Effects of gaseous air pollutants on secondary chemistry of Scots pine and norway spruce seedlings

Plant secondary compounds have an important role in defense responses against herbivores and pathogens. This study summarises published and some unpublished data from a series of fumigation experiments where Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seedlings were exposed to different concentrations of gaseous air pollutants, ozone (O₃), sulphur dioxide (SO₂) or nitrogen dioxide (NO₂), in growth chambers. Concentrations of monoterpenes, resin acids and total phenolics were studied. Overall, needle monoterpenes were not affected by pollutants. Only very high level of O₃ (600 ppb) decreased concentration of some individual monoterpenes in pine needles. O₃ did not have effect on concentrations of resin acids in pine needles. In contrast, the concentration of some individual resin acids increased in O₃-exposed pine shoots and in O₃-exposed needles of one spruce clone. The highest dose of SO₂ decreased concentrations of resin acids in pine needles, but low exposure levels did not have effects. However, SO₂ had no effects on the resin acids concentrations of spruce needles, except some minor individual compounds were affected in clonal spruces. Increased concentrations of resin acids was found in pine shoots exposed to NO₂. Total phenolics of needles were not affected by pollutants. These observations suggest that among secondary compounds there is variation in sensitivity to air pollutants and genetically different trees have different responses to air pollutants.     

Foliar symptoms,ethylene biosynthesis and water use of young Norway spruce (Picea abies (L.) Karst.) exposed to drought and ozone

Four-year old Norway spruce (Picea abies (L.) Karst.) trees were pretreated at low and high water supply, and then placed into a growth chamber containing four compartments so that two levels of ozone exposure, 0.02 and 0.4 Μl l^?1, could be replicated. They were exposed to ozone and drought stress for 59 days, and water use was determined by periodic weighing. Small effects of ozone treatment were detected on new shoot dry weight, and water use by trees receiving the high ozone treatment appeared higher. Both visual symptoms and ethylene biosynthesis showed that drought stress reduced damage to trees exposed to high ozone. Ethylene emission and 1-aminocyclopropane-1-carboxylic acid (ACC) levels increased after 18 days of exposure to 0.4 Μl l^?1 ozone, while visual symptoms were seen at 30 days. After 59 days of exposure to the combined stresses, ethylene and ACC levels were lower, but showed an ozone x water interaction. Most ethylene and ACC were produced by wet trees at high ozone concentration, but dry trees also had high ethylene and ACC levels at low ozone. Levels of needle malonyl-ACC (MACC) were not significantly affected by treatment, and did not change with time, but root MACC levels, which were twice needle levels, were high in wet trees at high ozone concentration, but also high in dry trees at low ozone concentration. These results suggest that drought stress occurring during ozone exposure could be expected to reduce damage to young Norway spruce, and that this damage may be related to ethylene biosynthesis.     

Effects of acid irrigation and liming in a norway spruce stand (Picea abies [L.] KARST.)

Acid irrigation (pH 2.7 to 2.8; mean annual input 4.1 kmol H⁺ ha^?1 as H₂SO₄) has caused significant changes in the chemistry of the soil of a mature Norway spruce stand (Picea abies [L.] KARST.) after 4 years of treatment. In the surface humus layer around 20% of the exchangeable Ca, Mg, K and Mn ions were leached. This was connected with a decrease of pH and cation exchange capacity. In the mineral soil no changes of pH and cation adsorption were observed. However there was a significant increase of Al³⁺ ions in the soil solution, exceeding 20 mg L^?1, mainly caused by dissolution of Al-hydroxides and Al-hydroxosulphates. Also the concentrations of ionic Cu, Zn and Cd were nearly doubled. Manganese concentrations are fluctuating according to periods with and without acid irrigation, showing reduction and oxidation phases. In contrast to microorganisms, certain moss species and Oxalis acetosella, the mature spruce stand was not severely damaged up to now. It is hypothesized that Ca/Al and Mg/Al ratios of single horizons are insufficient for characterizing Al stress in the field. Liming (4 Mg ha^?1) led to a significant increase of dissolved organic C, which is associated with mobilization of metals such as Pb, Cu and Al in organic complexation. Also nitrification increased in the surface humus layer. As a consequence the nitrate concentrations in the seepage water exceeded 250 mg NO₃ L^?1.     

Relationships between symptoms expressed by Norway spruce and foliar and soil elemental status

Surveys conducted from 1987 to 1990 of Norway spruce [Picea abies(L.) Karst.] within 12 plantations across 4 northeastern states revealed symptoms of crown discoloration and defoliation on a site-specific basis. Foliar N. K. and Ca concentrations of most of the sampled trees were above deficiency ranges, while foliar Mg concentrations of most of the symptomatic trees were below the deficiency range within the plantations. Soil pH, exchangeable Mg, K, Ca, and their corresponding percent saturations in soils were lower, while soil Al concentrations were higher for most of the symptomatic trees in comparison to the healthy trees. Foliar concentrations of Mg, Ca, K, P, Al, Mn, Pb, and Zn were positively correlated with concentrations of corresponding soil elements. Knowledge of nutrient deficiency ranges may help diagnose foliar symptoms, but their exclusive use may overly simplify relationships between foliar symptoms and foliar elements. Principal component regression analysis of the data provided assessment of interactions and balances among foliar elements, and among soil elements and their possible influences on crown symptoms. Crown symptoms were not only associated with concentrations of individual elements of foliage and soils, but also associated with interactions and balances between these elements. The influences of individual soil elements on discoloration and defoliation may depend upon other elements in soils. Soil Al may induce crown discoloration and defoliation by interfering with Mg, Ca, and K uptake in acidic soils.     

Effects of fertilization with MgSO4 and (NH4)2SO4 on soil solution chemistry,mycorrhiza and nutrient content of fine roots in a norway spruce stand

This paper focuses on the short-term reaction of fine root and mycorrhiza on changes in soil solution chemistry following application of MgSO₄ (Kieserite) and (NH₄)₂SO₄ (ammonium sulfate). The experiments were conducted within the ARINUS Experimental Watershed Area near Schluchsee in the Black Forest (SW Germany). Yellowing of the older needles as related to Mg deficiency was the typical symptom observed within this 45 yr old Norway spruce stand. On the N treated plot the relative mycorrhiza frequency declined and the percentage of nonmycorrhizal root tips increased, whereas in the Mg fertilized plot these parameters did not differ from the control. The observed changes cannot be caused by Al, because elevated concentrations of potentially toxic Al species and extremely low Ca/A1 molar ratios appeared in the soil solution of both treatments and did not result in reduced growth of long roots as reported from solution culture experiments. Moreover, the Al content of fine roots did not increase. Therefore, it is concluded that the thresholds for Al toxicity derived from solution culture experiments with nonmycorrhizal seedlings cannot be transferred to forest stands. A direct toxic effect of elevated NH₄ ⁺ concentrations on mycorrhiza is unlikely, but cannot be excluded. Enhanced root growth due to a higher uptake of NH₄ ⁺ from soil solution may provide a more plausible explanation for the observed increase in the percentage of nonmycorrhizal root tips after N application. Even though the N content of fine roots did not increase, the diminished K content gives some indirect indication for NH₄ ⁺ uptake by the roots. This is also consistent with reduced Mg content due to NH ₄ ⁺ /Mg²⁺ antagonism. On the MgSO₄ treated plot, Mg contents of the fine roots increased thus reflecting Mg uptake by the deficient stand.     

Foliar potassium,calcium, magnesium,zinc, and manganese content in soybean cultivars at different stages of development

Plant tissue accumulation of potassium (K), calcium (Ca), magnesium (Mg), zinc (Zn), and manganese (Mn) was determined for six soybean [Glycine max (L.) Merr.] cultivars at successive stages of development. No nutrient accumulation patterns among the cultivars were found. The results obtained showed that the highest concentrations of K were found at the vegetative stage (V) and the lowest towards the end of the life cycle of the plant (R55). By contrast, Ca was lowest at the vegetative stage while increasing in the leaves in later growth stages. No significant differences in Mg content were found between growth stages. Manganese levels were lower at R2 and R4 than at R55 stages of growth with an accumulation towards the end of the reproductive cycle. Changes in Zn content between stages were different for each cultivar. The differing behavior of these elements is related to the difference in their mobility and transport capacities within the plant.     

Elemental leaf content and deficiency symptoms in rabbiteye blueberries: 2. Calcium and magnesium

In separate tests, rabbiteye blueberries (Vaccinium ashei Reade) grown in sand culture were subjected to varying levels of Ca (0–81 mg/liter) and Mg (0–24 mg/liter) applied at rates of 250 ml/plant daily. Other essential nutrients were kept constant. Leaf concentrations of N, P, K, Mg, Ca, Mn, Fe, Cu, B, Zn, Co, and Al were determined. The concentration of Ca in the leaves increased linearly but that of Cu decreased in response to increasing levels of Ca fertilization. Leaf concentrations of other elements were not significantly influenced by Ca fertilization. Leaf Mg and Al concentrations increased linearly in response to increasing levels of Mg fertilization. The P content in leaves followed a quadratic curve with increased Mg fertilization. Percent P increased from the 0 to 12 mg/liter levels and then decreased from the 12 to 24 mg/liter levels of Mg. High levels of Mg fertilization resulted in reduced Cu content of leaves.

Fertilization rates of Ca or Mg had little effect on shoot dry weight except at the 0 mg/liter levels. As leaf Ca decreased below 0.20% Ca, Ca deficiency symptoms became more prevalent. Magnesium deficiency symptoms increased as leaf Mg decreased below 0.15% Mg.     

Morphophysiological and Grain Yield Responses to Foliar and Soil Application of Boric Acid on Soybean

ABSTRACT

Boric acid (H₃BO₃) fertilization as source of boron (B) is a common practice in modern agriculture, aims to correct the deficiency of this micronutrient in the Cerrado soils, and ensure the maintenance of plant metabolism for the proper crops’ development. Therefore, the aim of this work was to evaluate the effects of H₃BO₃ fertilization on soil and leaves during the soybean development. The experimental design was completely randomized with six replicates. The treatments were obtained in a 3 × 2 factorial scheme, fertilization with H₃BO₃ for three doses of B in the soil: 0 (control); 0.62 and 3.4 kg ha^?1 and two foliar supplementation conditions: absence and presence. The best results for the variables length, dry mass and leaf area of soybean plants occurred with B applied to soil at doses 0 and 3.4 kg ha^?1 in the absence of foliar supplementation. B content in the plants gradually increased with the micronutrient supply via soil and in leaves. Physiological apparatus of the plants was more efficient in the absence of foliar supplementation, independently of the fertilization with doses in the soil. The grain mass was up to 57% higher in the control treatment. Fertilization with H₃BO₃ in the soil and foliar did not improve the morphophysiological traits and the production of soybeans grown in greenhouse using clayey soil with initial B content of 0.30 mg dm^?3.     

Foliar response of wild and domesticated Phaseolus vulgaris L. to water stress

It is surmised that domestication has reduced geneticvariability in the common bean (Phaseolusvulgaris L.). However, little is known about leaf anatomy responses to water stress in wild or domesticated forms ofP. vulgaris. In this study,anatomical variation was evaluated in watered and water stressed plants of wild and domesticated genotypes of P.vulgaris from Mexico, growing under greenhouse conditions. Five terminal leaflets of completely expanded leaves wereused to evaluate leaf area (LA) and theirmiddle-regions to evaluate leaf thickness (LT), and various anatomical features. Domesticated genotypes showed bigger LAthan that of the wild ones; there was an effect due to the origin of materials, LA being bigger in genotypes from warm and humid lands that those from dry and temperate ones. No differences were detected in LT among materials; however, in domesticated plants the palisadeparenchyma predominated over the spongy one, contrasting with thewild genotypes. Under drought conditions, stomatal abortion was observed in wild and domesticated genotypes, especially on theabaxial surface. We conclude that, in fact, there are contrasting differences in leaf anatomy among wild and domesticated forms of Mexican Phaseolus vulgaris. Results suggest that domestication not only favours the enlargement of the LA, but also an increase in palisade parenchyma, suggesting a divergence toward assimilation in domesticated forms, in contrast with a better internal gas diffusion in wild forms. Domestication seems to have accentuated stomatal abortion as means of a transpirational control mechanism to counteract the effects of drought.     

Forest soil community responses to plant growth-promoting rhizobacteria and spruce seedlings

The influence of plant-growth-promoting rhizobacteria (PGPR) and spruce seedlings on the composition and activity of forest soil microbial communities was studied in a microcosm experiment in which sterile, sand-filled 25mm×150mm glass tubes were treated with a forest soil suspension containing Bacillus or Pseudomonas PGPR and 2-week-old spruce seedlings. Eighteen weeks after treatments were established, bacterial, actinomycete and fungal population sizes were determined by dilution plating, as were seedling dry weights and soil carbon substrate utilization profiles using Biolog plates. PGPR inoculation had little influence on the population sizes of actinomycetes or fungi. However, significant effects were detected on the total bacterial population size, primarily in microcosms without seedlings. Euclidean distances between treatments plotted on two dimensions by multidimensional scaling showed that the introduction of PGPR strains changed the type of microbial community, particularly when inoculated into soil without seedlings. Significant changes were also detected in one soil type in the presence of seedlings. Our results suggest that the type of soil community and the presence of seedlings are significant factors influencing the responses of soil communities to bacterial inoculation, and that for some soil communities, the presence of seedlings may mitigate perturbations caused by the introduction of PGPR. Received: 24 February 1997     

Foliar, Physiologial and Growth Responses of Four Maple Species Exposed to Ozone

In order to restore the forest ecosystem in the vicinity of an industrial park, Ulsan, southeastern Korea, which has been heavily acidified by air pollution, a preliminary experiment by applying tolerant plants selected through several procedures, and dolomite and sewage sludge as soil ameliorators was carried out. Furthermore, a restoration based on the results was executed and the effects were evaluated based on the creation of safe sites, where new species can establish: regeneration of the forest with species similar in composition to the natural vegetation of native forests that are distant from the industrial park; increase in species diversity. In a preliminary study, the necessity of soil amelioration was diagnosed. Quercus serrata, Alnus firma and Ligustrum japonicum, which represent for tree, subtree, and shrub layers of vegetation in this region, were used as sample plants. Dolomite, sludge, and a mixture of both materials were applied as soil ameliorators. Bare ground (BG), and two grasslands dominated by forbs (GF) and grass (GG), respectively were designated as experimental plots based on a vegetation map of the corresponding area. BG and GF plots, which have lower organic matter contents, increased the growth of sample plants in response to soil amelioration, whereas that with higher contents, GG plot, did not show this response. The result suggests that necessity of soil amelioration depends on site quality. The effects of soil amelioration depended also on the sample plants. This difference is due to an ecological property of A. firma, which can fix atmospheric nitrogen through a symbiotic relationship with actinomycetic fungi. This result implies that this alder could be used as a substitute for soil ameliorators in restoration plan of this area. The height and standing crop of undergrowth, which forms dense grass mat and thereby impedes establishment of new plants, decreased in the restored stands. Such a decrease in the height and biomass of undergrowth could be recognized as providing safe sites, in which the other plants can invade, by removing the dense carpet formed by Miscanthus sinensis. The results of stand ordination showed a progression of the former bare grounds to either M. sinensis (GG) or Pueraria thunbergiana (GF) stands, suggesting a natural recovery through succession toward the stands dominated by both plants. But the change was not progressed beyond the grassland stage. Active restoration practice, which was carried out by applying tolerant plants, however, led to a change toward species composition similar to the natural vegetation before devastation. Furthermore, restored stands reflected the restoration effect by showing higher diversity than the stands in the degraded state. These results showed that the restorative treatment carried out by introducing tolerant plants functioned toward increasing both biological integrity and ecological stability and thereby could meet the restoration goal.     

Foliar analysis of sulphur in different soybean cultivar stages and its relation to yield

Abstract

Six soybean cultivars (maturity group V) were sown in a Typic Argiudoll. Experimental plots were arranged in a randomized block design with three replications. Sampling dates were at different stages: V, R2, R4, and R55. All the varieties showed that the greatest sulfur (S) concentrations were in stage V and the lowest in stage R55. No significant differences were found between the means of the S concentrations during the V, R4, and R55 stages. In the R2 stage, there was a poor correlation with the weight of 1,000 seeds.     

Foliar leaching and root uptake of Ca,Mg and K in relation to acid fog effects on Douglas-fir

The impact of acid fog on foliar leaching and root uptake of Ca, Mg, and K by Douglas-fir (Pseudotsuga menziesii) seedlings was examined. In a factorial experiment, 1-year old seedlings were grown in solution culture at two levels of nutrient availability (low and moderate) and exposed twice a week (4 hr per event) for 12 weeks to fog at pH 5.6 or pH 3.1. Throughfall enrichment of Ca, Mg and K was determined from drip collectors at the base of each seedling and root uptake rates for trees under the moderate nutrient regime were evaluated by monitoring nutrient solution depletion. Throughfall enrichment was higher in the pH 3.1 fog than the pH 5.6 fog but much of the enrichment appeared to be wash off of precipitate from previous fogs. The amounts of nutrients coming off of the foliage with the low pH fog were small relative to the daily uptake rates. Foliar concentrations of K and Mg at the end of the exposures were lower under the low nutrient regime but were not affected by fog pH. Comparisons of wax weight and examinations of epicuticular wax by electron microscopy did not indicate a significant impact from exposure to the low pH fog.     

Effect of Foliar and Substrate Fertilization on Lady Palm Seedling Growth and Development

Lady palm, [Rhapis excelsa (Thunberg) Henry ex. Rehder] is one of the most cultivated ornamental palms in the world, for use as a vase plant or in shaded landscapes. Because limited information exists on lady palm response to fertilizers, the objective of this study was to evaluate the effect of different types of fertilization and substrates on lady palm seedling growth and development. Three year old lady palms were planted in 8-L pots, filled with a mix of soil, manure, and sand 1:1:1 (v:v:v), placed under a 50% shade, and irrigated with microspray. Treatments were substrate fertilization with 500 g P₂O₅ and 100 g K₂O per m³; fertilization with 1.8 kg of P₂O₅ (simple superphosphate) per m³; 50 g of nitrogen (N), P₂O₅, and K₂O of a granulated fertilizer (10:10:10) per m³, control (without fertilization), and a foliar fertilization in addition to these treatments using the commercial product Biofert® (8:9:9). Treatments were replicated four times in a randomized block design. Each treatment plot consisted of four plants. Data were collected at 140, 170, 200, 230, 260, and 290 days after transplanting (DAT) for plant heights, stem diameter at substrate level, number of leaves, shoots, and canopy, roots fresh and dry matter samples were harvest at 290 days. Foliar fertilization resulted in significantly greater plant height in a 140, 120, 200, and 230 DAT and plant diameter on the 140, 260, and 290 DAT. There was interaction among factors for number of leaves with fertilization based on P₂O₅ and K₂O when leaf fertilizer was added that resulted in a greater number of leaves.     

Symptomatology and analyses of nutrient deficiencies produced on flowering annual plants

Abstract

Deficiency symptoms were produced on 11 different flowering annual plants grown in sand cultures containing Hoagland's complete and nutrient deficient solutions. Visual observations were recorded and leaf analyses run to establish standard and threshold levels of important macro‐and micro‐elements.     

Foliar application of urea to almond and olive: Leaf retention and kinetics of uptake

Regression equations relating volume of urea solutions retained on leaves initially and leaf area were developed to assess urea deposition nondestructively and facilitate measurement of urea uptake by leaves of olive (Olea europaea L.) and almond [Prunus dulcis (Mill.) D. A. Webb], Foliar uptake of urea was slower in olive than it was in almond, but uptake in both species was proportional to the concentration of the urea applied. Foliar uptake of urea was not influenced by previous applications. No phytotoxicity was apparent in almond and olive following single applications of 0.5% w/v urea and 4% (w/v), respectively. Approximately 15 times more urea could be applied per cm of an olive leaf than per cm of an almond leaf at the threshold of phytotoxicity. Leaf N content in olive was increased 47% with minimal phytotoxicity following 5 successive foliar applications of 2% urea within ten days.     

Impact of acid fog and ozone on coastal red spruce

High levels of ozone and acidic fog have been measured along the coast of Maine, U.S.A. Some of the ozone and nitrate are a consequence of direct transport from East Coast metropolitan centers, but we discuss evidence supporting N₂O₅, and perhaps ozone, generation at forested sites from NO_x precursors. Fogs with pH below 3.3 occur with greatest frequency in the mid-coast region. Ozone is consistently highest along the southwest coast, but peak hourly averages are often highest in the mid-coast. Historical evidence suggests an increase in fog acidity and nitrate levels, but no change in sulphate within the past 48 years. Red spruce with decline symptoms can be observed from the south-coast to mid-coast region, with the greatest symptom development in the mid-coast. Trees in the mid-coast on soils with high base saturation and Ca/Al ratios develop symptoms of late winter injury (reddening and casting of current year needles in late winter and spring). Trees on poorer soils develop chlorosis on upper surfaces of older needles. Nutrient analysis of soils and foliage reveals differences between stressed and unstressed sites. Scanning electron microscopy of needle surfaces also reveals response differences between pollutant stressed and unstressed trees. Hypotheses and research directions are discussed.     

The dry deposition of gaseous and participate nitrogen compounds to a spruce stand

The dry deposition of particle-bound NH₄ ⁺ and NO₃ ^– and of gaseous NH₃ and HNO₃ to a 45 year old Norway Spruce forest was determined by the inferential method. Deposition velocities were calculated from meteorological data and plant morphology by a multi-layer model which combines the transfer of the trace substances within the canopy and their absorption probabilities due to a variety of deposition mechanisms. For gaseous deposition the same mathematical concept was adopted as for particles. That means that this approach is an alternative to the common concept of resistance analogy. The mean deposition velocities found were 0.47 cm s^–1 for NH₄ ⁺ and 1.85 cm s^–1 for NO₃ ^–. While these values are in the range found in other studies, the mean deposition velocities for the gases were quite large. For NH₃ 13 cm s^–1 were found and for HNO₃ 11 cm s^–1. It is suggested that the absorption of these gases on the plant surfaces is not as effective as assumed in the model.     

Physiological Responses of Transgenic merA-TOBACCO (Nicotiana tabacum) to Foliar and Root Mercury Exposure

Plants expressing a modified bacterial mercury reductase, merA, are highly resistant to Hg(II) toxicity as a result of the enzymatically catalyzed electrochemical reduction of Hg(II) to the much less toxic and volatile Hg(0). merA expression may allow plants to manifest a suite of responses to mercury exposure, making them more capable than wild-type plants of interacting with and removing mercury from contaminated soil or water. We have engineered merA-expressing Nicotiana tabacum (tobacco) as a model plant for examining these responses. Mercury resistance was demonstrated by germinating and growing merA tobacco seeds on semi-solid medium spiked with a HgCl₂ concentration acutely toxic to wild-type plants. On similar growth medium, merA plant roots penetrated a highly concentrated, localized Hg(II) zone of HgS (cinnibar) more readily than wild-type roots. In hydroponic medium spiked with HgCl₂, merA plants maintained higher evapotranspiration activity than wild-type plants. The ability of merA Hg(II)-reductive activity to counter typical plant-catalyzed Hg(0) oxidation to Hg(II) was demonstrated by a lower net foliar absorption of atmospheric Hg(0) than wild-type plants. Mercury translocation through merA plants was examined through reciprocally grafted merA and wild-type tobacco grown on HgCl₂-spiked hydroponic medium. Elevated mercury concentrations in wild-type shoots grafted to merA roots suggest the vertical movement of mercury within merA tissues or plants may be facilitated by dynamic balance between native Hg(0) oxidation and MerA-catalyzed Hg(II) reduction. These experiments demonstrate that merA-engineered tobacco plants display an array of tissue-level and whole-plant attributes which should allow for more efficient mercury extraction and processing compared to the wild-type.     

Boron and Amino Acid Foliar Application on Wheat-Soybean Intercropping in a Non-Tillage System

Micronutrient and amino acid (AA) foliar fertilization has generally been sprayed onto plants to increase the crop yield. The experiment had the aim of evaluating the foliar boron (B) and AA application on grain yield (GY), physiological characteristics, nutritional status, and yield components in wheat (Triticum aestivum L.) and soybean [Glycine max (L.) Merrill] intercropping in a non-tillage system (NTS). The experiment was set up as a randomized block design with eight treatments and four replicates. The treatments had the following boron (B) rates: [0, 1, 2, 4, and 8 kg ha^?1, source: boric acid (H₃BO₃)] + AAs (2 L ha^?1) applied by foliar spraying and the additional treatments [(Control - without B and AAs), 2 kg ha^?1 B, 2 L ha^?1 AAs and 2 kg ha^?1 B + 1 L ha^?1 AAs] applied at the end of the elongation and spike beginning of wheat plants and development growth stage (V5) of soybean for two growing seasons. Boron and AAs had no influence on the physiological and yield components and had no increases in the foliar and grain B content in wheat and soybean. No matter the dose, the foliar B + AAs (2 L ha^?1) application did not increase the GY in wheat-soybean under a rotational NTS in loamy soil with suitable available B.