Fe Sprays Research Articles

The Effects of Exogenous Iron on the Photosynthetic Performance and Transcriptome of Rice under Salt–Alkali Stress

Saline-sodic stress induces iron deficiency in rice, reduces leaf photosynthetic performance, and inhibits yield enhancement. In this study, we investigated the effects of exogenous Fe on the photosynthetic performance and transcriptomics of two different tolerant rice cultivars CB9 (Changbai9: saline tolerant cultivar) and TH899 (Tonghe899: saline sensitive cultivar) with 4-week-old Fe-deficient rice seedlings under saline stress, Fe deficiency stress, and both co-stresses. The results showed that under saline and alkaline stress, spraying exogenous iron favored the growth of the two cultivars of rice, with a 32.68% and 39.82 increase in fresh weight, a 2.20-fold and 2.16-fold increase in pigment, respectively, and an 80.28% and 100.00% increase in net photosynthetic rate, respectively, as compared with the iron-deficiency treatment. Transcriptome analysis showed that we found a higher number of differentially expressed genes (7785 differentially expressed genes) in response to exogenous Fe spraying in the soda-salt sensitive variety TH899. The differentially expressed genes that are common to the two cultivars are primarily enriched in metabolic pathways, including plant hormone signal transduction (map04075) and phenylpropanoid biosynthesis (map00940). Specifically, among these genes, 14 are differentially expressed in the carotenoid biosynthetic metabolic pathway. The differentially expressed genes specific to the salinity-tolerant variety CB9 were mainly enriched in the metabolic pathways of glyoxylate and dicarboxylic acid methyl metabolism (map00630), and carbon fixation in photosynthetic organisms (map00710), among which 20 genes were significantly expressed in the pathway for carbon fixation in photosynthetic organisms (map00710). The research results offer specific theoretical support for enhancing the salt tolerance of rice.

Low iron ameliorates the salinity-induced growth cessation of seminal roots in wheat seedlings.

Wheat plants are ubiquitously simultaneously exposed to salinity and limited iron availability caused by soil saline-alkalisation. Through this study, we found that both low Fe and NaCl severely inhibited the growth of seminal roots in wheat seedlings; however, sufficient Fe caused greater growth cessation of seminal roots than low Fe under salt stress. Low Fe improved the root meristematic division activity, not altering the mature cell sizes compared with sufficient Fe under salt stress. Foliar Fe spray and split-root experiments showed that low Fe-alleviating the salinity-induced growth cessation of seminal roots was dependent on local low Fe signals in the roots. Ionomics combined with TEM/X-ray few differences in the root Na+ uptake and vacuolar Na+ sequestration between two Fe levelsunder salt stress. Phytohormone profiling and metabolomics revealed salinity-induced overaccumulation of ACC/ethylene and tryptophan/auxin in the roots under sufficient Fe than under low Fe. Differential gene expression, pharmacological inhibitor addition and the root growth performance of transgenic wheat plants revealed that the rootward auxin efflux and was responsible for the low Fe-mediated amelioration of the salinity-induced growth cessation of seminal roots. Our findings will provide novel insights into the modulation of crop root growth under salt stress.

Changes in flower yield, essential oil yield and oil composition after soil and foliage zinc and iron fertilization in German chamomile

In order to analyze the effects of zinc (Zn) and iron (Fe) on growth, yield, oil production and oil quality of German chamomile, an open field experiment was conducted at the Research Center, CSIR-Central Institute of Medicinal and Aromatic Plants (CIMAP), Pantnagar, Uttarakhand, India in 2019–2020 and 2020–2021. The experiment was set according to Randomized block design (RBD) with 7 treatments and three replications. Treatments were as follow: T1: control (without Zn or Fe fertilizers), T2: Foliar Fe spray @ 0.5%, T3: Foliar Fe spray @ 1.0%, T4: Foliar Zn spray @ 0.5%, T5: Foliar Zn spray @ 1.0%, T6: Mixing of Zn in soil @ 30 kg/ha before transplanting, T7: Mixing of Fe in soil @ 30 kg/ha before transplanting. Foliar spray of zinc (Zn) and iron (Fe) was conducted twice before flowering throughout the crop growth period. Obtained results showed that the plant height, canopy, number of flowers, fresh & dry flower yield, oil production, oil content and oil composition were radically increased and improved by foliar spray and soil mixing of Zn and Fe, compared to control. The maximum fresh flower & dry flower yield, oil content, and oil production were recorded in the treatment of foliar spray of Zn @ 0.5% followed by 1.0% in 2019–2020 and 2020–2021. The results also showed that Zn and Fe improved the oil quality and increased the concentration of major compounds like chamazulene, Z-spiroether, α-bisabolol oxide-A & B in oil compared with control.

Grain zinc and iron concentrations of Chinese wheat landraces and cultivars and their responses to foliar micronutrient applications

Grain zinc (Zn) and iron (Fe) concentrations and their responses to foliar application of micronutrients in 28 Chinese wheat landraces and 63 cultivars were investigated in a two-year field experiment. The average grain Zn and Fe concentrations were 41.8 mg kg−1 (29.0−63.3 mg kg−1) and 39.7 mg kg−1 (27.9−67.0 mg kg−1), respectively. Compared with cultivars, landraces had greater grain Zn (11.0%) and Fe (4.8%) concentrations but lower harvest index (HI), grain weight per spike (GWS), grain number per spike (GNS) and thousand grain weight (TGW). Both Zn and Fe concentrations were negatively and significantly correlated with HI, GWS, and GNS, while showed a poor association with TGW, suggesting that lower HI, GWS, and GNS, but not TGW, accounted for higher Zn and Fe concentrations for landraces than for cultivars. Grain Zn concentrations of both cultivars and landraces significantly increased after foliar Zn spray and the increase was two-fold greater for landraces (12.6 mg kg−1) than for cultivars (6.4 mg kg−1). Foliar Fe spray increased grain Fe concentrations of landraces (3.4 mg kg−1) and cultivars (1.2 mg kg−1), but these increases were not statistically significant. This study showed that Chinese wheat landraces had higher grain Zn and Fe concentrations than cultivars, and greater increases occurred in grain Zn concentration than in grain Fe concentration in response to fertilization, suggesting that Chinese wheat landraces could serve as a potential genetic source for enhancing grain mineral levels in modern wheat cultivars.

Iron efficiency of rice cultivars as related to iron dynamics in the rhizosphere

The present study aimed at investigating the iron (Fe) efficiency of rice cultivars with respect to Fe dynamics in the rhizosphere. A pot plant experiment was conducted using Fe-deficient (Diethylenetriamine pentaacetate-extractable Fe 2.41 mg/kg) loamy sand soil (pH 7.9, EC 0.24 dS m−1, and SOC 0.5%). Rice cultivars PR 114, PR 121, PR 126, PR 127 and PR 129 were grown in pots containing 5 kg soil. Treatments included foliar sprays of 0, 0.5 and 1.0% FeSO4 7H2O solution in triplicates. In no Fe spray treatment, rice cultivars produced 52–87% of the maximum shoot dry matter (SDM), which was achieved through foliar Fe. Considering the relative SDM as a measure of Fe efficiency, cv. PR 126 was the most efficient, followed by PR 129, PR 127, PR 121 and PR 114. In no-Fe spray treatment, PR 114 produced 60%, while PR 126 produced 55% of the maximum root length. Calculations with steady-state model demonstrated that in the absence of Fe spray application, cv. PR 126 developed 1.6-fold higher concentration gradient than PR 114 due to the depletion of Fe at root surface that derived 1.5-fold higher Fe influx. Cultivar PR 126 had lesser roots and lower root-to-shoot ratio but was more Fe efficient because of highest Fe influx and shoot demand on roots resulting from better Fe uptake mechanism.

Nutrient and residue management in zero tilled-direct seeded basmati rice (Oryza sativa)-wheat (Triticum aestivum) system

To assess the effect of nutrient and residue management on the performance of zero till - direct seed rice (DSR) (Oryza sativa L.)-wheat (Triticum aestivum L.) cropping system in partially reclaimed sodic soils, a three-year field experiment was conducted at ICAR-CSSRI during kharif and rabi 2016-18. The experiment was conducted in factorial randomized block design with 8 nutrient management options as first factor and two levels of residue management as second factor with three replications. Plant height, number of tillers and effective tillers were not affected significantly both in rice and wheat due to different nutrient and residue management treatments. Under different N management practices, basmati CSR 30 showed higher physiological efficiency in terms of SPAD reading, relative water content (RWC) and photosynthetic traits under treatments with recommended dose of fertilizers (RDF) + CSR bioformulation and RDF + CSR bioformulation + top cut at 75 days after sowing. Grain yield of basmati CSR 30 was the highest under transplanted conditions (36.0 q/ha) which was 20.0-30.6% higher than different nutrient and residue management treatments under DSR. Additional Zn application and foliar Fe sprays did not increase grain yield than RDF under ZT-DSR. Residual effect of nutrient and residue management was non-significant for all the yield attributes of wheat, viz. ear length, grains/ear and 1000-grain weight as well as for grain and straw yield of wheat. This study concludes that ZT-DSR is not suitable option for replacing puddled transplanted rice.

Foliar application of micronutrients enhances growth, flowering, minerals absorption and postharvest life of tuberose (Polianthes tuberosa L.) in calcareous soil

Micronutrients applications are effective for better crop production in calcareous soils because these soils are usually deficit in iron (Fe), zinc (Zn) and boron (B). In Pakistan, most of soils are calcareous in nature. When tuberose is grown in such soils as a cut flower, its production is negatively affected. Therefore, a study was aimed to evaluate the effects of micronutrients as foliar sprays on cut tuberose production in calcareous soil. Micronutrients (Fe, Zn and B) alone and in combinations were sprayed on the plants after 60, 90 and 120 days of planting. The mixture of all these three micronutrients increased the plant height (95.77 cm), chlorophyll content (38.13 SPAD), number of leaves (79.63), leaf length (44.73 cm), fresh (111.64 g) and dry (16.16 g) plant weights, root length (15.13 cm), number of stalks (3.73), stalk length (79.03 cm), spike length (22 cm), number of florets (51.67), floret fresh weight (11.85 g), leaf Zn concentration (53.6 mg/g) and vase life (8.4 days). Fe + Zn enhanced the number of leaves (76.60), leaf length (45.83 cm), root length (15.05 cm), spike length (22.33 cm), and leaf Fe (128.18 mg/g) and Zn concentrations (55.02 mg/g). The Fe spray increased the leaf length (44.10 cm), days to flower initiation (142.47 days) and leaf Fe concentration (130.75 mg/g) in tuberose plants. Application of Zn improved the leaf length (45.87 cm) and diameter (1.32 cm), root (15.03 cm), spike (21.77 cm) and floret lengths (4.74 cm), floret dry weight (1.49 g) and leaf Zn concentration (57.5 mg/g). Foliar spray of B increased the B concentration (21.1 mg/g) in tuberose leaves. It is concluded that foliar application of micronutrients alone and in combinations improved the plant growth, flowering, leaf minerals concentrations and vase life of tuberose spikes. However, mixture of Fe, Zn and B was more effective as compared to other treatments. Moreover, current study encourages the foliar application of micronutrients in tuberose when grown in calcareous soils.

Effect of Bio-Fertilization and Foliar Spraying with some Micro-Elements on Growth and Productivity of Two Faba Bean Cultivars

The aim of this study was to investigate the response of two faba bean cultivars (Misr-1 and Giza-40) to bio-fertilizers (Bacillus megatherium var. phosphaticum and Psedomonas) and foliar spraying with some micro- elements (Fe- Zn and Mn) on growth, yield and seeds quality. Two field experiments were carried out during winter seasons of 2017/2018 and 2018/2019 at the Experimental Farm of Agricultural Res. Center, Al-Azhar University , Assuit Governorate, Egypt. Split-split plot design was used with three replicates , where faba bean cultivars were assigned to the main plots , foliar spraying were distributed randomaly in the sub plots and bio-fertilizers were located in the sub-sub plots . Results concluded that faba bean cultivars exhibited significant difference in plant height, number of branches/plant, number of pods/plant, seed yield/plant, 100-seed weight , straw yield/fed , protein and phosphorus percentage of seeds in both seasons while faba bean cultivars exhibited significant difference in seed yield/fed in first season only. Where, cultivar Misr-1 superior to Giza-40 in all studied characters. Also, micro elements foliar application caused a signification increases in all studied characters. Where, the highest values were recorded with Fe spraying in both seasons. Also, application of phosphorein induced significant increases in all previous characters in both seasons. Therefore , this study recommends that Misr-1 cultivar inoculation with phosphorein and foliar spraying with Iron in order to improve the production of faba bean under the condition of Assuit Governorate, Egypt.

Complementary Evaluation of Iron Deficiency Root Responses to Assess the Effectiveness of Different Iron Foliar Applications for Chlorosis Remediation.

Iron deficiency in plants is caused by a low availability of iron in the soil, and its main visual symptom is leaf yellowing due to a decrease in chlorophyll content, along with a reduction in plant growth and fruit quality. Foliar sprays with Fe compounds are an economic alternative to the treatment with expensive synthetic Fe-chelates applied to the soil, although the efficacy of foliar treatments is rather limited. Generally, plant response to Fe-foliar treatments is monitored by measuring chlorophyll content (or related parameters as SPAD index). However, different studies have shown that foliar Fe sprays cause a local regreening and that translocation of the applied Fe within the plant is quite low. In this context, the aim of this study was to assess the effects of foliar applications of different Fe compounds [FeSO4, Fe(III)-EDTA, and Fe(III)-heptagluconate] on Fe-deficient cucumber plants, by studying the main physiological plant root responses to Fe deficiency [root Fe(III) chelate reductase (FCR) activity; acidification of the nutrient solution; and expression of the Fe deficiency responsive genes encoding FCR, CsFRO1, Fe(II) root transporter CsIRT1, and two plasma membrane H+-ATPases, CsHA1 and CsHA2], along with SPAD index, plant growth and Fe content. The results showed that the overall assessment of Fe-deficiency root responses improved the evaluation of the efficacy of the Fe-foliar treatments compared to just monitoring SPAD indexes. Thus, FCR activity and expression of Fe-deficiency response genes, especially CsFRO1 and CsHA1, preceded the trend of SPAD index and acted as indicators of whether the plant was sensing or not metabolically active Fe due to the treatments. Principal component analysis of the data also provided a graphical tool to evaluate the evolution of plant responses to foliar Fe treatments with time.

Super-Optimal NPK Along with Foliar Iron Application Influences Bioavailability of Iron and Zinc of Wheat

Deficiency of wheat grain iron (Fe) and zinc (Zn) is common nutritional problem in the developing countries and thus increasing their concentrations is a major challenge. Field experiments were conducted to investigate the effect of different levels of fertilizer nitrogen, phosphorus, potassium (100–200 % NPK) and foliar Fe application (3 % FeSO4.7H2O at 40, 60, and 75 days after sowing) on improving Fe and Zn concentrations in grain and molar ratio of phosphorus/iron (P/Fe) and phosphorus/zinc (P/Zn). Data obtained during the two year (2010–2011 and 2011–2012) field experiment reveals that foliar Fe spray along with fertilizer NPK significantly increased the grain Fe concentration by 6–15 %; whereas a sharp decrease in the grain Zn concentration under super optimal fertilization is attributed to the depressive effect of excessive phosphorus in the treatments. Molar ratio of P/Fe in wheat grains signifies the increased bioavailability of Fe in wheat grains but P/Zn increase under super-optimal NPK application calls for P management to correct the reduced level of Zn in wheat grains.

Interference of nickel with copper and iron homeostasis contributes to metal toxicity symptoms in the nickel hyperaccumulator plant Alyssum inflatum

The divalent cations of several transition metal elements have similar chemical properties and, when present in excess, one metal can interfere with the homeostasis of another. To better understand the role of interactions between transition metals in the development of metal toxicity symptoms in plants, the effects of exposure to excess nickel (Ni) on copper (Cu) and iron (Fe) homeostasis in the Ni hyperaccumulator plant Alyssum inflatum were examined. Alyssum inflatum was hypertolerant to Ni, but not to Cu. Exposure to elevated subtoxic Ni concentrations increased Cu sensitivity, associated with enhanced Cu accumulation and enhanced root surface Cu(II)-specific reductase activity. Exposure to elevated Ni concentrations resulted in an inhibition of root-to-shoot translocation of Fe and concentration-dependent progressive Fe accumulation in root pericycle, endodermis and cortex cells of the differentiation zone. Shoot Fe concentrations, chlorophyll concentrations and Fe-dependent antioxidant enzyme activities were decreased in Ni-exposed plants when compared with unexposed controls. Foliar Fe spraying or increased Fe supply to roots ameliorated the chlorosis observed under exposure to high Ni concentrations. These results suggest that Ni interferes with Cu regulation and that the disruption of root-to-shoot Fe translocation is a major cause of nickel toxicity symptoms in A. inflatum.

Foliar iron-fertilisation of fruit trees: present knowledge and future perspectives – a review

SummaryIron (Fe)-deficiency is a common physiological disorder affecting fruit crops in many areas of the World. Foliar Fe-fertilisation is a common agricultural strategy to control Fe-deficiency under field conditions. However, variable responses to Fe sprays have often been described and foliar Fe-fertilisation cannot yet be considered a reliable strategy to control plant Fe-deficiency. The lack of understanding of some factors relating to the penetration, distribution, and bio-activity of leaf-applied, Fe-containing solutions hinders the development of effective Fe formulations for foliar treatment. The current state-of-the-art and future perspectives for foliar Fe-fertilisation, as a strategy to control Fe-deficiency in fruit crops, is discussed.

Mobility of Iron and Manganese within Two Citrus Genotypes after Foliar Applications of Iron Sulfate and Manganese Sulfate

ABSTRACT Seedlings of sour orange (Citrus aurantium L.) and Carrizo citrange (C. sinensis L. cv. Washington navel x Poncirus trifoliata)] were grown in plastic pots containing a sand: perlite mixture and watered with a modified Hoagland No 2 nutrient solution throughout the experiment. Three-months-old plants were divided in three groups and sprayed with 0.018 M iron sulfate (FeSO4 .7H2O), 0.018 M manganese sulfate (MnSO4 .H2O), or deionized water. Two months later, plants were harvested and divided into top leaves that grown after the treatments, basal leaves that existed prior to the treatments, stems that partially came in contact with the spray, and roots. The manganese (Mn) spray resulted in a significant increase of Mn concentrations in top leaves, basal leaves, stems and roots of sour orange, and in top leaves, basal leaves, and stems of Carrizo citrange. The iron (Fe) spray significantly increased the concentrations of Fe in the stems and basal leaves of both genotypes. For both genotypes, transport of Mn from basal (sprayed) leaves to top (unsprayed) ones was found. However, the results of this experiment did not give any evidence neither for Mn translocation from sprayed tissues to roots nor for Fe transport from sprayed tissues to unsprayed ones (top leaves, roots). Mn and Fe were found to be relatively mobile and strictly immobile nutrients, respectively, within citrus plants after their foliar application as sulfate salts.

Foliar Iron Fertilization of Peach (Prunus persica (L.) Batsch): Effects of Iron Compounds, Surfactants and Other Adjuvants

Experiments to assess the capability of different combinations of iron (Fe) compounds and adjuvants to provide Fe via foliar application to Fe-deficient plants have been carried out. A total of 80 formulations containing (1) one of five Fe-compounds [FeSO4·7H2O, Fe(III)-citrate, Fe(III)-Ethylenediaminetetraacetic acid (EDTA), Fe(III)-Diethylenetriamine pentaacetic acid (DTPA), Fe(III)-Iminodisuccinic acid (IDHA)], (2) a surfactant (Mistol, alkyl-polyglucoside1 or alkyl-polyglucoside2), and (3) an adjuvant (glycerol, methanol or glycine–betaine) were studied with respect to leaf wetting ability and surface tension. From the initial formulations only 26 resulted in adequate leaf wetting, 20 with alkyl-polyglucoside2 and 3 each with Mistol and alkyl-polyglucoside1, and some of them (four with alkyl-polyglucoside2, one with Mistol, and three with alkyl-polyglucoside1) were found to have inadequate surface tension values for use as foliar fertilizers. In a second experiment, 20 formulations containing alkyl-polyglucoside2 and one each of the five Fe-compounds and adjuvants listed above, were used for a foliar experiment with Fe-deficient peach trees [Prunus persica (L.) Batsch] grown under field conditions. Iron-deficient shoots were sprayed only once and leaf re-greening was assessed over 6 weeks for leaf chlorophyll content (via SPAD measurements) and percentage of green leaf area (via image analysis). Foliar Fe application always resulted in leaf Chl increases, although different degrees of re-greening were observed for the various Fe-compounds tested. Best results were obtained after treatment with formulations containing (in a decreasing order): Fe(II)-sulfate, Fe(III)-citrate, Fe(III)-EDTA, Fe(III)-IDHA, and Fe(III)-DTPA. A positive effect of adding glycerol, methanol or glycine–betaine was often observed, although the effect depended on each Fe-containing compound, indicating the existence of significant interactions between spray components. Results are of importance while trying to critically evaluate the potential of Fe sprays as a viable strategy to remedy plant Fe deficiency under field conditions.

Foliar Iron Fertilization: A Critical Review

ABSTRACT Application of foliar iron (Fe) sprays is a common means of correcting Fe deficiency of agricultural crops. However, variable plant responses to iron sprays, ranging from no effect to defoliation, have often been described in the Fe-fertilization literature. Knowledge is still limited concerning the mechanisms of penetration of a leaf-applied, Fe-containing solution and the role of Fe in the leaf. The complex and multi-disciplinary character of the factors determining the effects of Fe sprays hinder the development of suitable foliar fertilization strategies, applicable under variable local conditions and for different plant types. This review describes some key factors involved on the process of penetration of a leaf-applied, Fe-containing solution before briefly analyzing the available foliar Fe-fertilization literature. Iron chemistry, leaf penetration, and plant-nutrition principles will be merged with the aim of clarifying the constraints, opportunities, and future perspectives of foliar Fe sprays to cure plant Fe deficiency.

CHLOROSIS IN WILD PLANTS: IS IT A SIGN OF IRON DEFICIENCY?

ABSTRACT Chlorosis in crops grown on calcareous soil is mainly due to iron (Fe) deficiency and can be alleviated by leaf application of soluble Fe2+ or diluted acids. Whether chlorosis in indigenous plants forced to grow on a calcareous soil is also caused by Fe deficiency has, however, not been demonstrated. Veronica officinalis, a widespread calcifuge plant in Central and Northern Europe, was cultivated in two experiments on acid and calcareous soils. As phosphorus (P) deficiency is one of the major causes of the inability of many calcifuges to grow on calcareous soil we added phosphate to half of the soils. Leaves in pots with the unfertilized and the P-fertilized soil, respectively, were either sprayed with FeSO4 solution or left unsprayed. Total Fe, P, and manganese (Mn) in leaves and roots and N remaining in the soil after the experiment were determined. In a second experiment, no P was added. Leaves were either sprayed with FeSO4 or with H2SO4 of the same pH as the FeSO4 solution. Degree of chlorosis and Fe content in leaves were determined. Calcareous soil grown plants suffered from chlorosis, which was even more pronounced in the soils supplied with P. Newly produced leaves were green with Fe spray but leaves that were chlorotic before the onset of spraying did not totally recover. H2SO4 spray even increased chlorosis. This demonstrated that chlorosis was due to Fe deficiency. As total leaf Fe was similar on acid and calcareous soil, it was a physiological Fe deficiency, caused by leaf tissue immobilization in a form that was not metabolically “active”. Iron in the leaves was also extracted by 1,10-phenanthroline, an Fe chelator. In both experiments, significant differences between leaves from acid and calcareous soil were found in 1,10-phenanthroline extractable Fe but not in total leaf Fe, when calculated on a dry weight basis. Differences in 1,10-phenanthroline extractable Fe were more pronounced when calculated per unit dry weight than calculated per leaf area, whereas the opposite condition was valid for total leaf Fe.

Iron Deficiency Chlorosis and Seed Yield in Dry Edible Beans Grown on High-pH Calcareous Soils

Iron deficiency chlorosis (FeDC) can cause significant seed yield reduction in dry beans (Phaseolus vulgaris L.) grown on high-pH calcareous soils. To determine the effects of FeDC on seed yield, and the effect of Fe-spray as a correction factor for FeDC, 22 breeding lines/cultivars were planted on high-pH (8.0), calcareous (3.2–3.5 calcium carbonate equivalent), and low-Fe (1.8–4.2 ppm DTPA) sandy clay loam Tripp soils at Mitchell and Scottsbluff in western Nebraska. A split-plot design was used with Fe treatments as main plots and breeding lines/cultivars as subplots. Three foliar sprays of Fe-EDDHA (2.4 kg·ha–1) were applied at V4, R5, and R7 dry bean growth stages, during 1996 and 1997. Leaf chlorosis was measured simultaneously by using a Minolta Chroma-meter (CIE L* a* b* color space system), a Minolta Chlorophyll-meter (chlorophyll content index), and by visual ratings (1 = normal green to 5 = severe chlorosis). In 1996 no significant Fe-spray × line interaction (P = 0.776) and Fe-spray effect (P = 0.884) on seed yield was observed. Breeding lines showed significant differences in seed yield (P = 0.0001) with WM2-96-5 being the highest-yielding line (4047 kg·ha–1). In 1997 a significant Fe spray × line interaction (P = 0.029) was observed. The cultivar Chase without Fe spray (3375 kg·ha–1), and lines WM2-96-5 (3281 kg·ha–1), WM2-96-8 (3171 kg·ha–1) with Fe spray were the highest yielding entries under those treatments. Differences in visual ratings after the third Fe spray in 1997 were significant (P = 0.004) for Fe spray × line interaction. In 1996 visual ratings were different only for breeding lines. Chlorophyll content index showed a significant Fe spray × line interaction after the second Fe spray (P = 0.022) and after the third Fe spray (P = 0.0003) in 1997.

657 PB 063 IRON DEFICIENCY IN POTATO IN THE MEDITERRANEAN REGION AND ITS CONTROL THROUGH RESISTANT GENOTYPES AND NUTRIENT APPLICATION

Iron-deficiency symptoms are observed on some genotypes of potato (Solanum tuberosum L.) grown on high-pH and calcareous soils. seven potato cultivars differing in response to iron deficiency chlorosis (FeDC) were grown on high-pH (8.1), calcareous (38% calcium carbonate equivalent in surface 20 cm) and silty clay soil in the field (Beka'a Valley, Lebanon), to determine the effects of FeDC on tuber yield of cultivars sprayed with Fe. A significant interactions between cultivars and Fe spray treatment were noted for visual FeDC ratings and tuber yield. Even though only slight FeDC was noted on some cultivars receiving no Fe spray, tuber yields were significantly increased when sprayed with Fe. Some cultivars with moderate FeDC ratings did not show a significant increase in yield when sprayed with Fe while other cultivars did. Sprayed cultivars generally produced higher tube; yields than unsprayed ones. Indicating that Fe-deficiency chlorosis in the Mediterranean region may be a serious limitation to potato tuber yield.

Bicarbonate‐induced iron chlorosis in java citronella

Abstract A field experiment was conducted during 1989–91 to investigate and resolve iron (Fe) chlorosis that appears in the summer season in Java citronella (Cymbopogon winterianus Jowitt). The experiment consisted of nitrogen (N) levels of 0, 200, and 400 kg N/ha/year as main plots and foliar applications of ferrous sulfate (FeSO4‐7H2O) (nil and spray once in two months) as subplots in a split‐plot design. A foliar application of a 3% FeSO4‐7H2O solution once in two months resulted in the disappearance of the Fe‐deficiency symptoms, increased the leaf chlorophyll content, and the total and ferrous‐Fe contents in the leaf tissue. At the 400 kg N/ha/year treatment level, the foliar Fe spray increased significantly herb and oil yields. Thus, under intensive cultivation of Java citronella, a foliar application of Fe will avoid economic losses of essential oil yields when Fe‐deficiency symptoms appear.

Yield of iron‐sprayed and non‐sprayed strawberry cultivars grown on high pH calcareous soil

Abstract Iron deficiency chlorosis (Fe‐DC) results in an extensive reduction in the fruit yield of strawberry (Fragaria x ananassa Duch.) grown on high pH calcareous soils. Three cultivars, differing in their response to Fe‐DC, were grown on a high pH (8.2) calcareous soil (15.4% calcium carbonate equivalent in surface 20 cm) in the field (Choueifat, coastal area of Lebanon) to determine what effect Fe‐DC had on fruit yield when the foliage was sprayed with Fe [FeEDDHA, Ferric ethylenediiminobis (2‐hydroxyphenyl) acetate], Unsprayed plants were used as the control. No significant interaction (p<0.05) between cultivar x Fe spray treatment was obtained, and no significant difference (p<0.05) between one and two Fe spray(s)/week treatments were noted for visual Fe‐DC rating, fruit numbers, and fruit yield. Cultivars sprayed once/week produced higher yields than unsprayed controls. Overall increases were 33% (13% for ‘Motto’, 30% for ‘Chandler’, and 56% for Douglas'). Even though only slight Fe‐DC was noted o...