摘要:

Tomato plants, two Fe‐efficient cultivars and one Fe‐inefficient cultivar, were grown in treatment combinations of normal and low Fe and K concentrations (Normal Fe, Normal K; Low Fe, Normal K; Low Fe, Low K). Iron‐stressed plants with normal K levels were the first to show elevation of root proton excretion and an enhanced ability to regreen. Roots from the Fe‐efficient cultivars had a marked increase in the rate of CO2dark fixation that was most prominent with a Normal K, Low Fe. The amount of14C labeling of root organic acids, particularly malate, citrate, lactate and oxaloacetate increased under Fe‐stress conditions in the Fe‐efficient cultivars; Fe stress with low K resulted in less14C labeling. A scheme for Fe reduction, uptake and transport is discussed related to CO2fixation and organic acids (malate, citrate and oxaloacetate.)

ISSN:0190-4167    

DOI:10.1080/01904169009364158

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Efficient nutrient utilization by plants is extremely important in developing countries and is becoming more important in the developed countries as the costs of fertilizers are increasing. Pearl millet is a world food and forage crop usually grown on droughty soils low in nutrients. Eighty‐five genetically diverse pearl millet,Pennisetum glaucum(L.) R. Br. lines were grown in low Mg and K sand for three weeks to screen for efficient Mg uptake. Magnesium free Hoagland's solution at one‐fourth strength was used to water the plants as needed. Forage produced was clipped, dried, ground, ashed, and analyzed for Mg and K content. A 2‐fold difference for Mg concentration in the forage existed among the lines. The data indicated that a low [K]/[Mg] ratio in the plant was indicative of a Mg efficient genotype. The data also suggest that caution should be used in making general nutrient recommendations based on tissue or soil tests without knowing the nutrient requirement of the cultivar.

ISSN:0190-4167    

DOI:10.1080/01904169009364159

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The identification and use of bean genotypes that can grow on phosphorus‐deficient soils, making efficient use of the limited nutrient resources present, would increase food production in many areas of the tropics where small farmers have limited ability to purchase fertilizer or where P fertilizers are inefficient. Twenty‐six bean lines were evaluated for P efficiency to determine what characteristics were responsible for the observed differences in grain yields under P‐deficient conditions. P accumulation, vegetative dry matter production, and P distribution within the plant were similar in efficient and inefficient lines. Differences in yield component development were, however, observed. Even though the efficient and inefficient lines had the same amount of P in their tissues at mid‐flowering, the inefficient lines still aborted more pod and had fewer seeds per pod while the efficient lines were better able to fully utilize their accumulated P.

ISSN:0190-4167    

DOI:10.1080/01904169009364160

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Experiments were conducted to study the effect of temperature and nutrition on seed germination and plant growth of different plant species. The nutrition studies of vegetables showed a normal response to fertilization rates on deficient soils at temperatures above their critical minimum. At soil temperatures below this little or no response was obtained to increased P concentration. Plant growth as affected by soil temperature was studied on beans, corn, cucumber, eggplant, pea, pepper, radish, spinach, and watermelon. Growth of peas, radish and spinach was significantly reduced by soil temperatures 10°C or lower. Corn growth was restricted when soil temperatures were maintained in the range of 12.3–14.5°C or lower, while growth of bean, cucumber, eggplant, pepper and watermelon was limited when soil temperatures were maintained in the 16.7–18.9°C temperature range or lower.

ISSN:0190-4167    

DOI:10.1080/01904169009364161

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Iron‐efficient tomato and soybean, when subjected to Fe‐deficiency stress, required K before the Fe‐stress response mechanism would function, ie, would (a) release H ions and reductants from their roots and (b) reduce Fe3+to Fe2+in their roots. In previous studies with tomato and soybean, H ion release ceased after Fe was made available to the plant. Muskmelon differed from tomatoes and soybeans in that H ion release was sustained even after Fe was made available. This study was conducted to determine if muskmelon also differs from soybean and tomato plants in its Fe‐K relationship. Muskmelon was grown in hydroponic solutions at varying levels of K in combination with low or no Fe and also in various combinations of Na or Rb (as substitutes for K). Hydrogen ion release and reduction of Fe3+at the roots as well as chlorosis ratings and leaf Fe concentrations were determined. Potassium‐deficiency stress did not prevent hydrogen ion release by muskmelon roots as had been previously observed in tomato and soybean. Adequate levels of K were, however, essential to maximizing the reduction of Fe3+to Fe2+at the root. Hydrogen ion release was enough of a response to maintain leaf Fe above 50μg/g even when Fe3+reduction was low without solution K. Neither Na nor Rb substituted for K in enhancing Fe3+reduction in muskmelon. Potassium does appear to have a specific role in the Fe‐stress response mechanism of dicotyledonous plants when subjected to Fe‐deficiency stress. Muskmelon could potentially serve in future studies directed toward defining the genetic differences in dicotyledenous species.

ISSN:0190-4167    

DOI:10.1080/01904169009364162

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Nonnodulated soybean plants(Glycine max.[L.] Merr. ‘Lee') were supplied with nutrient solutions containing growth limiting concentrations of N or P to examine effects on N‐ and P‐uptake efficiencies (mg nutrient accumulated/gdw root) and utilization efficiencies in dry matter production (gdw2/mg nutrient). Nutritional treatments were imposed in aerial environments containing either 350 or 700 μL/L atmospheric CO2to determine whether the nutrient interactions were modified when growth rates were altered.

ISSN:0190-4167    

DOI:10.1080/01904169009364163

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Plant analysis has been used to evaluate the nutritional status of many crops for diagnostic and corrective purposes. This study was initiated to establish critical nitrogen (N) plant tissue levels using midrib NO3‐N concentration for cauliflower (Brassica oleraceaL., var.Botrytis) during the growing season. Tissue samples for nitrate analysis were taken from cauliflower plants over a period of four growing seasons beginning at the 4 to 6 leaf stage of growth and biweekly through pre‐harvest. The midrib from the most recently full sized leaf was sampled for NO3‐N concentration determination.

ISSN:0190-4167    

DOI:10.1080/01904169009364164

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The effects of NaCl‐salinity and supplemental CaCI2on root elongation and osmotic adjustment were investigated for two corn (Zea maysL.) cultivars, Pioneer hybrid 3906 and Dekalb hybrid XL75. Increasing concentrations of NaCl (0 to 120 mM) progressively inhibited root elongation. Root elongation of Pioneer hybrid 3906 was more sensitive to salinity than that of Dekalb hybrid XL75. The osmolality of the growing zone of salt‐stressed roots increased with increasing salinity. High Ca2+increased the osmolality for both cultivars. Dekalb hybrid XL75 had a greater response to Ca2+than that of Pioneer hybrid 3906. The concentrations of soluble sugars, amino acids, proline, Na+, K+and Ch were determined to assess which solutes were involved in osmotic adjustment. Sodium and Cl were the principal solutes involved, although minor increases in K+and soluble sugars were also observed. We found no significant effects of salinity or Ca2+on concentrations of proline or amino acids.

ISSN:0190-4167    

DOI:10.1080/01904169009364165

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Toxic levels of aluminum can cause severe yield reduction in red clover (Trifolium pratenseL.), especially in the presence of drought stress. Aluminum tolerances of 17 red clover cultivars and germplasms representing a broad genetic base were evaluated in a Monmouth soil [26.2% Al saturation (pH 4.8) vs. 2.8% Al saturation (pH 5.7)] and in nutrient solutions (0 vs 111μM Al; pH 4.5). The soil and nutrient culture studies were harvested 29 and 27 d after seeding, respectively.

ISSN:0190-4167    

DOI:10.1080/01904169009364166

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0190-4167    

DOI:10.1080/01904169009364167

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor