Over-fertilization is a common practice in ornamental nursery production. Oftentimes, visual analysis is used to determine plant nutrient levels, leading to less accurate estimates of fertilizer application. This study focused on exploring the suitability of two non-destructive sensors, Soil Plant Analysis Development (SPAD-502) and GreenSeeker^TM, for measuring plant tissue nutrient uptake. Florikan Top-Dress fertilizer 12N-6P-8K was applied to Justicia brandegeana in various increments (0, 10, 20, 30, 40, and 50 g) to simulate plants with deficient to excessive nitrogen rates. Various parameters were recorded including Normalized Difference Vegetation Index (NDVI) and SPAD readings, soil leachate analysis (nitrates and phosphate), and total leaf carbon:nitrogen (C:N). The NDVI and SPAD readings were recorded biweekly for three months after the initial controlled release fertilizer (CRF) treatments. Leaf C:N was analyzed through dry combustion while nitrates and phosphate were determined from soil leachate. Results suggest that the smaller amount (20 g) of CRF is as effective in providing N to J. brandegeana as larger amounts (30, 40, 50 g). Implementation of this fertilizer regimen will result in reduced agricultural nutrient runoff and overall negative environmental impacts. Application of optical sensor technology using SPAD and GreenSeeker^TM showed promising results in determining the fertilizer requirements of J. brandegeana. This method could serve as a guideline for nursery producers and landscape personnel as a fast and non-destructive tool for sustainable fertilizer management practices within the ornamental plant industry.

Nitrogen (N) is an important component of proteins and chlorophyll, and has been correlated with optical sensors as a means to determine N status during crop production. In this experiment, chrysanthemum ‘Amico Bronze’ and ‘Jacqueline Yellow’ had initial controlled-release fertilizer rates of 0, 5, 10, 15, or 20 g. Normalized Difference Vegetation Index (NDVI), Soil Plant Analytical Development (SPAD), and atLEAF sensor readings were taken at 10, 17, 24, 31, 38, and 45 days after adding initial fertilizer treatments (DAT). NDVI was correlated with leaf N concentration at all sampling dates except 17 DAT. Values for NDVI increased linearly up to 31 DAT for all treatments then plateaued at 45 DAT. Values for SPAD were only correlated with leaf N at 24 DAT, whereas, NDVI was correlated as early as 10 DAT. The atLEAF sensor was not correlated with leaf N at any sampling date. With weeks combined, correlation analysis showed correlations among leaf N and fertilizer rates, fertilizer rates and SPAD, and SPAD with NDVI and atLEAF. Thirty-one days after initial fertilizer treatment, 10 pots per treatment per cultivar were supplemented as following: 15 g supplemented to the 0 g treatment, 10 g to the 5 g treatment, and 5 g to the 10 g treatment at 31 DAT. With supplemented fertilizer treatments (SFTs), NDVI increased weekly until 45 DAT for ‘Amico Bronze’, while SPAD values did not increase in any treatments. The greatest atLEAF values occurred with 10 (+5) g and 0 (+15) g N in both cultivars. All sensor readings were only taken on leaves without any flowers. The greatest number of flowers, plant height, and shoot dry weight occurred with 10 (+5) g of additional N, but no differences occurred between 5 (+10) g and 0 (+15) g for height and shoot dry weight. No correlations existed between fertilizer rates, SPAD, NDVI, and leaf N for SFT in either cultivar. In summary, results indicated that NDVI values correlated greater ( P ≤ 0.05 and P ≤ 0.01) with leaf N than SPAD and atLEAF chlorophyll sensors. Supplemental fertilizer application improved plant quality in terms of number of flowers, plant height, and shoot dry weight for all treatments, indicating that SFT could be used to correct N deficiency during crop production; however, not in combination with nondestructive sensor readings because of inconsistencies in the ability of all three sensors to separate among fertilizer treatments during a short production schedule.

The damask rose (Rosa damascena Mill.) is an ornamental–medicinal plant from the Rosaceae family, and its aromatic compounds and essential oils are applied globally in the food, cosmetic, and pharmaceutical industries. Due to its economic value, this research aimed to establish a protocol for an efficient, rapid, and cost-effective method for in vitro shoot multiplication and rooting of the R. damascena ‘Kashan’ and ‘Hervy Azerbaijan’ genotypes. Nodal segments (as primary explants) were cultured on the Murashige and Skoog (MS) medium with combinations of various plant growth regulators (PGRs) such as gibberellic acid (GA₃), 6-benzylaminopurine (BAP), and indole-3-butyric acid (IBA), as well as a PGR-like substance, phloroglucinol (PG), vitamins such as ascorbic acid (AA), and activated carbon in the form of active charcoal (AC). For the establishment stage, 0.1 mg·L⁻¹ PG, 0.2 mg·L⁻¹ GA₃, and 1 mg·L⁻¹ BAP were added to the media. Secondary explants (nodal segments containing axillary buds produced from primary explants) were obtained after 30 days of in vitro culture and transferred to the proliferation media supplemented with different concentrations of BAP (0, 0.5, 1, 1.5, 2, and 2.5 mg·L⁻¹) and GA₃ (0, 0.1, 0.2, 0.4, 0.8, and 1 mg·L⁻¹) together with 0.1 mg·L⁻¹ PG and 20 mg·L⁻¹ of AA. The rooting media were augmented with different concentrations of BAP and GA₃ with 0.1 mg·L⁻¹ of IBA, PG and 20 mg·L⁻¹ of AA and AC. The results showed that the highest regeneration coefficient (4.29 and 4.28) and the largest number of leaves (23.33–24.33) were obtained in the explants grown on the medium supplemented with 2 mg·L⁻¹ BAP and 0.4 mg·L⁻¹ GA₃ for the ‘Kashan’ and ‘Hervy Azerbaijan’ genotypes, respectively. Likewise, this PGR combination provided the shortest time until bud break (approximately 6.5 days) and root emergence (approximately 10 days) in both genotypes. The highest number of shoots (4.78 per explant) and roots (3.96) was achieved in this medium in the ‘Kashan’ rose. Stem and root lengths, as well as stem and root fresh and dry weights, were also analyzed. In most measured traits, the lowest values were found in the PGRs-free control medium. Rooted plantlets were transferred to pots filled with perlite and peat moss in a 2:1 proportion and were acclimatized to ambient greenhouse conditions with a mean 90.12% survival rate. This research contributes significantly to our understanding of Damask rose propagation and has practical implications for the cosmetic and ornamental plant industries. By offering insights into the manipulation of regeneration processes, our study opens up new possibilities for the effective production of high-quality plant material.

Research papers on horticulture crops, biotechnology, tomato, apple, fruits vegetables, irrigation, water stress, drought resistance, postharvest technology etc

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.

The use of sensor technology is essential in managing fertilization, especially in urban landscape where excessive fertilization is a common issue that can lead to environmental damage and increased costs. This study focused on optimizing nitrogen fertilizer application for Satinleaf (Chrysophyllum oliviforme), a native Florida plant commonly used in South Florida landscaping. Fertilizer with an 8N-3P-9K formulation was applied in six different treatments: 15 g (control), 15 g (15 g twice; T1), 15 g (15 g once; T2), 30 g (15 g twice; T3), 30 g (15 g once; T4), and 45 g (15 g twice; T5). Evaluations of plant growth and nutrient status were conducted at several intervals: baseline (0), and 30, 60, 90, 120, 150, and 180 days post-fertilizer application. Three types of optical sensors-GreenSeeker™, SPAD meter, and atLEAF chlorophyll sensor - were used to monitor chlorophyll levels as an indicator of nitrogen content. The study found that the 30 g (15 g twice; T3) treatment was most effective in promoting plant growth and increasing nitrogen content in leaves and soil, while the 45 g (15 g twice; T5) treatment resulted in higher nutrient runoff, indicating potential environmental risks. These findings emphasize the value of using optical sensors for precise nitrogen management in plant nurseries to enhance growth, lower costs, and minimize environmental impact.