Calcium phosphate nanoparticles were doped with zinc ions to produce multifunctional nanomaterials for efficient agronomic fortification and protection of plants. The resulting round-shaped nanoparticles (nanoZn) were composed of 20.3 wt % Ca, 14.8 wt % P, and 13.4 wt % Zn and showed a pH-controlled solubility. NanoZn were stable in aqueous solutions at neutral pH but dissolved in citric acid at pH 4.5 (i.e., the pH inside tomato fruits), producing a pH-responsive delivery of the essential nutrients Ca, P, and Zn. In fact, the foliar application of nanoZn on tomato plants provided tomatoes with the highest Zn, Ca, and P contents (causing, respectively, a 65, 65, and 15% increase with respect to a conventional treatment with ZnSO₄) and the highest yields. Additionally, nanoZn (100 ppm of Zn) inhibited in vitro the growth of Pseudomonas syringae (Ps), the main cause of bacterial speck, and significantly reduced Ps incidence and mortality in tomato seeds, previously inoculated with the pathogen. Therefore, nanoZn present dual agricultural applicability, enriching crops with nutrients with important metabolic functions in humans and simultaneously protecting the plants against important bacterial-based diseases, with considerable negative impact in crop production.

Saffron is traditionally cultivated in soil as a semi-perennial crop, although the feasibility of crop production is today constrained in Europe due to both agronomic and socioeconomic factors. Accordingly, interest has been increasing concerning its possible cultivation within protected environments through adoption of soilless cultivation technologies. The aim of the present study was to optimize nutrient solution features in the soilless cultivation of saffron corms. The trial was conducted in a greenhouse at Almeria University. Saffron was grown in 15-L pots filled with perlite. Three fertigation treatments were used, obtained by a linear increase of all nutrients of one standard in order to reach an electrical conductivity (EC) of 2.0 (control, EC_2.0), 2.5 (EC_2.5) and 3.0 (EC_3.0) dS·m⁻¹. Measurements included determinations of shoot length, corm yield, as well as nutrient uptake from the nutrient solution and concentrations within plant tissues. The nutrient solution with the highest EC (EC_3.0) allowed obtaining three to five times more corms above 25-mm diameter. The increasing EC had a significant effect on the increase of macronutrient uptake, except for NO₃⁻ and NH₄⁺ and resulted in a general increase of nutrient concentrations in tissues, such as corms and roots. Both macronutrient uptake and accumulation in plant tissues were highest under EC_3.0. Nutrient uptake was significantly correlated with production of larger corms due to higher horizontal diameter.

The concept of active Fe has been seldom applied to the extractable fraction to study its changes through time. Neither its relationships to physiological balance of Fe Index in plants has been investigated to any extent. The study reported here was conducted on Castanea sativa Miller trees, autoctonous, not grown by man, as the relationships il‐plant is better balanced. In this work we studied the contents and changes of P, K, Fe, Mn and Zn which are found in extractable form in leaves, the balances of Fe‐Mn‐Zn, and the Fe Index obtained from data of the extractable fraction and their changes throughout the vegetative cycle. The data obtained were related to those obtained from the analysis of the total plant to study their significance in the foliar analysis values, and the possibility to diagnose Fe disorders from balances Fe‐Mn‐Zn and Fe Index obtained from the extractable fraction. Likewise, the relationships among the extracted nutrients and the total present in the foliar tissues were also studied. The nutritional state of individual Castanea sativa Miller trees were diagnosed and some of the nutritional problems limiting their production were considered. The critical levels of P, K, Fe, Mn and Zn extractable during the vegetative cycle 1.2 mg.g^‐1 , 5.3 mg.g^‐1 , 28 μg.g^‐1, 117 ug.g^‐1 and 20 μg.g^‐1, respectively. The concentrations of total P, K, Fe. Mn and Zn were: 1.9 mg.g^‐1, 7.9 mg.g^‐1,148 μg.g^‐1, 270 μg.g^‐1 and 28 μg.g^‐1. The value of Fe‐Mn‐Zn balance extractable were 18–70–12, while the value of balance of the totals was: 34–59–7. From Fe extractable index had values of 3.09 and for the total it would be 0,91. The changes in the concentration of total and extractable nutrients present in leaves were the same in both the forms.

The effects of different priming techniques were evaluated to improve the dormancy and germination of wild seeds of “Piquín” chili pepper (Capsicum annuum var. glabriusculum). Three experiments were designed for pre-sowing treatment of seeds: (a) chemical seeds digestion; (b) halopriming (with K⁺ or NH₄⁺ of NO₃⁻, SO₄^2- or Cl⁻) at different priming times (24, 48 or 72 h) and osmotic potential (−5, −10 or −15 atm) and (c) previously selected halopriming (KNO₃ and NH₄NO₃) + Gibberellic acid (GA₃, at 100 or 200 mg·L⁻¹) were tested. Digestion treatments did show any effect on seed germination. Recommended values of osmotic potential (Ψs), to improve Piquín chili seed germination, must be between −10 and −15 atm (−1.0 and −1.5 MPa) and the priming time must be between 48 and 72 h. Priming techniques can considerably reduce Capsaicinoids content on seeds, improve dormancy, seed germination performance, and increase the rate and uniformity of seedling establishment. KNO₃ and secondly GA₃ treatments may improve rapid and uniform germination and seedling emergence. The results provide basic information to develop guidelines for commercial establishment of Piquín pepper crops.