Fertigation rate,leaching fraction,and growth of potted poinsettia

Single‐pinched poinsettia (Euphorbia pulcherrima ’V‐14 Glory') in 15‐cm pots received constant fertigation with 50, 100, 200, and 300 mg.L^‐1 nitrogen (N) from a 20N‐4.4 phosphorus (P)‐16.6 potassium (K) fertilizer with a leaching fraction (LF) of 0, 0.2, or 0.4. Plants received 25 irrigations during the 13‐week study. The shoot fresh and dry masses with 50, 100, and 300 mg.L^‐1 N at the 0.4 LF were 30% larger than at the 0 LF. The 300 mg.L^‐1 N fertigated plants had approximately 15% more leaf area and almost 122% more bract area than the 50 mg.L^‐1 N fertigated plants. The leaf N concentration of plants fertigated with 100, 200, and 300 mg.L^‐1 N was near or in the normal range of 4 to 6%, but was below the critical level of 3.5% with 50 mg.L^‐1 N fertigation. In contrast, the leaf P concentration approached or exceeded the toxic level of 0.9% with 100 to 300 mg.L^‐1 N. The N fertigation of 100 to 200 mg.L^‐1 is adequate for producing a quality poinsettia crop. Quality poinsettias can be grown at a 0 LF if quality irrigation water is available. With 11 mg.L^‐1 P via fertigation, the leaf P concentration was in the acceptable range. The P concentration in the 20N‐4.4P‐16.6K complete fertilizer was excessive for poinsettia and would contribute to unnecessary P leaching.     

The effect of calcium spray on leaf and bract distortion,bound:unbound calcium ratio,and calcium distribution in two poinsettia cultivars

To determine if direct Ca sprays could affect the distribution and binding of Ca in the leaves and the severity of leaf/bract distortion in two varieties of poinsettia (Euphorbia pulcherimma Willd.), we applied either 100 mg.l^‐1 or 400 mg.1^‐1 of Ca either one time or weekly to leaves of distortion‐ susceptible ('V‐14 Glory') and nonsusceptible ('Annette Hegg Dark Red,’ AHDR) cultivars. Only weekly spraying with 400 mg.l^‐1 Ca reduced distortion in V‐14 plants, compared to controls or AHDR plants. Both bound and unbound Ca concentrations were higher in AHDR leaves than in V‐14 leaves, but these differences were not correlated with distortion severity. EDX analysis demonstrated that distorted regions of V‐14 leaves and bracts had lower Ca concentrations than did undistorted regions or AHDR leaves; weekly spraying with 400 mg.l^‐1 Ca produced relatively uniform leaf Ca distribution in V‐14 leaves. Localized Ca deficiencies appear to produce the bract/leaf distortion in ‘V‐14 Glory’ plants, and these deficiencies can be partially overcome by weekly Ca spray applications.     

The effect of calcium spray on leaf and bract distortion,bound:Unbound calcium ratio,and calcium distribution in two poinsettia cultivars

To deteimine if direct Ca sprays could affect the distribution and binding of Ca in the leaves and the severity of leaf/bract distortion in two varieties of poinsettia (Euphorbia pulcherimma Willd.), we applied either 100 mg.l^‐1 or 400 mg.l^‐1 of Ca either one time or weekly to leaves of distortion‐ susceptible ('V‐14 Glory') and nonsusceptible ('Annette Hegg Dark Red,’ AHDR) cultivars. Only weekly spraying with 400 mg.l^‐1 Ca reduced distortion in V‐14 plants, compared to controls or AHDR plants. Both bound and unbound Ca concentrations were higher in AHDR leaves than in V‐14 leaves, but these differences were not correlated with distortion severity. EDX analysis demonstrated that distorted regions of V‐14 leaves and bracts had lower Ca concentrations than did undistorted regions or AHDR leaves; weekly spraying with 400 mg.r¹ Ca produced relatively uniform leaf Ca distribution in V‐14 leaves. Localized Ca deficiencies appear to produce the bract/leaf distortion in ‘V‐14 Glory plants, and these deficiencies can be partially overcome by weekly Ca spray applications.     

Vanadium induced manganese toxicity in bush bean plants grown in solution culture

Seedlings of two bush bean cultivars (Phaseolus vulqaris L. cvs. Mn‐sensitive ‘Wonder Crop 2’ and Mn‐tolerant ‘Green Lord') were grown for 14 days in full strength Hoagland No. 2 nutrient solution containing 0.05 ‐ 2 mg L^‐1 of vanadium (V) as ammonium vanadate.

Increasing V concentration in the solution decreased total dry weight of both cultivars. Plant tops were stunted and leaf color became dark green at 1 ‐ 2 mg L^‐1 V, especially in ‘Green Lord’. Veinal necrosis similar to that of Mn toxicity was observed in the primary leaves of ‘Wonder Crop 2’ at 0.2 mg L^‐1 V or above, but not in those of ‘Green Lord’.

The V concentrations in the roots increased exponentially with increasing V concentration in the solution; however, V concentrations in the leaves and stems were not affected. The Mn concentrations in the primary leaves increased under the higher V treatment in ‘Wonder Crop 2'; but not in ‘Green Lord’. In contrast, Fe concentration in the leaves of ‘Wonder Crop 2’ decreased markedly with increasing V concentration in the solution. Enhanced Mn uptake and greater reduction of Fe uptake by ‘Wonder Crop 2’ may explain the incidence of V‐induced Mn toxicity.     

IRON STRESS INDUCES PRIMARY AND SECONDARY MICRONUTRIENT STRESSES IN HIGH YIELDING TROPICAL RICE

Two indica rice (Oryza sativa L.) cultivars, viz. ‘Swarna’ and ‘Kalinga III’ were compared for their response to iron (Fe) stress. The cultivars were raised with four Fe levels viz. 0.05, 1, 5, 10 mg L^?1 in hydroponic culture. Plant growth, soluble protein, chlorophyll content and phytoferritin of leaves increased significantly with increase in Fe concentration up to 5 mg L^?1, but decreased at 10 mg L^?1. In contrast, lipid peroxidation, decreased up to 5 mg L^?1 then increased at 10 mg L^?1. However, at 10 mg L^?1 of Fe these parameters were more adversely affected in ‘Swarna’ than ‘Kalinga III’. The later also accumulated relatively more Fe, zinc (Zn), manganese (Mn), and copper (Cu) from the growing medium. Zinc concentrations of the tissue, on the other hand, exhibited the opposite trend. Iron stress may, thus lead to secondary metallic ion stresses and under such situations cultivars like ‘Kalinga III’ will perform better than ‘Swarna’.     

Growth and nutrient content of poinsettia (Euphorbia pulcherrima Willd. ex Klotz) in a soilless growth medium containing sewage sludge pellet fertilizer

The effectiveness sewage sludge pellet fertilizer (SPF) as a nutrient source for containerized poinsettia (Euphorbia pulcherrima Willd. ex Klotz) was determined by comparing the growth and nutrient element content of ‘Eckespoint Celebrate 2’ plants grown with SPF in the growth medium versus plants fertilized with conventional water‐soluble fertilizer (WSF). Plants were grown in 1.6‐L pots of soilless growth medium with SPF incorporated at planting at the rates of 1.0, 1.5, 2.0, 2.5, or 3.0 gm nitrogen (N) pot^‐1. Sludge pellet fertilizer plants received either no WSF or a dilute solution of 2ON‐4.3P‐16.6 potassium (K) (50 mg N L^‐1) twice a week. Control plants had no SPF and were fertilized with WSF at 250 mg N L^‐1 twice a week. At the end of the experiment plant growth measurements were made, leaves were analyzed for their nutrient element content, and growth medium was analyzed for pH and electrical conductivity (EC). Plants grown with SPF, with or without dilute WSF, were of commercially acceptable quality, but were somewhat smaller than the control plants. Plants growing with SPF alone and no WSF developed a chlorosis suggestive of N deficiency which was largely prevented by the application of WSF. Foliar analysis revealed that N in the leaves of plants receiving SPF alone was at the critical level for deficiency established for poinsettia. In treatments where dilute WSF was applied, the N content of the leaves was within the normal range. The foliar levels of all other nutrients fell within the normal ranges established for poinsettia in all SPF treatments. In addition to N deficiency, high growth medium EC at planting and low EC by the end of the experiment might also explain the inhibition of growth with SPF versus the WSF control. Results of this study suggest that poinsettia can be successfully grown using SPF as the sole source of nutrition, however the best growth is possible only when a dilute solution of N‐containing WSF is applied on a regular basis.     

The influence of phosphate fertilizer application levels and cultivars on cadmium uptake by Komatsuna (Brassica rapa L. var. perviridis)

Cadmium (Cd) is a common impurity in phosphate fertilizers and application of phosphate fertilizer may contribute to soil Cd accumulation. Changes in Cd burdens to agricultural soils and the potential for plant Cd accumulation resulting from fertilizer input were investigated in this study. A field experiment was conducted on Haplaquept to investigate the influence of calcium superphosphate on extractable and total soil Cd and on growth and Cd uptake of different Komatsuna (Brassica rapa L. var. perviridis) cultivars. Four cultivars of Komatsuna were grown on the soil and harvested after 60 days. The superphosphate application increased total soil Cd from 2.51 to 2.75?mg?kg^?1, 0.1?mol?L^?1 hydrochloric acid (HCl) extractable Cd from 1.48 to 1.55?mg?kg^?1, 0.01?mol?L^?1 HCl extractable Cd from 0.043 to 0.046?mg?kg^?1 and water extractable Cd from 0.0057 to 0.0077?mg?kg^?1. Cd input reached 5.68?g?ha^–1 at a rate of 240?kg?ha^–1 superphosphate fertilizer application. Superphosphate affected dry-matter yield of leaves to different degrees in each cultivar. ‘Nakamachi’ produced the highest yield in 2008 and ‘Hamami No. 2’ in 2009. Compared with the control (no phosphate fertilizer), application of superphosphate at a rate of 240?kg?ha^–1 increased the Cd concentration in dry leaves by 0.14?mg?kg^?1 in ‘Maruha’, 1.03?mg?kg^?1 in ‘Nakamachi’, 0.63?mg?kg^?1 in ‘SC8-007’ in 2008, and by 0.19?mg?kg^?1 in Maruha’, 0.17?mg?kg^?1 in ‘Hamami No. 2’, while it decreased by 0.27?mg?kg^?1 in ‘Nakamachi’ in 2009. Field experiments in two years demonstrated that applications of different levels of calcium superphosphate did not influence Cd concentration in soil and Komatsuna significantly. However, there was a significant difference in Cd concentration of fresh and dry Komatsuna leaves among four cultivars in 2008 and 2009. The highest Cd concentration was found in the ‘Nakamachi’ cultivar (2.14?mg?kg^?1 in 2008 and 1.91?mg?kg^?1 in 2009). The lowest Cd concentration was observed in the ‘Maruha’ cultivar (1.51?mg?kg^?1?dry weight (DW)) in 2008 and in the ‘Hamami No. 2’ cultivar (1.56?mg?kg^?1?DW) in 2009. A decreasing trend in Cd concentration was found in ‘Nakamachi’, followed by ‘SC8-007’, ‘Hamami No. 2’ and ‘Maruha’ successively. It is necessary to consider a low-uptake cultivar for growing in a Cd polluted soil. In these two years’ results, ‘Maruha’ cultivar was the lowest Cd uptake cultivar compared to the others.     

Differential tolerances of oat cultivars to aluminum in nutrient solutions and in acid soils of Poland

Aluminum tolerant oat cultivars are needed for use on acid soil sites where neutralization of soil acidity by liming is not economically feasible. Oat germplasm in Poland has not been examined for range of Al tolerance. Eleven Polish oat cultivars were screened for Al tolerance in nutrient solutions containing 0, 5 and 15 mg L^‐1 Al. Three of these cultivars showing high to moderate tolerance to Al in nutrient solutions were also grown in greenhouse pots of soil and in field plots of soil over a pH range of 3.8 to 5.5 as determined in 1 N KC1.

The eleven oat cultivars differed significantly in tolerance to Al in nutrient solutions. Based on relative root yield (15 mg L^‐1 Al/no A1%), the cultivars ‘Solidor’ and ‘Diadem’ were most tolerant and ‘Pegaz’ and ‘B‐20’ were least tolerant. For these three cultivars, the order of tolerance to acid soil agreed with the order of tolerance to Al in nutrient solution ‐ namely, Solidor > Diadem > Leanda. Hence, for these cultivars, the nutrient solution methods used appear adequate for selecting plants that are more tolerant to Al in strongly acid soils. Additional study is needed to assess the value of this method for screening a broad range of germplasm.

Superior tolerance of the Solidor cultivar to acid soil was associated with significantly higher concentrations of N in the grain. Hence, results suggest that selecting for acid soil or Al tolerance may increase N efficiency in oats.     

Zinc accumulation in lettuce cultivars grown with organic or chemical based nutritional regimes

This study determined the potential to increase Zn density of lettuce (Lactuca sativa L.) through cultivar selection and nutrient management. Organic fertilizer and Hoagland and Arnon no.1 solution factored with three zinc (Zn) levels provided as zinc sulfate (ZnSO₄) were the fertilizer regimes in a greenhouse experiment. Modern cultivars had a 32% higher fresh head weight than heritage cultivars, but each accumulated the same Zn concentration (65 mg kg^?1 dry wt). Butterhead phenotypes had a 38% lower yield than loose-leaf and had the highest Zn concentration (78 mg kg^?1 dry wt) followed by romaine (66 mg kg^?1 dry wt) and loose-leaf (53 mg kg^?1 dry wt). Concentration of Zn did not differ between fertility regimes, being about 66 mg kg^?1 dry wt with each regime. Differences in Zn concentrations were significant among individual cultivars with ranges from 42 mg g^?1 dry wt to 91 mg kg^?1 dry wt. ‘Tom Thumb’, ‘Adriana’, ‘Claremont’, and ‘Focea’ were the top in cultivar ranking, with mean Zn concentration of 63 mg kg^?1 dry wt. The results signify that selection of cultivars may be utilized to increase Zn accumulation in lettuce but that nutritional regimes had little effect on accumulation.     

Optimum Nutrient Level on Growth,Flowering, and Rhizome Production in Curcuma

ABSTRACT

This study investigated the effect of liquid fertilizer treatments on growth, flowering, leaf mineral content, and rhizome production during forcing of Curcuma alismatifolia ‘Chiang Mai Pink’ and C. thorelii ‘Chiang Mai Snow’. Plants were irrigated with 200 mL of 1.3 g L^?1 of 15 nitrogen (N) -7 phosphorus (P) -14 potassium (K) water soluble fertilizer at 0, 1.3, 2.7, 4.0, 5.3, or 6.6 g L^?1 weekly. Days to flower, flower stem length, and leaf length were recorded, the mineral contents in leaves were analyzed, and the number of rhizomes with tuberous roots were recorded at harvest. Flowering of the first inflorescence in both C. alismatifolia ‘Chiang Mai Pink’ and C. thorelii ‘Chiang Mai Snow’ was significantly delayed when plants received 6.6 g L^?1 fertilizer as compared to the control plants. The number of rhizomes with more than 4 tuberous roots was highest when plants received 2.7 g L^?1 fertilizer. No medium-sized rhizomes with more than seven tuberous roots were produced when ‘Chiang Mai Pink’ plants received 0, 4.0, 5.3, and 6.6 g L^?1 fertilizer. Based on the production of rhizomes with four to six tuberous roots, optimum concentration of 15N -7P -14K water soluble fertilizer is 2.7 g L^?1 for C. alismatifolia ‘Chiang Mai Pink’ and 1.3 to 4.0 g L^?1 for C. thorelii ‘Chiang Mai Snow’. Although high boron content occurred only in the outer part of the second leaf when fertilizer concentrations were increased, leaf-margin burn (LMB) symptoms were not observed in both species and this could not be related to the production of rhizomes.     

Effect of applying calcium chloride and three milk supplements to poinsettia ‘Prestige Red’

Some poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) cultivars are susceptible to bract calcium (Ca) deficiency in developing bracts. In this study, we evaluated the efficacy of foliar uptake of Ca from milk-based products plus calcium chloride (CaCl₂) as a potential Ca source. Weekly foliar applications of 237 mL L^?1 whole milk, 80 mL L^?1 powdered milk, 30 mL L^?1 condensed milk, 0.94 g L^?1 CaCl₂, or distilled water (used as a control) were applied to runoff of ‘Prestige Red’ for four weeks. The four largest bracts with petioles on three different inflorescences and three leaves with petioles below the transitional leaf per inflorescence were collected per pot. None of the treatments affected bract or leaf Ca concentration. Powdered milk treatments resulted in a higher concentration of zinc (Zn) in bracts and aluminum (Al) in bracts and leaves. White residue remained on the bracts and leaves after treatment with powdered milk, which would reduce marketability.     

Effect of saline irrigation on the biomass yield,and the protein,nitrogen, phosphorus,and potassium composition of alfalfa in a pot experiment

During 1994–1995, field experiments were conducted in six apple orchards located in the southwest of Finland (the mainland and the Åland Islands). The cultivars were ‘Melba’, ‘Raike’, ‘Red Atlas’, ‘Lobo’, ‘Aroma’, and ‘Åkero’. Fruit samples were picked at about one week before commercial maturity and stored for three to six months at 2 to 4°C and 85–95% relative humidity. During storage the percentage of physiological disorders was visually recorded. Fruit nitrogen (N) and calcium (Ca), firmness, diameter, juice titratable acidity (TA), and soluble solids concentrations (SSC) were determined at harvest. Nitrogen and Ca in the soil and leaves collected during fruit development were determined. The ranges in fruit N were 296–624 and Ca 27–68 mg kg^‐1 fresh weight, and in the leaves N 15–23 and Ca 9–19 g kg^‐1 dry matter. The N/Ca ratio was 5 and 16 and 0.9 and 2.3 in fruit and leaves, respectively. There was more variation between years in N and Ca contents of leaves than that of fruit. Other fruit quality characteristics varied between seasons and cultivars. Leaf N correlated positively with fruit diameter and negatively with fruit dry matter. The incidence of physiological disorders on apples after three month storage was 2 to 13% and after six months 10 to 95%. Fruit with Ca content below 45 mg kg^‐1 fresh weight were susceptible to bitter pit ('Aroma’ and ‘Åkero') and Jonathan spot ('Red Atlas'). The cultivar ‘Melba’ was susceptible to bruising damages and ‘Raike’ and ‘Red Atlas’ were affected more with internal breakdown and core browning.     

Growth and cadmium accumulation in selected switchgrass cultivars

Abstract

Switchgrass (Panicum virgatum L.) has potential as a sustainable biofuel crop. Utilizing alternative sources of fertilizer nutrients could enhance production of switchgrass. However, alternative sources of fertilizer such as sewage sludge sometimes contain heavy metals such as cadmium (Cd) and the response of switchgrass to Cd is not known. Four switchgrass cultivars (Alamo, Blackwell, Cave‐in‐Rock, and Trailblazer) grown in sand culture were watered twice weekly with a nutrient solution containing Cd. Cadmium levels in solution were 0, 1, 2, 4, 8, and 16 mg Cd L^‐1. Plants were harvested 63 d after planting and separated into leaf blade, stem (culm + leaf sheath), and root components. Tissue Cd concentrations were determined using atomic absorption spectrophotometry. Cultivars differed (P<0.05) by less than 15% for biomass accumulation and allocation among plant parts. Cadmium levels of 16 mg L^‐1 reduced biomass yields by 31% for roots, 39% for leaf blades, and 47% for stems as compared to no added Cd. At 16 mg Cd L^‐1, Cd concentration in leaf blades was 9.9 mg kg^‐1. The highest levels of Cd (329 mg kg^‐1) were found in roots of Blackwell and Trailblazer grown at the highest Cd level. Cadmium at 16 mg Cd L^‐1 is phytotoxic to switchgrass and accumulates in all plant parts. The cultivars tested in this study did not differ in biomass accumulation in response to Cd; however, Cd accumulation in plant parts differed among cultivars. Consideration of Cd uptake should be a part of switchgrass cultivar selection when grown in the presence of Cd.     

SUBSOIL ROOT GROWTH OF FIELD GROWN SPRING WHEAT GENOTYPES (TRITICUM AESTIVUM L.) DIFFERING IN NITROGEN USE EFFICIENCY PARAMETERS

In a two-year (1999–2000) field experiment four Swiss spring wheat (Triticum aestivum L.) genotypes (cvs. ‘Albis’, ‘Toronit’ and ‘Pizol’ and an experimental line ‘L94491’) were compared for genotypic differences in the root parameters that determine uptake potential and nitrogen use efficiency (NUE):root surface area (RSA) and its components, root length density (RLD) and the diameter of the roots. The genotypes were grown under no (N0) and under ample fertilizer nitrogen (N) [ammonium nitrate (NH₄NO₃); N1; 250 kg N ha^?1] supply. Root samples were taken from all the genotypes at anthesis from the subsoil (30–60 cm). Genotypic effects on RLD and RSA were evident only in 2000 and large amounts of N fertilizer usually diminished root growth. Adequate soil moisture in 1999 may have favored the establishment of the root system of all the genotypes before anthesis. Parameters of NUE for each genotype were also determined at anthesis and at physiological maturity. ‘Albis’ the least efficient cv. in recovering fertilizer N (ranged from 36.5 to 61.1%) with the lowest N uptake efficiency (0.47 to 0.79 kg kg^?1) had the lowest RLD and RSA in both seasons. Among genotypes ‘Toronit’, a high-yielding cv., efficient in recovering fertilizer N, exhibited the higher NUE (22.4 to 29.3 kg kg^?1) and tended to have the highest values of RLD and RSA. Nitrogen fertilization also led to an increase in the proportion of roots with diameters less than 300 μm and decreased the proportion of roots with diameters of 300 to 700 μm. These trends were more pronounced for cv. ‘Pizol’ in 1999 and for cv. ‘Toronit’ in 1999 and 2000. By anthesis in a humid temperate climate, there are no marked differences in the subsoil root growth of the examined genotypes. Some peculiarities on the root growth characteristics of the cultivars ‘Albis’ and ‘Toronit’ may partially explain their different NUE performance.     

Phosphorus and acid phosphatase enzyme activity in leaves of tomato cultivars in relation to zinc supply

Abstract

Tomato cultivars Blizzard and Liberto were grown hydroponically in a controlled temperature (C.T.) room for 35 days. The objective was to investigate the relationship between phosphorus (P) concentration and acid phosphatase enzyme [EC.3.1.3.2.] (APE) activity in leaves in relation to zinc (Zn) concentration in nutrient solution. Zinc was added at concentrations of 0.01,0.5, and 5 mg L^‐1. The 0.01 and 5 mg L^‐1 Zn treatments led to a significant reduction in dry matter and total chlorophyll content compared with 0.5 mg L^‐1 for both cultivars. Zinc concentration was considered inadequate in the leaves of plants subjected to 0.01 mg L^‐1 Zn, while it was at toxic level in those in the 5 mg L^‐1 Zn treatment according to values stated for tomato plants. Optimal results for all criteria tested in this experiment were for plants grown in 0.5 mg L^‐1 Zn treatment. In the leaves of plants grown at 0.01 mg L^‐1 Zn, APE concentrations were significantly the lowest and concentrations of P were at a toxic level. The APE activity was noticeably higher in the P‐deficient plants of both cultivars grown in the solutions with high Zn (5 mg L^‐1).     

Supplements of Nickel Affect Yield,Quality, and Nitrogen Metabolism When Urea or Nitrate is the Sole Nitrogen Source for Cucumber

ABSTRACT

Influences of nickel (Ni) concentrations in the nutrient solution on yield, quality, and nitrogen (N) metabolism of cucumber plants (Cucumis sativus cv ‘RS189’ and ‘Vikima’) were evaluated when plants were grown either with urea or nitrate as the sole N source. The cucumber plants were treated with two N sources, urea and nitrate as sodium nitrate (NaNO₃) at 200 mg L^?1, and three concentrations of Ni as nickel sulfate (NiSO₄·6H₂O; 0, 0.5, and 1 mg L^?1). Treatments were arranged in a randomized block design with six replicates. The highest concentration of Ni in the leaves (1.2 mg kg^?1 Dwt) was observed in the urea-fed plants at 1 mg L^?1 Ni concentration. Additions of Ni up to 0.5 mg L^?1 had no effect on the fruit Ni concentration in the both urea and nitrate-fed plants. Yield significantly (p < 0.05) increased with the Ni supplements from 0 to 0.5 mg L^?1 (10 and 15% in ‘RS189’ and ‘Vikima’, respectively), but decreased when 1 mg L^?1 Ni applied to the solutions in urea-fed plants. Nitrate-fed plants had a higher percentage of total soluble solids compare to those urea-fed plants. Nitrate concentrations of the fruits in urea-fed plants in both cultivars were reduced by approximately 50% compared to those nitrate-fed plants. The reduction of nitrate concentration in the fruits became more pronounced as the Ni concentration increased in the solution. The rate of photosynthesis (Pn) increased with the increase of the Ni concentration in the solution with urea-fed plants. Both N concentration and nitrate reductase (NR) activity of young leaves were higher in urea-fed plants at 0.5 mg l^?1 Ni concentration. Ni supplements enhanced the growth and yield of urea-fed plants by increasing Pn, N concentration and NR activity. It can be concluded that Ni supplements (0.5 mg l^?1) improve yield, quality, and NR activity in urea-fed cucumber plants.     

Effects of Compost Source and Timing of Fertigation Initiation on Growth of Potted Poinsettia

Treatment combinations of four poinsettia (Euphorbia pulcherrima) cultivars, 20 substrates, and three fertigation treatments were evaluated in a completely randomized block design. Poinsettia cultivars included ‘V-14 Glory’, ‘Red Sails’, ‘Lilo Pink’, and ‘Annette Hegg Top White’. The compost substrates were compost:peat:perlite blended (by vol.) at 2:3:3, 1:1:1, and 2:1:1 ratios. Sunshine Mix 1 and Pro Gro 300S were used as controls. Composts tested were those prepared from crab offal, lime and polymer-dewatered biosolids, municipal solid waste (MSW), yard waste, and poultry litter. Fertigation treatments were initiated on the week of potting, delayed one or two week after potting and applied once per week. Controls produced premium quality plants. Composts prepared from poultry litter, yard waste, polymer-dewatered biosolids, crab offal, and MSW produced good quality plants. Plant width in 25 percent compost treatments were greater than those in 50 percent compost treatments. Total number of branches, plant height, canopy diameter, and plant grade on plants treated with fertilizer on the first week were only three percent greater than in treatments where fertilizer application was delayed one or two weeks.     

DETERMINING THE ZINC REQUIREMENT OF ONION BY SEED ANALYSIS

Our study analyzed the effect of foliar tissues and seed tissue for determining the micronutrient status of a crop. Zinc (Zn) requirements of onion (Allium cepa L.) leaves and seeds were estimated from yield response curves based on field experiment conducted on a Zn-deficient calcareous soil. Three onion cultivars, i.e., ‘Swat-1’, ‘Phulkara’, and ‘Sariab Red’ were grown by applying 0, 2, 4, 8, and 16 kg Zn ha^?1. Zinc application significantly increased seed yield of all the three cultivars of onion. The order of seed yield response to Zn fertilization was: ‘Swat-1’ < ‘Phulkara’ < ‘Sariab Red’. Fertilizer Zn requirement for near-maximum seed yield was 2 kg Zn ha^?1. Zinc concentration in mature onion seed also appeared to be a good indicator of soil Zn availability status. Critical Zn concentration in seed was 18 mg Zn kg^?1, and in matured leaves was 21 mg kg^?1.     

Effects of Some Organic Nitrogen Sources and Antibiotics on Callus Growth of Indica Rice Cultivars

A factorial experiment based on a completely randomized design with three replicates was conducted to evaluate effects of sixteen different mixtures of organic nitrogen sources and antibiotics which were supplemented to an Murashige and Skoog (MS) medium containing 4 mg L^?1 2,4-Dichlorophenoxyacetic acid (2,4-D), 0.4 mg L^?1 benzyl-aminopurine (BAP), 30 g L^?1 sucrose, 8 g L^?1 Agar-agar on fresh weight and dry weight (assessed after three days of drying at 70°C) of calli and in vitro callogenesis from scutellum of four indigenous Iranian Indica rice (Oryza sativa L.) cultivars, including ‘Hashemi’, ‘Gerdeh’, ‘Hasani’, and ‘Gharib’. It was found that proline at 2.8 g L^?1 is the most effective source of organic nitrogen in enhancing growth, whereas asparagine at 0.75 g L^?1 inhibited the calli growth. Hygromycin at 50 mg L^?1, with slight differences between the cultivars, could effectively stunt the growth of untransformed calli. Mixture of cefotaxime (250 mg L^?1) and vancomycin (250 mg L^?1) did not have any significant effects on calli growth, although this treatment was slightly phytotoxic.     

Comparison of hydroponic solutions for poinsettia nutritional studies 1

Poinsettia cultivars Supjibi and Freedom were grown in eight hydroponic solutions to develop a baseline solution for further nutritional studies. Four solutions contained nitrogen (N) from Ca(NO₃)₂‐4H₂O and KNO₃ (denoted as ‐NH₄) and four contained Ca(NO₃)₂‐4H₂O, KNO₃, nitric acid, and NH₄NO₃ as the N sources (denoted as +NH₄). The four ‐NH₄ and +NH₄ solutions were further divided by an IX or 2X rate of micronutrients [boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), and zinc (Zn)] (denoted as IX or 2X). A factorial of these four solutions at 2 concentrations (100 mg L¹ of N and potassium (K) and 15 mg L¹ phosphorus (P), or 300 mg L¹ of N and K and 46 mg L^‐1 P) was studied. Greater leaf and stem dry weight for both ‘Supjibi’ and ‘Freedom’ was observed in plants grown with the +NH₄ solutions, with a larger increase occurring with’ Supjibi’. Leaf NH₄‐N content for both cultivars was higher for both the 100 and 300 mg L^‐1 N and K fertilization rates when NH₄‐N was included. The leaf K content was highest for the plants grown with the +NH/2X solution for ‘Supjibi’, for both fertilization rates, and leaf K content increased as the K application rate increased. Results indicate that for nutritional studies with poinsettias, hydroponic solutions should include between 12.5% to 33% of the N in the NH₄ form, a calcium magnesium (Ca:Mg) ratio of 2:1, and a micronutrient concentration of (mg I/¹) 0.5, 0.02, 6.6, 0.5, 0.1, and 0.05, respectively, for B, Cu, Fe, Mn, Mo, and Zn, for adequate plant growth.