Changes in the content of chlorophylls and carotenoids in the rind of Fino 49 lemons during maturation and their relationship with parameters from the CIELAB color space

In the present work, the coordinates L*, a* and b* from the CIELAB color space, as well as the chlorophyll, total carotenoids and the content of the carotenoids Lutein and β-cryptoxanthin were measured in the skin of fruits from the Fino 49 lemon during its development, with the aim of understanding the relationship that exists between the color changes of the fruit’s skin (color coordinates) and the pigment content. Also, the understanding of the relative importance of the contents of lutein and β-cryptoxanthin with respect to the total content of carotenoids was sought. The period of study lasted three years; from September 2015 to January 2016, from September 2016 to January 2017, and from September 2017 to January 2018, the periods that comprised the color changes of the lemon fruit until its harvest. The fruits were measured every two weeks in the experimental plot of the IMIDA (Murcian Institute of Agricultural and Food Research and Development) located at La Alberca (Murcia, Spain) and in the experimental orchards from the CEBAS-CSIC, located in Santomera (Murcia). During he experiment, the color and chlorophyll, Lutein and β-cryptoxanthin concentrations were measured. The results showed that there was a good correlation between the color coordinates and the pigments responsible for the lemon’s skin color: all the color pigments were correlated with the a*, b* color coordinates and the Hue angle index. Throughout the fruit’s maturation, a degradation of the chlorophylls was observed, as well as an increase of β-cryptoxanthin, which is responsible for the green and yellow color of the fruits, respectively. Lutein, which was found in high concentrations, decreased with time, but did not contribute to the fruit’s color

Respuestas fisiológicas de los cítricos al exceso de boro. Estudio de portainjertos y micorrización

Las concentraciones de boro (B) en las aguas de riego procedentes de plantas de desalinizadoras, depuradoras, etc. podrían suponer un problema importante a corto plazo en la zona del Levante Español, ya que este elemento podría alcanzar niveles tóxicos para un gran número de nuestros cultivos, entre ellos los cítricos. La tolerancia de los cítricos a los estreses medioambientales como sequía, salinidad, inundación, deficiencias nutricionales dependen de una un gran número de factores, pero uno de los principales es el portainjerto en el que se injerta la variedad. Por ello, es de gran importancia conocer la tolerancia relativa al exceso de boro de los portainjertos de cítricos utilizados en el levante español, para identificar cuáles son tolerantes o sensibles, así como abordar una serie de estrategias que nos permitan mejorar esta tolerancia en aquellos portainjertos más sensibles. Por ello, el objetivo principal de esta tesis fue mejorar la tolerancia de los cítricos al estrés por exceso de boro seleccionando portainjertos tolerantes, o mejorando los portainjertos sensibles mediante la micorrización. Para la consecución de este objetivo se plantearon tres experimentos. En el primer experimento se estudiaron los efectos del exceso de B (0,25 y 10 mg L-1, aplicado como H3BO3 en la solución nutritiva) sobre los tres portainjertos más utilizados en la citricultura española: citrange Carrizo (CC), Citrus macrophylla (CM) y naranjo Amargo (NA). El segundo experimento consistió en comparar los portainjertos citrange Carrizo (CC), mandarino Cleopatra (CL) y Forner-Alcaide nº 5 (hibrido entre mandarino Cleopatra × citrange Carrizo; F5) con tres tratamientos de boro: 0,25 (control), 5 y 10 mg L-1. En el tercer experimento se evaluó la micorrización como una estrategia para mejorar la tolerancia al exceso de boro de las plantas de citrange Carrizo, regando con 0,25 (control), 5 y 10 mg L-1 de B. En los tres experimentos se midieron parámetros de crecimiento vegetativo, intercambio gaseoso, fluorescencia de clorofilas, nutrición mineral, solutos orgánicos y estrés oxidativo. Según los resultados, en el primer experimento se llegó a la conclusión que el portainjerto de NA fue el más tolerante, mientras que CC el más sensible al exceso de boro. Esto fue debido a que las plantas de NA acumularon una menor concentración de boro como consecuencia de la menor absorción de boro por las raíces y su transporte hacia la parte aérea con respecto a los otros dos portainjertos. Además, en el portainjerto NA detectamos un potente sistema antioxidante capaz de contrarrestar los efectos tóxicos del boro. Al ver que las plantas de citrange Carrizo eran las menos tolerantes, se evaluó si la combinación de este portainjerto con mandarino Cleopatra (Forner-Alcaide nº 5) podría mejorar la tolerancia de citrange Carrizo. Los resultados obtenidos indicaron que efectivamente F5 presentó una mayor tolerancia al exceso de boro que su progenitor CC, aunque no mejoró dicha tolerancia con respecto a CL. No obstante, F5 podría ser un buen portainjerto para cítricos cultivados en condiciones de exceso de B, porque su raíz no muestra ninguna sensibilidad a la toxicidad del B. Por otro lado, se evaluó la micorrización como una estrategia más a corto plazo para mejorar la tolerancia al exceso de boro de variedades injertadas ya en citrange Carrizo. Se observó que las plantas micorrizadas son más tolerantes al exceso de boro ya que tuvieron una menor concentración de B en las hojas; y además, en estas plantas, su maquinaria fotosintética parece ser menos sensible a la concentración de B que las plantas no micorrizadas. Los datos de estos tres experimentos también nos permitieron conocer cómo afecta la toxicidad por boro a la asimilación neta de CO2, y qué papel juegan los azúcares y el sistema antioxidante en los posibles mecanismos que tienen las plantas para reducir la sensibilidad a la toxicidad por boro en los cítricosThe concentrations of boron (B) in irrigation water coming from desalination and water treatment plants could become a major concern at a short term in the Spanish region of Mediterranean areas, since this element may reach toxic levels for many of their horticultural crops, including among them citrus trees. Citrus tolerance to environmental stresses such as drought, salinity, flooding, nutritional deficiencies depend on many factors, but one of them is the rootstock on which the scion is grafted. It is therefore very important to know the relative tolerance to boron excess of citrus rootstocks used in the Spanish, to identify which are tolerant or sensitive as well as address agronomical strategies that allow improving the tolerance of those more sensitive rootstocks. Therefore, the main objective of this thesis was to improve tolerance to stress excess boron in citrus trees selecting rootstocks tolerant, or improving sensive rootstocks by mycorrhizae. To achieve these objective three independent experiments were carried out. In the first experiment, the effects of excess B (0,25 and 10 mg L-1, applied as H3BO3 in the nutrient solution) over the three citrus rootstocks most used in the Spanish studied Carrizo citrange (CC), Citrus macrophylla and Sour orange (NA) was studied. The second experiment was done to compare rootstocks Carrizo citrange (CC), Cleopatra mandarin (CL) and Forner-Alcaide Nº 5 (F5; hybrid of Cleopatra mandarin × Carrizo citrange) with three boron treatments: 0,25 (control), 5 and 10 mg L-1. The third experiment, mycorrhizal colonization was evaluated as a strategy to improve the tolerance of Carrizo citrange plants, watered with 0,25 (control), 5 and 10 mg L-1 B. In all three experiments parameters of vegetative growth, gas exchange, chlorophyll fluorescence, mineral nutrition, organic solutes and oxidative stress were measured. According to the results in the first experiment it was concluded that the NA rootstock was the most tolerant, while CC was the most sensitive to excess boron. This was because the NA plants accumulated a lower concentration of boron as a result of lower boron uptake by the roots and transport to the aerial part with respect to the other two rootstocks. In addition, in the rootstock NA was detected a powerful antioxidant system able to counteract the toxic effects of boron. As CC plants were less tolerant, we evaluated whether the combination of CC with CL rootstock (F5) could improve tolerance of citrange Carrizo. The results showed that effectively F5 showed a higher tolerance to excess boron relative to its parent CC, but it did not improve the tolerance with respect to CL. With this data, we concluded that F5 could be a good rootstock for citrus grown in conditions of excess B, because its root shows no sensitivity to the toxicity. On the other hand, the mycorrhizae were evaluated as a more short-term strategy to improve excess boron tolerance of grafted trees in CC. It was observed that mycorrhizal plants are more tolerant to excess boron as they had a lower concentration of B in leaves; and furthermore, in these plants the photosynthetic machinery appears to be less sensitive to the concentration of B relative to non-mycorrhizal plants. Data from these three experiments also let us know how it affects boron toxicity net CO2 assimilation rate and the role the sugars and antioxidant system in the possible mechanisms of citrus plants to reduce sensitivity the toxicity of boron in their tissue

Scientific Advances in Biostimulation Reported in the 5th Biostimulant World Congress

Biostimulants are agronomic products that have become highly important in agriculture, as they are formulated with substances capable of stimulating physiological and biochemical processes in plants that help them adapt to different detrimental environmental conditions such as drought, salinity, high temperatures, nutritional deficiencies, etc. in such a way that the crops, under these conditions, maintain a good agronomic yield and quality of harvest. Every two years, the International Congress on Biostimulants is held with the aim of publicizing the most innovative and recent advances in every relevant type of product: new active ingredients, modes of action, cultivation protocols, test platforms and phenotyping, use of analytical omics tools, etc. In December 2021, the 5th World Congress on Biostimulants was held in Miami (Florida, USA). This publication summarizes the most relevant results that were presented at this congress, in which biostimulants formulated with algae extracts and amino acids stood out in a number of presentations. The various studies presented were carried out on diverse crops such as apple, blackberry, carrot, celery, cherry, corn, grape (table and wine), olive, pear, pepper, potato, rapeseed, spinach, sunflower, soybean, tomato, and wheat. The future lines of the new generation of biostimulants were also marked

The high tolerance of different pomegranate cultivars to the excess of boron in irrigation water is due to their capacity to limit boron transport from the root to the leaves

Background: Presently, irrigation waters often have a high concentration of boron (B), and the fruit trees in the Mediterranean areas, in general, are exposed to a high risk of B toxicity. Aims: To test the hypothesis that pomegranate trees are very tolerant to the presence of B in the irrigation water, to elucidate the physiological mechanisms behind this tolerance, and to assess differences between different varieties. Methods: In this study, the physiological and nutritional behavior of three pomegranate cultivars (‘Mollar de Elche', ‘Valenciana', and ‘Wonderful'), treated with five B concentrations (0.25, 1.25, 2.5, 5.0, 10.0 mg L), were studied. At day 30 and 60 after the start of the treatments, growth measurements, gas exchange parameters and organic solutes were recorded. Results: Almost no significant differences were observed between the B treatments for any of the cultivars. Increasing the B concentration in the nutrient solution increased B concentrations in the leaves, but they never exceed 40 mg kg of B. In the roots, however, B concentrations were very high, up to 400 mg kg. Conclusion: Pomegranate trees are very tolerant to B excess due to their ability to accumulate B in great quantities in the root, without causing toxicity to this part of the plant, thus limiting its transport to the shoots.The authors are grateful to the Project on Genetic Resources, Preservation of Endangered Species: pomegranate and quince. Ref. RFP2012-00009-00-00, funded by INIAMINECO and FEDER for the maintenance of pomegranate tree and quince collection with which this study was performe

Application of Biostimulants Containing Amino Acids to Tomatoes Could Favor Sustainable Cultivation: Implications for Tyrosine, Lysine, and Methionine

© 2020 by the authors.Tomato (Solanum lycopersicum L.) is one of the most important crops worldwide as per its production and the surface cultivated. The use of biostimulant products plays a fundamental role in mitigating the negative effects of climate change and reducing the use of conventional fertilizers. Many of these products are formulated with amino acids (AAs). This study was conducted to elucidate the effects of the foliar application of tyrosine (Tyr) (15 mM), lysine (Lys) (15 mM), methionine (Met) (15 mM), and a Tyr + Lys + Met (15 mM + 15 mM + 15 mM) mixture on the physiological and metabolic processes, vegetative growth, and nutritional state of Optima variety tomato plants. The results showed that application of the AAs, individually and combined, was beneficial for the growth of the aerial part, net assimilation of CO2, and water use efficiency (WUE). Application of Tyr resulted in the best WUE. The metabolomics study revealed that AA treatments increased the concentration of proline, fructose, and glucose, whose role was to stimulate glycolysis and the Krebs cycle. Thus, the plants could have greater reduction power and energy, as well as more carbon molecules for their growth processes.This research was funded by the State R&D Program Oriented to the Challenges of the Society, Innovation, and Ministerial Science (Spain government), grant number RTC-2016-4568-2.Peer reviewe

Ionomic, metabolic and hormonal characterization of the phenological phases of different tomato genotypes using omics tools

Biostimulants have become highly important in agriculture. For these products to be efficient, they need to be formulated, for a specific crop, according to the mineral nutrients and metabolites requirements in each phenological phase of the crops. In this study, the agronomical behavior of 10 tomato varieties was evaluated (‘Cherry’, ‘Corazón de Buey’, ‘Green Zebra’, ‘Marglobe’, ‘Marmande VR’, ‘Montserrat’, ‘Muchamiel’, ‘Óptima’, ‘Roma VF’ and ‘Tres Cantos’), in other to select four varieties with the greatest agronomical differences between them to be analyzed by omics tools. So, the varieties ‘Cherry’, ‘Green Zebra’, ‘Montserrat’, and ‘Tres Cantos’ were selected for an ionomic, metabolic, and hormone study to determine the predominant nutrients and metabolites in the different phenological phases, and to relate it with its agronomic characteristics. It was observed that the variability of the results could be mainly explained by the different phenological phases during the development of the crop, rather than by the variety. The major compounds were N (4.71 g 100 g dw), K (3.86 g 100 g dw), P (0.53 mg g dw), glutamate (5.21 mg g dw), glutamine (2.89 mg g dw), aspartate (1.54 mg g dw), tyrosine (2.36 mg g dw), phenylalanine (1.70 mg g dw), sucrose (14.4 mg g dw), malate (13.2 mg g dw), and isopentenyladenine (iP) (2.65 ng g dw). No correlation was found between any specific compound and an agronomic characteristic. But, it can be concluded that Biostimulant products must contain these compounds in other to stimulate growth and increase the production of tomatoes plants, as they comprise most of the metabolites and nutrients needed in some or all of the phenological phases.Acknowledgments This research was funded by State R&D Program Oriented to the Challenges of the Society, Innovation and Science Ministerial (Spain Government), grant number RTC-2016–4568–2. We acknowledge the support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI)

Effects of Se Application on Polyamines and Carbon–Nitrogen Metabolism of Pepper Plants Suffering from Cd Toxicity

Previous studies have shown that the application of selenium (Se) can efficiently mitigate the toxic effects of cadmium (Cd) on various crops. The objective of the present work is to decipher the mechanisms responsible for the efficiency of Se against the effects of Cd in pepper plants, with respect to the carbon and nitrogen metabolism. The following were analyzed: the concentrations of anions related with this metabolism, such as nitrates, nitrites, and ammonium, the activities of different enzymes such as nitrate reductase, nitrite reductase, and glutamate synthase, polyamines in their different forms, organic acid salts, amino acids, and sugars in the leaf and root tissues of the pepper plants grown in a hydroponics system. Four different treatments were applied: plants without Cd or Se applied (−Cd/−Se); plants grown with Cd added to the nutrient solution (NS) but without Se (+Cd/−Se); plants grown with Cd in the NS, and with the foliar application of Se (+CD/+SeF); and lastly, plants grown with Cd in the NS, and with Se applied to the root (+Cd/+SeR). The metabolites and enzymes related with carbon and nitrogen metabolism were analyzed 15 days after the application. The results showed the superiority of the +Cd/+SeR treatment with respect to the +Cd/+SeF treatment, as shown by an increase in the conjugated polyamines, the decrease in glutamate and phenylalanine, and the increase of malate and chlorogenic acid. The results indicated that SeR decreased the accumulation and toxicity of Se as polyamine homeostasis improved, defense mechanisms such as the phenylpropanoid increased, and the entry of Cd into the plants was blocked

Application of Biocat G, Selenium, and Chitosan to Counteract the Negative Effects of Cd in Broccoli Plants Grown in Soilless Culture

The accumulation of cadmium in plants produces phytotoxic damage and a decrease in crop yield. To avoid this effect, it is necessary to prevent its absorption by roots and reduce its toxicity in plant tissues. The current study was aimed to evaluate the effect of the exogenous applications of Biocat G (fulvic/humic acids), selenium (Se), and chitosan to roots and leaves of broccoli plants exposed to Cd stress. The applied treatments were: (i) T1: Hoagland nutrient solution (NS), (ii) T2: NS + Cd at 3 mg L-1 (NS + Cd), (iii) T3: NS + Cd + root application of Biocat G (NS + Cd + BioG), (iv) T4: NS + Cd + foliar application of Se (NS + Cd + Se1), (v) T5: NS + Cd + root application of Se (NS + Cd + Se2), (vi) T6: NS + Cd + foliar application of chitosan (NS + Cd + chitosan1), and (vii) T7: NS + Cd + root application of chitosan (NS + Cd + chitosan2). The results showed that the exogenous application of Biocat G and Se (T3 and T5) ameliorated the adverse effects caused by Cd toxicity and significantly improved plant growth rate by decreasing Cd toxicity; besides, Biocat G was able to limit the transport of Cd from the leaves to the inflorescences, reducing the content of Cd in the edible part. These treatments (T3 and T5) yielded the best results, act on the plants by deactivating Cd toxicity, but they did not affect its accumulation in the plant tissue. In addition, Biocat G limits the transport of Cd from the non-edible to the edible part