scholarly journals Studies on CO2 Exchange in Crop Plants. : X. The probrems on the degree of CO2 depletion in the plant chamber during measurement of photosynthesis under natural conditions.

1960 ◽  
Vol 29 (1) ◽  
pp. 34-36
Author(s):  
Tomoshiro TAKEDA
Keyword(s):  
Co2 Exchange ◽  
Crop Plants ◽  
Natural Conditions

scholarly journals Zbiorowiska chwastów segetalnych Równiny Piotrkomskiej i ich współczesne przemiany w związku z intensyfikacja, rolnictwa (Mezoregion Nizin Środkowopolskich) [Communities of segetal weeds of the Piotrkdw plain and their contemporary transformations in connection with the intensification of agriculture Central Polish Lowland Mesoregion)]

2015 ◽  
Vol 27 (2) ◽  
pp. 95-194 ◽  
Author(s):  
Urszula A. Warcholińska
Keyword(s):  
Floristic Composition ◽  
Crop Plants ◽  
Natural Conditions ◽  
Ecological Characteristic ◽  
Soil Cultivation ◽  
Central Poland ◽  
Segetal Communities

The work is a monograph of the regional vegetation accompanying crop plants in one of the most interesting mesoregions of central Poland. The standing phytosociological and ecological characteristic is given of 18 communities of segetal weeds against the natural conditions and changes in soil cultivation. On the basis of ecological and floristic analyses some regularities were established concerning: the structure and floristic composition of segetal communities, their dynamics distribution and spread, and the directions and extent of the contemporary transformations of these communities, due to the activity of man.

scholarly journals ACROSTALAGMUS APHIDUM OUD. AND APHID CONTROL

1969 ◽  
Vol 13 (2) ◽  
pp. 59-72
Author(s):  
J. A. B. Nolla
Keyword(s):  
Higher Plants ◽  
Crop Plants ◽  
Plant Diseases ◽  
Natural Conditions ◽  
Greenhouse Soil ◽  
Oatmeal Agar ◽  
Lace Bug ◽  
Important Crop ◽  
Aphid Control ◽  
Field Control

1. A fungus, Acrostalagmus aphidum Oud., parasitizes aphids in Porto Rico. It had been reported as A. albus Preuss. 2. The size of the spores in the various natural strata is more or less uniform. 3. The size of the spores appears to be larger for those produced on the natural strata than those developing on oatmeal agar cultures. 4. There seems to be a wider range of length and width of spores on our form than on the A. aphidum Oud. described in Saccardo's "Sylloge Fungorum". 5. Some of the conidia become one-to several-septate prior to germination. 6. Conidia or head-like structures are produced on germinating spores. 7. Some young conidia germinate while still attached to the head or to the branch tips. 8. Spores germinate rapidly in sugar solutions. 9. Spores rapidly lose their germinating power when dried. 10. Experiments indicate a possible stimulating effect of aphid juices on germination and development of spores. There are probably variations in the degree of that influence, according to species. 11. The fungus grows best at reactions of pH 6.93 to 7.93. 12. So far as is known, Acrostalagmus aphidum attacks the aphids on 17 species of the higher plants. Of these 8 had been reported previously and the remaining 9 are new additions. Among these are important crop plants. 13. The aphids which may be parasitized comprise five different genera of which two are here first reported. Aphis pseudobrassicae is first here reported parasitized by the fungus. 14. The fungus does not parasitize the corn aphid under natural conditions. 15. The fungus has also been reported on the eggplant lace-bug, Corythaica monacha. 16. Acrostalagmus aphidum can be employed successfully and cheaply in the control of the aphids of the eggplant. The method will probably be effective in field control of the aphids of other vegetables. 17. The pathogene lives in greenhouse soil. No experiment proof is at hand which would demonstrate whether the fungus is eliminated by the application of fungicides used for the control of plant diseases.

Metabolic signalling and the partitioning of resources in plant storage organs

1999 ◽  
Vol 133 (3) ◽  
pp. 243-249 ◽  
Author(s):  
NIGEL G. HALFORD
Keyword(s):  
Dry Weight ◽  
Wild Relatives ◽  
Crop Plants ◽  
Wild Plants ◽  
Young Plant ◽  
Carbon And Nitrogen ◽  
Cultivated Potato ◽  
Metabolic Signalling ◽  
Storage Organs ◽  
Plant Storage

The most important harvested organs of crop plants, such as seeds, tubers and fruits, are often described as assimilate sinks. They play little or no part in the fixation of carbon through the production of sugars through photosynthesis, or in the uptake of nitrogen and sulphur, but import these assimilated resources to support metabolism and to store them in the form of starch, oils and proteins. Wild plants store resources in seeds and tubers to later support an emergent young plant. Cultivated crops are effectively storing resources to provide us with food and many have been bred to accumulate much more than would be required otherwise. For example, approximately 80% of a cultivated potato plant's dry weight is contained in its tubers, ten times the proportion in the tubers of its wild relatives (Inoue & Tanaka 1978). Cultivation and breeding has brought about a shift in the partitioning of carbon and nitrogen assimilate between the organs of the plant.

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