Silicon spraying alleviates calcium deficiency in tomato plants, but Ca‐EDTA is toxic

Abstract

Background: The occurrence of calcium (Ca)‐related disorders is common in tomato production and may be due to factors such as excess nitrogen (N) fertilization. Thus, Ca sprays are often applied as preventive measure to avoid the occurrence of blossom‐end rot. In addition, evidence indicates that Si can act beneficially on tomatoes and relieve Ca deficiency. Aims: We aimed to verify the effects of Ca‐EDTA and Si application on tomatoes experiencing moderate Ca deficiency. Methods: Tomato plants were grown in nutrient solutions with Ca sufficiency (+CaR) or Ca deficiency (–CaR) or under conditions of –CaR plus 25 mM Ca‐EDTA shoot sprays (–CaR +CaS), –CaR plus 7.1 mM Si shoot sprays (–CaR +SiS) or –CaR +CaSiS, with a total of nineteen sprays being supplied after anthesis, per foliar treatment. Results: Plants grown under –CaR had smaller leaves and fruits, and new shoots were deformed. Plants that were sprayed with Ca‐EDTA and Ca‐EDTA plus Si in the same solution developed more blossoms than those grown without Ca; however, they showed chlorosis and necrosis on the edges of older leaves, i.e., Ca‐EDTA was toxic. However, the plants sprayed with Si alone were the most similar to control plants, showing only deformations in the younger leaves. Conclusion: Ca‐EDTA at 25 mM sprayed twice a week after anthesis, totaling 19 sprays, caused toxicity in MT tomatoes. Sodium silicate (7.1 mM Si) sprayed twice a week after anthesis, totaling 19 sprays, made MT tomatoes less sensitive to Ca deficiency. Thus, we highlighted the potential of Si spraying to alleviate the slight Ca deficiency, which is relatively common in horticulture.

Mineral Monitorization in Different Tissues of Solanum tuberosum L. during Calcium Biofortification Process

“…Moreover, regarding both the orthophotomap and the NDVI model of both fields (Figure 2), overall, there is a good vigor for all the treatments except for 12 kg•ha −1 Ca-EDTA (in Picasso and Agria) and 24 kg•ha −1 CaCl 2 (in Agria), where chlorosis and necrosis on the tips of the leaves were observed. In fact, the negative effects of Ca-EDTA when applied repeatedly in plants were already being reported in tomato plants [46], and the symptoms associated with chloride toxicity were also being reported in S. tuberosum L. [47]. Additionally, Ca-EDTA toxicity symptoms can be due to the fact that treatments with EDTA have higher loads of Na or Cl [46], considering that potato plants are known as Na-sensitive plants and Cl-nonsensitive plants [47].…”

Application of Exogenous Silicon for Alleviating Photosynthetic Inhibition in Tomato Seedlings under Low−Calcium Stress

“…In addition, previous studies have indicated that Si can alleviate nutrient imbalance stress by promoting root growth and development [ 76 , 77 ]. Simultaneously, it has also been reported that Si application improves calcium use efficiency and has the potential to alleviate mild calcium deficiency [ 22 , 78 ]. We thus hypothesized that under low calcium stress, Si application might alleviate the growth inhibition caused with low calcium by reducing the stress on the photosynthetic system and promoting calcium uptake and translocation.…”

“…Some studies have shown that supplementation with Si can provide some relief in case of excess or deficiency of certain essential elements, and hence, several countries have begun to pay attention to the role of Si in practical production [ 21 ]. Si might have the potential to alleviate mild Ca deficiency by improving root growth and the efficiency of Ca utilization under Ca deficient conditions [ 15 , 22 ], thus improving tomato yield and quality [ 23 ].…”

Monitoring of a Calcium Biofortification Workflow for Tubers of Solanum tuberosum L. cv. Picasso Using Smart Farming Technology

“…Additionally, by calculating the average NDVI in each treatment (Figure 2), it is possible to verify an NDVI lower than the control plants. In fact, in biofortification workflows, foliar spraying with Ca is more often applied as a salt, mainly as CaCl 2 [29]. Although, recently, some studies have been carried out with chelated Ca sources, mainly Ca-EDTA [29][30][31]; this compound can cause toxicity (promoting chlorosis and necrosis on the edges of leaves) [29].…”

“…In fact, in biofortification workflows, foliar spraying with Ca is more often applied as a salt, mainly as CaCl 2 [29]. Although, recently, some studies have been carried out with chelated Ca sources, mainly Ca-EDTA [29][30][31]; this compound can cause toxicity (promoting chlorosis and necrosis on the edges of leaves) [29]. As such, the NDVI map (Figure 1) shows the beginning of toxicity symptoms in potato plants with 12 kg•ha −1 Ca-EDTA treatment, after four foliar applications.…”