Widespread malnutrition of zinc (Zn), iodine (I), iron (Fe) and selenium (Se), known as hidden hunger, represents a predominant cause of several health complications in human populations where rice (
...Oryza sativa
L.) is the major staple food. Therefore, increasing concentrations of these micronutrients in rice grain represents a sustainable solution to hidden hunger. This study aimed at enhancing concentration of Zn, I, Fe and Se in rice grains by agronomic biofortification. We evaluated effects of foliar application of Zn, I, Fe and Se on grain yield and grain concentration of these micronutrients in rice grown at 21 field sites during 2015 to 2017 in Brazil, China, India, Pakistan and Thailand. Experimental treatments were: (i) local control (LC); (ii) foliar Zn; (iii) foliar I; and (iv) foliar micronutrient cocktail (i.e., Zn + I + Fe + Se). Foliar-applied Zn, I, Fe or Se did not affect rice grain yield. However, brown rice Zn increased with foliar Zn and micronutrient cocktail treatments at all except three field sites. On average, brown rice Zn increased from 21.4 mg kg
–1
to 28.1 mg kg
–1
with the application of Zn alone and to 26.8 mg kg
–1
with the micronutrient cocktail solution. Brown rice I showed particular enhancements and increased from 11 μg kg
–1
to 204 μg kg
–1
with the application of I alone and to 181 μg kg
–1
with the cocktail. Grain Se also responded very positively to foliar spray of micronutrients and increased from 95 to 380 μg kg
–1
. By contrast, grain Fe was increased by the same cocktail spray at only two sites. There was no relationship between soil extractable concentrations of these micronutrients with their grain concentrations. The results demonstrate that irrespective of the rice cultivars used and the diverse soil conditions existing in five major rice-producing countries, the foliar application of the micronutrient cocktail solution was highly effective in increasing grain Zn, I and Se. Adoption of this agronomic practice in the target countries would contribute significantly to the daily micronutrient intake and alleviation of micronutrient malnutrition in human populations.
Aims
Taking into account the relevance of biofortification of crop plants with selenium (Se) - an essential element for humans and animals -, this study assessed the effect of adding Se in the soil ...(as selenate) on: i) rice grains yield; ii) Se contents in polished rice grains; iii) physiological traits in rice leaves; and, iv) spatial distribution of Se and other elements in biofortified grains.
Methods
A field trial was conducted using five Se rates (12, 21, 38, 68, and 120 g ha
−1
). Physiologic and enzymatic evaluations were carried out in rice leaves. Rice grain yield and Se contents were assessed. Spatial distributions of Se and other elements were visualized mapping the biofortified rice grains with μXRF at Brazilian Synchrotron Light Source.
Results
Results showed that soil Se application was effective in producing rice grains with higher Se contents, yet no effects were verified on rice yield. Antioxidant enzyme activities and gas exchanges in rice leaves changed following the application of Se. The spatial distribution of different elements in biofortified grains varied, with Se being accumulated mainly in the rice endosperm.
Conclusion
Our results suggest that soil application of 47 and 36 g ha
−1
of Se (as sodium selenate) may guarantee the production of rice grains with adequate Se levels for human consumption in Brazil and worldwide, respectively.
Glauconitic siltstone is sedimentary rock used as raw material to produce a multinutrient fertilizer that can combine with urea to increase their agronomic efficiency. The purpose of this study was ...to evaluate glauconitic siltstone as additive to reduce nitrogen losses by ammonia volatilization in nitrogen fertilizers. The experiment used randomized block, in a portion subdivided over time, following a 6 x 8 factorial with four replications and treatments comprising glauconitic siltstone mixture at a dose of 100 kg N ha-1 (control, without the application of nitrogen; conventional urea – 45% N; commercial fertilizer registered with the trade name of Super N®; urea with addition of glauconitic siltstone: 9% N; 20 and 31% N) and the remaining portion divided in the collection time at 3, 6, 9, 12, 15, 18, 24 and 30 days after fertilizer application. The collection of the volatilized ammonia was made in a semi-opened free static chamber. The use of glauconitic siltstone associated with urea provided a reduction in loss by volatilization from 10 to 27% in relation to conventional urea. The treatments with application of urea with the urease inhibitor showed the lowest volatilization rate and delay in the volatilization peak, which occurred 17 days after fertilizer application. In addition to providing nutrients to the plants, glauconitic siltstone reduces ammonia losses.
Core Ideas
Captan and difenoconazole compromise in vitro survival of Rhizobium tropici CIAT 899.
In the field, native rhizobia were clearly tolerant to most of the fungicides evaluated.
Among the ...fungicide treatments assessed in the field, only difenoconazole is potentially damaging.
When difenoconazole treatment is indispensable, in‐furrow inoculation may be the most alternative.
Due to the effects observed in vitro, similar precautions should also be taken with captan in the field.
Though some studies observed negative effects of fungicide seed treatment on yield of common bean (Phaseolus vulgaris L.), few studies have directly evaluated fungicide compatibility with seed inoculation treatments in field conditions. For fungicides that are incompatible, rhizobia inoculation in the planting furrow (in‐furrow inoculation) would permit combined use of both management practices since this would avoid direct contact between the chemical compound and the rhizobia. Thus, the aim of this study was to evaluate the compatibility of seed fungicide treatment and rhizobia inoculation techniques to improve N derived from rhizobia symbiosis in common bean. A preliminary in vitro experiment evaluated the survival of Rhizobium tropici after contact with fungicides compared with an untreated control. Two field experiments were conducted in a 6 × 4 factorial arrangement involving the same treatments used for the in vitro survival test, as well as four sources of N two types of liquid inoculation (inoculation on the seed or in‐furrow inoculation), plus two controls without inoculation. We concluded that captan and difenoconazole fungicides reduced in vitro survival of rhizobia inoculated on the seed. Yield measurements in the field studies indicated that symbiotic nitrogen fixation could replace N fertilization, regardless of the inoculation treatment method and environmental conditions. Difenoconazole is potentially harmful to native bacteria in the field; therefore, in‐furrow inoculation may be recommended when the use of difenoconazole is necessary. Moreover, based on the harmful effects observed in vitro, precautions similar to the use of difenoconazole should also be taken when using captan fungicide in field conditions.
ABSTRACT The current recommendations for nitrogen (N) doses may not contemplate the complex dynamics of N in the soil, what may imply in insufficiency to the crop demand. This study aimed to evaluate ...the use of two portable chlorophyll meters (Minolta SPAD 502 and ClorofiLOG model CFL 1030), after defining the nitrogen sufficiency index (NSI), to estimate the nitrogen fertilization factor in modern bean genotypes. A block design was used, with four replications. Each experiment consisted of four treatments, with doses of 0, 5, 10 and 20 kg ha-1 of N for each 1 % considered below the NSI defined as adequate for each cultivar. At the end of the cycle, the production components and yield were evaluated. It was not possible to obtain precise adjustments in the methodology for the TAA Gol cultivar. The fertilization factor of 12.5 kg ha-1 of N for each 1 % below the NSI of 90 % proved to be efficient for the Pérola cultivar, when the SPAD-502 chlorophyll meter was used. In genotypes with size and cycle characteristics similar to those of the BRSMG Uai cultivar and the VR 20 strain, using a fertilization factor between 14 and 16 kg ha-1 of N, the NSI of 95 % must be reduced, in order to increase the efficiency of the nitrogen fertilization.
RESUMO As atuais recomendações de doses de nitrogênio (N) podem não contemplar a dinâmica complexa do N no solo, o que pode implicar em insuficiência à demanda da cultura. Objetivou-se avaliar o uso de dois medidores portáteis de clorofila (Minolta SPAD 502 e ClorofiLOG modelo CFL 1030), após a definição do índice de suficiência de nitrogênio (ISN), para estimar o fator de adubação nitrogenada em genótipos modernos de feijão. Utilizou-se delineamento em blocos, com 4 repetições. Cada experimento foi composto por quatro tratamentos, com doses de 0; 5; 10; e 20 kg ha-1 de N para cada 1 % considerado abaixo do ISN definido como adequado para cada cultivar. Ao final do ciclo, foram avaliados os componentes de produção e a produtividade. Não foi possível a obtenção de ajustes precisos na metodologia para a cultivar TAA Gol. O fator de adubação de 12,5 kg ha-1 de N a cada 1 % abaixo do ISN de 90 % mostrou-se eficiente para a cultivar Pérola, quando utilizado o clorofilômetro SPAD-502. Em genótipos com características de porte e ciclo semelhantes às da cultivar BRSMG Uai e linhagem VR 20, com a utilização de fator de adubação entre 14 e 16 kg ha-1 de N, o ISN de 95 % deve ser reduzido, visando aumentar a eficiência da adubação nitrogenada.
Agronomic biofortification with selenium (Se) effectively reduces hidden hunger and increases the nutritional intake of Se in people and animals. Because sorghum is a staple diet for millions of ...people and is used in animal feed, it becomes a crop with biofortification potential. Consequently, this study aimed to compare organoselenium compounds with selenate, which is effective in numerous crops, and to assess grain yield, the effect in the antioxidant system, and macronutrient/micronutrient contents of different sorghum genotypes treated with Se, via foliar spray. The trials used a 4 × 8 factorial design, with four Se sources (control-without Se supply, sodium selenate, potassium hydroxy-selenide, acetylselenide) and eight genotypes (BM737, BRS310, Enforcer, K200, Nugrain320, Nugrain420, Nugrain430, and SHS410). The Se rate used was 0.125 mg plant
. All genotypes reacted effectively to foliar fertilization with Se through sodium selenate. In this experiment, potassium hydroxy-selenide and acetylselenide showed low Se levels and lower Se uptake and absorption efficiency than selenate. Selenium fertilization increased grain yield and altered lipid peroxidation by malondialdehyde content, hydrogen peroxide content, catalase activity, ascorbate peroxidase, superoxide dismutase, and macronutrients and micronutrients content of the studied genotypes. In sum, biofortification with selenium led to an overall yield increase of sorghum plants and supplementation with selenium through sodium selenate was more efficient than organoselenium compounds, yet acetylselenide had a positive effect on the antioxidant system. Sorghum can be effectively biofortified through the foliar application of sodium selenate; however, studying the interaction between organic and inorganic Se compounds in plants is necessary.
Selenium is beneficial to plants and is essential for animals and humans, which justifies any efforts for producing Se-enriched wheat grains worldwide. This study aimed to (i) verify if wheat is an ...efficient species to be used for Se biofortification in tropical agroecosystems and (ii) assess the influence of Se on the physiological and biochemical parameters of wheat plants. Selenium was applied as sodium selenate (Na2SeO4) at different doses (12, 21, 38, 68, and 120 g ha−1) in soil. The dose of 120 g ha−1 of Se resulted in Se contents of 7.98 and 2.27 mg kg−1 in the leaves and grains, respectively. The supply of 38 g ha−1 of Se increased the total soluble sugar content by 50%, with reducing sugars increasing by 17% and sucrose augmenting 53%, compared with that in the control. The doses of 12, 68, and 120 g of Se ha−1 promoted a significant increase in catalase activity. In addition, Se application increased carbohydrate and nutrient contents. Our findings indicate that wheat is a good species for agronomic biofortification with Se via soil application in tropical agroecosystems. Selenium proved to be a valuable element for plants since it provides physiological and biochemical benefits.
Rare earth elements (REEs) have been intentionally used in Chinese agriculture since the 1980s to improve crop yields. Around the world, REEs are also involuntarily applied to soils through phosphate ...fertilizers. These elements are known to alleviate damage in plants under abiotic stresses, yet there is no information on how these elements act in the physiology of plants. The REE mode of action falls within the scope of the hormesis effect, with low-dose stimulation and high-dose adverse reactions. This study aimed to verify how REEs affect rice plants’ physiology to test the threshold dose at which REEs could act as biostimulants in these plants. In experiment 1, 0.411 kg ha−1 (foliar application) of a mixture of REE (containing 41.38% Ce, 23.95% La, 13.58% Pr, and 4.32% Nd) was applied, as well as two products containing 41.38% Ce and 23.95% La separately. The characteristics of chlorophyll a fluorescence, gas exchanges, SPAD index, and biomass (pot conditions) were evaluated. For experiment 2, increasing rates of the REE mix (0, 0.1, 0.225, 0.5, and 1 kg ha−1) (field conditions) were used to study their effect on rice grain yield and nutrient concentration of rice leaves. Adding REEs to plants increased biomass production (23% with Ce, 31% with La, and 63% with REE Mix application) due to improved photosynthetic rate (8% with Ce, 15% with La, and 27% with REE mix), favored by the higher electronic flow (photosynthetic electron transport chain) (increase of 17%) and by the higher Fv/Fm (increase of 14%) and quantum yield of photosystem II (increase of 20% with Ce and La, and 29% with REE Mix), as well as by increased stomatal conductance (increase of 36%) and SPAD index (increase of 10% with Ce, 12% with La, and 15% with REE mix). Moreover, adding REEs potentiated the photosynthetic process by increasing rice leaves’ N, Mg, K, and Mn concentrations (24–46%). The dose for the higher rice grain yield (an increase of 113%) was estimated for the REE mix at 0.72 kg ha−1.
The aim of this study was to evaluate the genetic variability and performance of the agronomic traits of wheat cultivars in the southern region of Minas Gerais for the purpose of choosing parents for ...a rainfed wheat breeding program. We evaluated 78 wheat cultivars in two locations in Minas Gerais regarding different agronomic traits. The statistical analyses were carried out using Henderson’s mixed-model approach. The genetic values of the cultivars were predicted, and the heritabilities and accuracies were estimated for selection of cultivars. The cultivar × location interaction was decomposed into its simple and complex fractions. The genetic and environmental correlations between the traits were estimated, and selection was made for multiple traits using the sum of the standardized variables (Z-index). The genetic variance was significant for all the traits, and the cultivar × location interaction was significant. By the Z-index, 15 wheat cultivars more adapted were identified.
The BRSMG Uai common bean cultivar (Phaseolus vulgaris L.) unites traits required by producers, such as high yield and upright stands, the latter of which is considerably improved in relation to ...previously released cultivars such as BRSMG Madrepérola and Pérola. However, the potential of the cultivar to form symbiotic relationships with rhizobia to fix N2 has not yet been assessed. Here, field experiments were conducted to assess the efficiency of biological nitrogen fixation (BNF) in the cultivar, and to compare this to the efficiencies of other genetic materials widely grown throughout Brazil (BRSMG Madrepérola and Pérola). Experiments were conducted on two Oxisols in Minas Gerais State, Brazil (one during the dry season in the south, and the other during the winter season in the Alto-Paranaíba region), under a no-tillage system over maize stover. A randomized block experimental design was implemented in a 3 × 3 factorial arrangement with four replicates. Individual and combined Analysis of Variance were performed and the data were normalized. Homogeneity of the residual mean squares was observed. Significant effects of factors were identified by Scott-Knott tests and F tests. The BRSMG Uai cultivar responded to inoculation with the rhizobial strain CIAT 899, with yields similar to those achieved upon fertilization with 80 kg ha-1 of N-urea and to the yields of the BRSMG Madrepérola and Pérola cultivars inoculated with the same rhizobial strain. In terms of commercial use, this cultivar may be successful under either of the management practices adopted for N supply, and from the perspective of plant breeding, it has potential for inclusion in breeding programs directed toward improving BNF.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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