Iron Biofortification of Greenhouse Soilless Lettuce: An Effective Agronomic Tool to Improve the Dietary Mineral Intake

The present experiment addressed the effects of different iron (Fe) concentrations in the nutrient solution supplied as Fe-HBED, i.e., 0.02 (Fe0, control), 1.02 (Fe1), and 2.02 mmol L-1 (Fe2) on lettuce ('Nauplus' and 'Romana') yield and compositional traits. This experiment was carried out in a greenhouse using an open soilless cultivation system, at the experimental farm of the University of Catania (Sicily, Italy: 37 degrees 24'31.5 '' N, 15 degrees 03'32.8 '' E, 6 m a.s.l.). The addition of Fe-HBED reduced the plants' aboveground biomass (-18%, averaged over Fe1 and Fe2), but promoted their dry matter content (+16% in Fe2). The concentration of chlorophylls, carotenoids, anthocyanins, and antioxidants peaked at Fe2, along with the antioxidant capacity and concentration of stress indicators in leaves. The Fe content in leaves was promoted in the Fe-treated plants (+187% averaged over Fe1 and Fe2). 'Romana' showed the highest Fe accumulation (reaching 29.8 mg kg(-1) FW in Fe1), but 'Nauplus' proved a higher tolerance to the Fe-derived oxidative stress. The Fe2 treatment maximized leaf N, P, K, S, and Zn contents, while those of Ca, Mg, Mn, and B peaked at Fe1. Overall, our study revealed the effectiveness of Fe-HBED in increasing the Fe content and improving the nutritional quality of lettuce grown in soilless cultivation systems

Yield, quality, alternate bearing and long-term yield index in pecan, as a response to mineral and organic nutrition

The pecan nut is produced in 57 countries in the world. Alternate bearing is one of the main biological problems that affect pecan cultivation. Mineral and organic fertilization is a good strategy to maintain and increase pecan nut production. In this study, several mineral and organic doses of fertilization were tested using a factorial arrangement 56 bounded to 25 treatments was used in structure Taguchi L25: nitrogen (N) 0 - 240 kg ha-1, phosphate (P2O5) 0 - 120 kg ha-1, potassium (K2O) 0 - 100 kg ha-1, calcium (CaO) 0 - 400 kg ha-1, liquid humus 0 - 3600 L ha-1 and solid humus 0 - 8000 kg ha-1. The study was carried out in Aldama city, Chihuahua (Mexico). An average yield of 2.4 t ha-1 was obtained, 157 nuts per kilogram and 58.9% of edible nut. The average alternate bearing intensity was 31.58%, and the long-term yield index (IRLP) was 9.59%. It is concluded that the factors whit the greatest impact on the analyzed variables were N and P2O5. In addition, it was found these mineral and organic fertilization systems help to reduce alternate bearing in pecan and simultaneously improve production and long-term productivity index. Optimal fertilization doses were defined: 181.4 kg ha-1 of N, 93.5 kg ha-1 of P2O5 and 3287.2 L ha-1 of liquid humus. Finally, the mineral fertilization complemented with organic fertilization is considered a good fertilization strategy for pecan trees, to increase production and with lower environmental impact

Application of an Enzymatic Hydrolysed L-alpha-Amino Acid Based Biostimulant to Improve Sunflower Tolerance to Imazamox

Herbicides, commonly used in agriculture to control weeds, often cause negative effects on crops. Safeners are applied to reduce the damage to crops without affecting the effectiveness of herbicides against weeds. Plant biostimulants have the potential to increase tolerance to a series of abiotic stresses, but very limited information exists about their effects on herbicide-stressed plants. This study aims to verify whether the application of a potential safener such as Terra-Sorb®, an L- -amino acid-based biostimulant, reduces the phytotoxicity of an Imazamox-based herbicide and to elucidate which tolerance mechanisms are induced. Sunflower plants were treated with Pulsar® 40 (4% Imazamox) both alone and in combination with Terra-Sorb®. Plants treated with the herbicide in combination with Terra-Sorb® showed higher growth, increased acetolactate synthase (ALS) activity, and amino acid concentration with respect to the plants treated with Imazamox alone. Moreover, the biostimulant protected photosynthetic activity and reduced oxidative stress. This protective effect could be due to the glutathione S-transferase (GST) induction and antioxidant systems dependent on glutathione (GSH). However, no effect of the biostimulant application was observed regarding phenolic compound phenylalanine ammonium-lyase (PAL) activity. Therefore, this study opens the perspective of using Terra-Sorb® in protecting sunflower plants against an imazamox-based herbicide effect.PAI program (Plan Andaluz de Investigacion, Grupo de Investigacion) AGR28

Improvement of the physiological response of barley plants to both Zinc deficiency and toxicity by the application of calcium silicate

V.P. Acknowledges Erasmus traineeship program by the University of Naples "Federico II". Funding for open access charge: Universidad de Granada / CBUA.An adequate availability of Zinc (Zn) is crucial for plant growth and development given the essentiality of this element. Thus, both Zn deficiency and Zn toxicity can limit crop yields. In plants, the responses to Zn imbalances involve important physiological aspects such as reactive oxygen species (ROS) accumulation, phytohormone balance, tricarboxylic acid cycle (TCA) metabolism, and organic acids (OAs) accumulation. However, a way to improve tolerance to stresses such as those produced by nutritional imbalances is the application of beneficial elements such as silicon (Si). In this study, we grew barley plants in hydroponics under Zn deficiency and toxicity conditions, applying Si in the form of CaSiO3 in order to assess its effectiveness against Zn imbalances. Parameters related to plant growth, oxidative stress, TCA enzyme activities, phytohormones and OAs accumulation were analyzed. Both Zn deficiency and toxicity reduced leaf biomass, increased ROS accumulation, and affected phytohormone and OAs concentrations and TCA enzyme activities. CaSiO3 treatment was effective in counteracting these effects enhancing Zn accumulation under Zn deficient conditions and limiting its accumulation under toxic conditions. In addition, this treatment decreased ROS levels, and improved ascorbate/glutathione and phytohormonal responses, citrate synthase activity, and malate/oxalate ratio. Therefore, this study enhanced the notion of the efficacy of CaSiO3 in improving tolerance to Zn imbalances.Universidad de Granada / CBU

Evaluation of the alkalinity stress tolerance of three Brassica rapa CAX1 TILLING mutants

Alkalinity is an important environmental factor that affects crop production and will be exacerbated in the current climate change scenario. Thus, the presence of carbonates and high pH in soils negatively impacts nutrient assimilation and photosynthesis and causes oxidative stress. A potential strategy to improve tolerance to alkalinity could be the modification of cation exchanger (CAX) activity, given that these transporters are involved in calcium (Ca2+) signaling under stresses. In this study, we used three Brassica rapa mutants (BraA. cax1a-4, BraA.cax1a-7, and BraA.cax1a-12) from the parental line ‘R-o-18’ that were generated by Targeting Induced Local Lesions in Genomes (TILLING) and grown under control and alkaline conditions. The objective was to assess the tolerance of these mutants to alkalinity stress. Biomass, nutrient accumulation, oxidative stress, and photosynthesis parameters were analyzed. The results showed that BraA.cax1a-7 mutation was negative for alkalinity tolerance because it reduced plant biomass, increased oxidative stress, partially inhibited antioxidant response, and lowered photosynthesis performance. Conversely, the BraA.cax1a-12 mutation increased plant biomass and Ca2+ accumulation, reduced oxidative stress, and improved antioxidant response and photosynthesis performance. Hence, this study identifies BraA.cax1a-12 as a useful CAX1 mutation to enhance the tolerance of plants grown under alkaline conditions.Plan Propio de Investigación y Transferencia, University of Granada awarde

Physiological Study of the Efficacy of Archer® Eclipse in the Protection against Sunburn in Cucumber Plants

Sunburn is an important issue affecting the yield of many crops, mainly in arid and semi-arid regions. Excessive solar radiation and high temperatures can reduce growth and cause leaf chlorosis, oxidative stress, and photosynthesis impairment. It is thus necessary to develop agricultural techniques to protect plants in a cost-effective and reproducible manner. A potential method is through the spray of protective compounds based on particulate films, such as those based on kaolin. The objective of this study is to evaluate the effects of spraying the protective product Archer((R)) Eclipse, created by Atlantica Agricola S.A. (Alicante, Spain), on sunburn damage in a sensitive species such as the cucumber plants (Cucumis sativus L.). To evaluate the effects of sunburn on the plants, parameters related to biomass, leaf temperature, photosynthesis, and oxidative stress were analysed. Plants sprayed with Archer((R)) Eclipse showed fewer sunburn symptoms and obtained 43% more shoot biomass than those that were not treated. In addition, plants sprayed with Archer((R)) Eclipse showed 3 degrees C lower leaf temperatures, higher photosynthesis performance, 88% more water use efficiency, and 21% more chlorophyll concentration. Finally, plants treated with Archer((R)) Eclipse presented 6% less accumulations of carotenoids and 67% less total phenols, but lower oxidative stress indicators. In conclusion, this study confirms the efficiency of Archer((R)) Eclipse in protecting a sensitive vegetable plant such as the cucumber from sunburn-inducing conditions.PAI programme (Plan Andaluz de Investigacion, Grupo de Investigacion) AGR28

A New Calcium Vectoring Technology: Concentration and Distribution of Ca and Agronomic Efficiency in Pepper Plants

This work was supported by the PAI program (Plan Andaluz de Investigacion, Grupo de Investigacion AGR282). The funders had no role in the design of the study, in the collection, analyses, or interpretation of data, in the writing of the manuscript, or in the decision to publish the results.Calcium (Ca) is an important macronutrient for plants, although its low mobility through the phloem makes more difficult the translocation to growing tissues, including fruits. The blossom end rot (BER) physiopathy occurs mainly in fruits and is associated with water stress, and especially with low Ca levels, which has a very negative effect on the production of many crops. Currently, through the vectoring process, it is possible to increase the transport of immobile elements to the fruits. The objective of this study is to evaluate the effect of BRANDT® MANNI-PLEX® Ca, which contains Ca with a vector (polyalcohols), provided by the company BRANDT EUROPE S.L. (Carmona, Spain), on Ca accumulation and the production and quality of pepper fruits, both at harvest and post-harvest stage. Pepper plants were grown in a shaded greenhouse and supplied with BRANDT® MANNI-PLEX® Ca and parameters related to biomass, production, and fruit quality were analyzed. The results showed that the product increased shoot biomass, photosynthesis performance, Ca accumulation and quality of pepper fruits both at harvest and post-harvest, while reducing the incidence of Ca physiopathies by 70%. Therefore, this study proves the BRANDT® MANNI-PLEX® Ca efficacy in a crop with a high incidence of Ca physiopathies, such as pepper.PAI program (Plan Andaluz de Investigacion, Grupo de Investigacion) AGR28

Calcium silicate ameliorates zinc defciency and toxicity symptoms in barley plants through improvements in nitrogen metabolism and photosynthesis

This work was supported by the PAI programme (Plan Andaluz de Investigacion, Grupo de Investigacion AGR282). V. P. Acknowledges Erasmus traineeship program by the University of Naples "Federico II". The results presented in this paper are based on the PhD Thesis by Paradisone ( 2018).Zinc (Zn) deficiency causes serious issues to plant growth and development, negatively affecting crops in many world regions. On the other hand, Zn toxicity impairs plant growth, producing physiological alterations, and even cell death. In plants, two of the processes that most determine growth are nitrogen (N) metabolism and photosynthesis. In the last decades, several authors proved that silicon (Si) and calcium (Ca) mitigate the effects of various abiotic and biotic stresses in plants. The objective of this research is to study the effect of Si application to barley (Hordeum vulgare cv. Nure) plants grown under Zn deficiency and Zn toxicity. Hence, barley plants were grown in hydroponics and supplied with a low Zn dose (0.01 mu M ZnSO4) and a high Zn dose (100 mu M ZnSO4) and were supplied with CaSiO3. Parameters related to Zn accumulation, N metabolism, and photosynthesis were measured. Zn stress affected leaf Zn concentration and reduced biomass in barley plants. Both Zn toxicity and deficiency inhibited N metabolism and enhanced photorespiration, increasing stress symptoms. CaSiO3 mitigated Zn stress effects, probably regulating Zn levels in plant cells and enhancing N metabolism and photosynthesis. We conclude that CaSiO3 could be beneficial to grow barley plants in soils with high or low availability of Zn.PAI programme (Plan Andaluz de Investigacion, Grupo de Investigacion) AGR28

Analysis of RAZORMIN® as a Biostimulant and Its Effect on the Phytotoxicity Mitigation Caused by Fungicide Azoxystrobin in Pepper

Use of biostimulants for stimulating plant growth and mitigating the negative impacts of biotic and abiotic stresses is a promising strategy to achieve higher crop yields. Fungicides such as azoxystrobin are used to control several pests and fungal diseases in plants but at the cost of altering various physiological processes; thereby, leading to reduced crop yields. The efficiency of the compound RAZORMIN® as a biostimulant product while taking into account its role in plant growth stimulation and fungicide azoxystrobin stress mitigation was evaluated in this study. The efficacy of RAZORMIN® was assessed considering its impact on the stimulation of growthrelated physiological processes and stress mitigation mechanism, e.g., reactive oxygen species (ROS) detoxification. Application of RAZORMIN® significantly increased plant growth by improving fresh weight, photosynthetic efficiency, net photosynthesis rate, gas exchange, nitrogen (N) metabolism (with increases in soluble amino acids, foliar N concentration, and N use efficiency), growth hormone concentrations (mainly gibberellins and cytokinins), nutritional status of plants (producing a greater accumulation of phosphorus, potassium, calcium, magnesium, sulfur, zinc, molybdenum, iron, and boron), and sugars concentration. Furthermore, the application of RAZORMIN® on plants under fungicide azoxystrobin stress demonstrated its anti-stress and protective role by stimulating the antioxidant defense system and improving photosynthetic efficiencyPAI program (Plan Andaluz de Investigacion, Grupo de Investigacion) AGR28

Evaluation of Physiological and Quality Parameters of Green Asparagus Spears Subjected to Three Treatments against the Decline Syndrome

Green asparagus (Asparagus officinalis L.) is a widely grown and consumed crop which provides high-level nutritional interest. In recent years, the decline syndrome in asparagus plantations has been rapidly augmenting. This syndrome causes the early death of whole plants, also negatively affecting the new replanting. Decline causes notable economic losses in the sector. The objective of this work was to verify the effect of different treatments against asparagus decline syndrome on the physiological parameters and nutritional quality of the spears. To meet the objective, four different treatments were applied to asparagus plots strongly affected by decline syndrome: (T1) untreated control soil, (T2) biofumigation with Brassica pellets, (T3) biofumigation with chicken manure pellets, and (T4) disinfestation of the soil with Dazomet. The cumulative yield and physiological and quality parameters of green asparagus spears were studied. Thus, malondialdehyde (MDA), photosynthetic pigments, glutathione (GSH), ascorbate (AsA), total phenols, flavonoids, anthocyanin, antioxidant test, mineral nutrients, and the amino acid profile were measured on asparagus spears. The results showed that the Brassica pellets and Dazomet treatments were the most effective against the damage caused by the decline syndrome. However, it would be necessary to monitor the evolution in the following years.INIA and ERDF 2014-2020Project RTA2015-00008-C02,State Training Subprogram of the State Program for the Promotion of Talent and its Employability, at the IFAPA. Grant number [BES-2017-080123].ES