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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.
3.
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
4.
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
5.
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
6.
DANIEL TRAN TAKASHI KADONO MARIA LIA MOLAS RAFIK ERRAKHI JOËL BRIAND BERNADETTE BILIGUI TOMONORI KAWANO FRANÇOIS BOUTEAU 《Plant, cell & environment》2013,36(3):569-578
Ozone (O3) is an air pollutant with an impact increasingly important in our industrialized world. It affects human health and productivity in various crops. We provide the evidences that treatment of Arabidopsis thaliana with O3 results in ascorbate‐derived oxalic acid production. Using cultured cells of A. thaliana as a model, here we further showed that oxalic acid induces activation of anion channels that trigger depolarization of the cell, increase in cytosolic Ca2+ concentration, generation of reactive oxygen species and cell death. We confirmed that O3 reacts with ascorbate in the culture, thus resulting in production of oxalic acid and this could be part of the O3‐induced signalling pathways that trigger programmed cell death. 相似文献
7.
Preliminary estimates of the potential for carbon mitigation in European soils through no-till farming 总被引:9,自引:0,他引:9
PETE. SMITH DAVID S. POWLSON MARGARET J. GLENDINING JO. U. SMITH 《Global Change Biology》1998,4(6):679-685
In this paper we estimate the European potential for carbon mitigation of no-till farming using results from European tillage experiments. Our calculations suggest some potential in terms of (a) reduced agricultural fossil fuel emissions, and (b) increased soil carbon sequestration. We estimate that 100% conversion to no-till farming would be likely to sequester about 23 Tg C y–1 in the European Union or about 43 Tg C y–1 in the wider Europe (excluding the former Soviet Union). In addition, up to 3.2 Tg C y–1 could be saved in agricultural fossil fuel emissions. Compared to estimates of the potential for carbon sequestration of other carbon mitigation options, no-till agriculture shows nearly twice the potential of scenarios whereby soils are amended with organic materials. Our calculations suggest that 100% conversion to no-till agriculture in Europe could mitigate all fossil fuel-carbon emissions from agriculture in Europe. However, this is equivalent to only about 4.1% of total anthropogenic CO2-carbon produced annually in Europe (excluding the former Soviet Union) which in turn is equivalent to about 0.8% of global annual anthropogenic CO2-carbon emissions. 相似文献
8.
ISABELLE DE CAUWER MATHILDE DUFAY JOËL CUGUEN JEAN‐FRANÇOIS ARNAUD 《Molecular ecology》2010,19(8):1540-1558
Plant mating systems are known to influence population genetic structure because pollen and seed dispersal are often spatially restricted. However, the reciprocal outcomes of population structure on the dynamics of polymorphic mating systems have received little attention. In gynodioecious sea beet (Beta vulgaris ssp. maritima), three sexual types co‐occur: females carrying a cytoplasmic male sterility (CMS) gene, hermaphrodites carrying a non‐CMS cytoplasm and restored hermaphrodites that carry CMS genes and nuclear restorer alleles. This study investigated the effects of fine‐scale genetic structure on male reproductive success of the two hermaphroditic forms. Our study population was strongly structured and characterized by contrasting local sex‐ratios. Pollen flow was constrained over short distances and depended on local plant density. Interestingly, restored hermaphrodites sired significantly more seedlings than non‐CMS hermaphrodites, despite the previous observation that the former produce pollen of lower quality than the latter. This result was explained by the higher frequency of females in the local vicinity of restored (CMS) hermaphrodites as compared to non‐CMS hermaphrodites. Population structure thus strongly influences individual fitness and may locally counteract the expected effects of selection, suggesting that understanding fine scale population processes is central to predicting the evolution of gender polymorphism in angiosperms. 相似文献
9.
10.
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