The aim of this study was to evaluate the remediation of ferric chlorosis using by iron (Fe)-o,o-EDDHA in fertigation of soilless crops compared with Fe-EDTA (ethylene diamine tetra acetic acid) and its effects on production. Two separate greenhouse experiments were conducted in slab or bag cultures using the tomato (Lycopersicon esculentum Mill. cv. Daniela) and green bean crops (Phaseolus vulgaris L. cv. Maite) in Almería (southeast Spain). The crops were subjected to the following experimental setup: 1) At first phase, all plants were treated with a standard nutrient solution and Fe was supplied as Fe-EDTA. 2) No Fe was supplied in the nutrient solution to bean crops 46 days after transplanting. For tomato plants, this element was eliminated from the nutrient solution since 102 days after transplanting. In this phase, Fe-EDTA was supplied to the control plants (T1). This phase was ended when signs of ferric chlorosis appeared on the leaves. 3) The ferric chlorosis was remediated with either Fe-EDTA (T2) or Fe-o,o-EDDHA (T3). The T4 group did not receive any supplements. The total tomato and bean production was improved after the Fe deficiency had been corrected by either EDTA and Fe o,o-EDDHA supplements in the fertigation of these crops. The synthetic Fe o,o-EDDHA chelate alleviated Fe deficiency by increasing the amount of iron in the rhizosphere and its supply to the leaves and petioles. Consequently, the decrease in tomato and bean production resulting from ferric chlorosis could be prevented. As a conclusion, the remediation of ferric chlorosis through fertigation with Fe o,o-EDDHA is as effective as the use of traditional Fe-EDTA.
The effect of pH and silicon (Si) in the nutrient solution on the vegetative development of 2-year-old blueberry plants (Vaccinium corymbosum L. cv. Ventura) was studied. Two independent experiments were performed on coir fiber (CF) and sand as substrates. In experiment 1, Si was applied in the nutrient solution at a dose of 0.0, 0.3, 0.6, and 1.2 mm. In experiment 2, plants were treated with nutrient solution at pH 4.00, 4.75, 5.50, and 6.25, using two sources of acidification: nitric acid and citric acid. The parameters of plant growth, foliar surface, and stem biomass were measured. With the application of 1.2 mm Si to CF, plant height registered a significant increase of 8%, and shoot dry and fresh biomass increased by 21% and 25%, respectively. The results of experiment 1 indicated that the application of Si benefits the vegetative growth of blueberry plants in CF, but no effect was observed in the sand substrate. In the results of experiment 2, the pH level of 6.25 in CF decreased the dry weight of stems and leaves by 21% and 18%, respectively. A significant increase in the pH range of 4.00 to 5.50 was recorded in both the citric acid and nitric acid treatments, but these significant effects were not found in sand. Citric acid presented a similar behavior to nitric acid, which indicates that it can be a good source of acidification in organic and ecologically friendly crops.