摘要:

Cowpea (Vigna unguiculata[L.] Walp. ‘California Blackeye') plants were grown at seven rates of phosphorus (P) fertilization: 0.0 to 3.6 mM P provided weekly. When plants were eight weeks old, stomatal conductance (Cs) was measured before and after lowering soil water potential to ‐1.0 MPa with a sorbitol solution. Prestress Cs was between 4 and 5 mm/s in 0.0 to 2.4 P plants and varied between 5 and 7 mm/s in 3.0 and 3.6 P plants. Declines in Cs were similar after lowering of soil water potential in plants of all treatments except 0.6 P, which tended to have lower Cs.

ISSN:0190-4167    

DOI:10.1080/01904169209364318

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Exceptional symbiotic nitrogen fixation withSesbaniahas provided high soil fertility for many past centuries of paddy rice production. Unique stem nodulation results in high nitrogenase activity levels ofS. rostrata,Brem, during rapid growth in continuously flooded rice fields that greatly disfavor legume root nodulation and this functional development. The objective of this study was to determine plant nutrient interactions that influence contrasting root and aerial stem nodule histology governing effective nitrogenase activity levels and nitrogen fixation. Top growth, nodulation, and nitrogenase activity levels were significantly increased with increased available soil P. Response to K levels and Ca additions resulted only when soil P was adequate in all treatment combinations. However, there was no significant correlation between fresh nodule weight, nitrogenase activity, and nodules plant‐1for both root nodules and aerial stem nodules. Nodule histology was highly contrastive with nodule type andRhizobiummorphology, cytosol composition, and governing enzyme activity levels. Distinctive nonpleomorphic cocci bacteroids of functional aerial stem nodules have tentative designation asAzorhizobium caulinodansgen. nov. sp. nov.

ISSN:0190-4167    

DOI:10.1080/01904169209364319

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Six‐week old seedlings of tomato[Lycopersicon esculentum)were placed in growth chambers, hypocotyl and the root system (in the lower part of the chamber) being precisely separated from the stem (the upper part of the chamber). The composition of the medium was modified by enriching it with KHCO3(converted to the value of about 0.1% CO2concentration) or additionally with14C. The total radioactivity associated with roots, shoots, and leaves after 72 h chase period was determined. About 61% of the total radioactivity were found in root and 39% in shoots and leaves. Differences in the concentration of HCOâ in the medium significantly modified the concentration of malic acid (MA) in the tissues. An increase in KHCO3concentration in the medium to the level equivalent to about 0.1% CO2raised the level of MA by about 854%, 150%, and 134% in root, shoot, and leaf, respectively, in relation to the control (without KHCO3). The occurrence of phosphoenolpyruvate carboxylase (E.C. 4.1.1.31) was found in longitudinal‐sections of roots, using immunofluorescent technique method. The obtained results confirm a significant role of absorption of CO2forms dissolved in the medium, by roots and also of the massive transport of carbon compounds from roots to shoot and leaves. The results also suggest that this kind of root absorption might play an important role as an alternative source of CO2besides the photosynthetic carboxylation of CO2from atmospheric air.

ISSN:0190-4167    

DOI:10.1080/01904169209364320

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The Kallar grass leaf is linear with spiny surfaces. On its margins were found spines with a broad base, and on the upper and the lower surface, vesicles or swollen epidermal hairs with pointed, capped ends. On cellulose‐acetate film moistened with acetone and pressed against the leaf surface, the vesicles appeared as bladder‐like structures located above the epidermis. More vesicles were found on the upper than on the lower surface. In young field plants, the vesicles of the sheath were less developed and fewer in number than those of the blade. Vesicles in the leaf sheath were found largely on the lower (outer) surface. Using a pressure probe, he vesicles were found to contain sap and a turgor pressure of about 0.3 MPa which decreased with 100 mM NaCl and 10 mM PEG 6000. The sheath cells which were chlorophyllous, larger and rectangular, had a turgor pressure of about 0.1 MPa, which was either little affected or was increased when the leaf sheath was exposed to 100 mM NaCl or PEG 6000. The importance of these structures is discussed in relation to salt regulation in Kallar grass.

ISSN:0190-4167    

DOI:10.1080/01904169209364321

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0190-4167    

DOI:10.1080/01904169209364322

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Crop yield and nutrient uptake are often impaired under salt, water, or both stress conditions. This study was designed to gather further information concerning NaCl stress effects on these components. Therefore, dry‐matter yield, nitrogen (total and15N) uptake, Na+, Cl‐and K+content of leaves, stems, and roots of tomato(Lycopersicum esculentumMill., cv. ‘Columbia') plants subjected to NaCl stress were studied in a greenhouse. Saline treatments consisted of 0.3 (control), 4.3, and 8.3 bars osmotic pressures. Plants were 80 days old at the start of salt and15N treatments, and each plant was in a pot containing 1.8 kg of washed quartz sand. The15N as K15NO3solution was provided to plants at 10‐day intervals over a 30‐day period. Plants were harvested at 5‐day intervals during the 30‐day15N treatment period.

ISSN:0190-4167    

DOI:10.1080/01904169209364323

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Winter wheat(Triticum aestivumL. cv. Astral) was grown under seven fertilizer treatments on five experimental sites. Regression analysis was performed to model the relationships between different organ weights in the same or consecutive stages. The frequency of highly significant relationships between weights was higher during flowering and shooting than during the other stages studied:i.e.tillering, post‐anthesis, and harvesting. The relationship between the plant weight and the weights of the flag leaf or the 2nd youngest leaf was closer than that between the plant weight and that of the third youngest leaf and plant weight. The coefficent of correlation was higher than when ear weight was related to the plant weight in post‐anthesis, where there was no 2nd or 3rd youngest leaves. This relationship was closer than in flowering. Plant growth before anthesis was more regular than after anthesis. It appeared that the development of the leaf and of the ear affected the relationships between themselves and the rest of the plant. In terms of weight, the relationships were closest at the stage of maximum development. The weight of the youngest leaves at anthesis, when it attained a maximum, was a suitable indicator of plant biomass. It can, therefore, be used as a reference in the relationship between plant biomass and mineral content that expresses the nutritional status of the plant.

ISSN:0190-4167    

DOI:10.1080/01904169209364324

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The frequency of a a highly significant relationship between mineral composition and the weight of wheat leaves indicates that leaf growth is substantially affected by the nutritional status of the plant. Nitrogen and calcium have an important influence on the nutritional status at flowering, while the other cations studied had an important influence at post‐anthesis. The regression coefficient for the mathematical models obtained may have a well‐defined value for each physiological stage of the plant or leaf development. Relationships between the mineral composition of wheat leaves and their wheight were most significant at flowering. Due to their close relationship with the yield parameter,i.e.grain, young leaves are suitable organs for this analysis. Eventually, a thorough study of the dynamics of leaf development and the use of leaves from different positions on the stem is suggested.

ISSN:0190-4167    

DOI:10.1080/01904169209364325

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0190-4167    

DOI:10.1080/01904169209364326

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0190-4167    

DOI:10.1080/01904169209364317

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor