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161.
Tyler W. Rider Jeffrey W. Vogel J. Anita Dille Kevin C. Dhuyvetter Terry L. Kastens 《Precision Agriculture》2006,7(6):379-392
The objective of this study was to determine if site-specific application of postemergence herbicide was economically viable with current technologies. This objective was accomplished by: developing an algorithm that determined the economic optimal postemergence herbicide rate; creating models to determine the impact that postemergence herbicide rate has on yield; and determining whether site-specific application of postemergence herbicide has greater net returns than those from a uniform application of postemergence herbicide. Weed species identification and population counts were done on a regular grid in five fields across Kansas. A decision algorithm was developed to determine the economic optimal rate of postemergence herbicide for each grid cell. The site-specific herbicide rate and four standard herbicide rates [0, 0.5, 0.75, and full (1×) label rate] were applied according to a split-plot design. Weed population observations made three weeks after application showed that the site-specific treatment controlled the weeds present in the fields. Production functions developed to determine whether postemergence herbicide rate had an impact on yield showed that it had a positive, yet statistically insignificant, effect on yield. The difference in estimated net returns between applications of site-specific rate and uniform full-label rate covered all of the costs associated with site-specific application of postemergence herbicide. The margin between the estimated net returns for site-specific and uniform application of the economic optimal rate covered only a portion of the costs associated with site-specific application of postemergence herbicide. 相似文献
162.
Changes in the fresh and dry weight of leaf blades, petioles, internodes, and their ion concentrations as well as rates of root exudation were investigated in cucumber grown in hydroponic culture and treated with physiological concentrations of lead (Pb). The growth of flowering cucumber supplied with FeCl3 shows a typical bell‐shaped curve derived from leaf dry weights, where the 4th, 5th, and 6th leaves are the largest ones. Lead inhibited growth up to 20% (except the youngest leaves which were stimulated), but did not cause morphological changes. Whereas root growth was also retarded by about 20%, exudation was inhibited to 50%, that is, the root resistance to water transport was increased by Pb. In spite of that the dry matter yield of internodes and petioles hardly reached 10 and 5% of that of leaf blades, respectively, their calcium (Ca), magnesium (Mg), and zinc (Zn) concentrations were almost the same. Similarly, the concentrations of these metals in the specific leaf blades are equal despite their different growth characteristics but the concentration of Mn is independent of the growth of the examined tissues. Lead was the only cation to accumulate in the largest leaves. The inhibitory effect of Pb on ion uptake was proportional to the growth inhibition of the tissues except manganese (Mn), the accumulation of which was stimulated by Pb in all the analyzed tissues and copper (Cu) which increased only in the internodes. We could not explain the extremely different ion distributions observed during the growth of cucumber. However, it is evident that the measurement of ion concentrations at whole shoot level is not enough to characterize ion interactions because only some ions accumulate at the same rate as tissues grow. These ions maintain stable concentration levels in shoot parts whereas others decrease or increase independently from growth. 相似文献
163.
Pelegrino Marcelo Henrique Procópio Silva Sérgio Henrique Godinho de Faria Álvaro José Gomes Mancini Marcelo Teixeira Anita Fernanda dos Santos Chakraborty Somsubhra Weindorf David C. Guilherme Luiz Roberto Guimarães Curi Nilton 《Precision Agriculture》2022,23(1):18-34
Precision Agriculture - Precision agriculture provides detailed information on the spatial variability of soil properties, including nutrient content, allowing for local-specific decision making.... 相似文献
164.
Effects of intraspecific competition on yield of early potato grown in mediterranean environment 总被引:1,自引:0,他引:1
Giovanni Mauromicale Paolo Signorelli Anita Ierna Salvatore Foti 《American Journal of Potato Research》2003,80(4):281-288
Since the environment of the Mediterranean regions allows offseason production, potatoes are planted in autumn-winter and harvested in spring. During this period, potatoes are subjected to low temperatures and short day lengths which modify the growth characteristics of plants. For this reason, our analysis of competition response was conducted to better clarify the biological relationship between yield and plant density. Field trials were conducted in Sicily (south Italy), a highly representative area of early potato crop in the Mediterranean Basin, with the aim of studying effects of intraspecific competition on tuber yield and yield components. Ten planting densities (ranging from 3.0 to 8.0 plants m?2) were studied on cv. Spunta using “tuberpieces” with a different number of eyes (one eye or all the eyes in 1996; one eye, two eyes, or all the eyes in 1997). Intraspecific competition reduced the tuber yield of individual plants, which became gradually less evident with increasing plant density. Competition affected the number of tubers per plant in the lower plant populations only (from 3.0 to 5.8 plants m?2), whereas effects on average tuber weight were at times more marked in the higher populations (from 5.8 to 8.0 plants m?2) and at other times in the lower densities (from 3.0 to 5.8 plants m?2). As a consequence of increased plant density, and notwithstanding the higher intraspecific competition, the yield of tubers per unit area increased linearly. Regardless of the number of eyes per tuber-piece, when passing from the lower to the higher plant density, yield increased from 34.0 to 54.11 ha?1 in 1996 and from 39.9 to 56.7 t ha?1 in 1997. 相似文献
165.
Anita E. Swanepoel 《Potato Research》1990,33(2):287-290
Summary Potato plants, after inoculation with a South African strain of biovar 2 or a strain of biovar 3 ofPseudomonas solanacearum were grown in growth chambers at temperatures ranging from 14/16°C (dark/light) up to 25/30°C. When grown at 14/16°C or higher,
plants inoculated with the biovar 2 strain developed wilting symptoms and internal symptoms on progeny tubers and the disease
was transmitted by the progeny tubers. When the plants were inoculated with the biovar 3 strain, wilting symptoms developed
from 18/20°C, internal symptoms on progeny tubers from 20/22°C and the disease was transmitted by progeny tubers from plants
grown at 16/18°C or higher. 相似文献
166.
Summary Induced systemic resistance to late blight was found in the potato cultivar Bintje which has no major or minor resistance
genes to late blight. The prerequisite was a local inoculation with 5×103 zoospores/mo, ofPhytophthora infestans race 1, 3, 4, 7, 8, a local inoculation with 2×103 zoospores/ml ofPhytophthora cryptogea isolated from wheat or local treatment with 50–100 mM solution of K2HPO4. Potato plants used in the experiments were propagated in vitro from nodal cuttings. Protection caused by the different inductions
was 30 to 70% (assessed as a reduced number of lesions/plant and reduced necrotic tissue/leaf or plant) and tended to positively
influence yield and dry matter of the haulm. The induced protection in the potato plant was better in young developing leaves
than in fully expanded leaves. 相似文献
167.
Kanika Miglani Sunil Kumar Anita Yadav Neeraj Aggarwal Ranjan Gupta 《Iranian Biomedical Journal》2021,25(1):47
Background:Single nucleotide polymorphisms in OGG1 gene modulates DNA repair capacity and functions as one of the first lines of protective mechanisms against 8-OHdG mutagenicity. OGG1-Cys326 gene polymorphism may decrease DNA repair function, causing oxidative stress due to higher oxidative DNA damage. The main purpose of this study was to examine the link of oxidative and genotoxic DNA damage with DNA repair OGG1 gene polymorphism, in charcoal workers exposed to polyaromatic hydrocarbons. Methods:Urinary 8-OHdG excretion (a biomarker of oxidative DNA damage) was determined in both exposed and control populations. Genotyping of OGG1 DNA repair gene in the blood samples of subjects was carried out by PCR-RFLP method. Results:The 8-OHdG urinary concentration was significantly higher (p < 0.05) in the exposed (geometric mean 12.33 ± 3.78) than in the unexposed (geometric mean 7.36 ± 2.29) population. DNA damage, as measured by 8-OHdG and TM content, was found to be significantly higher in OGG1 homozygous mutants (mt/mt; 18.81 ± 3.34; 6.04 ± 0.52) as compared to wild-type genotypes (wt/wt; 10.34 ± 2.25; 5.19 ± 2.50) and heterozygous (wt/mt) mutants (12.82 ± 2.81; 6.04 ± 0.93) in the exposed group. Conclusion:We found a significant association of OGG1 heterozygous (wt/mt) and homozygous (mt/mt) variants with oxidative and genotoxic damage, suggesting that these polymorphisms may modulate the effects of PAH exposure in occupational workers. Key Words: 8-hydroxy-2’-deoxyguanosine, 1-hydroxypyrene, Polycyclic aromatic hydrocarbons 相似文献
168.
Mansson M Nielsen A Kjærulff L Gotfredsen CH Wietz M Ingmer H Gram L Larsen TO 《Marine drugs》2011,9(12):2537-2552
During a global research expedition, more than five hundred marine bacterial strains capable of inhibiting the growth of pathogenic bacteria were collected. The purpose of the present study was to determine if these marine bacteria are also a source of compounds that interfere with the agr quorum sensing system that controls virulence gene expression in Staphylococcus aureus. Using a gene reporter fusion bioassay, we recorded agr interference as enhanced expression of spa, encoding Protein A, concomitantly with reduced expression of hla, encoding α-hemolysin, and rnaIII encoding RNAIII, the effector molecule of agr. A marine Photobacterium produced compounds interfering with agr in S. aureus strain 8325-4, and bioassay-guided fractionation of crude extracts led to the isolation of two novel cyclodepsipeptides, designated solonamide A and B. Northern blot analysis confirmed the agr interfering activity of pure solonamides in both S. aureus strain 8325-4 and the highly virulent, community-acquired strain USA300 (CA-MRSA). To our knowledge, this is the first report of inhibitors of the agr system by a marine bacterium. 相似文献
169.
Anita Kataria B. M. Chauhan 《Plant foods for human nutrition (Dordrecht, Netherlands)》1988,38(1):51-59
Effects of common processing and cooking methods on sugar and starch contents and starch digestibility (in vitro) of mung bean (Vigna radiata L.) were investigated. Soaking reduced the level of total soluble sugars, reducing sugars, non-reducing sugars and starch and improved starch digestibility, significantly. Cooking (both ordinary and pressure cooking) increased the concentrations of the sugars and digestibility of starch of soaked as well a unsoaked seeds. Starch contents, however, were decreased. Germination decreased starch thereby raising the level of the soluble sugars. Starch digetibility was increased appreciably. 相似文献
170.
Bartosz WOJCIECHOWICZ Genowefa KOTWICA Justyna KOLAKOWSKA Anita FRANCZAK 《The Journal of reproduction and development》2013,59(1):49-58
Steroid hormones are produced by the porcine uterus. We hypothesized that the uterus in
pigs possesses active 3β-hydroxysteroid dehydrogenase/Δ5-Δ4
isomerase (3β-HSD) responsible for progesterone and androstenedione production, that
uterine steroids may supplement the amount of steroid hormones produced by embryos and
corpus luteum and that these steroids are necessary for maintenance of pregnancy. In this
study, we examined 1) endometrial and myometrial expression of 3β-HSD
mRNA, 2) uterine 3β-HSD protein activity and 3) in vitro production of
A4 and P4 by uterine slices harvested from pigs on days 10 to 11,
12 to 13 and 15 to 16 of pregnancy and the estrous cycle. The expression of
3β-HSD and the presence and activity of 3β-HSD protein were different
in the endometrium and the myometrium during the examined periods of pregnancy and the
estrous cycle. Production of A4 by the endometrium and myometrium was highest
on days 12 to 13 of pregnancy and the estrous cycle. Endometrial secretion of
P4 did not differ in the course of early pregnancy and on the respective days
of the estrous cycle. The gravid myometrium was the highest source of P4 in
pregnant pigs on days 12 to 13. The release of P4 by the cyclic myometrium rose
during the examined days of the estrous cycle. The steroidogenic activity of the uterus,
as described in this study, may support early pregnancy or the luteal phase of the estrous
cycle in pigs. 相似文献