摘要:

In this report we predict the rate of aluminum absorption into root cytoplasm as solutes that are common in acid soil solutions. Our predictions of passive influx rely upon permeability coefficients estimated from known values for similar compounds. We also consider aluminum absorption by endocytosis and absorption by competition with iron for iron‐specific transport mechanisms. Our calculations indicate that passive flux of Al3+or of common charged Al‐complexes is unlikely to contribute measurably to total aluminum absorption , but endocytosis of Al3+bound to the plasma membrane surface may dominate uptake under some conditions. Among neutral Al‐complexes, AlF3oabsorption should be detectable; by comparison, passive influx by Al‐citrateoshould not be detectable.

ISSN:0190-4167    

DOI:10.1080/01904169009364093

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The Cl concentration in laminae and midribs at each harvest of flue‐cured tobacco (cv C139) is presented for a number of experiments in which irrigation, topping and N fertilizing were tested. Irrigating with water containing 60–100 mg L‐1Cl increased leaf Cl at all harvests, but topping and N fertilizing (70–160 kg N ha‐1) hardly affected it. However, irrespective of any treatment effects, lamina Cl was highest at the first harvest and declined to a varying degree, but mostly linearly, in the subsequent harvests. The percent maximum relative decrease at any one harvest, compared to that of the first harvest, was 12 to 45%. Obviously, lamina Cl at the first harvest is the maximum to be expected for a crop, and extrapolations can be made from it for subsequent harvests. Chloride concentration (%) for the whole leaf (Y) can be calculated from percent lamina Cl (X) as: Y = 0.61 + 1.02 X.

ISSN:0190-4167    

DOI:10.1080/01904169009364094

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

In a greenhouse, radish(Raphanus sativusL.), corn(Zea maysL.), soybean(Glycine maxMerr), and wheat(Triticum aestivumL.) were grown in soil‐based medium with captan at 60 mg/kg and truban at 30 mg/kg and with different levels of N from (NH4)2SO4or NaNO3. Growth of radish, soybean, and corn was restricted by NH4‐N compared with NO3‐N. Captan and truban stunted growth of radish and soybean. As NH4‐N or NO3‐N fertilizer increased, the concentration of Ca and Mg in all plants decreased, and the percentage of K in corn, soybean, and wheat increased. Application of captan and truban increased all cation concentrations in corn, wheat, and soybean but decreased Ca concentration in radish. The amount of residual NH4‐N in the medium supplied with (NH4)2SO4was increased by application of captan or truban. Captan increased the residual NO3‐N in the medium treated with NaNO3. Chemical names used: captan, (N‐(trichloro)methylthio)‐4‐cyclo‐hexene‐l, 2‐dicarboximide); truban, (5‐ethoxy‐3‐trichloromethyl‐l, 2, 4,‐thiadiazole).

ISSN:0190-4167    

DOI:10.1080/01904169009364095

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Two experiments are described in which tomato plants(Lycopersicon esculentumL. var Ailsa Craig) were grown in water culture supplied with 10–300 μM Mn. Toxicity symptoms associated with a yield reduction were observed only in treatments in excess of 50 μM Mn indicating that this species is relatively tolerant of high Mn supply. Dark brown/black spots appeared first in the cotyledons. Similar symptoms were observed in the leaves, progressively from the oldest leaf. Manganese concentration in the shoot tissues ranged from 286 to 4240 μg. g‐1dry weight. The high Mn concentration values found in the shoot tissues of the toxic plants indicate that Mn was highly mobile in the xylem as confirmed by xylem sap analysis.

ISSN:0190-4167    

DOI:10.1080/01904169009364096

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Pearl millet[Pennisetum glaucum(L.) R. Br.] is a potentially productive, high‐yielding grain crop in the southeastern USA. A lack of response in pearl millet grain yield to fertilizer N in field studies indicates pearl millet may be able to remobilize N from vegetative to reproductive tissue. The N remobilization capabilities of a plant can be affected by the form of N supplemented. The objectives of this study were to evaluate the effects of N‐form ratio (NH4+: NO3‐) on the N remobilization capabilities of pearl millet when N is removed from the nutrient solution at the boot stage and to evaluate the effects of changing N‐form ratios at the boot stage on the seed yield and N content of pearl millet. Pearl millet was grown in solution culture under greenhouse conditions. There were 10 treatments: an initial NH4+: NO3‐ratio of 3:1 followed by a change at the boot stage to either all NO3‐, no N, or a continuation of the initial ratio; an initial NH4+: NO3‐ratio of 1:1 followed by a change at the boot stage to either all NO3‐, all NH4+no N, or a continuation of the initial ratio; and an initial NH4+: NO3‐ratio of 1:3 followed by a change at the boot stage to either all NH4+no N, or a continuation of the initial ratio. Pearl millet dry matter accumulation was insensitive to changes in N‐form ratio or N removal at the boot stage. The lack of seed yield response to removal of N was a result of pearl millet utilizing N present in culms and leaves for seed production. Applications of N after the boot stage did not increase seed yield, but led to luxury consumption of N.

ISSN:0190-4167    

DOI:10.1080/01904169009364097

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Pearl millet [Pennisetumglaucum(L.) R. Br.] is a potentially high‐yielding grain crop for the Southern Coastal Plain region of the USA. Information on the growth and N nutrition of pearl millet is limited; therefore, this study was initiated with the objective of studying pearl millet growth, N content, N uptake patterns and N‐form preference. Plants were grown in solution culture using a modified Hoagland's solution. Solutions were changed weekly and transpirational losses replaced daily. The N‐form ratios were 1:0, 3:1, 1:1, 1:3 and 0:1 NH4+to NO3‐Uptake was determined by difference between the initial and final solutions. Nitrate and NH4+uptake patterns were different from each other and were influenced by the ratio of NH4+to NO3‐. After the plants had been transferred to the solutions, ammonium was preferred for the first two weeks, with NO3‐preferred thereafter. Nitrate uptake was highest during the grain filling period. Plant growth as measured by leaf, stem, root, and seed weight, plant height, average seed weight, and head length was generally reduced as NH4+increased. The largest reduction was observed between the 3:1 and 1:0 ratios. Ammonium nutrition had an overall negative effect on pearl millet growth. Ammonium fertilization of pearl millet under conditions that increase absorption of NH4+over NO3‐may have a negative effect on pearl millet growth and development.

ISSN:0190-4167    

DOI:10.1080/01904169009364098

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The effectivenness of different Fe chelates to correct lime induced chlorosis of peanut (Arachis hypogaea) was tested on calcareous soils in Cyprus. Among the chelates tested, Fe‐DTPA and Fe‐EDTA were less effective than Fe‐EDDHA. In one experiment. Fe‐EDDHMA Was less effective while in another experiment was equally effective compared to Fe‐EDDHA . Three different commercial chelates of the form Fe‐EDDHA were equally effective in correcting iron chlorosis. The stability of the Fe‐EDDHA chelate in the soil does not affect its efficiency in curing chlorosis of peanut due to the short growing season for this crop. Ferrous sulfate applied without an acidifying soil amendment was not effective to correct iron chlorosis of peanut.

ISSN:0190-4167    

DOI:10.1080/01904169009364099

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Dry matter yield and nitrogen (total and15N) uptake of tomato plants (Lycopersicum esculentumMill., cv. Columbia) subjected to saline stress by NaCl were studied in a greenhouse. The treatments consisted of low (control), medium (4 bars), and high (8 bars) salinity. The saline treatments were prepared by adding NaCl to culture solutions. The plants were 80 days old at the start of the15N treatments and each was in a pot containing 1.8 kg of quartz sand. The15N was provided to plants by adding K15NO3to the pots and the15N treatment period continued for 30 days. The plants were harvested at each 5‐day interval during the15N treatment period. Dry matter production and nitrogen (total and15N) uptake were significantly lower for the saline treatments as compared with the control. The significant difference in the above factors (dry matter production, total‐N, and15N content of plants) was first noted on day 15 of the15N treatment, and this difference continued to the end of the study period. Also, differences in both dry matter production and15N uptake appeared in the last (day 30) harvest between the two saline treatments.

ISSN:0190-4167    

DOI:10.1080/01904169009364100

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The influence of nitrogen nutrition and Russian wheat aphid (Diuraphis noxiaMordvilko) infestation on morphology and grain yield of wheat (Triticum aestivumL.) was studied in growth chamber experiments. Plants were grown with nutrient solution containing 100, 50, 10, or 0 percent of the normal complement of nitrogen. Plants were infested with eight apterous adult Russian wheat aphids at the flag leaf stage (approximately 53 days after planting). The aphids remained on the plant for a period of 25 days. Aphid infestation reduced mature plant height across all nutrient solution nitrogen concentrations tested. Grain yield was reduced by aphid infestation under all nutrient solution nitrogen concentrations except 0 percent. However, the percentage of yield loss caused by aphid infestation was reduced by increased levels of nitrogen in the nutrient solution. These results suggest that nitrogen fertilization might be a useful strategy for limiting yield loss caused by Russian wheat aphid in plants that are deficient in nitrogen.

ISSN:0190-4167    

DOI:10.1080/01904169009364101

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Acid phosphatase activity and vesicular‐arbuscular mycorrhizal (VAM) infection associated with four spring wheat genotype roots were investigated. Plants were grown in a typic low P volcanic soil with and without P‐fertilizer addition and harvested at 21, 42, 63, 84 and 96 days. Results show that phosphatase activity, expresed as ug p‐nitrophenol released per g dry root, decreased from 21 to 96 days in all cultivars. Conversely, trends of VAM infection were similar in all genotypes being higher in P added plants at 63 days after sown. This opposite effects may be viewed as alternative and/or complementary adaptations for P‐uptake by plants growing in low nutrient situations. It was concluded that one of the ways of P‐alleviation in wheat growing in our volcanic soils might be the search of genotypes having high biochemical and/or biological root activities.

ISSN:0190-4167    

DOI:10.1080/01904169009364102

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor