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排序方式: 共有60条查询结果,搜索用时 15 毫秒
1.
Photosynthesis and transpiration of monterey pine seedlings as a function of soil water suction and soil temperature 总被引:4,自引:0,他引:4
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Rates of photosynthesis, respiration, and transpiration of Monterey pine (Pinus radiata D. Don) were measured under controlled conditions of soil water suction and soil temperature. Air temperature, relative humidity, light intensity, and air movement were maintained constant. Rates of net photosynthesis, respiration, and transpiration decreased with increasing soil water suction. The decrease in the rates of net photosynthesis and transpiration as a function of the soil temperature at low soil water suctions may be attributed to changes in the viscosity of water. At soil water suctions larger than 0.70 bars rates of transpiration and net photosynthesis may be affected in the same proportion by changes in stomatal apertures. 相似文献
2.
Summary A series of factoral experiments involving the effects of gravel concentration in the subsoil horizon, the effect of inter-gravel
bulk density, the depth of the surface soil above the gravel horizon and the interaction between soil moisture regime and
gravel concentration, on growth and development of maize roots were conducted in the greenhouse. Increasing sub soil gravel
concentration decreased the total porosity and the available waterholding capacity. Though the root growth of maize seedlings
was adversely affected by gravel concentration above 20 per cent, lower concentration of gravels had a beneficial effect on
roots. The root development and the leaf concentration of N, P and K improved with increasing depth of surface soil above
the gravel horizon. The symptoms of mechanical impedance, such as thickening of root tips and profuse branching behind the
tip were commonly observed on the root axis penetrating the gravelly horizon. re]19750916 相似文献
3.
E-cadherin expression during the differentiation of human trophoblasts 总被引:14,自引:0,他引:14
C Coutifaris L C Kao H M Sehdev U Chin G O Babalola O W Blaschuk J F Strauss 《Development (Cambridge, England)》1991,113(3):767-777
4.
The effects of three levels of moisture under greenhouse conditions and also identical moisture levels under field conditions, on the growth yield and water relations of two tomato cultivars, Fireball and Ife I, were investigated. The objective was to ascertain the drought susceptibility of these two tomato cultivars. The cultivar, Ife I, was more drought susceptible than Fireball and the drought susceptibility increased with the level of soil water stress. The drought tolerance, of Fireball is attributed to a lower leaf area, better root system development in terms of average root length and rooting depth, and a higher leaf water potential. The higher leaf stomatal resistances of Fireball variety suggest an inbuilt mechanism to regulate water vapour flow in times of stress. 相似文献
5.
Mark C. Derbyshire Toby E. Newman Yuphin Khentry Akeem Owolabi Taiwo 《Molecular Plant Pathology》2022,23(8):1075-1090
Sclerotinia sclerotiorum is a pathogenic fungus that infects hundreds of plant species, including many of the world's most important crops. Key features of S. sclerotiorum include its extraordinary host range, preference for dicotyledonous plants, relatively slow evolution, and production of protein effectors that are active in multiple host species. Plant resistance to this pathogen is highly complex, typically involving numerous polymorphisms with infinitesimally small effects, which makes resistance breeding a major challenge. Due to its economic significance, S. sclerotiorum has been subjected to a large amount of molecular and evolutionary research. In this updated pathogen profile, we review the evolutionary and molecular features of S. sclerotiorum and discuss avenues for future research into this important species. 相似文献
6.
Beneficial bacteria of agricultural importance 总被引:5,自引:0,他引:5
Olubukola Oluranti Babalola 《Biotechnology letters》2010,32(11):1559-1570
The rhizosphere is the soil–plant root interphase and in practice consists of the soil adhering to the root besides the loose
soil surrounding it. Plant growth-promoting rhizobacteria (PGPR) are potential agents for the biological control of plant
pathogens. A biocontrol strain should be able to protect the host plant from pathogens and fulfill the requirement for strong
colonization. Numerous compounds that are toxic to pathogens, such as HCN, phenazines, pyrrolnitrin, and pyoluteorin as well
as, other enzymes, antibiotics, metabolites and phytohormones are the means by which PGPR act, just as quorum sensing and
chemotaxis which are vital for rhizosphere competence and colonization. The presence of root exudates has a pronounced effect
on the rhizosphere where they serve as an energy source, promoting growth and influencing the root system for the rhizobacteria.
In certain instances they have products that inhibit the growth of soil-borne pathogens to the advantage of the plant root.
A major source of concern is reproducibility in the field due to the complex interaction between the plant (plant species),
microbe and the environment (soil fertility and moisture, day length, light intensity, length of growing season, and temperature).
This review listed most of the documented PGPR genera and discussed their exploitation. 相似文献
7.
Anetor JI Ajose OA Adebiyi JA Akingbola TS Iyanda AA Ebesunu MO Babalola OO Aadeniyi FA 《Biological trace element research》2007,116(1):43-51
The relationship between blood lead (Pb) and serum levels of calcium and of neural nutrients such as thiamine and magnesium (Mg) has been determined in a Nigerian population that is occupationally exposed to Pb. Forty-seven male Pb workers were recruited as test subjects and 25 males unexposed to Pb served as controls. The test subjects were classified into three groups, based on severity of exposure to Pb. Blood lead (BPb) and the serum levels of Mg, thiamine, and calcium were determined in both test subjects and controls. The mean blood Pb level was not significantly higher in Pb workers. In contrast, Mg and thiamine levels were significantly decreased (p<0.05; p<0.01, respectively). However, the calcium level was not significantly lower in test subjects than in controls. Also, there was a significant negative correlation between serum thiamine and blood Pb levels (r=-0.50; p<0.01). Furthermore, there was a significant negative correlation between serum calcium and BPb levels (r=-0.41; p<0.01). This study has shown that relatively low BPb levels can enhance Pb absorption and also potentiate Pb neurotoxicity in the presence of decreased serum thiamine and Mg levels. 相似文献
8.
Olubukola O. Babalola Abiodun I. Sanni George D. Odhiambo Baldwyn Torto 《World journal of microbiology & biotechnology》2007,23(6):747-752
Summary The use of trap crops such as cowpea could reduce the effects of the root parasitic weed, Striga hermonthica and its subsequent constraints on the growth of cereals. Certain bacteria could augment the trap crop stimulatory effect.
We studied the effect of three bacteria introduced to the rhizosphere of three cowpea varieties at planting. Number of days
to cowpea flowering was noted and at harvest, data were collected on pod characteristics and biomass. Means of data subjected
to ANOVA were compared using Tukey’s Studentized Range Test. We analysed bacterial headspace volatiles for ethylene by gas
chromatography and gas chromatography–mass spectrometry. Bacterial type significantly influenced the cowpea varieties with
better performance over the non-inoculated control. Average pod weight (g) with bacterial treatment was 37.97 for Enterobacter sakazakii 8MR5, 34.38 for Pseudomonas 44MS8 and 27.46 for Pseudomonas 10M3. Non-inoculated control had an average weight of 20.98 g. Bacteria promoted a significant increase in pod weight (≥30.89%),
fresh biomass (≥24.22%), and improved pod number (≥20.54%) and pod wall thickness (≥7.33%) with no deleterious effect on plant
health. Ethylene released by the bacteria ranged from trace concentrations in Pseudomonas sp. to 210 nmoles/108 c. f. u./ml in Ent. sakazakii 8MR5. 相似文献
9.
We demonstrate that 5,5'-dithiobis(2-nitrobenzoate) - DTNB - reacts with only CysF9[93]beta and CysB5[23]beta among the multiple sulfhydryl groups of the major and minor hemoglobins of the Japanese quail (Cortunix cortunix japonica). K(equ), the equilibrium constant for the reaction, does not differ very significantly between the two hemoglobins. It decreases 430-fold between pH approximately 5.6 and pH approximately 9: from a mean of 7+/-1 to a mean of 0.016+/-0.003. Quantitative analyses of the K(equ) data based on published X-ray and temperature-jump evidence for a tertiary structure transition in liganded hemoglobin enable the calculation of K(rt), the equilibrium constant for the r<---->t tertiary structure transition. K(rt) differs significantly between the two hemoglobins: 0.744+/-0.04 for the major, 0.401+/-0.01 for the minor hemoglobin. The mean pK(a)s of the two groups whose ionizations are coupled to the DTNB reaction are about the same as previously reported for mammalian hemoglobins. 相似文献
10.
Soil‐dwelling insect pests of tree crops in Sub‐Saharan Africa,problems and management strategies—A review
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F. C. Ambele H. B. Bisseleua Daghela O. O. Babalola S. Ekesi 《Journal of Applied Entomology》2018,142(6):539-552
This review aims to draw the attention of researchers, ecologists and farmers to the threats of soil‐dwelling insect pests on important tree crops in sub‐Saharan Africa, with a special focus on termites. It synthesizes the information on the effects of various factors affecting soil pest occurrence and damage, suggesting that the resultant undesirable effects of soil pests in this region are largely as a result of indiscriminate tree cutting, slash‐and‐burn agriculture and indiscriminate use of pesticides. Major insect orders, their host ranges and the nature of damage on selected tree crops are described. This study further critiques existing soil pest management practices, showing that majority of soil pest management practices are ineffective. Thus, management strategies like “attract and kill” approach based on entomopathogenic fungi need to be studied, developed and emphasized for the management of soil insect pests in sub‐Saharan Africa. A conclusion section attempts to offer suggestions for ways in which future work on soil pests in sub‐Saharan Africa could proceed. 相似文献