Boron-deficient Plants Research Articles

Is it possible to detect boron deficiency in eucalyptus using hyper and multispectral sensors?

Boron (B) is an essential element whose deficiency results in rapid inhibition in the growth of plants, acting on their meristematic growth. Real-time monitoring of B fertilization in eucalyptus is helpful for guiding precision diagnosis and efficient management of plant boron nutrition. This research hypothesizes that different boron levels alter the reflectance of different wavelengths in eucalyptus. In this context, the objective of this study was to identify spectral ranges that can be used to monitor the boron status in eucalyptus plants. The experiment was carried out in a greenhouse, in which the treatments consisted of increasing boron levels in the form of boric acid (17% of B), whose levels varied from deficit to toxicity. Thus, five treatments were established: no boron, 1, 10, 20, and 40 mg/dm3 of boron. The remote sensing data used were bands, heights, and vegetation indices calculated after obtaining the spectral curves in each treatment. Our findings show that it is possible to accurately distinguish the boron levels in eucalyptus using hyper and multispectral bands. The 350–371 nm spectral range can be used for detecting boron-deficient plants. Plants with adequate boron levels can be identified by using the 426–444 nm, 1811–1910 nm, 1948–2115 nm, and 2124–2208 nm spectral ranges. Finally, the 425–475 nm spectral range can be used to find boron-toxicity plants.

One-Time Foliar Application and Continuous Resupply via Roots Equally Improved the Growth and Physiological Response of B-Deficient Oilseed Rape.

Oilseed rape (Brassica napus L.) is a high-boron (B)-demanding crop, and initially, normal growing plants might show B deficiency at advanced growth stages on soils with marginal B availability. Hence, we compared the effects of B resupply via roots and leaves on growth and physiological response, and relative expression of B transporters in B-deficient oilseed rape plants. Four-week-old plants initially grown with inadequate B (1 µM B for the first two weeks and 0.25 µM B for the next two weeks) were later grown either as such with 0.25 µM B, with 25 µM B in nutrient solution or foliar sprayed with 7 mL of 30, 60 and 150 mM B solution plant−1 as boric acid. Plants grown with 25 µM B in the nutrient solution from the beginning were included as adequate B treatment. Results showed that B resupply to B-deficient plants via roots and leaves (60 mM B) equally improved root and shoot dry matter, but not to the level of plants grown with adequate B supply. Foliar-applied 150 mM B proved toxic, causing leaf burn but not affecting dry matter. Resupply of B via roots increased B concentration in roots and leaves, while leaf-applied B did so only in leaves. Net carbon assimilation had a positive relationship with dry matter accumulation. Except for the highest foliar B level, B resupply via roots and leaves increased the accumulation of glucose, fructose and sucrose in leaves. Boron-deficient plants showed significant upregulation of BnaNIP5;1 in leaves and roots and of BnaBOR1;2 in roots. Boron resupply via roots reversed the B-deficiency-induced upregulation of BnaNIP5;1 in roots, whereas the expression of BnaBOR1;2 was reversed by both root and foliar B resupply. In leaves, B resupply by both methods reversed the expression of BnaNIP5;1 to the level of B-adequate plants. It is concluded that B resupply to B-deficient plants via roots and leaves equally but partially corrected B deficiency in B. napus grown in hydroponics.

Diagnosis of Boron Deficiency in Green Dwarf Coconut Palm

The diagnosis of boron deficiency in coconut palms has been hampered by lack of information about its distribution in the plant. Two experiments were conducted, one in a greenhouse to induce boron deficiency in dwarf green coconut palms, and other in the field, in which the plants received doses of boric acid, B(OH)3. The objective was to verify symptoms of boron deficiency and boron content variation in canopy, leaves and folioles (or leaflets). Boron deficient plants led leaves and folioles to become deformed. The deficient and sufficient contents of boron varied significantly in the canopy, but did not vary in leaves. The boron content increased significantly from bottom to the apex of the folioles in both treatments. To survey the level of boron in the coconut palm, the ideal is, using samples taken from the youngest leaf, to calculate the relation between the boron content in the apex of the foliole and the content in the center or in the folioles bottom, with minimum values 2.2 or 2.7, respectively.

PHYSIOLOGICAL AND BIOCHEMICAL CHANGES IN CATHARANTHUS ROSEUS L. IN RESPONSE TO BORON NUTRITION

Catharanthus roseus L., a medicinally important plant was grown till maturity at varying levels of boron (0.033, 0.066, 0.33 and 3.3 mg B L−1) supply. Optimum yield was observed in plants receiving 0.33 mg B L−1. Plants receiving deficient boron showed growth reduction and visual symptoms such as chlorosis and cupping of young emerging leaves and apical tip necrosis. The number and size of the flowers, pods and seeds formed and the pollen viability of the boron deficient plants was markedly reduced. The threshold values for deficiency and toxicity were 57 and 79 μg B g−1 dry weight for vegetative growth and 60.4 and 68.9 μg B g−1 dry weight for reproductive growth, respectively, and is reported for the first time in periwinkle. An increase was observed in reducing and non-reducing sugars and in activity of acid phosphatase and ribonuclease in boron stressed plants.

ROOT ENDOPHYTIC FUNGI AND BORON NUTRITION: EFFECT ON AVOCADO (PERSEA AMERICANA MILL.) 'HASS' PLANTS GROWING ON AN ANDISOL

In commercial orchards, avocado Persea americana Mill 'Hass' grafted onto a Mexican rootstock is always associated with fungal endophytes; their role in boron nutrition was studied under greenhouse conditions, in andisol from Michoacan, Mexico. The effect of mycorrhized roots on boron accumulation in different plant parts, on stem firmness and on soluble boron in soil was evaluated. Treatments were derived from a factorial 3 2 with inoculum (indigenous root endophytic fungi - REF, Glomus intraradices - Gi and endophyte free plants - T) as one factor. Soluble boron supply (0.13 - original soil concentration, 0.25, and 0.50 mg kg -1 dry soil) was the second factor. Boron was added as boric acid. Results showed that: i) REF raised total plant boron content; ii) Gi had no evident effect on boron accumulation and iii) there are statistical differences as independent factors for total boron and for inoculum type, but their interaction was not significant. Further research on the role of REF is required because: 1) plants that grew for 6 months on a boron deficient soil with REF did not show any symptoms of boron deficiency; 2) when soil was inoculated with REF, total boron increased after one year and also increased soluble boron concentration in the soil; 3) boron deficient plant stems were weaker, and; 4) REF increased stem firmness of boron deficient plants.

BORON DEFICIENCY AFFECTS GAS EXCHANGE AND PHOTOCHEMICAL EFFICIENCY (JPI TEST PARAMETERS) IN GREEN DWARF COCONUT

Boron (B) deficiency causes a wide array of symptoms, not only among species of palms, but also within a single species (i.e. Cocos nucifera). A better understanding of the effects of B deficiency in coconut will be important to try optimizing a rational fertilization management in coconut plants. Thus, modification of PSII photochemistry (using a group of fluorescence parameters, called the JIP- test, that quantify the stepwise flow of energy through Photosystem II) and gas-exchange in boron deficient green dwarf coconut plants were investigated. Our results suggest that a modification of PSII photochemistry (non-stomatic effects) and gas-exchange (stomatic effects) were induced by boron deficiency. Such modifications are manifested by (1) increase the ratio of total dissipation to the amount of active reaction centers (RCs) [dissipation (DI)/RC] and (2) leaf-to-air vapor pressure difference (VPDleaf-air). These modifications (on PSII photochemistry and gas-exchange) were caused by a decrease in energy absorbed per excited cross-section [absorption flux (ABS)/cross section of the sample (CS0)], density of active reaction centers (RC/CS), maximal trapping rate of an exciton that will lead to QA reduction measured over a cross- section of active and inactive RCs [trapping flux (TR)/CS0], electron transport per excited cross-section [electron transport flux (ET0)/CS)], area above curve (proportional to the pool size of the electron acceptors QA on the reducing side of PSII), photosynthesis (A), stomatal conductance (gs), transpiration (E), chlorophyll concentration (SPAD readings), growth parameters (root DW and height plant). Our results demonstrate that by analyzing fluorescence (JIP test parameters) derived from the polyphasic fluorescence transients measurements were able to estimate the functional changes of PSII in B deficient coconut plants. The results in this study suggest that fluorescence analysis (JIP test) and instantaneous measurements of gas-exchange can be useful tools in assessing the physiological effects of B deficiency in green dwarf coconut.

Boron deficiency decreases plasmalemma H+-ATPase expression and nitrate uptake, and promotes ammonium assimilation into asparagine in tobacco roots

The effects of short-term boron deficiency on several aspects (growth, biomass allocation, metabolite concentrations, gene expression, enzyme activities) related with nitrate assimilation were studied in tobacco (Nicotiana tabacum L.) plants in order to know the early changes caused by this mineral deficiency. For this purpose, plants were grown hydroponically in a nutrient solution supplemented with 10 microM boron and then transferred to a boron-free medium for 1-5 days. Nitrate concentration decreased in both leaves and roots under boron deficiency, which was not observed in control plants. This correlated with the lower net nitrate uptake rate found in boron-deficient plants when compared to boron-sufficient ones. Results suggest that boron deficiency decreases net nitrate uptake by declining the activity of nitrate transporters rather than affecting their transcript levels. This is supported by a drop in the levels of root PMA2 transcript during the boron deficient treatment, which could lead to a decrease in the plasma membrane H+-ATPase activity necessary to get protons out of cell for the cotransport with nitrate inwards. In addition, boron deficiency led to an increase in root Asn content and a decline in glutamine synthetase activity when compared to control plants, which suggest that this mineral deficiency may promote ammonium assimilation via asparagine synthetase in tobacco roots.

Boron deficiency increases putrescine levels in tobacco plants

Polyamine concentrations were determined in leaves and roots of tobacco plants (Nicotiana tabacum L.) subjected to a short-term boron deficiency. A decrease in the growth of shoots and, especially, roots was found under this mineral deficiency. Boron deficiency did not lead to a significant decrease in leaf or root ion concentrations when compared to control treatment; however, as expected, leaf boron concentration was lower in boron-deficient plants in comparison to the control. In leaves, the levels of free putrescine and spermidine were similar in both treatments. In roots, a short-term boron deficiency caused an increase in free putrescine. Moreover, boron-deficient plants had higher conjugated polyamine concentration than boron-sufficient plants, which was especially evident for conjugated putrescine in leaves. A possible link between boron and polyamine levels is proposed and discussed.

Relação entre a flexibilidade do caule de seringueira e a carência de boro

Em algumas culturas com carência de B, observou-se menor deposição de lignina nos elementos do xilema, formando paredes finas e pouco resistentes e menor translocação de carboidratos das folhas para outras partes da planta. Com o objetivo de detectar essas alterações anatômicas no xilema de caules extremamente flexíveis de seringueira (Hevea spp.), que apresentavam sintomas de deficiência de B, realizou-se um estudo anatômico comparativo entre plantas com e sem sintomas de deficiência, quanto à espessura das paredes e grau de deposição de lignina e celulose, bem como quanto à concentração de grãos de amido no parênquima do xilema. Não foi observada variação significativa entre a espessura e o grau de deposição de lignina nas paredes dos elementos do xilema de plantas com e sem sintomas. No entanto, plantas com sintomas apresentaram lamela média de espessura muito reduzida, com menor intensidade de coloração, o que reflete a insuficiência de pectato de cálcio, composto responsável pela adesão entre as células e cuja síntese é bloqueada pela carência de boro. A causa da flexibilidade dos caules foi atribuída à menor coesão entre as células.

Effects of mineral nutrient deficiencies on leaf development, visual symptoms and shoot–root ratio of Spathiphyllum

Effects of deficiencies in N, P, K, Ca, Mg, B and Fe on leaf development, visual symptoms and shoot–root dry weight ratio were studied in Spathiphyllum ‘Sensation’ grown hydroponically. Leaf nutrient contents of treated plants were analyzed to confirm suspected deficiencies. Leaf number, leaf area and chlorophyll content were all significantly reduced in the nitrogen-deficient plants similar to plants grown in distilled water. The phosphorus-deficient plants grew slowly but no deficiency symptoms were visible on leaves. Many small yellow specks, usually 2 mm or less in diameter, developed on the adaxial surface of lower leaves in the potassium-deficient plants. Leaf area, but not leaf number, was significantly suppressed by the calcium-deficient treatment and the young leaves developed necrotic margins on the middle and basal leaf blade. Fully expanded leaves in the magnesium-deficient plants were distorted and had lower chlorophyll contents than the controls. The iron-deficient plants showed interveinal chlorosis on younger leaves. The boron-deficient plants showed two types of deficiency symptoms: a marginal necrosis at the leaf apex and distorted and crinkled petioles break at the leaf blade. Shoot–root dry weight ratio was decreased under N, P and Fe deficiencies but was increased under deficiencies of Ca and B. A key was developed for the identification of mineral nutrient deficiencies.

Boron deficiency causes a drastic decrease in nitrate content and nitrate reductase activity, and increases the content of carbohydrates in leaves from tobacco plants

Tobacco (Nicotiana tabacum L.) plants were used to study connections between deficiency in boron and nitrate reduction. Boron deficiency caused a substantial decrease in shoot and, particularly, root weights that resulted in a notably high shoot/root ratio in comparison to boron-sufficient plants. One of the most important effects caused by boron deficiency was the strong decrease in leaf nitrate content. Leaf contents of magnesium, calcium and, especially, potassium also declined under this deficiency, but nitrate content decreased in a higher proportion than these cations. Nitrate reductase (EC 1.6.6.1) activity of boron-deficient plants declined from the beginning of the light period; this decline did not occur in boron-sufficient plants. This fact could be attributed to the faster decrease in transcript levels of Nia, the nitrate reductase structural gene, during the light period in boron-deficient plants. Leaf protein content of boron-deficient plants also declined in the course of light periods. Boron deficiency caused an appreciable accumulation of hexoses and sucrose in leaves. This build-up of soluble sugars might correct the osmotic imbalance elicited by the low content of nitrate and cations in plants subjected to boron deficiency. Boron-deficient plants had much higher starch contents than boron-sufficient ones, and there was an inverse relationship between the contents of nitrate and starch in leaves.

External Boron Requirements for Canola (Brassica napusL.) in Boron Buffered Solution Culture

Quantitative relationships between external boron concentrations that could elicit boron deficiency and plant growth, boron uptake rate, and plant boron concentrations have not been previously investigated due to the lack of water culture systems that provide satisfactory control over solution boron concentrations. Two approaches were tested to buffer the boron concentrations in nutrient solutions: supplying different amounts of boron saturated resin Amberlite IRA 743 per unit solution volume; and loading the resin with boron at 1 to 100% of full saturation. Mean boron concentrations (μ M ) ranged from 0.17 to 2.85 and from 0.047 to 27.03 in the two approaches, respectively, and in individual pots with plants solutions remained constant in boron concentrations for at least 10 to 12 d. At solution boron concentrations from 0.04 to 0.3 μ M , canola ( Brassica napus L.) plants remained alive, but shoot and root growth was stunted and showed classical boron deficiency symptoms. Increasing solution boron concentrations progressively increased boron concentrations in shoots and roots. Boron concentrations in roots were less than one-third of those in lower shoots, and less than those in upper shoots, except in boron deficient plants. In boron buffered solutions, dry matter of canola at both 12 and 24 d increased with increasing solution boron concentration up to 0.54–0.87 μ M . With increasing solution boron concentrations up to 26.5 μ M there was no further increase in dry matter, and no detrimental effects on plant growth. At 0.04 μ M boron, plants absorbed no boron from solution. Increasing solution boron concentrations from 0.1 to 26.5 μ M increased relative boron uptake rates from 0.005 to 0.1 μmol g −1 root f.wt d −1 . Maximum root efficiency, defined as relative uptake rate divided by the solution boron concentration, was achieved at 0.04 to 0.3 μ M boron in solution. With increasing solution boron concentrations, relative uptake rates of calcium decreased from 248 to 10 μmol g −1 root f.wt. d −1 . The results suggest that boron specifically inhibits calcium absorption.

Photosynthesis, chlorophyll fluorescence and soluble carbohydrates in sunflower leaves as affected by boron deficiency

Abstract The effect of various boron levels in the nutrient solution on the growth, boron and chlorophyll content, photosynthesis and chlorophyll fluorescence in the leaves of young sunflower (Helianthus annuus L.) plants was studied under greenhouse conditions. Deficiency of boron decreased the dry matter yield of the roots, shoots and leaves. The content of boron in all analyzed plant parts increased with the increase of boron levels in the nutrient solution, more so in the shoots than in the roots. Leaf area was reduced under boron deficiency as well as the content of chlorophyll in the leaves. The content of analyzed sugars was increased in boron deficient plants, glucose content exhibited the highest increase under boron deficiency. Boron deficiency appreciably decreased photosynthetic oxygen evolution by leaves, the apparent quantum yield and quantum efficiency of photosystem two electron transport. The diminished rate of photosynthesis in boron deficient sunflower leaves could be correlated to the ...

Deficiência de boro em soja

A deficiência de boro é rara na cultura da soja no Brasil. A deficiência aqui descrita ocorreu em Guaíra, SP, numa várzea onde houve excessiva aplicação de calcário, elevando a saturação por bases a valores próximos de 90%. Nas áreas deficientes, o teor de boro no solo foi de 0,06 ppm e nas áreas aparentemente sem sintomas, 0,11 ppm. Nas folhas das plantas com sintomas, a concentração era de 10 ppm de boro e nas sem sintomas, de 19 ppm. Nas plantas deficientes, as folhas primárias eram coriáceas e espessas, e houve morte da gema apical, com brotamento de gemas laterais, nanismo, poucas flores e pequeno pegamento de vagens, com sensível redução na produtividade.

Metabolic Changes Associated with Boron-Calcium Interaction in Maize

Maize (Zea mays L.) cv. T42 was grown in refined sand at low (0.1 μM) and normal (30 μu) concentrations of boron each under low (1 mM), normal (4 mM), and excess (8 mM) supply of calcium. Visible symptoms of boron deficiency which appeared first, were accentuated by calcium deficiency and were least evident when calcium was added in excess. The yield was maximum at normal levels of boron and calcium and was the lowest under boron and calcium deficiency. In maize leaves when both calcium and boron were deficient together the activity of starch phosphorylase increased markedly and that of ribonuclease and polyphenol oxidase also increased. The increase in the calcium content inhibited the starch phosphorylase activity when boron was deficient. The activity of peroxidase was stimulated under boron deficiency at all levels of calcium and that of ATPase was depressed significantly when calcium was deficient alone. A decrease in the tissue boron (except in old leaves) and tissue calcium content as well as sugar and starch contents was observed under the combined deficiency of calcium and boron. Excess calcium at both levels of boron increased the tissue boron and calcium contents and decreased the concentration of starch, sugars, nucleic acids, total and inorganic phosphorus, and the activities of starch phosphorylase and ATPase. The activity of ATPase increased upon the addition of calcium to plants deficient in calcium and boron respectively. The tissue concentration of the element added increased when the element was applied to calcium or boron deficient maize plants.

The Influence of Boron Deficiency on Glandular Scale Development and Structure inMentha piperita

The influence of boron deficiency on glandular scale development in MENTHA PIPERITA was studied under controlled experimental conditions in solution culture. Young leaves of peppermint were examined by light and electron microscope. The differentiation stages of glands from the initial gland cell up to a 10-cell glandular scale were the same in both control and boron-deficient plants. Boron had no influence on the numer of cells in glandular scale development. During gland development a number of ultrastructural alterations occured. The most striking and earliest ultrastructural response to boron deficiency was thickness and irregularity of cell walls. The ultrastructural changes observed in young glands are believed to be senescing phenomena, which normally appear at the postsecretory stage. The acceleration of cell aging during boron deficiency restricts essential oil secretion to a short period.

Synthesis, Salvage, and Catabolism of Uridine Nucleotides in Boron-Deficient Squash Roots

Previous work has provided evidence that plants may require boron to maintain adequate levels of pyrimidine nucleotides, suggesting that the state of boron deficiency may actually be one of pyrimidine starvation. Since the availability of pyrimidine nucleotides is influenced by their rates of synthesis, salvage, and catabolism, we compared these activities in the terminal 3 centimeters of roots excised from boron-deficient and -sufficient squash plants (Cucurbita pepo L.). Transferring 5-day-old squash plants to a boron-deficient nutrient solution resulted in cessation of root elongation within 18 hours. However, withholding boron for up to 30 hours did not result in either impaired de novo pyrimidine biosynthesis or a change in the sensitivity of the de novo pathway to regulation by end product inhibition. Boron deprivation had no significant effect on pyrimidine salvage or catabolism. These results provide evidence that boron-deficient plants are not starved for uridine nucleotides collectively. Whether a particular pyrimidine nucleotide or derivative is limiting during boron deprivation remains to be examined.

Development and enzymatic changes during pollen development in boron deficient maize plants

Abstract Maize (Zea mays L.) plants subjected to severe deficiency of boron (0.0026 ppm B) failed to produce tassels with functional flowers. In plants subjected to moderate deficiency of boron (0.013 ppm B), emergence of tassels and anthesis was suppressed and delayed. In a large percentage of boron deficient plants the stamens lacked sporogenous tissue and appeared as staminodes or floral appendages that either lacked or had branched vascular supply. The apparently normal stamens of these plants also failed to dehisce and showed a marked decrease in pollen producing capacity, pollen size and pollen germination. Even in plants that were only marginally deficient in boron (0.066 ppm B), without any foliar symptoms of boron deficiency, pollen grains showed poor germination and changes in enzyme activities. Pollen grains of such plants had low activities of catalase, acid phosphatase, starch phosphorylase and invertase and high activities of ribonuclease and amylase.

Boron requirement and deficiency symptoms of fenugreek (Trigonella foenum–graecum) as shown in a water culture experiment with inoculation of Rhizobium

SummaryThis experiment was made to determine the possible reason for deficiency symptoms seen on fenugreek (Trigonella foenum-graecum) in field trials during the dry summer of 1976. Using rockwool cubes for root support, it was shown that symptoms seen in the field plants resulted from boron deficiency.The symptoms of boron deficiency in fenugreek are described and illustrated. The main symptoms were failure offloweringor fertilization, decreased apical growth, small crisped leaves in a terminal rosette and a gradual yellowing of the lower leaves. In combination with low nitrogen, the boron-deficient plants had yellow, succulent leaves at a very early stage. High calcium and high nitrogen increased the demand for boron.Inoculation with Rhizobium meliloti of plants with a low nitrogen supply was performed with success. The bacteria formed healthy, pink nodules on the roots inside the rockwool cubes.The lowest content of boron in whole plants showing boron deficiency symptoms (no pods formed) was 13 μg/g and in this respect fenugreek is very similar to lucerne (Medicago sativa), a plant known to have a high boron requirement. Fenugreek has a high tolerance of excess boron.

THE EFFECT OF BORON DEFICIENCY ON CALLOSE FORMATION AND 14C TRANSLOCATION IN BEAN (PHASEOLUS VULGARIS L.) AND COTTON (GOSSYPIUM HIRSUTUM L.)

Callose accumulated in the tissues of boron deficient bean and cotton plants, the extent and distribution of which depended on the species. Sieve plates in the phloem of boron deficient bean were characterized by heavy plugs of callose, while the sieve plates of boron deficient cotton were essentially unaffected. Translocation of 14C was, however, drastically reduced in both plants. It is suggested that callose deposition in boron deficient plants is a secondary effect of cellular damage.