Higher Water Uptake Rate Research Articles

Plant water source effects on plant-soil feedback for primary succession of terrestrial ecosystems in a glacier region in China

Despite the extensive research conducted on plant-soil-water interactions, the understanding of the role of plant water sources in different plant successional stages remains limited. In this study, we employed a combination of water isotopes (δ2H and δ18O) and leaf δ13C to investigate water use patterns and leaf water use efficiency (WUE) during the growing season (May to September 2021) in Hailuogou glacier forefronts in China. Our findings revealed that surface soil water and soil nutrient gradually increased during primary succession. Dominant plant species exhibited a preference for upper soil water uptake during the peak leaf out period (June to August), while they relied more on lower soil water sources during the post-leaf out period (May) or senescence (September to October). Furthermore, plants in late successional stages showed higher rates of water uptake from uppermost soil layers. Notably, there was a significant positive correlation between the percentage of water uptake by plants and available soil water content in middle and late stages. Additionally, our results indicated a gradual decrease in WUE with progression through succession, with shallow soil moisture utilization negatively impacting overall WUE across all succession stages. Path analysis further highlighted that surface soil moisture (0– 20 cm) and middle layer nutrient availability (20– 50 cm) played crucial roles in determining WUE. Overall, this research emphasizes the critical influence of water source selection on plant succession dynamics while elucidating underlying mechanisms linking succession with plant water consumption.

Porous hydrogel composite with whey protein isolate and galactomannans of Leucaena leucocephala (subabul) seeds: Stability, rheological, thermal, and morphological characterization.

The present study was aimed at curating a porous KCl crosslinked hydrogel with purified subabul galactomannans (SG) from the defatted seeds of Leucaena leucocephala (subabul) and κ-carrageenan (κC) by inducing whey protein isolate (WPI). WPI showed 345% foam overrun and minimal foam drainage (%) at 70°C when whipped for 5min at pH 6.8 in the hydrogel prepared with 6.5% w/v SG+1% w/v κC+0.63% w/v KCl+2% w/v WPI. The SG and WPI incorporated porous hydrogel (SGWP) showed maximum G' (3010Pa) and frequency independence (>30Hz) at 65°C. NMR (1 H), scanning electron microscopy, and thermal characterization of SGWP showed a crosslinked microporous gel network formation. SGWP had high water uptake rate (Q) (432%) at 45°C. The stability of SGWP at neutral pH and high temperature (65°C) added an impetus to this study as it could be used for a wide range of applications. Hence the protein-polysaccharide complexation improvised the functional properties of the porous hydrogels. The results suggested a possible valorization of galactomannans from subabul, a forest resource, into a porous hydrogel suitable as a matrix for delivery of bioactive(s) or an aerogel for multifarious industrial applications. PRACTICAL APPLICATION: A porous hydrogel is defined as a solid, or collection of solid bodies, with sufficient open space to enable a fluid to pass through or around them. Leucaena leucocephala seed (forest resource) galactomannans are non-starch polysaccharides having weak gelling capacity. Whey protein isolates (WPI) are a dairy industry byproduct having excellent foaming properties. Incorporation of WPI in the hydrogel prepared with subabul galactomannan and κ-carrageenan using KCl as a crosslin could form a stable porous structure having high water uptake rate (Q) at neutral pH and elevated temperature. The hydrogel so developed could be a step toward circular economy.

Idioblasts and peltate hairs as distribution networks for water absorbed by xerophilous leaves.

Capparis odoratissima is a tree species native to semi-arid environments of South America where low soil water availability coexists with frequent night-time fog. A previous study showed that water applied to leaf surfaces enhanced leaf hydration, photosynthesis and growth, but the mechanisms of foliar water uptake are unknown. Here, we combine detailed anatomical evaluations with water and dye uptake experiments in the laboratory, and use immunolocalization of pectin and arabinogalactan protein epitopes to characterize water uptake pathways in leaves. Abaxially, the leaves of C. odoratissima are covered with peltate hairs, while the adaxial surfaces are glabrous. Both surfaces are able to absorb condensed water, but the abaxial surface has higher rates of water uptake. Thousands of idioblasts per cm2 , a higher density than stomata, connect the adaxial leaf surface and the abaxial peltate hairs, both of which contain hygroscopic substances such as arabinogalactan proteins and pectins. The highly specialized anatomy of the leaves of C odoratissima fulfils the dual function of minimizing water loss when stomata are closed, while maintaining the ability to absorb liquid water. Cell-wall related hygroscopic compounds in the peltate hairs and idioblasts create a network of microchannels that maintain leaf hydration and promote water uptake.

Morphological and physiological factors contributing to early vigor in the elite rice cultivar 9,311

Huanghuazhan (HHZ) and 9,311 are two elite rice cultivars in China. They have achieved high yield through quite different mechanisms. One of the major features that gives high yield capacity to 9,311 is its strong early vigor, i.e., faster establishment of its seedling as well as its better growth in its early stages. To understand the mechanistic basis of early vigor in 9,311, as compared to HHZ the cultivar, we have examined, under controlled environmental conditions, different morphological and physiological traits that may contribute to its early vigor. Our results show that the fresh weight of the seeds, at germination, not only determined the seedling biomass at 10 days after germination (DAG), but was also responsible for ~ 80% of variations in plant biomass between the two cultivars even up to 30 DAG. Furthermore, the 9,311 cultivar had a larger root system, which led to its higher nitrogen uptake capacity. Other noteworthy observations about 9,311 being a better cultivar than HHZ are: (i) Ten out of 15 genes involved in nitrogen metabolism were much more highly expressed in its roots; (ii) it had a higher water uptake rate, promoting better root-to-shoot nitrogen transfer; and (iii) consistent with the above, it had higher leaf photosynthetic rate and stomatal conductance. All of the above identified features explain, to a large extent, why the 9,311, as compared to HHZ, exhibits much more vigorous early growth.

Solar powered atmospheric water harvesting with enhanced LiCl /MgSO4/ACF composite

Air humidity, as a source of water, is more or less available everywhere. The sorption capacity of water is a significant factor for the efficiency of atmospheric water harvesting (AWH) systems, which are based on the adsorption phenomenon. Lithium chloride has a high water-uptake rate, but has a very low delinquency relative humidity (DRH). Therefore, a host is required to make a stable composite. Composite of activated carbon fiber (ACF) and lithium chloride can keep the adsorbent immobile even after the occurrence of deliquescence, which also causes the three-phase sorption. However, the amount of salt inside the composite is limited by the prevention of leakage. In this paper, a binary salt composite is produced by a new method in order to enhance the water sorption capacity in terms of volume, and mass and the prevention the leakage. The effect of adding MgSO4 to the composite has been experimentally investigated for at different levels of relative humidity. The results showed that sorption capacity per unit volume and mass can be improved by the two-stage addition of MgSO4 without leaking in the adsorbent, reaching 0.78 g water/cm3 and 2.29 gwater/gadsorbent. The prototype made by the selected composite showed that AWH energy intensity was lower at higher relative humidity. The device was tested successfully in an arid climate and produced 0.92 gwater/gadsorbent when maximum RH reached 35% during the adsorption process.

Hygrothermal characterization and modeling of cross-laminated timber in the building envelope

Cross-laminated timber (CLT) is a type of mass timber panel used in floor, wall, and roof assemblies. An important consideration in design and construction of timber buildings is moisture durability. This study characterized the hygrothermal performance of CLT panels with laboratory measurements at multiple scales, field measurements, and modeling. The CLT panels consisted of five layers, four with spruce-pine-fir lumber and one with Douglas-fir lumber. Laboratory characterization involved measurements on small specimens that included material from only one or two layers and large specimens that included all five layers of the CLT panel. Water absorption was measured with panel specimens partially immersed in water, and a new method was developed where panels were exposed to ponded water on the top surface. This configuration gave a higher rate of water uptake than the partial immersion test. The rate of drying was much slower when the wetted surface was covered with an impermeable membrane. Measured hygrothermal properties were implemented in a one-dimensional transient hygrothermal model. Simulation of water uptake indicated that vapor diffusion had a significant contribution in parallel with liquid transport. A simple approximation for liquid transport coefficients, with identical coefficients for suction and redistribution, was adequate for simulating panel-scale wetting and drying. Finally, hygrothermal simulation of a CLT roof assembly that had been monitored in a companion field study showed agreement in most cases within the sensor uncertainty. Although the hygrothermal properties are particular to the wood species and CLT panels investigated here, the modeling approach is broadly applicable.

Seed morphology, quality traits and imbibition behaviour study of atypical lentil (Lens culinaris Medik.) from Rajasthan, India

An atypical morphotype of lentil (Lens culinaris Medik.) was identified during mega germplasm characterization programme at ICAR-National Bureau of Plant Genetic Resources, New Delhi undertaken during rabi 2017–2018. On the basis of the comparative evaluation of lentil morphotype with two distinct subspecies, viz., L. culinaris subsp. macrosperma and L. culinaris subsp. microsperma, this atypical morphotype was classified under the latter subspecies. Based on comparative study with selected accessions for seed morphology, quality traits and physiology, this accession was identified with very distinct and prominent funiculus on the seed coat, higher rate of water uptake and nutritional traits (rich in sugar, starch, protein and minerals). Present studies identified this germplasm as unique type that deserves for the detailed study to explore its genetic resource potential.

Characterizing roots and water uptake in a ground cover rice production system.

Background and aimsWater-saving ground cover rice production systems (GCRPS) are gaining popularity in many parts of the world. We aimed to describe the characteristics of root growth, morphology, distribution, and water uptake for a GCRPS.MethodsA traditional paddy rice production system (TPRPS) was compared with GCRPS in greenhouse and field experiments. In the greenhouse, GCRPS where root zone average soil water content was kept near saturation (GCRPSsat), field capacity (GCRPSfwc) and 80% field capacity (GCRPS80%), were evaluated. In a two-year field experiment, GCRPSsat and GCRPS80% were applied.ResultsSimilar results were found in greenhouse and field experiments. Before mid-tillering the upper soil temperature was higher for GCRPS, leading to enhanced root dry weight, length, surface area, specific root length, and smaller diameter of roots but lower water uptake rate per root length compared to TPRPS. In subsequent growth stages, the reduced soil water content under GCRPS caused that the preponderance of root growth under GCRPSsat disappeared in comparison to TPRPS. Under other GCRPS treatments (GCRPSfwc and GCRPS80%), significant limitation on root growth, bigger root diameter and higher water uptake rate per root length were found.ConclusionsDiscrepancies in soil water and temperature between TPRPS and GCRPS caused adjustments to root growth, morphology, distribution and function. Even though drought stress was inevitable after mid-tillering under GCRPS, especially GCRPS80%, similar or even enhanced root water uptake capacity in comparison to TPRPS might promote allocation of photosynthetic products to shoots and increase water productivity.

Associations of water balance and thermal sensitivity of toads with macroclimatic characteristics of geographical distribution

Interspecific variation in patterns of geographical distribution of phylogenetically related species of amphibians might be related to physiological adaptation to different climatic conditions. In this way, a comparative study of resistance to evaporative water loss, rehydration rates and sensitivity of locomotor performance to variations on hydration level and temperature was performed for five species of Bufonidae toads (Rhinella granulosa, R. jimi, R. ornata, R. schneideri and R. icterica) inhabiting different Brazilian biomes. The hypotheses tested were that, when compared to species inhabiting mesic environments, species living at hot and dry areas would show: (1) greater resistance to evaporative water loss, (2) higher rates of water uptake, (3) lower sensitivity of locomotor performance to dehydration and (4) lower sensitivity of locomotor performance at higher temperatures and higher sensitivity of locomotor performance at lower temperatures. This comparative analysis showed relations between body mass and interspecific variation in rehydration rates and resistance to evaporative water loss in opposite directions. These results might represent a functional compensation associated with relatively lower absorption areas in larger toads and higher evaporative areas in smaller ones. Moreover, species from the semi-arid Caatinga showed locomotor performance less sensitive to dehydration but highly affected by lower temperatures, as well greater resistance to evaporative water loss, when compared to the other species from the mesic Atlantic Forest and the savannah-like area called Cerrado. These results suggest adaptation patterns to environmental conditions.

Relation between Water Balance and Climatic Variables Associated with the Geographical Distribution of Anurans.

Amphibian species richness increases toward the equator, particularly in humid tropical forests. This relation between amphibian species richness and environmental water availability has been proposed to be a consequence of their high rates of evaporative water loss. In this way, traits that estimate water balance are expected to covary with climate and constrain a species’ geographic distribution. Furthermore, we predicted that coexisting species of anurans would have traits that are adapted to local hydric conditions. We compared the traits that describe water balance in 17 species of anurans that occur in the mesic Atlantic Forest and xeric Cerrado (savannah) habitats of Brazil. We predicted that species found in the warmer and dryer areas would show a lower sensitivity of locomotor performance to dehydration (SLPD), increased resistance to evaporative water loss (REWL) and higher rates of water uptake (RWU) than species restricted to the more mesic areas. We estimated the allometric relations between the hydric traits and body mass using phylogenetic generalized least squares. These regressions showed that REWL scaled negatively with body mass, whereas RWU scaled positively with body mass. Additionally, species inhabiting areas characterized by higher and more seasonally uniform temperatures, and lower and more seasonally concentrated precipitation, such as the Cerrado, had higher RWU and SLPD than species with geographical distributions more restricted to mesic environments, such as the Atlantic Forest. These results support the hypothesis that the interspecific variation of physiological traits shows an adaptation pattern to abiotic environmental traits.

Drought resistance and soil water extraction of a perennial C4 grass: contributions of root and rhizome traits.

Previously, we showed that genotypic differences in soil water extraction were associated with drought response, but we did not study underground root and rhizome characteristics. In this study, we demonstrate a similar relationship between drought resistance and soil water extraction but investigate the role of underground organs. Eighteen bermudagrass genotypes (Cynodon spp.) from four climatic zones were assessed under continuous drought at two locations with contrasting soils and climates. The criterion for drought resistance was the duration required to reach 50% green cover (GC50) after water was withheld. GC50, physiological traits, rhizome dry matter (RhDM), root length density (RLD) and average root diameter (ARD) were determined in both locations; water extraction was measured in one location. Large genotypic variation for drought resistance was observed in both locations, with GC50 being 187-277 days in a clay soil and 15-27 days in a sandy soil. Drought-resistant genotypes had greater soil water extraction and a higher water uptake rate. GC50 was correlated with relative water content (r=0.76), canopy temperature differential (r=-0.94) and photosynthetic rate (r=0.87) measured during drought; RhDM (r=0.78 to ~0.93) before and after drought; and ARD after drought (r=0.82 to ~0.94); GC50 was not correlated with RLD. Ecotypes collected from the Australian Mediterranean zone had superior drought resistance and were characterised by a large rhizome network. This is the first comprehensive study with perennial C4 grasses describing the association between water extraction, root distribution, rhizomes and drought resistance.

Synthesis and Characterization of Sulfonated Polybenzimidazole (SPBI) Copolymer for Polymer Exchange Membrane Fuel Cell

A diverse sulfonated polybenzimidazole copolymer (SPBI) as proton exchange membrane was synthesiszed via one-step high temperature polymerization method with 3,3-diaminobenzidine (DABD), 5-sulfoisophthalic acid (SIPA), 4,4-sulfonyldibenzoic acid (SDBA) and biphenyl-4,4-dicarboxylic acid (BDCA). The SPBI membrane was prepared through a direct hot-casting and in situ phase inversion technique. Characterization tests were carried out on the membranes including surface morphology, distribution of elements on the membrane, determination of functional groups, thermal stability, ion exchange capacity, water uptake rate and proton conductivity. The as-synthesized SPBI membrane displayed a smooth surface via scanning electron microscopy (SEM) analysis which is thermally stable up to 443 °C. The SPBI membrane showed higher water uptake rate (WUR) and proton conductivity though it had lower ion exchange capacity (IEC) value compared to recast Nafion membrane. The proton conductivity of the SPBI membrane with IEC of 0.60 mmol/g was 4.50 × 10-2 S/cm at 90 °C. This study shows that the SPBI membrane has great potential in polymer exchange membrane fuel cell (PEMFC) applications.

Drought-Induced Root Aerenchyma Formation Restricts Water Uptake in Rice Seedlings Supplied with Nitrate

Previous studies demonstrated that ammonium nutrition results in higher water uptake rate than does nitrate nutrition under water stress, and thus enhances the tolerance of rice plants to water stress. However, the process by which water uptake is related to nitrogen form under water stress remains unknown. A hydroponic experiment with simulated water stress induced by polyethylene glycol (PEG6000) was conducted in a greenhouse to study the relationship between root aerenchyma formation and water uptake rate, such as xylem sap flow rate and hydraulic conductance, in two different rice cultivars (cv. 'Shanyou 63' hybrid indica and cv. 'Yangdao 6' indica, China). The results showed that root aerenchyma tissue increased in water-stressed plants of both cultivars fed by nitrate. No significant difference was found in root hydraulic conductivity and/or xylem sap flow rate between the two rice cultivars fed by ammonium regardless of water status, whereas these parameters decreased significantly in water-stressed plants fed by nitrate. It was concluded that aerenchyma that formed in the root cortex impeded the radial transport of water in the root cylinder and decreased water uptake in water-stressed rice plants fed by nitrate. Water transport occurred mainly through Hg-sensitive water channels in rice roots supplied with ammonium.

Psidium guajavaandPiper betleLeaf Extracts Prolong Vase Life of Cut Carnation (Dianthus caryophyllus) Flowers

The effect of leaf extracts of Psidium guajava and Piper betle on prolonging vase life of cut carnation flowers was studied. “Carola” and “Pallas Orange” carnation flowers, at bud stage, were pulsed 24 hours with a floral preservative. Then, flowers were placed in a vase solution containing sprite and a “germicide” (leaf extracts of P. guajava and P. betle, 8-HQC, or a copper coin). Flowers treated with 8-HQC, copper coin, and leaf extracts had longer vase life, larger flower diameter, and higher rate of water uptake compared to control (tap water). The leaf extracts of P. guajava and P. betle showed highest antibacterial and antifungal activities compared to the other treatments. Both showed similar effects on flower quality as the synthetic germicide, 8-HQC. Therefore, these extracts are likely natural germicides to prolong vase life of cut flowers.

A novel hybrid Nafion-PBI-ZP membrane for direct methanol fuel cells

Methanol crossover through proton conducting membranes represents one of the main drawbacks in DMFCs. This study presented a novel organic-inorganic hybrid membrane with several different compositions by casting mixtures of zirconium phosphate (ZP), polybenzimidazole (PBI) and Nafion dispersion in dimethylacetamide. The presence of PBI and ZP in the membranes was demonstrated with energy dispersive X-ray (EDX) analysis. From the scanning electron microscopy (SEM) analysis, it was observed that the hybrid Nafion-PBI-ZP membrane had the finest structure. This is because the synthesized films were homogeneous and therefore formed a dense membrane. The water content was higher in the hybrid membrane: 39.91% compared with 35.52% in Nafion117. The water content is important for the ion transportation in the membrane; therefore, a higher water uptake rate will contribute to a better fuel cell performance. It was determined that the proton conductivity of the hybrid membrane was 0.020 S cm−1, which was comparable with Nafion117, which had a proton-conductivity of 0.022 S cm−1. The methanol permeability of the hybrid membrane was 2.34 × 10−7 cm2 s−1, while the value for Nafion117 was 8.91 × 10−7 cm2 s−1. This showed that the methanol permeability of the hybrid membrane was almost 4 times lower than that of Nafion117. The selectivity factor for the Nafion-PBI 1%–ZP 1% membrane was 8.64 × 104 Scm−3, while that of Nafion117 was 2.48 × 104 S scm−3. From a thermogravimetry analysis (TGA), the addition of PBI and zirconium phosphate was shown to improve the thermal durability in the temperature range from room temperature to 450 °C over that of Nafion117. This study proofed that the Nafion-PBI 1%–ZP 1% performed better than commercial Nafion117 and other type of membranes. The membrane was tested on as single cell of DMFC. It gave the highest power density as compared to other type of membrane and proofed that it has potential to be used in DMFCs.

Causes of differences in seed quality among cowpea (<i>Vigna unguiculata</i> (L.) Walp) cultivars

Three cowpea cultivars differing in seed coat colour, IT83S-818 (white, black-eye), TVX 2724-01F (brown) and IT82D-32 (dark brown), were aged using the controlled deterioration method (20% seed moisture content and incubated at 40 oC) for 0, 1, 2 and 4 days. Time to 50 per cent germination (t50) and final germination percentage were determined to assess the vigour differences that exist among these cultivars. In unaged seeds, the white cultivar germinated quicker than the pigmented cultivars as a result of the characteristically higher rate of water uptake, which enhanced rapid hydration of the embryonic cells for quicker germination. When ageing progressed, however, the white cultivar germinated more slowly with a lower final germination percentage since the embryonic cells possibly became weaker and leaky leading to reduced vigour and eventually, loss of germinability. In contrast, the pigmented cultivars germinated more slowly before seeds were aged due to their slower rates of water uptake; germination became quicker as ageing progressed due to increasing softening of the seed coats. Thus, the pigmented cultivars showed decreases in the time to 50 per cent germination during ageing. They, however, retained high germination percentages throughout the ageing period, which is an indication of high vigour. These three cultivars, together with two other unpigmented cultivars, IT81D-1137 (white) and TVX 3236 (cream and brown) were subsequently examined for the incidence of disease pathogens. It was observed that the unpigmented cultivars had higher levels of the importasnt seed pathogens such as Fusarium species and Aspergillus flavus which cause reduction in germination. These seeds also showed susceptibility to mechanical damage caused by hand-beating of dry pods in sacs. These differences in behaviour between the two groups of cowpea cultivars, pigmented and unpigmented, were attributed to differences in tannin and lignin contents in their seed coats.

A root is a root is a root? Water uptake rates of Citrus root orders

Knowledge about the physiological function of root orders is scant. In this study, a system to monitor the water flux among root orders was developed using miniaturized chambers. Different root orders of 4-year-old Citrus volkameriana trees were analysed with respect to root morphology and water flux. The eight root orders showed a broad overlap in diameter, but differences in tissue densities and specific root area (SRA) were clearly distinguishable. Thirty per cent of the root branch biomass but 50% of the surface area (SA) was possessed by the first root order, while the fifth accounted for 5% of the SA (20% biomass). The root order was identified as a determinant of water flux. First-order roots showed a significantly higher rate of water uptake than the second and third root orders, whereas the fourth and fifth root orders showed water excess. The water excess suggested the occurrence of hydraulic redistribution (HR) as a result of differences in osmotic potentials. We suggest that plants may utilize hydraulic redistribution to prevent coarse root desiccation and/or to increase nutrient acquisition. Our study showed that the novel 'miniature depletion chamber' method enabled direct measurement of water fluxes per root order and can be a major tool for future studies on root order traits.

닭고기 함수율이 저장기간 동안 지방산패도, 육색, 미생물 변화에 미치는 영향

본 연구는 함수율을 달리하여 폴리에틸렌(PE)으로 포장된 닭고기를 냉장 저장하면서 닭고기의 신선도, 미생물 및 육색의 변화를 구명하고자 수행하였다. 함수율에 따른 닭고기 가슴부위의 pH는 저장 3일에는 함수율 6% 처리구에서 6.00을 나타내었으나, 함수율이 8, 10%에서는 6.04, 6.05%를 나타내어 함수율이 증가함에 따라 증가하는 경향을 나타내었다. 이러한 경향은 저장 5일에도 비슷한 경향을 나타내었다. 육색 변화에서 명도(<TEX>$L^*$</TEX>)는 저장 3일에 가슴육의 함수율 6% 처리구에서 73.40을 나타내었으나, 8, 10% 처리구에서는 75.27, 75.31로 닭고기의 함수율이 증가할수록 증가하는 경향을 나타내었다. 적색도(<TEX>$a^*$</TEX>)는 저장 3일에 10% 처리구에서 2.52로 가장 높은 값을 나타내었으나, <TEX>$6{\sim}8%$</TEX> 처리구에서는 서로 비슷한 경향을 나타내었다. 저장 5일에서도 비슷한 경향을 나타내었다. 황색도(<TEX>$b^*$</TEX>)는 저장 3일에 가슴육의 함수율 6% 처리구는 4.31, 8% 처리구 4.33, 10% 처리구는 4.34로 10% 처리구에서 가장 높은 값을 보여 저장 1일과 비슷한 경향을 나타내었다. 지방산패도(TBARS)의 변화는 저장 3일에 함수율 6% 처리구에서 0.107, 8% 처리구 0.104, 10% 처리구 0.113 mgMA/kg으로 함수율이 가장 높은 10% 처리구에서 가장 높은 TBARS 가를 나타내었다. 미생물 변화에서 총 균수는 저장 3일에 함수율 6% 처리구에서 4.04, 8% 처리구 4.12, 10% 처리구 4.56 <TEX>$logCFU/cm^2$</TEX>로 함수율이 증가할수록 약간씩 증가하는 경향을 나타내었다. E. coli 수는 저장 3일에 함수율 6% 처리구에서 0.93, 8% 처리구 1.40, 10% 처리구 1.28 <TEX>$logCFU/cm^2$</TEX>로 함수율이 낮을수록 감소하였다. 이러한 경향은 coliform 수에서도 비슷한 경향을 나타내었다. 이상의 결과로 보아 포장 닭고기에서 함수율이 증가함에 따라 육색이 달라지고, 지방산패도가 증가할 뿐 아니라 미생물 증식이 활성화 되는 것으로 나타나 포장 닭고기에 대한 함수율은 낮을수록 유통 중에 저장성이 향상될 것으로 사료된다. This study was performed to evaluate change of lipid oxidation, microbes, and color of chicken meat containing 6, 8, and 10% of water uptake rate(WUR) during cold storage. pH of chicken containing 6, 8, and 10% of WUR showed 6.00, 6.04, and 6.05%, at day 3, respectively. Lightness(<TEX>$L^*$</TEX>) of chicken containing 6, 8, and 10% of WUR was 73.40, 75.27, and 75.31, at day 3, respectively. Redness(<TEX>$a^*$</TEX>) of chicken with 10% of WUR was 2.52, which was the highest value, while no difference was found between chicken with 6 and 8% of WUR. Yellowness(<TEX>$b^*$</TEX>) of chicken containing 6, 8, and 10% of WUR was 4.31, 4.33, and 4.36. Thiobarbituric acid reactive substances(TBARS) value of chicken containing 6, 8, and 10% of WUR was 0.107, 0.104, and 0.113 mg malondialdehyde/kg meat. The higher WUR, the higher TBARS value was shown. Total microbial number of chicken with 6, 8, and 10% of WUR was 4.04, 4.12, and 4.56 <TEX>$log\;CFU/cm^2$</TEX> at day 3. E. coli of chicken with 6, 8, and 10% of WUR was 0.93, 1.40, and 1.28 <TEX>$log\;CFU/cm^2$</TEX>. From this result high WUR increases <TEX>$L^*$</TEX> value, TBARS, and microbes of chicken meat during storage. Therefore, lower WUR would be beneficial to extend shelf life of chicken meat during storage.

Association of seedcoat color with seed water uptake, germination, and seed components in guar ( Cyamopsis tetragonoloba (L.) Taub)

Seeds of guar black in color are believed to be of low quality. In the present experiment, seeds varying in color were studied to examine the effect of seedcoat color on water uptake, germination, and quantity of seed component. Results showed that the rate of water uptake for black-colored seeds was greater than that of dull-white-colored seeds. Black seeds had a higher germination than that of dull-white-colored seeds. Seedcoat quantity in black-colored seeds was less than dull-white seeds. Endosperm quantity and embryo quantity of black-colored seeds were not significantly different from those in dull-white-colored seeds. The higher water uptake rate and germination in black-colored seeds are likely due to the degeneration of seedcoat. This research suggests that guar seeds black in color may be recommended for planting or gum-extracting purposes with little expected loss in stand or gum yield.

Diurnal Change in Water Balance of Heat-Tolerant Snap Bean (Phaseolus vulgaris) Cultivar and Its Association with Growth under High Temperature

A snap bean (Phaseolus vulgaris L.) cultivar Haibushi shows high productivity under high-temperature conditions. Together with intensive radiation, high temperature enhances transpiration and causes water deficit in plants even when they are irrigated enough. To characterize daily change in water balance of the heat-tolerant cultivar, we compared parameters of water balance, dry matter production and pod yield among cultivars. Four snap bean cultivars, Haibushi, Kurodane-Kinugasa, Oregon and Kentucky Wonder, were grown under optimal temperature (spring cropping) and high temperature (summer cropping) condition in the field. The daily water balance and gas exchange rate in the heat-tolerant cultivar Haibushi were compared with those in the heat-sensitive cultivar Kentucky Wonder, grown in 0.02 m2 Wagner pots. In the summer cropping in the field, dry matter production, pod yield, stomatal conductance, photosynthetic rate and transpiration rate were higher in Haibushi and Kurodane-Kinugasa than in the other cultivars. In a glasshouse, the sap flow rate was lower than the transpiration rate in the morning when the transpiration rate rapidly increased in both Haibushi and Kentucky Wonder. In spite of the higher transpiration rate, Haibushi showed a higher sap flow rate and smaller cumulative water loss in the morning than Kentucky Wonder. We conclude that better growth of the heat-tolerant snap bean cultivar Haibushi under high temperature was due to higher photosynthetic rate resulting from higher stomatal conductance during the daytime, which had a higher water uptake rate.