The objective of this study was to determine the silicon concentration that would provide good growth in passion fruit plants. Passion fruit seeds were sown in polystyrene. After 60 days, when they were approximately 15 cm tall, the plants were transplanted into polyethylene pots containing 1.1 kg Tropstrato® substrate. Treatments consisted of four concentrations (0, 0.28, 0.55, and 0.83 g pot^-1) of silicon applied as a silicic acid solution 1%. This solution was applied around the stem of the plants (drenched), with the first application being administered 15 days after transplanting. In total, three applications were made at intervals of 15 days. After the last application, the plants were subjected to chemical analysis to determine the silicon concentration and to X-ray microanalysis and flow cytometry. Phytotechnical analyses were performed during the applications. The use of silicon in concentrations of 0.28 and 0.55 g pot^-1 provides better growth of the passion fruit, and the absorption and deposition of the silicon in the passion fruit leaves are proportional to the availability of this element in the plant. The roots of the passion fruit plant are silicon accumulators, and the DNA stability and amount are preserved in the silicon-treated passion fruit plants.

The objective of this work was to evaluate the effect of silicon fertilization on gas exchange, leaf anatomy, and ultrastructural characteristics of passion fruit (Passiflora edulis). The treatments comprised four concentrations of silicon (0, 0.28, 0.55, and 0.83 g per pot) at 1% silicic acid solution (SiO₂.XH₂O). This solution was applied around the stems of the plants. The first application was made 15 days after seedlings were transplanted. In total, three applications were made at 15-day intervals. The pots that constituted the control treatment received water in the same amount. After the final application, the plants were subjected to analyses of gas exchange, anatomical changes, and ultrastructural characteristics. The use of silicon promotes anatomical changes in passion fruit seedlings, such as increased adaxial epidermis thickness, reduced palisade parenchyma, and increased polar diameter/equatorial diameter ratio, which is related to stomata functionality. The concentrations of 0.55 and 0.83 g silicon per pot provide higher rates of photosynthesis, of transpiration, and stomatal conductance. The concentration of 0.83 g silicon per pot results in the greatest deposition of silicon in the abaxial epidermis of leaf surface.

Cocoplum (Chrysobalanus icaco) is an ecologically significant native species to Southern Florida. Application of precision agriculture technologies such as optical sensors reduces the cost of over-fertilization and nutrient runoff. The aim of this work was to establish a base line sensor value for fertilizer treatment in cocoplum by monitoring chlorophyll content using the Soil Plant Analytical Development (SPAD), atLEAF, and Normalized Difference Vegetation Index (NDVI) sensors. Initial slow-released fertilizer treatment 8N-3P-9K was used at 15 g (control), 15 g (supplemented with +15 g × 2; T1), 15 g (+15 g; T2), 30 g (+15 g × 2; T3), 30 g (+15 g; T4), and 45 g (+15 g × 2; T5). Evaluations were conducted at 0 (base reading), 30, 60, 90, 120, 150, and 180 days after treatment. Growth parameters, optical non-destructive chlorophyll meters, leaf and soil total nitrogen and total carbon, and total nitrogen of leachate were analyzed. The results demonstrated that the treatment using 30 g slow-released fertilizer (8N-3P-9K) supplemented twice with 15 g in November and March after the first fertilization in October provided the least contamination through runoff while still providing adequate nutrients for plant growth compared to higher fertilizer concentrations. These results demonstrate that the highest treatment of nitrogen can cause considerable losses of N, causing extra costs to producers and environmental damage due to the flow of nutrients. Thus, techniques that help in N monitoring to avoid the excessive use of nitrogen fertilization are necessary. This study can serve as a basis for future research and for nurseries and farms, since it demonstrated from the monitoring of the chlorophyll content by optical sensors and by foliar and substrate analysis that lower treatments of nitrogen fertilization are sufficient to provide nutrients suitable for the growth of cocoplum plants.

Reducing fertilizer costs and ensuring environmental sustainability are critical issues given the challenges posed by nutrient run-off. The use of smart technologies such as optical sensors is essential in achieving these goals. This study was conducted to determine the most efficient fertilizer regime based on chlorophyll content monitoring using optical sensor technology in cacao samplings in the nursery setting. The 8N-3P-9K (slow-released fertilizer) was used at 15 g (control), 15 g (supplemented with +15 g applied 2 times), 15 g (+15 g), 30 g (+15 g applied 2 times), 30 g (+15 g), and 45 g (+15 g applied two times). Chlorophyll content (measured using optical sensors such as soil plant analysis development (SPAD), atLEAF, normalized difference vegetation index (NDVI)), plant height, number of leaves, total nitrogen of leachate samples, and the total nitrogen and total carbon contents of the leaf and soil samples were evaluated over six months. The results show that the lower application of nitrogen fertilizer can provide the necessary required nutrients of cocoa plants and cause less contamination via run-off. Using 45 g (+15 g applied 2 times) causes more pollution through nutrient run-off. This study demonstrates the importance of handheld sensor technology in determining the best nitrogen management practices in fruit nurseries to reduce excessive fertilization while decreasing the extra costs and mitigating environmental pollution.

Banana is a crop with outstanding economic and social expression throughout the world, therefore, it is important to use appropriate methods of propagation. The micropropagation is an appropriate method because it is disease-free, unlike traditional methods that spread pests and diseases. The objective of this study was to evaluate the effect of silicon on foliar anatomy and chlorophyll content of banana plants culturedin vitro using temporary immersion bioreactor technology. Explants of ‘Dwarf Cavendish’ banana established in vitro were inoculated in bioreactors containing MS liquid medium. Treatments included silicon concentration (0 and 1 mLL-1) and frequency of immersions (every 4, 6, and 8 hours) lasting 1 minute per immersion. Cultures were maintained in a growth room at 27 ± 2 °C under LED light (50 μmol m-² s-¹) with a 16 h of photoperiod for 36 days. After that period, anatomical characteristics and chlorophyll content were evaluated. Higher values were observed for some characteristics validated in plants cultivated with silicon when compared to control. Silicon addition resulted in increased thickness of the leaf’s limb tissues, resulting in a larger mesophyll (563.122µm) which is the set of measurements of all leaf’s limb tissues, it also provided greater adaxial and abaxial stomatal density (0.108817µm and 0.305085µm) respectively, greater adaxial and abaxial polar diameter/equatorial diameter ratio (1.982 and 2.069) respectively, and increased chlorophyll a content (0.000134 mg·g-1 fresh weight) and a/b ratio (1.710425) of plants of banana ‘Dwarf Cavendish’ cultured in bioreactors.

The jelly palm plant [Butia capitata (Martius) Beccari] is a native palm of the Cerrado biome used for many purposes in northern Minas Gerais State, Brazil. Dormancy is common in palm seeds, resulting in slow and uneven germination that may take years to complete. Modification in the growth pattern, anatomical parameters, physiological and biochemical characteristics of the plant can be verified due to changes in the light spectrum transmitted through colored shade nets used. Therefore, the objective of this study is to evaluate the effect of colored shade nets on the leaf and root anatomy of the jelly palm plant. The experiment was performed in a completely randomized design, with five treatments, ten replicates and eight plants per replicate, totaling 400 plants. Four colored photo-converter nets with 50% shading and different radiation proportions were employed: white (985 μmol.m^-2.s^-1), red (327 μmol.m^-2.s-1), black (433 μmol.m^-2.s^-1) and silver (405 μmol.m^-2.s^-1). The plants cultivated under direct sunlight (1000 μmol.m^-2.s^-1) were considered as the control group. Leaf and root anatomical analysis was performed on 10 plants per treatment. It is possible to conclude that the colored shade nets caused changes in leaf and root anatomy of the jelly palm plant (Butia capitata).