首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
《Field Crops Research》2001,72(3):211-219
Genetics of days to first flowering, first pod maturity, 90% pod maturity, and duration of the period from first flower to 90% pod maturity (DDd1) and from first pod maturity to 90% pod maturity (DDd2) [degree of non-synchrony of pod maturity] were investigated in mungbean using the triple test cross (TTC) technique. Ten diverse genotypes were crossed with two true breeding testers (L1 and L2) and the F1 hybrid of the tester lines (L3). The resultant single and three-way crosses were evaluated in two seasons (kharif and spring/summer).Epistatic variation was found to be an integral part of inheritance of days to first flower in both seasons and days to first pod maturity only in kharif season. Further partitioning of total epistasis revealed that additive×additive (i type) interactions had a major role in the inheritance of these traits.In the absence of epistasis both additive and dominance genetic components were significant for days to 90% pod maturity, DDd1, and DDd2 in both seasons, and for days to first flower in spring/summer season. The additive genetic component was predominant for days to 90% pod maturity and DDd2 in both seasons and for DDd1 in spring/summer season, whereas the dominance component was important for days to first flower and DDd1 in the spring/summer season. The direction of dominance was towards early maturity of 90% pods and late maturity of the first pod. The significant additive genetic component in DDd1 and DDd2 could be exploited in later generations for developing mungbean genotypes with improved synchrony in pod maturity.  相似文献   

2.
The B low Mr subunits of glutenin of the F2 generation from three durum wheat crosses were analysed. Three new alleles were found at three different loci: Glu-A3i coding for 5+20 subunits, Glu-B2c coding for subunit 12* and Glu-B3l coding for 1+3+13*+16 subunits. The genetic distances between Glu-A3-Gli-A1, Glu-B2-Gli-B1, Glu-B3-Glu-B2 and Glu-B3-Gli-B1 were calculated. The effects of the allelic variation at the Glu-A3, Glu-B2 and Glu-B3 on protein content and gluten strength, as measured by the SDS-sedimentation test, were determined using F4 lines from the three crosses. All the new alleles affected significantly gluten strength. The presence of Glu-A3i had a negative influence on SDSS values compared with the allele a. For Glu-B2 and Glu-B3 the data obtained enable the effects of the alleles on SDSS volume to be ranked: a=b>c for Glu-B2 and a>b>l for Glu-B3. The results also shown that the allelic variants at Glu-B3 had a much greater effect on gluten strength than the variants at Glu-A3 or Glu-B2 loci. A high percentage of variation in sedimentation volume was explained by the prolamins (52 and 70%).  相似文献   

3.
Amine-functionalized supports were prepared by chemical modification of cotton fibers using amino compounds namely diethylenetriamine (DET) and 1,4-diaminobutane (DB) in order to be loaded with copper ions. Evidence of attaching amine groups onto cellulosic fibers was confirmed through nitrogen and SEM analysis. Adsorption behavior of Acid Blue 25 from aqueous solutions onto [Cu(II)/DET-cotton] and [Cu(II)/DB-cotton] has been evaluated via batch and column mode systems. During the batch experiments, the effects of temperature and type of adsorbent on dye removal were investigated. Results revealed the formation of ternary complexes of the type [AB25/Cu(II)/adsorbent] with a [5/2:3:1] stoichiometry for DET-cotton and a [1:1:1] stoichiometry for DB-cotton at 20 °C. In the isotherm studies, Langmuir, Freundlich, and Jossens equations were applied and it was found that the experimental data conformed to Jossens model. Thermodynamic parameters such as change in free energy (ΔG 0), enthalpy (ΔH 0), and entropy (ΔS 0) have also been calculated in this paper, and it was found that the adsorption process was exothermic and spontaneous. The column experiments were conducted to study the effect of bed height on adsorption performance of both adsorbents. Results exhibited that the column capacity of [Cu(II)/DET-cotton] complex was found to be higher than that of [Cu(II)/DB-cotton] as was obtained in batch process. BDST model was applied to experimental data in order to predict the breakthrough curves and determine the characteristics parameters of the column useful for process design. Results revealed that the used model was appropriate to fit the experimental data. Desorption studies to recover the adsorbed dye from both adsorbents were performed with NaOH and NH4Cl solutions.  相似文献   

4.
Saflufenacil is a new herbicide being developed for pre-plant burndown and pre-emergence broadleaf weed control in field crops, including maize, soybean, sorghum and wheat. Field experiments were conducted in 2007 and 2008 in northeast Nebraska, USA to describe dose-response curves of saflufenacil applied in mid (early post-emergence, EPOST) and late May (late post-emergence, LPOST) with several adjuvants for spring emerging broadleaf weed control. Dose-response curves based on log-logistic model were utilized to determine the ED90 values (effective dose that provides 90% weed control efficacy) for Convolvulus arvensis, Lactuca serriola, Lamium amplexicaule, Capsella bursa-pastoris, Taraxacum officinale, Thlaspi arvense and Conyza canadensis. In general, weed control efficacy was influenced by application timing and type of adjuvant. EPOST application of saflufenacil resulted better efficacy of saflufenacil compared to LPOST. Addition of spray adjuvants improved efficacy of saflufenacil. For example, 90% control of T. arvense was obtained at EPOST application with 251, 161, 96 and 59 g a.i. ha−1 for saflufenacil applied alone, or tank-mixed with NIS (nonionic surfactant), COC (crop oil concentrate), or MSO (methylated seed oil), respectively. In contrast, the ED90 values with LPOST application were 333, 201, 127 and 79 g a.i. ha−1 for saflufenacil applied alone, or with NIS, COC and MSO, respectively. MSO was the best adjuvant, which provided the most enhancement of saflufenacil. COC was the second best, or similar to MSO, on many weed species. NIS provided the least enhancement of saflufenacil. The ED90 values determined for different broadleaf weed species are within the proposed label dose of saflufenacil.  相似文献   

5.
Due to the woven structure textile materials have excellent formability properties but their behaviour is difficult to investigate. Digital image analysis as non-disturbing and low cost method for the textile investigations has paid a lot of attention, still this method has some limits. The aim of the research is to analyse the accuracy and reliability of the method based on digital image analysis for the textile local deformations investigation and to determine the measurement errors. Depending on the results of experiments when input image acquisition parameters (capture distance d i and lighting angle γ j ) were changed the image analysis system was composed. To estimate the measurement errors of the method the scanned image was used as reference sample and parameters of each grid point A 0, h 0 ir b 0 were compared calculating the measurement error depending on image resolution δ Ai and illumination conditions δ h60, δ w60, δ A60. Image quality evaluation while investigating different material types has shown that image analysis method can be applied for the fabrics the colour intensity of which differs, however it is necessary to ensure sufficient contrast of input image and to apply additional image processing operations.  相似文献   

6.
Plant responses to water deficit need to be monitored for producing a profitable crop as water deficit is a major constraint on crop yield. The objective of this study was to evaluate physiological responses of cotton (Gossypium hirsutum) to various environmental conditions under limited water availability using commercially available varieties grown in South Texas. Soil moisture and variables of leaf gas exchange were measured to monitor water deficit for various varieties under different irrigation treatments. Lint yield and growth variables were also measured and correlations among growth parameters of interest were investigated. Significant differences were found in soil moisture, leaf net assimilation (An), stomatal conductance (g), transpiration rate (Tr), and instantaneous water use efficiency (WUEi) among irrigation treatments in 2006 while no significant differences were found in these parameters in 2007. Some leaf gas exchange parameters, e.g., Tr, and leaf temperature (TL) have strong correlations with An and g. An and WUE were increased by 30–35% and 30–40%, respectively, at 600 μmol (CO2) m−2 s−1 in comparison with 400 μmol (CO2) m−2 s−1. Lint yield was strongly correlated with g, Tr, WUE, and soil moisture at 60 cm depth. Relative An, Tr, and TL started to decrease from FTSW 0.3 at 60 cm and FTSW 0.2 at 40 cm. The results demonstrate that plant water status under limited irrigation management can be qualitatively monitored using the measures of soil moisture as well as leaf gas exchange, which in turn can be useful for describing yield reduction due to water deficit. We found that using normalized An, Tr, and TL is feasible to quantify plant water deficit.  相似文献   

7.
Wheat flour was washed with Tris-HCl buffer containing 4% Triton X114 before extracting the residual gluten with 70% ethanol. The glutenin extraction with 50% ethanol was performed at various ratios of DTT/protein; a minimum ratio of 0·1 g/g was needed to solubilise the maximum amount of glutenin. An experimental design was used to optimise the extraction conditions to obtain the best yield and purity of lowMrand highMrglutenin subunits. The purity of each glutenin subunit fraction was measured by RP-HPLC analysis after reduction and alkylation. Both temperature and protein concentration had an effect on the preparation of these fractions. An increase in the protein concentration enhanced the yield of the highMrglutenin fraction and simultaneously decreased that of the lowMrglutenin. Using the Deringer desirability function, conditions giving the optimum separation were determined. The procedure was scaled up and permitted the preparation of 0·96 g of highMrand 1·64 g of lowMrglutenin subunits from 5 g of gluten. The purities of these fractions, determined by RP-HPLC, were 90% and 95%, respectively, and their amino acid compositions were similar to those of high and lowMrsubunits separated by RP-HPLC.  相似文献   

8.
Toxicities of the eight quinones were evaluated through leaf dip bioassays conducted against Tetranychus urticae, Myzus persicae, Myzocallis walshii, and Illinoia liriodendri. Based on LC50 values, plumbagin (LC50 = 0.001%) was the most active compound against T. urticae and ubiquinone Q0 (LC50 = 0.005%), plumbagin (LC50 = 0.010%), and dibromothymoquinone (LC50 = 0.012%) were the most active compounds against M. persicae. The most active compounds against M. walshii were juglone (LC50 = 0.011%) and ubiquinone Q0 (LC50 = 0.019%), whereas dibromothymoquinone (LC50 = 0.030%), plumbagin (LC50 = 0.033%) and ubiquinone Q0 (LC50 = 0.058%) were the most toxic to I. liriodendri. Ecotrol (positive control) was the least toxic compound (LC50 = 0.39%) against T. urticae and M. persicae (LC50 = 0.447%). Although the majority of the compounds tested were toxic to all four test species in residual bioassays, there was little overlap among the test species in terms of susceptibility to the compounds and interspecific differences were observed. Regarding structure-activity relationships for quinones, the addition of a hydroxyl group resulted in a significant increase in the toxicity of the 1,4-naphthoquinones, and those possessing a methyl group exhibited the highest levels of activity in T. urticae. The bromine atom at the 2- and 5-positions of the benzoquinone ring is crucial to the toxicity of the compounds against I. liriodendri. Toxicity was greatly affected not only by the number of hydroxyl groups, but also by their positions in the ring in the case of M. walshii. Juglone and plumbagin as residual toxins in the laboratory also reduced the population of two-spotted spider mites compared to EcoTrol™ (positive control) and the negative control in the greenhouse experiment. Some quinones tested may have potential as commercial insecticides and miticides, or alternatively, could serve as lead compounds for the development of more potent crop protection agents.  相似文献   

9.
Barley (Hordeum vulgare L.) grain germination is required to perform the malting process. Maintenance of barley seed viability during storage is crucial for the malt industry; and modern cultivars are bred for rapid grain dormancy release after physiological maturity. Low dormancy level combined with rain close to harvest induces pre-germination/pre-harvest sprouting damage. Pre-germination might not affect viability in the short term after harvest, but it could reduce potential longevity (Ki) of a barley seed lot. Ki value is inherent for each barley lot; however, its determination is time-consuming which precludes its assessment at an industrial scale. In this study we sought quantitative relationships between Ki and the pre-germination degree of barley grain lots, assessed through quality tests routinely performed by malthouses [Falling Number (FN), α-Amylase Activity and Carlsberg]. Field pre-germinated lots from one old barley cultivar (Quilmes Palomar) and artificially pre-germinated lots from major varieties currently grown in Argentina were used. Associations between Ki and values obtained from all quality tests analysed were found for Q. Palomar. However, FN was the parameter that yielded the best and simplest explanation of Ki variability. A significant positive linear Ki -FN relationship was also obtained for each modern barley cultivar.  相似文献   

10.
The objective of this study was to identify physiological processes that result in genotypic and N fertilization effects on rice yield response to elevated atmospheric CO2 concentrations ([CO2]). This study conducted growth and yield simulations for 9 rice genotypes grown at 4 climatically different sites in Asia, assuming the current atmospheric [CO2] (360 ppm) and elevated [CO2] (700 ppm) using 5 levels of N fertilizer (4, 8, 12, 16, 20 g m−2 N fertilizer). A rice growth model that was developed and already validated for 9 different genotypes grown under 7 sites in Asia was used for the simulation, integrating additional components into the model to explain the direct effect of [CO2] on several physiological processes. The model predicted that the relative yield response to elevated [CO2] (RY, the ratio of yield under 700 ppm [CO2] to that under 360 ppm [CO2]) increased with increasing N fertilizer, ranging from 1.12 at 4 g m−2 N fertilizer to 1.22 at 20 g m−2 N fertilizer, averaged overall genotypes and locations. The model also predicted a large genotypic variation in RY at the 20 g N treatment, ranging from 1.08 for ‘WAB450-I-B-P-38-HB’ to 1.41 for ‘Takanari’ averaged overall locations. Combining all genotypes grown at the 5N fertilization conditions, a close 1:1 relationship was predicted between RY and the relative [CO2] response in spikelet number for crops with a small number of spikelets (less than 30,000 m−2) under the current atmospheric [CO2] (n = 18, r = 0.89***). In contrast, crops with a large number of spikelets under the current atmospheric [CO2] showed a significantly larger RY than the relative [CO2] response for spikelet number per unit area. The model predicted that crops with a larger number of spikelets under the current atmospheric [CO2] derived great benefit from elevated [CO2] by directly allocating increased carbohydrate to their large, vacant sink, whereas crops with a smaller number of spikelets primarily required an increased spikelet number to use the increased carbohydrate to fill grains. The simulation analyses suggested that rice with a larger sink capacity relative to source availability under the current atmospheric [CO2] showed a larger yield response to elevated [CO2], irrespective of whether genotype or N availability was the major factor for the large sink capacity under the current [CO2]. The model predicted that the RY response to nitrogen was brought about through the N effects on spikelet number and non-structural carbohydrate accumulation. The genotypic variation in RY was related to differences in spikelet differentiation efficiency per unit plant N content. Further model validation about the effects of [CO2] on growth processes is required to confirm these findings considering data from experimental studies.  相似文献   

11.
For a small library of natural products from marine sponges and ascidians, in silico docking to the Lymnaea stagnalis acetylcholine-binding protein (AChBP), a model for the ligand-binding domains of nicotinic acetylcholine receptors (nAChRs), was carried out and the possibility of complex formation was revealed. It was further experimentally confirmed via competition with radioiodinated α-bungarotoxin ([125I]-αBgt) for binding to AChBP of the majority of analyzed compounds. Alkaloids pibocin, varacin and makaluvamines С and G had relatively high affinities (Ki 0.5–1.3 μM). With the muscle-type nAChR from Torpedo californica ray and human neuronal α7 nAChR, heterologously expressed in the GH4C1 cell line, no competition with [125I]-αBgt was detected in four compounds, while the rest showed an inhibition. Makaluvamines (Ki ~ 1.5 μM) were the most active compounds, but only makaluvamine G and crambescidine 359 revealed a weak selectivity towards muscle-type nAChR. Rhizochalin, aglycone of rhizochalin, pibocin, makaluvamine G, monanchocidin, crambescidine 359 and aaptamine showed inhibitory activities in electrophysiology experiments on the mouse muscle and human α7 nAChRs, expressed in Xenopus laevis oocytes. Thus, our results confirm the utility of the modeling studies on AChBPs in a search for natural compounds with cholinergic activity and demonstrate the presence of the latter in the analyzed marine biological sources.  相似文献   

12.
The system of rice intensification (SRI) is reported to have advantages like lower seed requirement,less pest attack,shorter crop duration,higher water use efficiency and the ability to withstand higher degree of moisture stress than traditional method of rice cultivation.With this background,SRI was compared with traditional transplanting technique at Indian Agricultural Research Institute,New Delhi,India during two wet seasons (2009-2011).In the experiment laid out in a factorial randomized block design,two methods of rice cultivation [conventional transplanting (CT) and SRI] and two rice varieties (Pusa Basmati 1 and Pusa 44) were used under seven crop nutrition treatments,viz.T 1,120 kg/hm2 N,26.2 kg/hm2 P and 33 kg/hm2 K;T 2,20 t/hm2 farmyard manure (FYM);T 3,10 t/hm2 FYM+ 60 kg/hm2 N;T 4,5 t/hm2 FYM+ 90 kg/hm2 N;T 5,5 t/hm2 FYM+ 60 kg/hm2 N+ 1.5 kg/hm2 blue green algae (BGA);T 6,5 t/hm2 FYM+ 60 kg/hm2 N+ 1.0 t/hm2 Azolla,and T 7,N 0 P 0 K 0 (control,no NPK application) to study the effect on seed quality,yield and water use.In SRI,soil was kept at saturated moisture condition throughout vegetative phase and thin layer of water (2-3 cm) was maintained during the reproductive phase of rice,however,in CT,standing water was maintained in crop growing season.Results revealed that CT and SRI gave statistically at par grain yield but straw yield was significantly higher in CT as compared to SRI.Seed quality was superior in SRI as compared to CT.Integrated nutrient management (INM) resulted in higher plant height with longer leaves than chemical fertilizer alone in both the rice varieties.Grain yield attributes such as number of effective tillers per hill,panicle length and panicle weight of rice in both the varieties were significantly higher in INM as compared to chemical fertilizer alone.Grain yields of both the varieties were the highest in INM followed by the recommended doses of chemical fertilizer.The grain yield and its attributes of Pusa 44 were significantly higher than those of Pusa Basmati 1.The seed quality parameters like germination rate and vigor index as well as N uptake and soil organic carbon content were higher in INM than those in chemical fertilizer alone.CT rice used higher amount of water than SRI,with water saving of 37.6% to 34.5% in SRI.Significantly higher water productivity was recorded in SRI as compared to CT rice.  相似文献   

13.
This study was carried out to explore the possibility of making cement-bonded wood-wool composite building products using eucalypt (Eucalyptus camaldulensis) and poplar (Populus deltoides). The experimental design consisted of three treatments - ratio of wood-wool mixture, percentage concentration of cement, and calcium chloride (CaCl2). The mechanical properties in terms of modulus of rupture (MOR), modulus of elasticity (MOE) and internal bond (IB) strength were investigated. The ratios of wood-wool to cement were 40:60 and 60:40 by weight. The addition of the woody material to cement clearly reduced the maximum hydration temperature and increased the time to maximum temperature. Eucalypt was generally less compatible with cement than poplar wood. Test results showed that boards made with poplar wood-wools had superior properties compared to the eucalypt and mixed wood-wools. The presence of eucalypt in mixture of woody materials typically resulted in decrease in mechanical properties. It has been noted that a dose of 5% of CaCl2 by weight of cement can enhance the effect of cement. Application of Duncan's Multiple Range Test for the mean values of the results showed that the effects of all variables and their interactions on the mechanical properties in terms of MOR, MOE and IB were highly significant (p ≤ 0.01%). The mechanical properties of most produced boards were found to satisfy the minimum requirements of ISO standard.  相似文献   

14.
In order to investigate the intra-specific variation of wheat grain quality response to elevated atmospheric CO2 concentration (e[CO2]), eight wheat (Triticum aestivum L.)cultivars were grown at two CO2 concentrations ([CO2]) (current atmospheric, 389 CO2 μmol mol−1vs. e[CO2], FACE (Free-Air CO2 Enrichment), 550  ±  10% CO2 μmol mol−1), at two water levels (rain-fed vs. irrigated) and at two times of sowing (TOS1, vs. TOS2). The TOS treatment was mainly imposed to understand whether e[CO2] could modify the effects of timing of higher grain filling temperatures on grain quality. When plants were grown at TOS1, TKW (thousand kernel weight), grain test weight, hardness index, P, Ca, Na and phytate were not significantly changed under e[CO2]. On the other hand, e[CO2] increased TKW (16%), hardness index (9%), kernel diameter (6%), test weight (2%) but decreased grain protein (10%) and grain phytate (11%) at TOS2. In regard to grain Zn, Mn and Cu concentrations and some flour rheological properties, cultivar specific responses to e[CO2] were observed at both sowing times. Observed genetic variability in response to e[CO2] in terms of grain minerals and flour rheological properties could be easily incorporated into future wheat breeding programs to enable adaptation to climate change.  相似文献   

15.
Polypropylene/polystyrene blends with different viscosity ratios, p, ranging from 1.6×10?2 to 10.8, were prepared by using textile-grade isotactic polypropylene (iPP) and five kinds of atactic polystyrene (aPS), named PS1, PS2, PS3, PS31 and PS46 with different molecular weight, and then melt-spun into composite fibers with matrix-fibril morphology at different take-up velocities, v L , ranging from 125 to 1000 m/min. The effects of p on the diameters and quantities of dispersed droplets in extrudate fibers, and the effects of p and v L on the size and quantities of fibrils in take-up fibers were discussed, respectively. Based on a quantitatively characterization for the coalescence and deformation of droplets during melt spinning, a theoretical analysis based on Newtonian fluids simplification and the deformation theory was presented to predict the deformation and breakup of droplets during melt spinning. It is found that there is a good fit between theoretical and observed experimental results at most discussed take-up velocities. Furthermore, the uncertainties of Newtonian fluids simplification and a hypothesis of local energy dissipation from migration and coalescence were noted to explain the deviations between predicted and experimental data.  相似文献   

16.
To study the radiation utilization efficiency, latent heat flux, and simulate growth of rice during post-flood period in eastern coast of India, on-farm trial was conducted with three water regimes in main plots (W 1 = continuous flooding of 5 cm, W 2 = irrigation after 2 days of water disappearance, and W 3 = irrigation after 5 days of water disappearance) and five nitrogen levels in subplots (N 1 = 0 kg N ha?1, N 2 = 60 kg N ha?1, N 3 = 90 kg N ha?1, N 4 = 120 kg N ha?1, and N 5 = 150 kg N ha?1) on a rice cultivar, ‘Lalat’. Average maximum radiation utilization efficiency (RUE) in terms of above ground dry biomass of 2.09 (±0.05), 2.10 (±0.02), and 1.9 (±0.08) g MJ?1 were computed under W 1, W 2, and W 3, respectively. Nitrogen increased the RUE significantly, mean RUE values were computed as 1.60 (±0.07), 1.78 (±0.02), 2.060 (±0.08), 2.30 (±0.07), and 2.34 (±0.08) g MJ?1 when the crop was grown with 0, 60, 90, 120, and 150 kg ha?1 nitrogen, respectively. Midday average latent heat flux (on clear days) varied from 7.4 to 14.9 and 8 to 13.6 MJ m?2 day?1 under W 2 and W 3 treatments, respectively, at different growth stages of the crop in different seasons. The DSSAT 4.5 model was used to simulate phenology, growth, and yield which predicted fairly well under higher dose of nitrogen (90 kg and above), but the model performance was found to be poor under low-nitrogen dose.  相似文献   

17.
The Formosan subterranean termite, Coptotermes formosanus Shiraki, is among the most devastating termite pests. Natural products derived from plant extracts were tested in a discovery programme for effective, environment friendly termite control agents. Screening for anti-termitic activity of plant extracts with some known medicinal attributes could lead to the discovery of new agents for termite control. The aim of this study was to investigate the anti-termitic activity of crude leaf hexane, ethyl acetate, acetone and methanol extracts of Andrographis lineata Wallich ex Nees. (Acanthaceae), Andrographis paniculata (Burm.f.) Wall. ex Nees. (Acanthaceae), Argemone mexicana L. (Papaveraceae), Aristolochia bracteolata Lam. (Aristolochiaceae), Datura metel L. (Solanaceae), Eclipta prostrata L. (Asteraceae), Sesbania grandiflora (L.) Pers. (Fibaceae) and Tagetes erecta L. (Compositae) against C. formosanus. An impregnated filter paper no-choice bioassay method was followed. All the crude extracts showed anti-termitic activity in a dose-dependent manner and exhibited a significant activity after 24 h and 48 h of exposure; the highest termite mortality was found in leaf hexane extract of A. bracteolata, ethyl acetate extract of A. paniculata, D. metel, E. prostrata, methanol extract of A. lineata and D. metel after 24 h (LD50 = 363, 371, 298, 292, 358 and 317 ppm; LD90 = 1433, 1659, 1308, 1538, 1703 and 1469 ppm), respectively. The hexane extract of T. erecta, acetone extract of A. mexicana, methanol extract of S. grandiflora and T. erecta showed activity after 48 h (LD50 = 245, 253, 289, 409 ppm; LD90 = 1378, 1511, 1508 and 2425 ppm), respectively. Among the natural products tested, may provide a renewable source of safe natural wood preservatives. These findings corroborate traditional insecticidal application of selected plants and the results can be extended for the control of termites. The primary objective of the present study was to identify novel, natural chemotypes from biologically active crude plant extracts that may be useful as part of termite treatment regimens in their natural form or as synthons for structure-activity studies in the future. The results reported here open the possibility of further investigations of efficacy on their anti-termitic properties of natural product extracts.  相似文献   

18.
Environmentally friendly green composites were prepared by conventional blending wheat gluten (WG) as matrix, methylcellulose (MC) microfibers as filler and glycerol as plasticizer followed by compression molding of the mixture at 127 °C to crosslink the matrix. Morphology, dynamic mechanical analysis (DMA), tensile properties (Young’s modulus E, tensile strength σb and elongation at break ?b), and moisture absorption (MA) and weight loss (WL) in water as well as thermogravimetric analysis (TGA) were evaluated in relation to MC content. It was found that addition of MC microfibers can significantly improve E and σb of the composite, which is accompanied by rises in glass transition temperatures of the WG matrix. Influences of MC content on the thermal decomposition and gluten solubility (GS) in water are also discussed.  相似文献   

19.
The potential of an imaging spectroscopy system with high spatial (0·16–1·45 mm2) and spectral resolution (5–13 nm) was explored for monitoring light interception and biomass of grass swards. Thirty‐six Lolium perenne L. mini‐swards were studied for a total of eleven consecutive growth periods. Hyperspectral images and light interception (LI) were recorded twice weekly. On two dates ground cover was scored visually (GCv). At harvest, leaf area index (LAI), fresh‐matter yield and dry‐matter yield (DMY) were determined. Classification of images yielded several estimates of the image ground cover (GCi) and the index of reflection intensity (IRI). The GCi was highly correlated with GCv ( = 0·94), LAI ( = 0·88) and LI ( = 0·95, for dense swards under cloudy skies). However, the relationship between GCi and LI depended on sky conditions and sward structure. Under cloudy skies, LI was linearly related to GCi, whereas under clear skies, this relation was logistic. Regression analysis of GCi and yields showed correlations with of between 0·75 and 0·82. The mean error of DMY estimates was 340 kg. In conclusion, estimates of GCi and IRI can be used to predict DMY, even for high yield levels (up to 3500 kg DM ha?1), allowing accurate, non‐destructive monitoring of biomass and light interception of grass swards.  相似文献   

20.
《Field Crops Research》1987,17(2):141-153
Four species of the C4 genus Amaranthus, A. cruentus, A. caudatus, A. hypochondriacus and A. hybridus, were grown at Salt Lake City, Utah for the determination of gas exchange characteristics of recently matured leaves.The response of CO2 assimilation to leaf temperature, measured at high quantum flux, was very similar in all species, each exhibiting a temperature optimum of approximately 37°C. Above about 40°C, all species showed high temperature inhibition, manifested as an irrversible time-dependent decline in CO2 assimilation.All four exhibited high rates of net CO2 assimilation exceeding 40 μmol m−2 s−1 at quantum fluxes of 2.0 mmol m−2 s−1, but none was completely light-saturated at such intensities. Leaf conductance to water vapor declined with decreasing quantum flux in all species, but less rapidly than assimilation, resulting in increasing values of internal CO2 concentration (ci). Quantum yield values in three species (x=0.048±0.003 mol(CO2/mol(photons))) were similar to those reported previously for NAD-malic enzyme type C4 dicots, but leaves of A. hybridus, which were deep purple in color, exhibited a lower quantum yield, presumably due to light absorption by betacyanin pigments not involved in photosynthesis.All four species had net photosynthesis versus ci responses typical of C4 species, with a steep initial linear response to ci followed by a fairly abrupt transition to saturation in the region of 100–150 μl l−1. Under near-optimal measurement conditions and high quantum flux, all species maintained ci values close to the region at which saturation was reached (x=148±17 μl l−1).Data pooled acrossspecies relating net photosynthesis measured at 2.0 mmol m−2 s−1 quantum flux and 35°C to Kjeldahl nitrogen content revealed a linear relationship, the slope of which was not significantly different (P=0.05) from those reported in two otudies employing C4 species.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号