Season-Dependent Fruit Loading: Effect on Nutrient Homeostasis of Tomato Plants

ABSTRACT

Greenhouse tomato plants were grown hydroponically during the period of lower temperatures of winter (LT) versus the period of higher temperatures of summer (HT). In these plants, the effect of season on fruit load was dramatic. In order to study the alterations season introduces to the developmental allocation of nutrients within the various organs, concentrations of total nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) were determined during each season at weekly intervals in the dry mass of leaves and roots and in the extract of upper, middle, and lower parts of the stem. The level of N/P ratio was always higher in the leaves than in the roots, and these differences were more intense during HT. The short-term changes of ratio in the leaves during HT and LT were positively related with the changes in temperature (r = 0.59 and 0.51 for HT and LT, respectively). In contrast, such correlations in the root were negative (r = ?0.54 and r = ?0.33 for HT and LT, respectively). The increase of temperature increased P uptake but not its translocation to upper plant parts. HT affected the translocation of N, K, Mg, and Ca more and their uptake less. Fruit load differentially affected the concentration of nutrients. In contrast to total N and K, Ca concentration in plant parts presented a positive relation with the increase of fruit load. Calcium and total N concentration (as opposed to P and micronutrient concentrations) were always higher in the leaves than in the roots. Under HT conditions, P was accumulated in roots in combination with high concentrations of Fe, Zn, and Mn. On the other hand, K and N were accumulated in the roots during the period of low temperature in winter. Calcium and K compared with other nutrients presented a pronounced tendency to be transported toward the top of the stem during HT, and their extractable concentration in the upper part of stem presented a significant increase during summer. Extractable K concentration was two to nine times higher than that of the other macronutrients. Our data suggest that the extractable concentration of nutrients of the stem is a good index for the diagnosis of the mineral nutritional status of the plant.     

Balance and concentration of nitrogen and potassium affect growth and nutrient status in soilless cultivated lisianthus

Purpose: Nitrogen (N) / potassium (K) nutrient balance has been studied for some ornamental plants, however, available information is limited. Here we investigate the optimum N and K balance and concentration for lisianthus production in soilless medium.

Materials and methods: The effect of three N / K balances: 1.43, 2.14 and 4.29, prepared by varying the concentration of N and K, were evaluated in lisianthus grown in soilless medium (volcanic rock).

Results: Plants fertigated with a N / K balance of 2.14 exhibited enhanced height and stem dry weight when compared to plants fertigated with a balance of 4.29, and a higher flower buds count and total dry weight than those fertigated with a balance of 1.43 or 4.29. Plants fertigated with a balance of 2.14 exhibited increased dry weight when N was reduced from 15 to 9?meq?L^?1 and K from 7 to 4.2?meq?L^?1, suggesting that lisianthus does not require high levels of these nutrients. Although shoot N concentration was not correlated with N concentration in the nutrient solution or balance, increasing N in the shoot was associated with higher P and Mg in the plant tissues. In general, P, Ca, and Mg in plant tissues were unaffected by the external N / K balance, however, the internal P and Mg concentrations were positively correlated with shoot dry weight. Shoot K concentration significantly increased when the N / K balance decreased, which is related to the higher concentrations of external K when the balance decreased.

Conclusions: The optimum N / K balance for lisianthus was 2.14. However, there was a concentration effect, as fertigation with solutions containing a N / K balance of 2.14 and an N and K concentration of 9 and 4.2?meq?L^?1 respectively, resulted in plants with the greatest dry weight.     

Influence of Potassium Substitution by Rubidium and Sodium on Growth,Ion Accumulation,and Ion Partitioning in Bean under High Alkalinity

ABSTRACT

The effects of partial and complete substitution of potassium (K⁺) by rubidium (Rb⁺) and sodium (Na⁺) on plant growth and ion accumulation and partitioning was studied in bean young plants cultivated in nutrient solution with or without bicarbonate (HCO₃ ^?)-induced alkalinity. Plant growth was significantly decreased due to alkalinity and the substitution of K⁺, being leaves more affected than roots. Rubidium caused a severe toxicity reflected in a reduction in root dry mass and total chlorophyll concentration. Ion partitioning was markedly altered by alkalinity. Content of nitrogen (N), calcium (Ca), magnesium (Mg), iron (Fe), K, and Na were more accumulated in the roots in HCO₃ ^?-treated plants, while decreased in the shoot. Iron (Fe) was accumulated at similar extent in plants with and without high alkalinity, except in plants grown in Rb⁺ solutions. However, Fe was more accumulated in the roots, suggesting that chlorophyll synthesis was impaired by reduced translocation or internal inactivation of Fe. Zinc total uptake was severely reduced under high alkalinity in plants grown in Na⁺ solutions, maybe due to decreased Zn activity. Calcium was translocated more actively to the leaves and Mg was accumulated more in the roots of plants in Na⁺solutions. Despite the severe decrease in plant dry mass caused by Rb⁺, there was a higher translocation of N, phosphorus (P), Ca, Mg, Fe, zinc (Zn), copper (Cu), and manganese (Mn) from the roots to the leaves.     

Cadmium bioavailability to Nicotiana tabacum L., Nicotiana rustica L., and Zea mays L. grown in soil amended or not amended with cadmium nitrate

Summary Mature (flowering) tobacco (Nicotiana tabacum cv. PBD6, Nicotiana rustica cv. Brasilia) and maize (Zea mays cv. INRA 260) plants were grown in an acid sandy-clay soil, enriched to 5.4 mg Cd kg^–1 dry weight soil with cadmium nitrate. The plants were grown in containers in the open air. No visible symptoms of Cd toxicity developed on plant shoots over the 2-month growing period. Dry-matter yields showed that while the Nicotiana spp. were unaffected by the Cd application the yield of Z. mays decreased by 21%. Cd accumulation and distribution in leaves, stems and roots were examined. In the control treatment (0.44 mg Cd kg^–1 dry weight soil), plant Cd levels ranged from 0.4 to 6.8 mg kg^–1 dry weight depending on plant species and plant parts. Soil Cd enrichment invariably increased the Cd concentrations in plant parts, which varied from 10.1 to 164 mg kg^–1 dry weight. The maximum Cd concentrations occurred in the leaves of N. tabacum. In N. rustica 75% of the total Cd taken up by the plant was transported to the leaves, and 81% for N. tabacum irrespective of the Cd level in the soil. In contrast, the Cd concentrations in maize roots were almost five times higher than those in the leaves. More than 50% of the total Cd taken up by maize was retained in the roots at both soil Cd levels. The Cd level in N. tabacum leaves was 1.5 and 2 times higher at the low and high Cd soil level, respectively, than that in N. rustica leaves, but no significant difference was found in root Cd concentrations between the two Nicotiana spp.Cd bioavailability was calculated as the ratio of the Cd level in the control plants to that in the soil or as the ratio of the additional Cd taken up from cadmium nitrate to the amount of Cd applied. The results showed that the plant species used can be ranked in a decreasing order as follows: N. tabacum > N. rustica > Z. mays.     

Growth and nitrogen fixation by Medicago littoralis in pot experiments: Effect of plant density and competition from Lolium multiflorum

The legume Medicago littoralis cv. Harbinger, was grown either alone (1–4 plants per pot) or with Lolium multiflorum (ryegrass) at a total of 4 plants per pot, using two soils of contrasting N status. An ¹⁵N dilution technique was used to distinguish the amounts of plant N due to N₂ fixation and to N uptake from soil. Medic outyielded (dry weight and total plant N) ryegrass in a soil which released low amounts of inorganic N (Roseworthy) but ryegrass outyielded medic in a soil of higher N availability (Avon).For both soils, all combinations of medic and ryegrass plants utilized 70–73% of the inorganic N released on incubation. Competition from ryegrass invariably reduced yields of dry matter, total N, and fixed N of the medic plants, especially in the Avon soil. For both soils, the percentage reduction in the amounts of fixed N resulting from competition from ryegrass was directly proportional to the percentage increase of plant dry matter due to ryegrass. Medic plants grown in Roseworthy soil contained much higher proportions of N due to N₂-fixation than did medic plants grown in Avon soil. The amounts of plant N, fixed N and plant dry weight increased with increasing numbers of medic plants, when grown alone in Roseworthy soil, but not in the Avon soil containing more than two plants per pot. Nevertheless, irrespective of the soil used, medic numbers per pot, or competition from ryegrass, the amounts of fixed N correlated well with total N and with dry matter yields of medic plants. The proportions of fixed N to total N varied consistently in each of the medic plant parts (roots < = leaves < stems < pods).     

Metabolite profiling of shoot extract,root extract,and root exudate of rice under nitrogen and phosphorus deficiency

ABSTRACT

Root exudate is derived from plant metabolites and its composition is affected by plant nutrient status. A deficiency of mineral nutrients, such as nitrogen (N) and phosphorus (P), strongly affects the type and amount of plant metabolites. We applied a metabolite profiling technique to investigate root exudates of rice plants under N and P deficiency. Oryza sativa was grown in culture solution containing two N levels (0 and 60 mg N L^?1) or two P levels (0 and 8 mg P L^?1). Shoot extracts, root extracts, and root exudates were obtained from the rice plants 5 and 15 days after transplanting and their metabolites were determined by capillary electrophoresis/time-of-flight mass spectrometry. Shoot N concentration and dry weight of rice plants grown at ?N level were lower than those of plants grown at +N level. Shoot P concentration and dry weight of rice plants grown at ?P level were lower than those of plants grown at +P level. One hundred and thirty-two, 127, and 98 metabolites were identified in shoot extracts, root extracts, and root exudates, respectively, at the two N levels. One hundred and thirty-two, 128, and 99 metabolites were identified in shoot extracts, root extracts, and root exudates, respectively, at the two P levels. Seventy-seven percent of the metabolites were exuded to the rhizosphere. The concentrations of betaine, gamma-aminobutyric acid, and glutarate in root exudates were higher at both ?N and ?P levels than at their respective high levels. The concentration of spermidine in root exudates was lower at both ?N and ?P levels than at their respective high levels. The concentrations of the other metabolites in root exudates were affected differently by plant N or P status. These results suggest that rice roots actively release many metabolites in response to N and P deficiency.     

高温胁迫下水稻氨基酸态氮与铵态氮营养效应研究

在高温胁迫无菌砂培条件下对无机氮 (硫酸铵 )、有机氮 (甘氨酸 ,谷氨酸和赖氨酸 )和缺氮 (对照 )培养的水稻植株干物重、总氮量及其根、叶谷草转氨酶 (GOT)和谷丙转氨酶 (GPT)活性作了研究。结果表明 ,有机、无机氮均被水稻吸收 ,且吸收量相当。低浓度无机氮 (N 10mg/L)或有机氮培养 2 0d后的水稻植株总氮量比对照的高 50%以上 ;无机氮培养的植株干物重显著低于有机氮培养和对照 ,表明植株受NH4+毒害。培养 15d后 ,多数有机氮培养的植株根或叶GOT或GPT活性显著高于对照 ,但根、叶间有较大差别 ;而无机氮培养的植株根GOT及根、叶GPT活性是对照的 2倍或以上。高浓度无机氮 (N 500mg/L)处理 6h后稻株根、叶GPT活性分别是对照的2.5和4倍 ,而高浓度甘氨酸 ,谷氨酸和赖氨酸态氮 (N 500mg /L)处理 6h后 ,根、叶GPT活性分别是对照的 5.7、9.4、1.9倍及1.8、2.3、1.4倍。     

施氮对镉胁迫下杂交相思树生长及镉吸收分配的影响

【目的】研究不同水平氮的供应对木本固氮植物杂交相思树适应镉环境胁迫及其生物修复能力的影响,可为有目的地进行相思树栽培提供施肥依据。【方法】以杂交相思树 (Acacia mangium × Acacia auriculiformis) 为试材进行了盆栽试验。Cd2+ 设3个水平(0、30、60 mg/kg),在Cd2+ 30 mg/kg的基础上设施尿素2个水平(0.4、0.8 g/kg) ,共5个处理。研究了杂交相思幼苗的干物质、氮(N)、磷(P)、钾(K)、镉(Cd)的积累和分配规律。【结果】Cd2+ 胁迫显著抑制了杂交相思幼苗根、茎、叶和总干物质的积累,限制了N、P、K等元素的吸收和积累;杂交相思Cd转移系数为0.044～0.224,根Cd含量明显高于茎和叶,并且根部Cd累积能力要大于地上部;但Cd2+ 60 mg/kg胁迫下,杂交相思通过向地上部分转移Cd以更好地适应强胁迫环境。Cd2+ 30 mg/kg胁迫下,高氮 (0.8 g/kg) 较低氮 (0.4 g/kg) 更显著地促进了茎、叶和植株总的P、K积累,而低氮更有效地增加了根的N、P、K积累量;高氮较低氮更显著地提高了茎、叶干重以及干物质在茎叶中的分配比例,低氮则提高了根干重以及干物质在根中的分配比例和根冠比;Cd2+ 胁迫下施氮显著促进了杂交相思对Cd的吸收和积累,提高了Cd转移系数;低氮更显著地促进了根、叶和总Cd的积累,高氮更显著地促进了茎Cd的积累及Cd在茎、叶中的分配比例。【结论】Cd2+ 胁迫下杂交相思通过改变干物质及N、P、K、Cd积累和分配规律以及提高N、P和K利用率的方式,保证根系生长,以更好地适应胁迫环境。低Cd2+ 胁迫下 (30 mg/kg),施氮可缓解杂交相思由镉胁迫所引起的对N、K吸收的抑制,促进杂交相思各器官干物质以及N、P、K、Cd的积累。低施氮量 (尿素 0.4 g/kg) 促进相思树生长的效果更佳,高施氮量 (尿素 0.8 g/kg) 促进Cd向地上部的运转,提高其对Cd生物修复能力。     

Supplementary Potassium Nitrate Improves Salt Tolerance in Bell Pepper Plants

Abstract

The effect of supplementary potassium nitrate (KNO₃) on growth and yield of bell pepper (Capsicum annum cv. 11B 14) plants grown in containers under high root‐zone salinity was investigated. Treatments were (1) control, soil only and (2) high salt treatment, as for control plus 3.5 g NaCl kg^?1 soil. Above treatments were combined with or without either 0.5 or 1 g supplementary KNO₃ kg^?1 soil. Plants grown at high NaCl had significantly less dry matter, fruit yield, and chlorophyll than those in the control treatment. Supplementing the high salt soil with 0.5 and 1 g KNO₃ kg^?1 increased plant dry matter, fruit yield, and chlorophyll concentrations as compared to high salt treatment. Membrane permeability increased significantly with high NaCl application, but less so when supplementary KNO₃ was applied. High NaCl resulted in plants with very leaky root systems as measured by high K efflux; rate of leakage was reduced by supplementary KNO₃. These data suggest that NaCl status affect root membrane integrity. Sodium (Na) concentration in plant tissues increased in leaves and roots in the elevated NaCl treatment as compared to control treatment. Concentrations of K and N in leaves were significantly lower in the high salt treatment than in the control. For the high salt treatment, supplementing the soil with KNO₃ at 1 g kg^?1 resulted in K and N levels similar to those of the control. These results support the view that supplementary KNO₃ can overcome the effects of high salinity on fruit yield and whole plant biomass in pepper plants.     

Organic amendments and urea nitrogen effects the growth and nutrient content of fenugreek (Trigonella foenumgraecum) and goat pea (Securigera securidaca)

Abstract

In Iran, the recent spike in herbal medicines has led to a corresponding price increase. Therefore, these montane species are now widely field cultivated. Medicinal plant consumers strongly prefer organically grown plants, and farmers are responding to this market. However, the effects of organic amendments on medicinal plant nutrient content and yield have been poorly studied. Therefore, this study measured the effects of different organic treatments on the growth of fenugreek and goat pea. Plants were grown to compare the effects of composted municipal waste (CMW), vermicompost (VC), and urea nitrogen (N) to untreated field soil (C0). Germination percentage was significantly higher in urea N (76.5%), CMW (75.5%), and VC (51.6%) compared to C0 (36.3%). Fenugreek performed better in organic amendment treatments than goat pea. Urea N also increased fenugreek plant dry matter significantly compared to C0, but this increment was not as high as CMW or VC. Plants grown in VC had higher whole plant N content (3.2%) than those grown in CMW (2.8%) and plants grown in urea N (2.6%). Plants treated with CMW (8613?mg kg^?1) and VC (8503?mg kg^?1) had a significantly higher P content than those treated with N (7430?mg kg^?1) or C0 control grown (7236?mg kg^?1). Application of VC significantly increased plant K content (2483?mg kg^?1) compared to CMW (1850?mg kg^?1), N (1750?mg kg^?1), and C0 control (1716?mg kg^?1). Even without fertilization, both plant species contained a considerable amount of micronutrient elements.     

Genotypic Variation of Sweetpotatoes Grown Under Low Potassium Stress

Abstract

Ninety‐four sweetpotato (Ipomoea batatas L.) genotypes were compared under low potassium (K) stress (35 mg kg^?1 dry soil) over two growing seasons. Potassium utilization efficiency ratio (KER), defined as the dry matter weight/K content, was significantly different among genotypes. Genotypes were divisible into four KER categories: high efficient, efficient, fairly efficient and inefficient with most of the genotypes falling in the efficient and fairly efficient groups. The K contents varied significantly within individual plants. Potassium concentration on a dry weight basis was greatest in the petioles followed by leaves, stems, and roots. On a total plant basis, K content in roots was greatest followed by stems, leaves, and petioles. Several genotypes (including 602 × 81‐3, Zhe15‐47 and Xushu18) were selected as most suitable for growth on soils low in available K due to their appreciable yields and higher KER under low K stress.     

Effects of humic and fulvic acids on growth of tobacco. 2. Tobacco growth and ion uptake 1

Experiments were conducted in growth chambers of the Phytotron to evaluate the effects of humic and fulvic acids on growth and ion uptake by tobacco plants grown to flowering.

When small amounts of humic or fulvic acids were added to media used to grow seedlings, the dry weight of roots and tops and the height of the plants subsequently grown in a nutrient solution with small amounts of humic or fulvic acids increased, while at high rates of humic acids they decreased. Generally, there was a trend for low rates of humic acids to increase concentration of Ca and Mg in roots and leaves and to decrease Fe concentration in roots.

The total content of N, K, P, Ca, Mg and Fe in the stalk and leaves increased in the presence of small amounts of humic or fulvic acids in the nutrient solution. Low rates of humic or fulvic acids in the growth medium facilitated the adsorption of Ca, Mg and Fe and their translocation within the plant. For high rates of humic acids there was a trend to decrease the total content of N, K, P, Ca and Fe in the roots and leaves of the plant.     

Translocation and accumulation of heavy metals in Ocimum basilicum L. plants grown in a mining-contaminated soil

Purpose

The evaluation of the ecotoxicity effects of some heavy metals on the plant growth and metal accumulation in Ocimum basilicum L. cultivated on unpolluted and polluted soils represented the objective of the present study.

Materials and methods

The basil aromatic herb was evaluated in a laboratory experiment using soil contaminated with Cd, Co, Cr, Cu, Ni, Pb, and Zn, similar to the one from a mining area. The soils and different organs of the basil plants were analyzed, the total contents of the added elements being determined using inductively coupled plasma optical emission spectrometry. The ability of basil plants to accumulate metals from soil and to translocate them in their organs was evaluated by transfer coefficient, translocation factor, enrichment factor, and geo-accumulation index determinations.

Results and discussion

The basil plants grown in the metal-polluted soil showed stimulation effects comparing with the plants from the control soil. At the end of the exposure period, the plants had a visible increase of biomass and presented inflorescences and the leaves’ green pigment was intensified. The metals gathered differently in plant organs: Cd, Co, Cr, and Pb were accumulated in roots, while Cu, Ni, and Zn in flowers. Cr and Pb exceeded the toxic levels in roots. Also, the heavy metal intake depends on the plant development stages; thus, Cd, Cr, and Pb were accumulated more in mature plant leaves. The Cd and Pb contents were higher than the World Health Organization and European Commission permissible limits.

Conclusions

The experimental results revealed that the basil plants exposed to a mixture of heavy metals have the potential to reduce the metal mobility from soil to plants. Translocation process from roots to flowers and to leaves was observed for Cu, Ni, and Zn, emphasizing a competition between metals. The calculated bioaccumulation factors were insignificant, but Cd and Pb concentrations exceeded the legal limits in the mature plants, being restricted for human or animal consumption.

     

Macronutrient deficiency and anatomic modifications in crambe leaves

Abstract

This study had the objective of assessing growth, deficiency symptoms and leaf anatomy of crambe plants submitted to macronutrient availability. The experimental design was the complete randomized with four replications. The first treatment consisted of cultivating crambe plants in a nutrient solution completed with N, P, K, Ca, Mg, and S. Using the diagnosis by subtraction, the other treatments consisted of the same solution with individual omission of each nutrient, totaling seven treatments. Supplement of different solutions took place two weeks after emergence. One week forward, visual symptoms of deficiency started to be evaluated. By the end of the experiment, the number of leaves, number of branches, shoot dry matter and leaf anatomic parameters were evaluated. Nutrient deficiency limited shoot dry matter in the following order: N?>?Ca?>?P>Mg?>?S?>?K. Subtracting Ca from the solution was most limiting to crambe growth once plants did not even reach reproductive stages. Individual subtractions of each macronutrient anatomically altered crambe leaves, especially omitting Ca, K, and S, which reduced tissue thickness.     

Effect of successive cuttings on uptake and partitioning of 15N among plant parts of Leucaena leucocephala

Summary We studied the effect of three successive cuttings on N uptake and fixation and N distribution in Leucaena leucocephala. Two isolines, uninoculated or inoculated with three different Rhizobium strains, were grown for 36 weeks and cut every 12 weeks. The soil was labelled with 50 ppm KNO₃ enriched with 10 atom % ¹⁵N excess soon after the first cutting. Except for the atom % ¹⁵N excess in branches of K28 at the second cutting, both the L. leucocephala isolines showed similar patterns of total N, fixed N₂, and N from fertilizer distribution in different parts of the plant at each cutting. The Rhizobium strain did not influence the partitioning of ¹⁵N among the different plant parts. Significant differences in ¹⁵N enrichment occurred in different parts. Live nodules of both isolines showed the lowest atom % ¹⁵N excess values (0.087), followed by leaves (0.492), branches (0.552), stems (0.591), and roots (0.857). The roots contained about 60% of the total plant N and about 70% of the total N derived from fertilizer over the successive cuttings. The total N₂ fixed in the roots was about 60% of that fixed in the whole plant, while the shoots contained only 20% of the fixed N₂. We conclude that N reserves in roots and nodules constitute another N source that must be taken into account when estimating fixed N₂ or the N balance after pruning or cutting plants. ¹⁵N enrichment declined up to about fivefold in the reference and the N₂-fixing plants over 24 weeks following the ¹⁵N application. The proportion and the amounts of N derived from fertilizer decreased, while the amount derived from N₂ fixation increased with time although its proportion remained constant.     

Biomass,carbon and nutrient stocks in different categories of rose (Rosa spp.) for optimizing input use

Abstract

The present study was carried out at ICAR-IIHR, Bengaluru to assess biomass accumulation, nutrient distribution, nutrient/water/energy use, plant available soil nutrients and carbon storage in different categories of roses in open-grown and protected systems. In open-grown roses, biomass of leaves, stalk and flowers represented 31.9%, 41.1% and 26.95%, respectively. In protected condition, flower biomass accounted for 17.62% of the total compared to leaf (51.0%), and stalk biomass (31.4%). The carbon stocks in plant biomass and soil accounted for 22% and 78% of total in open-grown rose system. In protected condition, plant and soil carbon stocks accounted for 11% and 89% of the total carbon stocks. Soil carbon stocks increased from 2.214 to 3.958?kg m^?2 during 4-year period in open field. In protected condition, soil carbon stock was increased from 3.315 to 5.104?kg m^?2 registering an increase of 1.789?kg m^?2. In rose production system, leaves registered highest levels of macronutrients while flowers acquired more micronutrients. The water use was 45% higher in protected cultivation (344?L yr^?1 m^?2) than in open condition (232?L yr^?1 m^?2). Based on nutrient use indicators and energy use of nutrient inputs, Arka Savi and Arka Swadesh were identified as efficient nutrient use and energy use (74.6% and 37.3%) genotypes in open and protected conditions, respectively. Plant available nutrient stocks in soil were optimum to above optimum in rose system. The results imply that precision nutrient application is most important to save inputs/energy, avoid environmental pollution and to develop sustainable land use system.     

Coffee‐Tree Floral Analysis as a Mean of Nutritional Diagnosis

Abstract

Plant part analysis for evaluating the nutritional state of the crops is a practice commonly used. The analysis of flowers can allow an earlier diagnosis of nutritional deficiencies, excesses or unbalances, which facilitates its correction before the occurrence of irreversible losses in productivity and quality. The objective of this study were to determine the coffee tree (Coffea arabica L.) flower nutrients sufficiency ranges, to compare and correlate concentrations of nutrients observed in flowers and leaves collected 90 days after bloom, and to correlate the concentrations of nutrients in flowers and leaves with fruit yield. Samples of 26 experimental plots were collected. The plots were set up in nine different orchards five to nine years old and with 3000–5000 plants/ha, in the region of Viçosa, Minas Gerais State, Brazil. Eleven experimental plots were selected with mean yield greater than 7.0 kg/plant of coffee berry for the calculation of the nutrients sufficiency ranges. The concentrations of nitrogen (N), potassium (K), boron (B), iron (Fe), and zinc (Zn) were similar in flowers and leaves, whereas those of phosphorus (P), calcium (Ca), magnesium (Mg), sulfur (S), copper (Cu), and manganese (Mn) differed among the parts. There was correlation among the contents of N, Mg, Fe, Mn, Zn, and Cu in flowers and in leaves. For flowers a model of six variables and for leaves a model of eight variables explained 80% of the variation in the mean yield of the coffee tree plants. It is concluded that, flowers permit earlier diagnosis and greater precision in the diagnosis of the nutritional state of the coffee tree.     

Physiological Response to Sodium Chloride of Wild Swiss Chard

ABSTRACT

The present work was aimed at determining the limits of tolerance to sodium chloride (NaCl) of a halophyte, Beta macrocarpa Guss (wild Swiss chard). Five week-old plants were cultivated with a nutritive solution to which was added 0, 100, 200, and 300 mM NaCl. Plants were harvested after four weeks of treatment. The growth (fresh and dry weight, leaf surface area, and leaf number), water contents, and the mineral composition (meq · g^?1 DW) of roots and leaves (reduced nitrogen (N), K⁺, Ca^{2 +}, Na⁺, Cl^?) were determined on individual plants. Results show that Beta macrocarpa can tolerate up to 200 mM NaCl. A significant decrease in biomass production (to 50% of control) was observed only for 300 mM NaCl. In the latter treatment, leaf mean surface area was 25% of control. The shoot-to-root ratio was not changed. Leaf hydration was not modified by salt treatment. This ability of the plant to maintain the hydric equilibrium of its leaves seemed associated with an efficient intracellular compartmentalization of Na⁺ and Cl^? ions. Salt treatment had little effect on N content (80% of control), but decreased significantly K⁺ and Ca^{2 +} contents. These three essential elements could be limiting for growth of leaves and roots of plants challenged by NaCl.     

The response of okra to molybdenum in sandculture

Abstract

The role of molybdenum in plant growth was examined by growing ‘Emerald’ okra (Abelmoschus esculentus L. Moench) to fruiting in sand‐culture.

Molybdenum treatment lower than 1 ppm, resulted in leaves that were generally pale yellow and curled upwards. At 1 ppm and 4 ppm Mo, plants were generally healthy with deep green leaves, while Mo application at 6 and 16 ppm resulted in stunted plant growth, deep green leaves, and dark brownish coating on the roots. Shoot/root ratio decreased with increasing rates of Mo. Total chlorophyll was unaffected by Mo application, whereas plant dry matter production and fruit yield were depressed at the 16 ppm Mo treatment.

Leaves of plants receiving less than 1 ppm Mo had higher concentrations of NO₃‐N, P, K, Ca and Mg than plants receiving above 1 ppm Mo treatments. The reverse was the case with the micronutrient levels. Specifically, Mo treatments higher than 1 ppm increased leaf‐Mo, ‐Fe, Mn and Zn and root‐Mo and Mn. The highest percentage of Fe and Mn, accumulated in the leaves, followed by the root and least in the wood, whereas the roots had the highest percentage of accumulated Mo, Cu and Zn. Leaf‐Mo was positively correlated with leaf‐Fe and Mn and root‐Mo and Mn. Molybdenum deficiency symptoms appeared in plants with leaf‐Mo of 5 ppm and treated with less than 1 ppm Mo. The 2 ppm Mo treatment with leaf‐Mo of 18 ppm produced normal and healthy plants, whereas. Mo application from 8 to 16 ppm with corresponding leaf‐Mo of 42 and 90 ppm Ho respectively produced plants that were severely stunted and had generally poor growth. The relatively high Ho concentration observed suggests that the okra plant is a Mo accumulator.     

Short‐term relationships between membrane permeability and growth parameters in three tomato cultivars grown at low and high zinc

Abstract

An experiment was carried out in a controlled temperature (CT) room for five weeks with tomato cvs., Moneymaker, Liberto, and Calypso, to investigate possible relationships between zinc (Zn) deficiency or toxicity and electrolyte leakage in plant leaves. The concentrations of Zn in nutrient solution were 0.01, 0.5, and 5.0 mg L^?1, respectively. There were significant reductions in the dry matter and chlorophyll content of all three cultivars grown both at 0.01 (low) and 5 mg L^?1 (high) Zn compared to 0.5 mg L^?1. The concentration of Zn at 0.01 mg L^?1 was not sufficient to provide for optimal plant growth, while 5 mg L^?1 in nutrient solution was detrimental to plant growth for all three cultivars. Dry matter production was generally lowest in the plants grown at low (0.01 mg L^?1) Zn except for Moneymaker where the lowest biomass was in the high Zn treatment. Zinc concentration was increased in the leaves and roots with increasing Zn concentration in nutrient solution. Phosphorus concentration was toxic in the leaves of the plants grown at low (0.01 mg L^?1) and was deficienct at high Zn (5 mg L^?1). The electrolyte leakage (%) gradually increased in the plants grown at low and high Zn concentrations and these increases were greatest in the leaves of plants grown at low Zn (except for Moneymaker grown at high Zn where reduction in dry matter was less). The best results for all growth parameters tested were for the plants grown at 0.5 mg L^?1 Zn. The results of this short‐term experiment show that electrolyte leakage which is relatively simple and easy to measure may be a good indicator of cultivar tolerance to Zn deficiency and toxicity.