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991.
A mixture neural methodology for computing rice consumptive water requirements in Fada N’Gourma Region, Eastern Burkina Faso 总被引:1,自引:1,他引:1
Seydou Traore Yu-Min Wang Chun-E. Kan Tienfuan Kerh Jan Mou Leu 《Paddy and Water Environment》2010,8(2):165-173
Crop consumptive water requirement (Crop-ET) is a key variable for developing management plans to optimize the efficiency
of water use for crop production particularly in semiarid zone. In Burkina Faso, the unfavorable climatic conditions characterized
by the low and unevenly distribution of rainfall have pushed water resources management to the forefront of the crop production
issue. Crop-ET is extremely required in rainwater effective management for mitigating the impact of water deficit on the crops.
Basically, Crop-ET determination involves reference evapotranspiration (ETo) and crop coefficient (Kc) which required complete
climatic data and specific site crop information, respectively. ETo estimation with the recommended FAO56 Penman–Monteith
(PM) equation is limited in Burkina Faso due to the numerous meteorological data required which are not always available in
many production sites. In such circumstances, research to compute directly Crop-ET as an alternative to the two-step approach
of calculating ETo and determining site specific Kc, seems desirable. Therefore, this study aims to evaluate the performance
of a mixture principal component analysis neural network (PCANN) model for computing rice Crop-ET directly from temperatures
data in Fada N’Gourma region located in Eastern Burkina Faso, Africa. From the statistical results, rice Crop-ET can be successfully
computed by using PCANN methodology, when only temperatures data are available in this African semiarid environment. Thus,
in poor data situation, Crop-ET direct computation can be rapidly addressed through PCANN model for agricultural water management
in African semiarid regions. 相似文献
992.
Maria Teresa Melillo Paola Leonetti Antonella Leone Pasqua Veronico Teresa Bleve-Zacheo 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(4):489-502
Nitric oxide (NO) has been shown to be an essential regulatory molecule in plant response to pathogen infection in synergy
with reactive oxygen species (ROS). At the present, nothing is known about the role of NO in disease resistance to nematode
infection. We used a resistant tomato cultivar with different sensitivity to avirulent and virulent populations of the root-knot
nematode Meloidogyne incognita to investigate the key components involved in oxidative and nitrosative metabolism. We analyzed the superoxide radical production,
hydrogen peroxide content, and nitric oxide synthase (NOS)-like and nitrate reductase activities, as potential sources of
NO. A rapid NO accumulation and ROS production were found at 12 h after infection in compatible and incompatible tomato-nematode
interactions, whereas the amount of NO and ROS gave different results 24 and 48 h after infection amongst compatible and incompatible
interactions. NOS-like arginine-dependent enzyme rather than nitrate reductase was the main source of NO production, and NOS-like
activity increased substantially in the incompatible interaction. We can envisage a functional overlap of both NO and ROS
in tomato defence response to nematode invasion, NO and H2O2 cooperating in triggering hypersensitive cell death. Therefore, NO and ROS are key molecules which may help to orchestrate
events following nematode challenge, and which may influence the host cellular metabolism. 相似文献
993.
Maria Pukalchik Maria Panova Mikhail Karpukhin Olga Yakimenko Kamila Kydralieva Vera Terekhova 《Journal of Soils and Sediments》2018,18(3):750-761
Purpose
Heavy metal contamination is a priority issue affecting millions of hectares of soil throughout the world. One of the most promising, environmentally friendly, and cost-effective approaches to restore polluted soils could be applying organic amendments. We investigated the remediation potential of three types of humic products with regard to their effect on the bioavailability of Pb and Zn, content of nutrients, and the ability to mitigate acute phytotoxicity in contaminated soil.Materials and methods
Spodosol samples were spiked with Pb (550 mg kg?1) and Zn (880 mg kg?1). Then, two different commercial humic products (from peat and lignosulfonate) and natural humic acids (from brown oxidized coal) were added in two doses to reach an equal content of carbon: a 10% increment and a 30% increment of the initial total organic carbon in the soil. After 30 days, the content of metals and nutrients (S, K, Na, Ca, Mn, P) was determined by the sequential extraction (i?H2O, ii?NH4COOH pH 4.8, iii–CH3COOH). The effect of humic products on heavy metals bioavailability was evaluated using the calculated partition indexes. Seed germination and root elongation of Sinapis alba were also determined. Chemical and biochemical variables were aggregated by the principal component analysis.Results and discussion
Humic products reduced the amount of bioavailable fractions of Pb and Zn in soils. The partition index, which quantitatively describes bioavailable fractions of the Zn and Pb in the soil, was 28–49% lower than in the spiked (Pb+Zn) control. The inhibition of root elongation and seed germination of mustard by Zn and Pb was significantly mitigated by humic products; in the soil test, the root length and seed germination were up to 36–87% higher than those of the Pb+Zn control and did not differ from those in the non-amended treatments. This effect may have been associated with the structural differences (H/C and O/C ratio) and content of nutrients (Na and K) in humic products.Conclusions
Commercial humic products used in poor multi-contaminated soils can maintain plant growth by improving nutrient status due to heavy metals immobilization and can be a promising approach to remediate the soil contaminated with heavy metals at extremely high concentrations.994.
Eight genomic SSR markers with a M13 tail attached were used to assess the genetic diversity of 72 Ussurian Pear accessions
(Pyrus ussuriensis Maxim.) in China. The M13-tailed method was effective in discriminating all the 32 wild accessions. All the 40 Ussurian Pear
cultivars could be successfully discriminated with the exception of 4 sets of synonymies or spots. A total of 108 alleles
were obtained with an average of 13.5 per locus. The expected heterozygosity, observed heterozygosity, and power of discrimination
were 0.78, 0.63, and 0.86 respectively. Three triploid cultivars (‘Anli’, ‘Ruan’er’, and ‘Pitaiguo’), and one wild accession,
P. ussuriensis ‘Xilin-3’, showed three alleles at some SSRs. The number of alleles and observed heterozygosity per locus for 40 Ussurian
Pear cultivars were 9.1 and 0.62, respectively, lower than the values of 32 wild accessions which were 11.3 and 0.65, respectively.
A dendrogram based on the SSR genotypes was obtained, showing two major groups corresponding to cultivated group and wild
group. All the cultivars fell into the cultivated group. Some subgroups (Nanguoli subgroup, Zhibazi subgroup, Xiangshuili
subgroup, Balixiang subgroup, Anli subgroup) could be found in the cultivated group. A very close relationship between ‘Huagaili’
and ‘Miansuan’, and a close relationship between ‘Anli’ and a wild accession, P. ussuriensis ‘Huangshanli’ could be found in Anli subgroup. ‘Nanguoli’ and ‘Xiaowuxiang’ showed a close relationship with at least one
identical allele at each locus with the exception of NH015a. 相似文献
995.
Eddy covariance (EC) systems are being used to assess the accuracy of remote sensing methods in mapping surface sensible and
latent heat fluxes and evapotranspiration (ET) from local to regional scales, and in crop coefficient development. Therefore,
the objective was to evaluate the accuracy of EC systems in measuring sensible heat (H) and latent heat (LE) fluxes. For this
purpose, two EC systems were installed near large monolithic weighing lysimeters, on irrigated cotton fields in the Texas
High Plains, during the months of June and July 2008. Sensible and latent heat fluxes were underestimated with an average
error of about 30%. Most of the errors were from nocturnal measurements. Energy balance (EB) closure was 73.2–78.0% for daytime
fluxes. Thus, daylight fluxes were adjusted for lack of EB closure using the Bowen ratio/preservation of energy principle,
which improved the resulting EC heat flux agreement with lysimetric values. Further adjustments to EC-based ET included nighttime
ET (composite) incorporation, and the use of ‘heat flux source area’ (footprint) functions to compensate ET when the footprint
expanded beyond the crop field boundary. As a result, ET values remarkably matched lysimetric ET values, with a ‘mean bias
error ± root mean square error’ of −0.03 ± 0.5 mm day−1 (or −0.6 ± 10.2%). 相似文献
996.
Siamak Rahmanpour David Backhouse Heather M. Nonhebel 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(4):429-433
The glucosinolate-myrosinase defence system, specific to Brassicales plants, produces toxic volatile compounds during mechanical
injury or pathogen attack. The reaction of this system to oxalic acid, known as a pathogenicity factor of Sclerotinia sclerotiorum, is not fully understood. The hydrolysis of glucosinolates was studied at varying conditions in the presence of oxalic acid
in the substrate. In a bioassay, colonies of the pathogen were exposed to volatiles from hydrated mustard powder used as a
myrosinase and glucosinolate source. The glucosinolate-myrosinase (GSL-M) system was activated in the presence of oxalic acid
at a concentration and pH similar to that expected in vivo. Volatile production was inhibited only when the pH fell to 3 or below. It is unlikely that oxalic acid plays a significant
role in disarming the GSL-M system during infection of Brassica hosts. 相似文献
997.
Quantitative trait loci for phytate in rice grain and their relationship with grain micronutrient content 总被引:6,自引:0,他引:6
James C. R. Stangoulis Bao-Lam Huynh Ross M. Welch Eun-Young Choi Robin D. Graham 《Euphytica》2007,154(3):289-294
Phytate (inositol-hexa-phosphate) has an important role in plants but it also may have anti-nutritional properties in animals
and humans. While there is debate within the plant breeding and nutrition communities regarding an optimum level in grain,
there appears to be little information at the molecular level for the genetics of this trait, and its association with important
trace elements, in particular, Fe and Zn. In this preliminary study, quantitative trait loci (QTL) for grain phytates, Zn
and Fe in glasshouse-grown rice lines from an IR64 × Azucena doubled haploid population were identified. Correlations between
phytate and essential nutrients were also studied. Transgressive segregation was found for most traits. Phytate and total
P concentrations had one QTL in common located on chromosome five with the (high concentration) allele contributed from Azucena.
There were significant positive correlations between phytate and inorganic phosphorus (P), total P, Fe, Zn, Cu and Mn concentrations
for both grain concentration and content. However, the QTLs of phytate were not located on the same chromosomal regions as
those found for Fe, Zn and Mn, suggesting that they were genetically different and thus using molecular markers in breeding
and selection would modify the phytate level without affecting grain micronutrient density. 相似文献
998.
The root parameters of forest trees can be indicators of a changing environment. We summarize the results of root studies
with regard to the effects of acidifying pollutants, especially soil acidification and aluminum toxicity, on various root
parameters of Japanese forest trees under experimentally controlled conditions. All root parameters such as biomass, morphology,
nutritional status, and physiology can be regarded as indicators, because, under laboratory conditions, root responses occur
prior to the responses in the aboveground parts. However, considering the conditions of forest sites, the nutritional status
and physiological changes are better indicators of soil acidification and Al stress than the biomass and morphological response.
The currently available data suggest that the most important indicator is the Ca/Al molar ratio in roots of Japanese tree
species. In order to predict and detect the initial effects of soil acidification, we postulate that the specific root response
to the Ca/Al molar ratio of tree roots should be considered as a parameter for use in long-term forest monitoring sites. 相似文献
999.
Helge Sierotzki Sandro Parisi Ute Steinfeld Isabel Tenzer Sylvie Poirey Ulrich Gisi 《Pest management science》2000,56(10):833-841
Field isolates of Mycosphaerella fijiensis, causing black Sigatoka of banana, were characterised for their sensitivity to different inhibitors of the cytochrome bc1 enzyme complex (Qo respiration inhibitors, strobilurin fungicides), using physiological, biochemical and molecular genetic methods. Strobilurin‐resistant isolates exhibited very high resistance factors both in mycelial growth inhibition and NADH consumption assays. Cross‐resistance was observed among all Qo inhibitors, including trifloxystrobin, azoxystrobin, famoxadone, strobilurin B and myxothiazol. However, the Qi and the cytochrome aa3 inhibitors, antimycin A and potassium cyanide, respectively, were not cross‐resistant to Qo inhibitors. In sensitive but not in resistant isolates, mixtures of Qo inhibitors and SHAM, an inhibitor of the alternative oxidase (AOX), were more active than the components alone, indicating that the alternative pathway is essential in metabolism, but not causal for resistance. In the cell‐free NADH‐consumption assay, the Qo inhibitors affected the sensitive but not the resistant isolates, suggesting that AOX was not active in sub‐mitochondrial particles. In whole cells, however, the AOX has a basic expression level and is probably not inducible by trifloxystrobin. Sequencing of the cytochrome b gene of sensitive and resistant M fijiensis isolates revealed a difference in the nucleotide sequence leading to a single amino acid change from glycine to alanine at position 143 in the resistant isolate. This change is known to occur also in the naturally tolerant basidiomycete Mycena galopoda. It is suggested that the field isolates of M fijiensis can acquire resistance to Qo inhibitors due to a target site alteration with a single base pair change. Resistant isolates do not seem to contain a mixture of mutated and non‐mutated DNA, indicating a complete selection of resistant mitochondria and a maternally donated mode of resistance. © 2000 Society of Chemical Industry 相似文献
1000.
Jennifer A. Kimball Tan D. Tuong Consuelo Arellano David P. Livingston III Susana R. Milla-Lewis 《Euphytica》2017,213(5):110
Winter hardiness is a major-limiting factor for St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] grown in the transitional climatic region of the United States. Lab-based freeze tests that mimic the range of field winter survivability in St. Augustinegrass can contribute to the selection of cold hardy genotypes. This study used a whole container method, four freezing temperatures, and two data collection systems to evaluate the freezing response of nine St. Augustinegrass genotypes ranging in their winter hardiness. Results indicated ?3 and ?4 °C with average regrowth ratings of 33.6 and 17.8% respectively, were more suitable temperatures for evaluating freeze survival in St. Augustinegrass than ?5 and ?6 °C with average regrowth ratings of 0.4 and 0%, respectively. Visual ratings of surviving green tissue and regrowth were generally well correlated when evaluated over a six week period post-freeze with Pearson correlation coefficients ranging of 0.17–0.62 for ?3 °C freeze tests and 0.79–0.93 for ?4 °C freeze tests. Additionally, measurement of percent green cover using digital imaging techniques commonly utilized in turfgrass field studies were significantly correlated (0.66) with visual ratings averaged across weekly post-freeze evaluation measurements for both ?3 and ?4 °C freezing temperatures. These results provide evidence that digital imaging analyses are useful in estimating surviving green tissue and regrowth in lab-based freeze tests. This study provides additional information regarding freezing temperatures, genotype responses, and data collection methods in St. Augustinegrass, which should aid breeders in the improvement of freeze tolerance in the species. 相似文献