Search

Cajanus cajan and Canavalia ensiformis are commonly used as cover crops due to their high biomass production, in addition they are also applied in recovery strategies for degraded areas. The objective of this study is to compare the tolerance, accumulation and translocation of Mn in the tissues of C. cajan and C. ensiformis, based on biomass production and the effects on the photosynthetic apparatus between species. The experiment was carried out in Red Latosol, contaminated with MnCl2 in the following concentrations: 0 (control), 80, 100, 120, 140 and 160 mg kg−1. Mn doses resulted in differentiated absorption, translocation and accumulation in plant organs, generating changes in the photosynthetic apparatus, reduction in dry mass and growth, and variations in tolerance and translocation levels between species. According to the results obtained, both species proved to be tolerant Mn and can be used in manganese management systems, they're able to accumulate Mn in tissues, and not only maintain but also improve biomass production at intermediate doses, C. cajan indicates to be a better option for phytostabilization of Mn, on the other hand C. ensiformis, indicates to be a better option for phytoextraction of Mn in soils with contents up to 160 mg kg−1. [ABSTRACT FROM AUTHOR]

The synthesis and differential allocation of reserve compounds is an important adaptive mechanism that enables species to resprout in fire-prone ecosystems. The analysis of compound allocation dynamics (differential accumulation of compounds between plant organs) provides insights into plant responses to disturbances. The aim was to quantify reserves in eight legume species from Cerrado open savannas with high fire frequency in order to investigate the patterns of allocation and distribution of compounds between leaves and underground organs, drawing ecophysiological inferences. The species were collected in 'campo sujo' areas of the Cerrado. Leaves and underground organs (xylopodium, taproot tubers) were subjected to physiological analyses. Overall, underground organs were characterised by greater deposits of carbohydrates, mainly soluble sugars, and also with the accumulation of proteins and amino acids. This suggests that nitrogen reserves, as well as carbohydrates, may have an ecophysiological function in response to fire, being allocated to the underground organs. Phenols were mainly evident in leaves, but a morphophysiological pattern was identified, where the two species with taproot tubers tended to concentrate more phenols in the underground portion compared to species with xylopodium, possibly due to functional differences between these organs. Such data allow inferring relevant ecophysiological dynamics in legumes from open savannas. In this paper, we explore the intricate world of savanna plant dynamics. Studying reserve allocation in these plants is crucial for understanding their response to disturbances. Our research quantifies reserves in savanna legumes, examining compound distribution between leaves and underground organs. Discoveries reveal the role of underground organs as carbohydrate depots and nitrogen reserves, shedding light on the diverse accumulation patterns across different organ types. These insights offer invaluable knowledge for understanding species survival in fire-prone savannas. [ABSTRACT FROM AUTHOR]

Brazilian soils are predominantly rich in aluminum, which becomes mobile at pH < 5, affecting sensitive plants; however, some species have developed aluminum tolerance mechanisms. The purpose of this study was to compare the physiological responses of Crotalaria genus species, family Fabaceae, which have the ability to associate with nitrogen-fixing bacteria under the influence of Al3+ in the soil. The soil used was Oxisol; the experimental design was in randomized blocks in a factorial scheme (2 × 3): soil factor (available toxic aluminum content; correction of dolomitic limestone—MgCO3) and species factor (C. juncea; C. spectabilis; C. ochroleuca); cultivated within 43, 53, and 53 days, respectively, with five replications; 30 experimental samples. Mass and length, pigments, gas exchange, and changes in nitrogen metabolism were evaluated. C. juncea showed a higher concentration of amino acids in the leaves, internal carbon, and stomatal conductance in soil with Al3+, as well as higher production of ureides, allantoinic acid, allantoic acid, proteins, and amino acids in the nodules, with 78% of the Al3+ accumulation occurring in the roots. C. ochroleuca demonstrated greater shoot length and nodule number production in limed soil; in soil with Al3+, it showed a 91% increase in chlorophyll a content and 93% in carotenoids. C. spectabilis showed a 93% increase in ureide production in the leaves in soil with Al3+. [ABSTRACT FROM AUTHOR]

Copper, a micronutrient in low concentrations, in excess causes negative changes in the growth and development of plants. This study advances understanding in the dynamics of potentially toxic elements in areas with different uses, making it possible to evaluate the potential of C. cajan to remedy/reduce excess Cu in the soil. It was observed that in C. cajan grown in agricultural soil with high P availability, the translocation of Cu to shoot was 5−7 times greater than in grassland and grassland contaminated with Cu, where the preferred allocation for Cu was the root. The efficiency of the photosynthetic and symbiotic system was not affected; but an increase in the concentration of amino acids was observed. Because of considerable accumulation of Cu in the root and shoot, C. cajan was tolerant to a dose of approximately 100 mg kg−1 of Cu in viticulture soil and may be indicated as a phyto-extractor agent for this metal in agricultural soils. [ABSTRACT FROM AUTHOR]

Soil contamination by boron (B) occurs in different ways, such as through mineral fertilisers and irrigation, and in surface waters it has increased significantly over the years. It is an important element for plants, participating in several physiological processes. This work aimed to evaluate the behaviour of Crotalaria juncea, widely used as green manure. The species that tolerates B up to a dose of 60 mg dm−3 has the capacity to phytoremediate B and is classified as a phytostabilizer. It is clear that a dose of 120 mg dm−3 of B is harmful to the growth of the species. [ABSTRACT FROM AUTHOR]

Soil contamination by trace elements is a worldwide concern that can result from several sources, such as mining, smelting, car traffic exhaust, agriculture plant protection products such as fungicides, and fertilizers. Among the metals involved, copper can cause alterations in the photosynthetic, respiratory, and enzymatic processes of plants, leading to reduced growth of roots and shoots. An alternative to dealing with metals present in the soil is phytoremediation, which consists of using plants to extract or stabilize these elements. The leguminous Crotalaria juncea is widely used as a green manure and may be advantageous due to its capacity for biological nitrogen fixation and biomass accumulation. This research aimed to evaluate the growth and physiological behaviour of C. juncea in copper-contaminated soil and its potential use as a phytoremediation plant. For the fresh and dry mass of shoots and roots, compared with 30 mg.dm−3 of Cu, there was a decrease in values with the increase in concentrations up to a dose of 480 mg.dm−3. The roots were less sensitive to increased Cu concentrations than the shoots. The tolerance index decreased as copper concentrations in the soil increased. From 60 mg.dm−3, its vegetative growth decreased, but C. Juncea was able to tolerate and accumulate copper in the root system, presenting high potential as a phytostabilizing species. [ABSTRACT FROM AUTHOR]

Introduction and aims: In the context of increasing population and decreasing soil fertility, food security is one of humanity's greatest challenges. Large amounts of waste, such as sewage sludge, are produced annually, with their final disposal causing environmental pollution and hazards to human health. Sludge has high amounts of nitrogen (N), and, when safely recycled by applying it into the soil as composted sewage sludge (CSS), its residual effect may provide gradual N release to crops. A field study was conducted in the Brazilian Cerrado. The aims were to investigate the residual effect of successive applications of CSS as a source of N in the common bean (Phaseolus vulgaris L. cv. BRS Estilo)-palisade grass (Urochloa brizantha (A.Rich.) R.D. Webster)-soybean (Glycine max L.) rotation under notillage. Additionally, N cycling was monitored through changes in N metabolism; the efficiency of biological N2 fixation (BNF) and its implications for plant nutrition, development, and productivity, was also assessed. Methods: The experiment consisted of a randomized complete block design comparing four CSS rates (10, 15, 20, and 25 Mg ha-1, wet basis) to a control treatment (without adding mineral or organic fertilizer) over two crop years. Multiple plant and soil analyses (plant development and crop yield, Falker chlorophyll index (FCI), enzymatic, biochemical, 15N natural abundance, was evaluated, root and shoot N accumulation, etc.) were evaluated. Results and discussion: Results showed that CSS: i) maintained adequate N levels for all crops, increasing their productivity; ii) promoted efficient BNF, due to the stability of ureide metabolism in plants and increased protein content; iii) increased the nitrate content and the nitrate reductase activity in soybean; iv) affected urease activity and ammonium content due to changes in the plant's urea metabolism; v) increased N accumulation in the aerial part of palisade grass. Composted sewage sludge can be used as an alternative source to meet crops' N requirements, promoting productivity gains and N cycling through forage and improving N metabolism. [ABSTRACT FROM AUTHOR]

Molybdenum (Mo) is a key element in the N fixing and assimilation processes in leguminous plants. This study aimed to evaluate the effects of Mo fertilization on the yield and seed vigor of the common bean. Molybdenum was applied at six rates (0, 20, 40, 80, 120 and 160 g ha−1) in field trials over 2 consecutive years (2015 and 2016). Foliar applications were performed during the phenological stages V4 (4th trifoliolate leaf unfolded) and R1 (early flowering). The SPAD index, height of first pod insertion, number of pods per plant, number of seeds per pod, weight of 100 seeds, yield and seed vigor were determined. Molybdenum affected the production of reproductive organs only in the second agricultural year. Application of Mo at T-V4 resulted in an increase in the number of pods per plant (11%), and at 120 g ha−1, there was an increase (41%) in the number of seeds per pod, but this did not result in a yield seed increase. Molybdenum applied at the T-V4 phase reduced electrical conductivity in the first year of the experiment at rates of 40 g ha−1 (17%) and 160 g ha−1 (13%). In the second agricultural year, Mo applied at the T-R1 phase reduced in 44% the electrical conductivity, as well as the application of 20 g ha−1 also at the T-R1 phase increased seed germination (28%), seedling length (8%), and length of the primary root (10%). Different responses to the Mo application time and dose between the experimental years suggest that common bean plants recycle Mo. Molybdenum applied in the first agricultural year may have satisfied the initial Mo demand of the common beans in the second year of crop due it's low Mo requirement. This study show that foliar Mo application is an important strategy to achieve sustainable production of higher quality seeds of common bean. [ABSTRACT FROM AUTHOR]

Soil contamination by toxic elements causes concern and is increasing through industrial development, mining activities and the overuse of chemical fertilisers. Some toxic elements, such as boron, also play a structural role. The present study aimed to evaluate the behaviour of S. aterrimum plants growing in boron artificially contaminated soils. It has been found that S. aterrimum is tolerant to low doses of boron, moderately tolerating doses of up to 240 mg.dm−3. But high doses (doses above the adequate zone) cause decreased plant growth and present symptoms of toxicity, such as foliar chlorosis. The dose of 240 mg.dm−3 can already be considered toxic, since the tolerance index (TI) was less than 50%. The species can be used as a phytoextractor in low doses of boron because it presented a high tolerance index (TI) and demonstrated the ability to uptake and accumulate boron in root tissue. [ABSTRACT FROM AUTHOR]