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71.
Two rice ( Oryza sativa L.) cultivars of contrasting morphologies, IR-36 and Fujiyama-5, were exposed to ambient (360 μl l−1 ) and ambient plus 300 μl l−1 CO2 from time of emergence until ca 50% grain fill at the Duke University Phytotron, Durham, North Carolina. Exposure to increased CO2 resulted in about a 50% increase in the photosynthetic rate for both cultivars and photosynthetic enhancement was still evident after 3 months of exposure to a high CO2 environment. The photosynthetic response at 5% CO2 and the response of CO2 assimilation (A) to internal CO2 (Ci ) suggest a reallocation of biochemical resources from RuBP carboxylation to RuBP regeneration. Increases in total plant biomass at elevated CO2 were approximately the same in both cultivars, although differences in allocation patterns were noted in root/shoot ratio. Differences in reproductive characteristics were also observed between cultivars at an elevated CO2 environment with a significant increase in harvest index for IR-36 but not for Fujiyama-5. Changes in carbon allocation in reproduction between these two cultivars suggest that lines of rice could be identified that would maximize reproductive output in a future high CO2 environment. 相似文献
72.
Redox potentials in microsites of the rhizosphere of flooded rice were continuously measured for several days. Close to the root tips redox potential markedly increased. The highest increase was measured in the rhizosphere of the tips of short lateral roots. Aerobic redox conditions were reached there, except in a very strongly reduced soil. Both the extension of the oxidation zone around the root tips and the maximum redox potential reached were influenced by the reducing capacity of the soil. The radius of the redox rhizosphere varied from less than 1 mm in a strongly reduced soil up to 4 mm in a weakly reduced one. The root-induced oxidation processes in the rhizosphere depended on the atmospheric oxygen supply to the roots. 相似文献
73.
Adelheid Gauly Alfred Batschauer Albrecht von Arnim Hans Kössel 《Plant molecular biology》1992,19(2):277-287
74.
The flow of jelly within a honeybee colony 总被引:8,自引:0,他引:8
Karl Crailsheim 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1992,162(8):681-689
Summary The flow of jelly from 100 nurse bees to the members of two normal-sized colonies was measured during one night. To follow the flow, nurses were injected with 14C-phenylalanine. They incorporated this label into the protein of their hypopharyngeal (brood food) glands and their own body protein. When they were allowed trophallactic contacts during the investigation period a loss of label and a shift away from the abdomen was observed, indicating protein synthesis in the hypopharyngeal glands from previously stored protein. Very young larvae were fed less frequently than older ones. Younger workers received larger amounts of jelly than older ones, but considerable amounts were given to foragers. Drones behaved similarly. Between one-third and one-half of the distributed jelly was given to imagines; 10% and 16% of all workers received radioactive jelly from 100 nurses in the two colonies during one night. Thus, jelly is a very important food for adult honey bees. There was a remarkable exchange of label within the class of nurses themselves that is interpreted as communication within the social system.Abbreviation dpm
decays per minute 相似文献
75.
Summary Comparison of different post-plating temperature regimes with a control treatment (27° C) revealed that a short-term cold (8/14°C:2/2 days or 14°C:4 days) as well as a heat treatment (30°C:14 days) increased the production of embryro-like-structures (ELS) from cultured maize anthers. The beneficial effects of short-term cold treatments were magnified 2–3 times when L-proline (PROL) was added to the induction medium (125–500 mg/L). In the best treatment (14°C:4 days, 125 mg/L L-proline) one genotype produced 143.5 ELS/100 anthers. Anthers subjected to high temperature (30°C:4 days, 30°C:7 days, 30°C:14 days) generally showed a lower response than did cold treated anthers, although genotypic differences were observed. Regeneration frequency did not appear to be affected by the presence of L-proline in the induction medium.Abbreviations ELS
Embryo-like-structures
- PROL
L-proline 相似文献
76.
A. Golan-Goldhirsh U. Schmidhalter M. Müller J. J. Oertli 《Sexual plant reproduction》1991,4(3):182-187
Summary The osmotic effect of Polyethylene glycol (PEG) has been shown to be sufficient to induce the germination of Pistacia vera L. pollen in liquid medium. The prehydration of the pollen in a saturated atmosphere for approximately 10 h was necessary to obtain maximum in vitro germination. Imbibition of the pollen in water resulted in the rapid leakage of solutes into the medium. These solutes consisted of approximately 50% carbohydrates, of which sucrose (0.65 mol/mg), glucose (0.77 mol/mg) and fructose (0.78 mol/mg) were the major sugars; the remaining 50% comprised proteins with the following major molecular weights 63 kDa, 60 kDa, 59 kDa, 40 kDa, 36 kDa, 35.5 kDa, 31 kDa, other organic matter and minerals. 相似文献
77.
Five polymorphic enzymatic loci were studied in 30 populations of Quercus ilex distributed from Crete to North Africa. A high within-population genetic diversity was found for each locus studied. Most of the alleles were common to all the populations, indicating that the holm oak corresponds to a single genetic entity. Observation of breeding system characteristics showed that the holm oak is monoecious, wind-pollinated, and likely to possess genetic autoincompatibility. Furthermore, studies of flowering phenology in a single population showed that the period of flowering varied notably among trees. An average of 29% of the trees showed inter-annual variation in flowering time. The male, female or vegetative investment also varied widely among trees from one year to another. This results in a diversification of pollen source received by a given tree each year, and also from one year to another. 相似文献
78.
H. Sztajer E. Zboińska I. Zbyryt J. Kleleczawa B. Lejczak P. Kafarski 《Biologia Plantarum》1990,32(1):28-34
Two classes of phosphonopeptides, those containing P-terminal 9-aminofluoren-9-ylphos-phonic acid and those of dialkyl 9-aminofluoren-9-ylphosphine
oxides, influence plant growth according to different mechanisms. The effect of these compounds on the growth of several bacterial
species, including the photosynthetic bacteriumRhodospirillum rubrum, as well as on the activity of photosystems 1 and 2 in isolatedPisum sativum andSpirodela oligorrhiza chloroplasts was studied. The peptides of free, unblocked 9-aminofluoren-9-ylphosphonic acid acted in a morphactin-like manner,
whereas those of dialkyl 9-aminofluoren-9-ylphosphine oxides influenced photosynthesis indirectly. 相似文献
79.
Addition of manganese, at levels of 50 ppm, to a liquid growth medium simulating adverse silage conditions had no effect on the growth or on the fermentation pattern of Enterobacter cloacae and Proteus vulgaris. Yet, the manganese strongly enhanced the growth of Lactobacillus plantarum. Co-cultures of L. plantarum and E. cloacae or P. vulgaris were, by addition of manganese ions, significantly altered in the favour of the former. This finding can be of use in mixed cultures where Enterobacteriaceae act as spoiler microorganisms. 相似文献
80.