient water supply. Thus, the leaves of L. tulipifera have an ecological plasticity in relation to illumination and temperature, which contributed to the acclimation of the species to the habitat conditions in arid climates.

Effects of Nutrient and Water Supply During Fruit Development on Metabolite Composition in Tomato Fruits (Solanum lycopersicum L.) Grown in Magnesium Excess Soils.

Tomato cultivation in the greenhouse or field may experience high surplus salts, including magnesium (Mg2+), which may result in differences in the growth and metabolite composition of fruits. This study hypothesized that decreasing the supply of nutrients and/or water would enhance tomato fruit quality in soils with excess Mg2+ that are frequently encountered in the field and aimed to find better supply conditions. For tomato plants cultivated in plastic pots using a plastic film house soil, the fertilizer supply varied in either the nitrogen (N) or potassium (K) concentration, which were either 0.1 (lowest) or 0.75 times (lower) than the standard fertilizer concentrations. Water was supplied either at 30 (sufficient) or 80 kPa (limited) of the soil water potential. Lycopene content on a dry-weight basis (mg/kg) was enhanced by the combination of lowest N supply and sufficient water supply. However, this enhancement was not occurred by the combination of the lowest N supply and limited water supply. Sugars and organic acids were decreased by limiting the water supply. Therefore, we carefully suggest that an adjustment of nitrogen with sufficient watering could be one of strategies to enhance fruit quality in excess Mg2+ soils.

Wood-Based Solar Interface Evaporation Device with Self-Desalting and High Antibacterial Activity for Efficient Solar Steam Generation.

The main challenges of a solar steam generation device based on biomass materials are complicated processing techniques and relatively low efficiency. To solve these problems, we reported a simple immersion treatment method by depositing polydopamine (PDA) and silver nanoparticles (AgNPs) on natural wood to prepare a novel solar interface evaporation device. Ag-PDA@wood exhibits a unique bilayer structure. The absorbance of the top light absorption layer is higher than 96% in a wide wavelength range (300-2500 nm). Owing to the synergistic photothermal effect between PDA and AgNPs, Ag-PDA@wood has ultrafast solar-thermal response (a temperature increase of 42.5 °C within 5 min under 1 sun), and more heat is located at the steam generation interface (the surface temperature is 45.1 °C). The natural wood layer at the bottom with low thermal conductivity provides sufficient water supply and reduces the bulk heat loss. A high evaporation rate of 1.58 kg m-2 h-1 is achieved using Ag-PDA@wood under 1 sun (1 kW m-2). Its evaporation efficiency reaches 88.6%. The results upon sewage treatment and seawater desalination indicate that Ag-PDA@wood has an excellent purification ability and self-desalting capacity. More importantly, when compared to traditional solar evaporators, Ag-PDA@wood exhibits high antibacterial activity. The result of this antibacterial experiment shows that this material almost completely kills harmful bacteria. Therefore, Ag-PDA@wood has a high application potential in seawater desalination and sewage purification, providing a significant incentive to solve the problem of insufficient freshwater supply.

The water transport profile of Phyllostachys edulis during the explosive growth phase of bamboo shoots

The new bamboo shoots do not generate leaves during the explosive growth period. Thus, they cannot perform photosynthesis during this period. The water use profile and control mechanism of water transport during the explosive growth period of Moso bamboo (Phyllostachys edulis) shoots are still unclear. This study applied thermal dissipate probe (TDP) technology for monitoring the sap flow rate (Fs) dynamics in Moso bamboo during explosive growth phases (2008¬2010). We investigated the underlying mechanism of rapid growth by analyzing the water transport profile in a system consisting of the stem, rhizome, and shoot. We found that the Fs increase during explosive growth periods was consistent with the grow rate of bamboo shoots, the explosive growth phase was controlled by the sap flow. Water flew mainly from the rhizome toward the stem before shoot development but switched to the shoot during shooting. The water flow direction shifted from the stem and rhizome to the new shoot, ensuring the water and nutrient transport needed for growth and metabolisms. Diurnal Fs variations during growth periods followed a typical “single-peak” pattern with a daytime peak, resulting in a higher growth rate of bamboo shoots during the daytime. On the annual scale, Fs has an on-off-year alternation with higher on¬year rates than off¬year rates, which was consistent with the regulation of the bamboo shoot emergence. Correlation analysis found that leaf area index variations could explain the observed Fs variations of 95–97%. Economic bamboo forest management should ensure sufficient water supply during the explosive growth period of bamboo shoots. Further research should strengthen our knowledge about the hydraulic characteristics of Moso bamboo during explosive growth periods to ensure efficient forest management.

Penentuan Pola Tanam Tanaman Pangan Berdasarkan Neraca Keseimbangan Air di Kecamatan Umbu Ratu Nggay Barat, Kabupaten Sumba Tengah, Provinsi Nusa Tenggara Timur

Cropping pattern is an agricultural business activity to obtain maximum results taking into account climatic and soil conditions. Setting the cropping patterns is part of planning agricultural activities to reduce the risk of crop failure. Planning and suitability of cropping pattern depends on the size of rainfall in certain areas. This study is aimed to determine the food cropping patterns of food crops based on the balance of water balance in west Umbu Ratu Nggay District, Central Sumba Region. This research was conducted in West Umbu Ratu Nggay District with method of primary and secondary data, and continued laboratory analysis . The data used are soil texture, soil temperature, air temperature, soil binding capacity and monthly rainfall data for the last ten years. The balance of water conditions culculated by using jNSM (Java Newhall Simulation Model), followed by geographic information system software (GIS) to map the area experiencing surplus period of groundwater deficit areas to be able to determine alternative cropping pattern. Based on the calculation of the water balance, an alternative cropping pattern is obtained for Umbu Ratu Nggay Barat sub-district with an average of sufficient water supply (surplus) in a different region from the choice of plants, namely the first area with the choice of sweet potato-bero; rice-bero and/or corn-bero with an area of 588.83 ha (2.09%). The second area with alternative plant choices is sweet potato-bero; rice-green beans-bero; corn-green beans-bero with an area of 7,856.96 ha (27.95%). The third area with alternative plant choices is sweet potato-bero; rice-rice-bero; rice-corn-bero; rice-green beans-bero; corn-corn-bero; corn-green beans-bero with an area of 19,662.96 ha (69.96%).

Future streamflow regime changes in the United States: assessment using functional classification

Abstract. Streamflow regimes are changing and expected to further change under the influence of climate change, with potential impacts on flow variability and the seasonality of extremes. However, not all types of regimes are going to change in the same way. Climate change impact assessments can therefore benefit from identifying classes of catchments with similar streamflow regimes. Traditional catchment classification approaches have focused on specific meteorological and/or streamflow indices, usually neglecting the temporal information stored in the data. The aim of this study is 2-fold: (1) develop a catchment classification scheme that enables incorporation of such temporal information and (2) use the scheme to evaluate changes in future flow regimes. We use the developed classification scheme, which relies on a functional data representation, to cluster a large set of catchments in the conterminous United States (CONUS) according to their mean annual hydrographs. We identify five regime classes that summarize the behavior of catchments in the CONUS: (1) intermittent regime, (2) weak winter regime, (3) strong winter regime, (4) New Year's regime, and (5) melt regime. Our results show that these spatially contiguous classes are not only similar in terms of their regimes, but also their flood and drought behavior as well as their physiographical and meteorological characteristics. We therefore deem the functional regime classes valuable for a number of applications going beyond change assessments, including model validation studies or predictions of streamflow characteristics in ungauged basins. To assess future regime changes, we use simulated discharge time series obtained from the Variable Infiltration Capacity hydrologic model driven with meteorological time series generated by five general circulation models. A comparison of the future regime classes derived from these simulations with current classes shows that robust regime changes are expected only for currently melt-influenced regions in the Rocky Mountains. These changes in mountainous, upstream regions may require adaption of water management strategies to ensure sufficient water supply in dependent downstream regions. Highlights. Functional data clustering enables formation of clusters of catchments with similar hydrological regimes and a similar drought and flood behavior. We identify five streamflow regime clusters: (1) intermittent regime, (2) weak winter regime, (3) strong winter regime, (4) New Year's regime, and (5) melt regime. Future regime changes are most pronounced for currently melt-dominated regimes in the Rocky Mountains. Functional regime clusters have widespread utility for predictions in ungauged basins and hydroclimate analyses.

Supplying water to the urban poor: Government's roles and challenges of participatory water governance

Supplying water to the urban poor has been one of the greatest challenges in the Global South. Many national and international organizations have recently taken initiatives to ensure sufficient water supply for the urban poor who are staying with enormous water scarcity. A remarkable solution is participatory water governance that suggests working in partnerships with all the relevant stakeholders. Using a case study method, this paper aims to examine a water supply programme based on participatory approach in a slum of Dhaka city. The main objective is to investigate the roles and challenges of government authorities in a new participatory governance arrangement to work with partner-organizations during implementing a water supply project for the urban poor. The challenges include disproportionate representations of actors in participation, lacks in decentralization and local sociopolitical and bureaucratic complexities. The paper argues that the challenges are a result of participation ‘from-a-distance’ by the government authorities which needs to be considered for successful implementation of participatory water governance. The paper concludes by suggesting that the new initiatives of participatory governance need revisiting and reformations particularly in the context of supplying environmental services for the urban poor.

Optimal Distribution of Heat Collecting Area of Two Collectors in Solar Water Heating Systems

In view of the large seasonal temperature difference, and the large temperature difference between day and night, difficulty in supplying domestic hot water supply in high altitude area, and the contradiction between low efficiency and cost of single type solar collector system, a hybrid heat collection system based on two different types of solar collectors has been considered in this paper, and a multi-objective optimization model for the heat collecting area optimization of the hybrid solar collectors has also established to solve the above problems. Besides, a fast and effective multi-objective optimization method was proposed for solving of this multi-objective optimization model. This method is based on the fast non-dominated genetic algorithm and the multi-objective decision-making analytic hierarchy process, and was used to analyze the practical hot water supply in a farm in Guoluo zone. The research results shown that this proposed optimization algorithm can quickly and effectively complete the heat collecting area distribution of two different types of collectors in the combined heat collecting system given a certain weight of system cost and heat collecting area. Under the premise of guaranteeing sufficient hot water supply, the system cost is significantly reduced. Therefore, the problem of difficulty and high cost of hot water supply in the plateau region is solved, which has a good practical significance.

Evaluation of cowpea for drought tolerance at seedling stage

Cowpea is a health-promoting diploid legume species [Vigna unguiculata (L.) Walp., 2n = 2x = 22]. The annual cowpea production is 5.4 million tons of dry seed globally. Despite the fact that cowpea is one of the most drought-tolerant crops, some genotypes with excellent agronomic traits such as high yield under sufficient water supplies have been reported to be highly drought-susceptible, thus still requiring the need for breeding drought-tolerant cowpea genotypes. Therefore, the objectives of this study were to evaluate drought tolerance in cowpea at seedling stage and to identify drought-tolerant cowpea genotypes. In this study, a total of 331 cowpea genotypes were evaluated for drought tolerance at seedling stage. The experiment was conducted in a greenhouse and repeated 3 times. Drought tolerance phenotyping was conducted using a previously described methodology and a total of 11 traits were analyzed. The experiment was validated by the use of drought-tolerant and susceptible controls. Results showed that: (1) a large variation in the evaluated traits for drought tolerance was identified among the 331 cowpea genotypes, (2) a high correlation was found for traits such as plant greenness score and tolerance to trifoliate leaf chlorosis under drought stress (r = 0.8), whereas no linear correlation was found for traits such as tolerance to trifoliate leaf chlorosis and unifoliate leaf SPAD chlorophyll under non-drought stress (r = 0.0), (3) a total of 21 genotypes were found to be drought-tolerant across different traits, and (4) country of origins could impact drought tolerance in cowpea. The top performing genotypes were repeated using an independent experiment to further validate the data. The results from this study would be of interest in breeding programs aiming at improving drought tolerance in cowpea.

Water stress altered photosynthesis‐vegetation index relationships for winter wheat

AbstractThe photosynthetic rate (Pn) of winter wheat (Triticum aestivum L.) is directly affected by water conditions, which can be effectively estimated by coupling vegetation indices (VIs). Establishing sound empirical models between VIs and Pn of winter wheat under different water conditions therefore is a sound approach for predicting Pn for broad applications. A rainout‐shelter field experiment was conducted to investigate the changes in Pn and VIs (normalized difference vegetation index [NDVI], enhanced vegetation index [EVI], ratio vegetation index [RVI], photochemical reflectance index [PRI]) under five water stress conditions. We found that: (a) heavy and moderate drought stress inhibited Pn, with their accumulated effects became more significant with the duration of treatments while the light drought stress and slight water logging produced minor effects on Pn. Heavy and moderate drought stress also caused the peak time of Pn preceded during the growth period; (b) NDVI showed low sensitivity to vegetation coverage while EVI explained more seasonal variation than other VIs when leaf area index (LAI) was >3; (c) the linear models between Pn and EVI under heavy () and moderate () water stress were selected as the best model for Pn, while a power function for Pn‐NDVI performed better under sufficient water supply (Pn = 37.982NDVI3.0101) and slight water logging (Pn = 28.024NDVI2.5646). Our results demonstrated that Pn–VI relationships varied by water stress for a winter wheat over the growing season. These results could be used for the prediction of winter wheat Pn under water stress at a large spatial scale.