Efficient detection of nutrient deficiencies and development of corrections in avocado through the Compositional Nutrient Diagnosis (CND)

Mexico is the main producer of avocado (Persea americana Mill.), contributing 31% of the world supply, which provides the country with an annual income of more than 2 billion dollars. The increase in national production is the result of a larger cultivated area, and not an increase in yields. In the State of Mexico, Mexico around 10 thousand hectares are cultivated with avocado trees, although 77% of the producers do not have specialized technical advice that offers reliable information on crop nutrition. This lack of advice and technical support detracts from volume and quality of production. The objective of this research was to carry out the nutritional diagnosis of an avocado orchard in Tejupilco, State of Mexico, Mexico, through the Compositional Nutrient Diagnosis (CND), and to generate specific fertilization recommendations for the study area, for which leaf and soil analyses were carried out. Each nutrient determined in the leaf analysis (N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, and B) was compared with its optimal concentration according to literature. The CND yielded relative deficiency or excess indices that determined the order of nutritional limitation. Zn, B, S, and K deficiencies were detected in all sampled areas, while P, Mn, and Cu were deficient only in some areas. N, Ca, Mg, and Fe did not show nutritional limitation. Recommendations were formulated to address each of the nutritional deficiencies and the problem of sodicity revealed by the soil analysis. This is the first work in which the CND is used to assess the nutritional situation of avocado orchards in the world

Thermal effects in Ni/Au and Mo/Au gate metallization AlGaN/GaN HEMT's reliability

AlGaN/GaN high electron mobility transistors (HEMT) are key devices for the next generation of high-power, high-frequency and high-temperature electronics applications. Although significant progress has been recently achieved [1], stability and reliability are still some of the main issues under investigation, particularly at high temperatures [2-3]. Taking into account that the gate contact metallization is one of the weakest points in AlGaN/GaN HEMTs, the reliability of Ni, Mo, Pt and refractory metal gates is crucial [4-6]. This work has been focused on the thermal stress and reliability assessment of AlGaN/GaN HEMTs. After an unbiased storage at 350 o C for 2000 hours, devices with Ni/Au gates exhibited detrimental IDS-VDS degradation in pulsed mode. In contrast, devices with Mo/Au gates showed no degradation after similar storage conditions. Further capacitance-voltage characterization as a function of temperature and frequency revealed two distinct trap-related effects in both kinds of devices. At low frequency (< 1MHz), increased capacitance near the threshold voltage was present at high temperatures and more pronounced for the Ni/Au gate HEMT and as the frequency is lower. Such an anomalous “bump” has been previously related to H-related surface polar charges [7]. This anomalous behavior in the C-V characteristics was also observed in Mo/Au gate HEMTs after 1000 h at a calculated channel temperatures of around from 250 o C (T2) up to 320 ºC (T4), under a DC bias (VDS= 25 V, IDS= 420 mA/mm) (DC-life test). The devices showed a higher “bump” as the channel temperature is higher (Fig. 1). At 1 MHz, the higher C-V curve slope of the Ni/Au gated HEMTs indicated higher trap density than Mo/Au metallization (Fig. 2). These results highlight that temperature is an acceleration factor in the device degradation, in good agreement with [3]. Interface state density analysis is being performed in order to estimate the trap density and activation energy

Effect of titanium foliar applications on tomato fruits from plants grown under salt stress conditions

Salt stress affects plant metabolism, while beneficial elements such as titanium (Ti) may stimulate adaptive responses to mitigate salt stress. Here we evaluated the main effects of sodium chloride (NaCl 0, 50 and 100 mM) in the nutrient solution, and of titanium foliar spray (Ti 0.75 and 150 mg L-1), as well as the interaction of these study factors, on tomato cv. ‘Rio Supremo’ performance in greenhouse. Plants were treated with NaCl during 80 d through automated drip irrigation; while eight Ti foliar sprayings were applied with a manual sprayer, at intervals of 10 d each. Yield and quality parameters of fruits were evaluated in the second cluster. NaCl reduced yield parameters, pH value and increased the titratable acidity (TA), electrical conductivity (EC), and total soluble solids (TSS), as well as the TSS/TA ration in the fruits. Ti did not affect yield parameters, though it reduced the pH and increased the TSS/TA ratio of fruits. NaCl and Ti have differential effects on fruit quality as separate factors, while the interaction of both factors revealed that Ti effects dependent on the presence of NaCl and its level in the nutrient solution. In conclusion, Ti did not mitigate the negative effects of saline stress on the evaluated yield parameters, but importantly, with moderate levels of NaCl in the nutrient solution (50 mM), Ti increased EC, TA and TSS of fruits

Biostimulant effects of lanthanum (La) on crop growth, yield, and quality

Objective: To analyze the various effects that the use of La as an inorganic biostimulant has on growth, yield and quality of different crop plants. Design/methodology/approach: A search in recent literature related to the effects of lanthanum on various economically important crops was conducted. Subsequently, the most relevant information was selected, analyzed and grouped by type of effect. Results: The addition of lanthanum at low doses has been tested in different crop plants. It has been proven that La increases growth, development and quality in various species. Likewise, positive effects have been reported in germination, in the absorption of nutrients, in mitigating the deficiencies of some essential elements, as well as in the promotion of physiological and biochemical responses. Limitations/implications of the study: The analyzed results have been generated in a great diversity of plant species, under different production systems, with dissimilar doses, as well as with different sources and application methods. This situation represents a challenge, since it hinders the possibility to issue general recommendations. Findings/conclusions: Lanthanum improves yield and quality, as well as some physiological, biochemical and nutritional responses in different crops of economic importance

Glucosinolates: Structure, classification, biosynthesis and functions in higher plants

ABSTRACT Objective: To analyze concepts, structure, classification, biosynthesis and functions of glucosinolates (GSLs) in higher plants. Design/methodology/approach: A search was performed into recent high-impact literature related to glucosinolates (GSLs). Results: GSLs are secondary metabolites rich in N and S. They are divided into aliphatic, aromatic, and indole GSLs depending on the amino acid from which they arise. The products of their hydrolysis, mediated by thioglucoside glucohydrolase, thioglucosidase or myrosinase enzymes (EC 3.2.1.147), play a role in increasing tolerance to biotic and abiotic stress factors. Furthermore, given their composition, they can serve as a nutrient reservoir under nutrient deficiency conditions. Limitations on study/implications: GSLs are synthesized only in species of the Capparidaceae, Brassicaceae, Resedaceae, and Moringaceae families. Findings/conclusions: GSLs are sulfur compounds that can serve as defense mechanisms against biotic and abiotic stress factors and as sources of nutrients in plants, and molecules with important nutraceutical properties in food and human health.Objective: To analyze concepts, structure, classification, biosynthesis and functions of glucosinolates (GSLs)in higher plants.Design/methodology/approach: A search was performed into recent high-impact literature related toglucosinolates (GSLs).Results: GSLs are secondary metabolites rich in N and S. They are divided into aliphatic, aromatic, andindole GSLs depending on the amino acid from which they arise. The products of their hydrolysis, mediated bythioglucoside glucohydrolase, thioglucosidase or myrosinase enzymes (EC 3.2.1.147), play a role in increasingtolerance to biotic and abiotic stress factors. Furthermore, given their composition, they can serve as a nutrientreservoir under nutrient deficiency conditions.Limitations on study/implications: GSLs are synthesized only in species of the Capparidaceae, Brassicaceae,Resedaceae, and Moringaceae families.Findings/conclusions: GSLs are sulfur compounds that can serve as defense mechanisms against bioticand abiotic stress factors and as sources of nutrients in plants, and molecules with important nutraceuticalproperties in food and human health

Silicon and titanium affect the percentage of juice and color attributes in tomato fruits of plants exposed to salt stress

Objective: To evaluate the leaf application of silicon (Si) and titanium (Ti) in three doses (0, 75, and 150 mg L-1), independently, on tomato plants cv. Río Supremo, subjected to saline stress (0, 50, and 100 mM NaCl), on the percentage of juice and color attributes of the fruit. Design/methodology/approach: Two independent essays were carried out under a completely randomized experimental design in a 32 factorial arrangement, where the first study factor was the NaCl concentration in the nutrient solution and the second factor was the leaf application of Si or Ti. The percentage of juice and color attributes in fruits were determined. An analysis of variance and the comparison of means by Tukey (p ≤ 0.05) with the SAS software were performed. Results: Salinity was found to reduce the percentage of juice, the color index, and the ratio of “a/b” indexes. Regarding the interactive effects, NaCl with both Ti and Si increases the “b” index. Leaf applications of Si increased the “b” index and reduced the percentage of juice, the color index, and the ratio of “a/b” indexes. Also, Ti improved the color index and the “b” index. Limitations of the study/implications: The results were obtained in the Río Supremo tomato variety under greenhouse conditions. Other varieties should be tested too. Findings/conclusions: Si and Ti applied to the leaves have positive effects on the color of the fruits of tomato plants under saline stress

Silicon increases seed weight and initial seedling growth of maize under non-stress conditions, and improves the index of velocity of germination under salt stress conditions

Salinity is one of the most critical factors affecting agriculture worldwide. The application of beneficial elements like silicon (Si) is one of the alternatives to mitigate its effects. In this research, we evaluated the effect of Si applied during seed imbibition on mitigating the negative effects caused by salinity during the germination and initial growth phases of maize (Zea mays L.) SB-308 seedlings. Seed pre-treatment during the imbibition was made with 0.0-, 1.5- and 3.0-mM Si. Afterwards, seeds that were imbibed were placed in plastic containers and treated with 0, 80, 160, and 240 mM NaCl. The evaluated concentrations of Si and NaCl gave rise to 12 treatments. Pre-treated seeds with 3 mM Si had an increase of weight after imbibition, 5.1% higher than the control. The treatments obtained from combining NaCl and Si levels did not affect the total and relative germination. The radicle length increased by 13.6% with 3 mM Si compared to the control. Conversely, it was lower with increasing salinity. These trends were observed in plant height. The interaction of the study factors produced an increase in the radicle length in the interval from 0 to 160 mM NaCl, when the Si dose was increased. However, there were no significant differences among equal levels of salinity without Si. It is concluded that Si increased the absorption of water during the imbibition and raised the index of velocity of germination under salinity, except in the dose 240 mM NaCl. Likewise, the pre-treatment of seeds with Si tends to increase radicle length under saline conditions

Evaluación de los agentes pro-oxidantes que influyen en la calidad de la carne de pollo

Objective: &nbsp;Analyze the main exogenous pro-oxidizing agents in chicken breast meat and its effect on the oxidative phenomenon. Design / methodology / approach: Chicken breast (Pectoralis major) in the form of patties (25g) was used to establish the different treatments: T1 - ground chicken breast, T2 - freeze and thaw cycle, T3 - vacuum packed, T4 - dehydrated, T5 - cooking in a water bath, T6 - addition of NaCl, T7 - ??cooking on the grill and T8 - exposure to LED light. After treatment, they were stored at 4 ° C 15 d and analyzed at 0, 3, 6, 9, 12 and 15 d. The variables analyzed were weight loss, color, pH, titratable acidity and TBARS, using a completely randomized design (DCA) and the Tukey test (P ? 0.05). Results: It was confirmed that ground chicken meat, subjected to heat treatment (grilled-T7 and water bath-T5) and stored in refrigeration at 4 ° C, presented greater pro-oxidant action reflected in the greater weight losses, luminosity and TBARS. Limitations / implications: Not having different levels of oxidative application in each treatment. Findings / conclusions: It is possible to understand the lipid oxidation of chicken meat under the study of the application of differents pro-oxidizing agents.Objetivo: Analizar los principales agentes pro-oxidantes exógenos en carne de pechuga de pollo y su efecto en el fenómeno oxidativo. Diseño/metodología/aproximación: Pechuga de pollo (Pectoralis major) en forma de patties (25 g) se utilizó para establecer los diferentes tratamientos: T1 - pechuga de pollo molida, T2 - ciclo de congelación y descongelación, T3 - envasadas al vacío, T4 - deshidratado, T5 - cocción en baño maría, T6 - adición de NaCl, T7 - cocción a la parrilla y T8 -exposición a luz LED. Posterior al tratamiento se almacenaron a 4 °C 15 d y se analizaron a 0, 3, 6, 9, 12 y 15 d. Las variables analizadas fueron pérdida de peso, color, pH, acidez titulable y TBARS, mediante un diseño completamente al azar (DCA) y la prueba de Tukey (P ? 0.05). Resultados: Se confirmó que la carne de pollo molida, sometida a tratamiento térmico (cocción a la parrilla-T7 y baño maría-T5) y almacenada en refrigeración a 4°C, presentó mayor acción pro-oxidante reflejado en las mayores pérdidas de peso, luminosidad y TBARS. Limitaciones/implicaciones: No contar con diferentes niveles de aplicación oxidativo para cada tratamiento. Hallazgos/conclusiones: Es posible entender la oxidación lipídica de la carne de pollo bajo el estudio de la aplicación de diferentes agentes pro-oxidantes

Effect of antioxidants and pH on browning and firmness of minimally processed eggplant

Minimal processing of eggplants (Solanum melongena L.) generates a rapid onset of enzymatic browning, tissue softening and water loss that limits their shelf life. The aim of this study was to evaluate the effect of 1% ascorbic acid and 2% calcium ascorbate in aqueous solution at natural pH of the antioxidant (pH 2.6 and 7.8, respectively), or adjusted to pH 5 with generally recognized as safe substances, to maintain the quality of minimally processed eggplant stored at 5 °C for 6 d. Water was used as a control. The colour, firmness, polyphenol oxidase activity, and visual quality was evaluated in the freshly cut fruit at 3 and 6 d of storage. No effect of the treatments on firmness or polyphenol oxidase activity was observed. At 3 d of storage, a correlation was observed between polyphenol oxidase activity and the visual evaluation of the cut product. Samples treated with 2% calcium ascorbate and the rest of the treatments at pH 5 had a lower browning index than those treated with 1% ascorbic acid and the control. At the end of the storage period, the visual quality of the eggplant samples treated with 1% ascorbic acid at pH 5 was evaluated above the marketing limit, whereas those treated with 1% ascorbic acid at pH 2.6 had the lowest quality indicators. An adjustment to pH 5 helps to preserve the luminosity and visual quality of the eggplant, however firmness was not affected by calcium ascorbate or the pH of the medium