摘要:

The influence of Co on Fe uptake and the Fe‐stress response mechanism of tomatoes (Lycopersicon esculentumMill.) and soybeans [Glycine max(L.) Merr.] was studied. Iron‐efficient and ‐inefficient plants (T3238fer+and T3238fertomatoes and A7 and T203 soybeans, respectively) were grown in nutrient solutions for seven and nine days at varying Fe and Co levels (0, 0; 1.0, 0; 1.0, 0.3; 1.0, 0.6; 1.0, 1.2; 1.0, 2.4; and 0, 1.2 mg liter–1Fe and Co, respectively). Cobalt significantly (p≤0.05) decreased chlorophyll and foliar Fe and increased foliar and root Co in all cultivars. Cobalt effects on root Fe varied among cultivars. The Fe‐inefficient cultivars were most susceptible to chlorosis in the presence of Co, yet apparently exhibited true Fe deficiency. The Fe‐efficient cultivars appeared to exhibit a combination of Fe deficiency and Co toxicity. Chlorophyll formation was generally limited when foliar Fe was below 50 ug Fe g–1dry weight regardless of Co treatment. Reductant and proton excretion from roots of efficient cultivars apparently did not occur at Co levels where Fe uptake was limiting chlorophyll formation. However, the Fe‐efficient cultivars appeared to remain efficient at low Co levels even though the outward measurable indicators (pH and excreted reductant) were not evident. The Fe‐stress response mechanism was not observed in Fe‐inefficient cultivars regardless of Co level.

ISSN:0190-4167    

DOI:10.1080/01904168509363321

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

In two experiments tall fescue (TF) and orchardgrass (OG) were fertilized in split applications on Julian days 107 and 135 with O, 294, or 882 kg NH4NO3/ha and O or 833 kg K2SO4/ha to determine the effect on TF and OG N and S components. Ammonium nitrate fertilization significantly increased total N, nonprotein N (NPN) and protein N (PN) concentrations in TF and OG. Nonprotein N (% of total N) was decreased (P<.001) in TF as level of NH4NO3fertilization increased. Potassium sulfate fertilization did not alter concentration of N components of either grass except NPN concentration was reduced (P<.05) in TF. The NH4NO3level x K2SO4level interaction was nonsignificant for all N fractions. For each grass ammonium nitrate fertilization reduced total S and nonprotein S (NPS) and increased protein S (PS) concentrations significantly while K2SO4fertilization increased all three S components significantly. The NH4NO3level x K2SO4level interactions were significant for all S fractions in TF and NPS and PS in OG. Total N:total S, NPN:NPS and PN:PS ratios significantly increased with increasing level of NH4NO3fertilization in TF and OG. Potassium sulfate application reduced total N:total S ratio significantly in both grasses as well as PN:PS ratio in TF. Herbage total N and NPN concentrations were positively (P<.001) correlated for TF (r = .79) and OG (r = .70). Similarly, correlations between total S and NPS were r = .76 and r = .86 (P<.001) for TF and OG, respectively. Total N and total S concentrations were not related for either grass. These data indicate TF composition was altered by NH4NO3and K2SO4fertilization. Orchardgrass N and S fractions changed as levels of fertilizer NH4NO3and K2SO4were varied.

ISSN:0190-4167    

DOI:10.1080/01904168509363322

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Dupontia fisheriwas grown hydroponically under optimum conditions in growth chambers at a constant temperature of 20°C and illuminated continuously by a combination of fluorescent and incandescent lamps set at an intensity of 21,500 lux (2,000 fc). The plants were nourished by modified half strength Hoagland's nutrient solution (H/2), containing the following amounts of nitrogen added one time only: zero, 0.25, 0.5, 1.0, 2.0, 4.0 and 8.0 me 1–1. Each treatment was replicated four times (eight for zero treatment) in pots containing 20 liters of nutrient solution. The solutions were aerated continuously with carbon filtered air. Ammonium (NH4‐N) was supplied as (NH4)2SO4, nitrate (NC3‐N) as Ca(NO3)2and ammonium plus nitrate (AN‐N) as NH4NO3. The reaction was adjusted as required: downward between pH 5.4 and 5.8 with 1.0 N H2SO4, and upward between 6.0 and 6.5 with 1.0 N NaOH. Plants were harvested after 49 days.

ISSN:0190-4167    

DOI:10.1080/01904168509363323

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Experiments were done to define the relationships between tissue N fractions and the growth rate of wheat (Triticum aestivumL.) seedlings. The crop was grown in the greenhouse at two levels of incident radiation in soils supplying different levels of nutrients, its growth rate measured and its tissues analyzed for different N fractions. Soluble reduced N (SRN) expressed as a fraction of “protein N”; was found to usefully predict relative growth rate (RGR). Maximum growth was associated with “SRN / protein N”; values approximating 12%, smaller values corresponded to reduced growth from N stress and low levels of light, while values above 18% were characteristic of plants in which amino compounds had accumulated due to deficiencies of nutrients other than N and to toxic factors.

ISSN:0190-4167    

DOI:10.1080/01904168509363324

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A P x K fertilizer experiment with five soybean cultivars was conducted to evaluate possible differential response of the different cultivars to moderate rates of fertilizer. Significant effects of fertilizer upon yield and leaf composition were observed in different years, suggesting possible interactions with other environmental variables. Significant differences in nutrient content of leaves and soybean seed were attributed to cultivar effects. The effects of P and K upon nutrient content of the seed differed among cultivars.

ISSN:0190-4167    

DOI:10.1080/01904168509363325

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Soybeans (Glvcine maxL.) cv. “Clark”; were grown in the greenhouse in sand‐filled plastic pots sub‐irrigated with Hoagland No. 1 solution to determine the possible inhibitory effects of Zn on the uptake of P. Zinc rates used were 0.05 (control), 0.25, 0.5 and 2.5 ppm. Yields equalled the control at Zn levels of 0.25 and 0.5 ppm, but plants grown in solutions containing 2.5 ppm Zn were stunted severely. Foliar Zn and P levels differed very little among Zn treatments. Zinc levels were highest and P levels were lowest, however, in the roots and stems of soybeans grown in solutions of 2.5 ppm Zn. Zinc and P uptake was significantly inhibited in the leaves, stems and roots of plants grown at the highest Zn rate. The recycling of wastes containing high Zn content could adversely affect plant growth by a suspected antagonism with P.

ISSN:0190-4167    

DOI:10.1080/01904168509363326

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

ISSN:0190-4167    

DOI:10.1080/01904168509363320

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor