摘要:

The photosynthetic pigment composition of chlorotic leaves ofCitrus limonL. cv. Verna, grown in the field under iron deficiency conditions was determined. A Fe‐polyflavonoid was used as fertilizer to control iron chloro‐ sis. The photosynthetic pigment content and the chlorophyllase activity were determined at 20 day intervals during the deficiency recovery period and compared to untreated similar material. The corresponding differences among treated and untreated control material were analyzed. Iron application increased the levels of all pigments, but the extent of the increase depended on the pigment affected. The chlorophylls/carotenoids and ß‐carotene/xantophylls ratios were increased as chlorosis diminished. A multivariance analysis was performed with the data obtained which revealed that chlorophyllaand ß‐carotene had the highest correlation coefficient. The chlorophyllase activity did not show significant changes, but it was lower in the treated leaves than in the untreated control leaves during all the sampling cycle.

ISSN:0190-4167    

DOI:10.1080/01904169109364272

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The popular foliage houseplant,Tolmiea Menziesii(piggyback plant), grown in an all NO3‐N, half‐strength Hoagland Solution No. 1 without Fe or with 0.5 g/liter Fe2O3became severely Fe chlorotic and caused the nutrient solution pH to rise from 5.1 initially to above 7. Plants supplied 90 μM Fe‐EDTA also raised solution pH but did not become chlorotic. When Fe chlorotic plants were transferred to a solution with 0.5 gAiter Fe2O3, modified to contain 25 to 100% of the N as NH4, the solution pH dropped to between 4.3 and 3.1, and the chlorotic plants regreened. However, if the pH of the modified solution was buffered above 7 with 1 g/liter CaCO3, no regreening occurred. Solution pH also dropped if the solution lacked N, and there was a temporary regreening of Fe chlorotic plants before N deficiency chlorosis appeared. These solution culture results indicate thatTolmieashould be classified as an Fe inefficient plant.

ISSN:0190-4167    

DOI:10.1080/01904169109364273

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A study was made on the effects of light and temperature combinations, nitrogen (N) carriers, and N levels on the growth and free amino‐N pool size of rice plants. The experiment was conducted in a growth chamber in nutrient solution. Combinations of high light supply (40,000 lux), or high temperature (35°C), or both, resulted in accumulation of large amino‐N pools.

ISSN:0190-4167    

DOI:10.1080/01904169109364274

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Uptake of NO3‐, NH4+, P, K++, Ca++and Mg++, as influenced by the stage of plant development and three NO3‐: NH4+ratios (1: 0, 1: 1, and 0: 1), was determined for sweet pepper (Capsicum annuumL. cv. ‘California Wonder'). Uptake was highest during fruit development and immediately after fruit harvest, indicating that fruit removal promotes nutrient uptake. When NO3‐and NH4+were supplied in equal concentrations, NO3‐was absorbed more readily. Each increment in NH4+decreased the uptake of K+, Ca++, and Mg++by fruit tissue, while no significant effect on the N and P content of the fruit was observed. Ammonium nutrition reduced plant dry weight and fruit yield in comparison to NO3‐. Results from this study suggest that NO3‐is the preferred N form, and that fertilizer application should be scheduled according to specific physiological stages to maximize nutrient uptake. Nutrient content of vegetative tissue was not indicative of potential yield.

ISSN:0190-4167    

DOI:10.1080/01904169109364275

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Calcium uptake by bell pepper(Capsicum annuum L.cv. ‘California Wonder') varied by stage of plant development and N form supplied (NO3‐NH4+ratios: 1:0, 3:1, 1:1, 1:3, and 0:1) in a hydroponic study. Uptake of Ca++was highest at bloom and during fruit expansion, making the fruit development stage the highest demand period. Calcium uptake declined with each increasing increment of NH4+relative to NO3‐supplied, although fruit yield was not significantly reduced until the ratio of NH4+to NO3‐exceeded 50%. Tissue Ca++levels in the blossom‐end of the fruit were reduced whenever NH4+was included with N supplied. Vegetative yield of plants followed the same trend as that observed for total fruit dry weights. Our results indicate that pepper yields are higher when NO3‐is the predominant form of N. Also, these results strongly suggest that Ca++fertilizer applications should precede the bloom period and continue during fruit development to ensure adequate Ca++availability for fruit development.

ISSN:0190-4167    

DOI:10.1080/01904169109364276

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

As a result of repeated applications, some fungicides may accumulate in the soil to levels high enough to have adverse effects on the activity of soil microorganisms and plant growth. Comparison of the effects of 10 mg kg‐1soil of the benlate, captan, and lime‐sulfur fungicides with the nitrification inhibitors (NI) nitrapyrin and terrazole on oxidation of NH4+in Tifton loamy sand (siliceous, thermic plinthic Typic Kandiudults) incubated at 30° C showed that benlate had no significant effects whereas captan inhibited nitrification 21% more than lime‐sulfur, but about 20% less than NI. Application of benlate enhanced NO3‐reduction to N2O and N2in liquid medium inoculated with soil whereas 50 and 100 mg L"1medium of captan and lime‐sulfur compared favorably with the NI in suppressing NO3‐and NO2‐reductions, but were less effective than the inhibitors when applied at the low rate of 10 mg L‐1medium. In a greenhouse study with tomato(Lycopersicon esculentumMill. cv. ‘Better Boy'), weekly drench applications of 0.25 mg kg‐1soil of the test biocides for four weeks with three NH4+‐N: NO3‐‐N ratios showed that benlate applied with 1: 0 N ratio and lime‐sulfur applied with 0: 1 N ratio restricted significantly the plant growth and N uptake. The largest root: shoot ratios, total plant dry weight, and N uptake were obtained with plants fertilized with 1: 1 N ratio in combination with the biocides.

ISSN:0190-4167    

DOI:10.1080/01904169109364277

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

During a normal growing season, sweetpotatoes shed a substantial number of leaves (Somda and Kays, 1990b). To ascertain the potential cost of leaf loss to the plant, the sequential loss of leaves over the entire growing season was monitored and related to losses of dry matter and individual elements when leaf shedding was induced via leaf shading. The number of leaves produced increased as the season progressed, but missing leaves outnumbered by 21% those remaining on the plant by the end of the growing season. Average dry weights of individual leaves increased progressively to a maximum 14 weeks after planting, and then declined until harvest. After the 6th week, leaf area decreased relative to plant dry weight for the remainder of the growing season. Mature leaves remobilized nearly 37% of their total dry matter prior to abscission; the remaining 63% was lost from the plant, representing an estimated dry matter loss of approximately 2.8 MT/ha during the growing season. A significant portion of P, K, and Mg that had accumulated in mature leaves was recycled into the plant prior to abscission. However, remobilization of Ca, Fe, Zn, Mn, B, Na, and Al was not significant. Leaf shedding in field populations of ‘Jewel’ sweetpotatoes was extensive, and while significant dry matter was recycled out of the leaves prior to abscission, leaf drop represented a substantial loss of P, K, and Mg and dry matter from the crop.

ISSN:0190-4167    

DOI:10.1080/01904169109364278

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Seasonal patterns of fruit growth and calcium (Ca) accumulation in ‘Delicious’ apple fruit were observed over four years and four growing regions. Although temperature and precipitation varied greatly, fruit consistently accumulated Ca in a quadratic fashion, with maximum uptake occurring early in the season. Little Ca accumulated in fruit during the three weeks prior to harvest. Under some conditions, fruit appeared to lose Ca during this time. Loss of fruit Ca was not closely associated with precipitation. Calcium uptake was greatest during periods of high evaporative demand.

ISSN:0190-4167    

DOI:10.1080/01904169109364279

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The objectives of this study were to determine and compare the Al tolerance of selected citrus rootstocks. Six‐month‐old seedlings of five citrus rootstocks were grown for 60 days in nutrient solutions. The solutions contained 7 levels of Al ranging from 4 to 1655μMand similar P concentration of 28μM.The nutrient solution pH was maintained at 4.0±0.1 and the temperature at 25±1°C. At high Al treatment levels, plants had thickened root tips and root caps covered with black gelatinous material. At high levels of Al treatments, seedlings of some rootstocks had yellow, mottled, and withered new leaves near end of experiment. New‐growth root lengths and shoot height responded differently to Al concentrations in the nutrient solution. New‐growth fresh weight of whole plants appeared to be the most sensitive indicator of Al tolerance. Based on response of fresh weight of whole plants to Al concentrations, relative Al tolerances of the rootstocks were Cleopatra mandarin > rough lemon > sour orange > Swingle citramelo > Carrizo citrange. The neutral or dividing Al concentrations in solution between beneficial and toxic effects were 371, 193, 189, 178, and < 100μMAl, respectively, for the above rootstocks. Concentrations below or above the neutral Al levels caused either beneficial or toxic effects, respectively. The apparent optimum Al concentrations for the growth of whole plants were 163, 93, 89, 85, and <50μM, respectively.

ISSN:0190-4167    

DOI:10.1080/01904169109364280

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The objective of this study was to determine relations between Al effects and mineral concentrations in citrus seedlings. Six‐month‐old seedlings of five citrus rootstocks were grown for 60 days in supernatant nutrient solutions of Al, P, and other nutrients. The solutions contained seven levels of Al ranging from 4 to 1655μM.Al and similar P concentrations of 28μMP. Aluminum concentrations in roots and shoots increased with increasing Al concentration in the nutrient solution. Aluminum concentrations in roots of Al‐tolerant rootstocks were higher than those of Al‐sensitive rootstocks. When Al concentrations in nutrient solution increased from 4 to 178μM,the K, Mg, and P concentrations in roots and the K and P levels in shoots increased. Conversely, Ca, Zn, Cu, Mn, and Fe in the roots and Ca, Mg, Cu, and Fe in the shoots decreased. The more tolerant rootstocks contained higher Fe concentrations in their roots than did the less tolerant ones when Al concentrations in solution were lower than 308μM.Concentrations of other elements (Ca, K, P, Mg, Zn, and Mn) in roots or shoots exhibited no apparent relationship to the Al tolerance for root or shoot growth of the rootstocks. Calcium, K, Zn, Mn, and Fe concentrations in roots and Mg and K concentrations in shoots of all five rootstocks seedlings had significant negative correlations with Al concentrations in corresponding roots or shoots.

ISSN:0190-4167    

DOI:10.1080/01904169109364281

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor