International Journal of Horticultural Science and Technology
Volume:12 Issue: 3, Summer 2025

Drought stress mitigation may involve multiple strategies that engage plants physiologically, one of which is the application of beneficial rhizobacteria that enhance plant tolerance. This study aimed to assess the ability of phosphate-solubilizing bacteria (PSB) to improve the growth and physiology of Achillea santolina (Santalin yarrow) under drought stress. The interaction effects of PSB (Pseudomonas fluorescens isolates FRPF4, FRPF6, and FRPF12) (at 107 CFU mL-1) and drought stress (30, 50, and 80% field capacity) appeared in a factorial test based on a completely randomized design located in a greenhouse (n=3; P<0.05). Several vegetative and physiological parameters came under study at full flowering. Measurable growth factors were plant shoot height, canopy diameter, root length, and fresh and dry weights. The results revealed a significant decrease in all growth parameters under drought stress. However, PSB isolates, especially FRPF4, significantly mitigated the adverse effects of stress on vegetative factors. Drought stress significantly affected the leaf samples by increasing their total soluble sugars (TSS), free proline, total flavonoids (TF), and DPPH contents. Drought-stressed plants inoculated with the PSB isolates showed a significant decrease in free proline and DPPH concentrations. However, the TSS and TF contents increased in the stressed plants treated with PSB isolates. Carotenoid, chlorophyll a, b, and total chlorophyll contents also decreased in the stressed plants. However, these factors increased in plants treated with PSB isolates in response to water-deficit stress. Thus, PSB isolates may mitigate the adverse effects of drought stress on Santalin yarrow plants through several direct and indirect mechanisms.

Products without synthetic chemicals are of global interest due to the presence of active compounds such as phenolic substances and their antioxidant properties. This research applied various concentrations of chitosan, salicylic acid, Aloe vera gel, and mallow mucilage treatments on Citrus unshiu tangerines. The research aim was to find their best concentrations, leading to optimal fruit quality maintenance. The experiments were in a factorial design and laid out as a completely randomized block in a research orchard at Islamic Azad University, Sari Branch. The experimental treatments were chitosan (0.5, 1, and 1.5%), salicylic acid (SA: 1, 1.5, and 2 mM), A. vera gel (15, 30, and 45%), and mallow mucilage (15, 30, and 45%). Treatment applications were applied in immersion form, followed by storage at four storage periods (0, 15, 30, and 45 days) for 45 days. Total protein content and superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities were investigated in the experiment. The results showed that chitosan 1.5%, A. vera gel (30% and 45%), and 2 mM SA prevented total protein degradation and improved POD activities during 45 days of storage. However, they had no significant effect on SOD and CAT activity.

Nutrient resorption is a process of nutrient remobilization from senesced organs to living tissues inside a plant. Since the Northern Territory (NT) has relatively poor soil conditions and a limited supply of plant nutrients, it is crucial to determine suitable scions for efficient macronutrient resorption in the Kensington Pride (KP) mango rootstock. The scions used in this study were NMBP 1201 (T1), NMBP 1243 (T2), NMBP 4069 (T3), B74 (T4), and KP (T5). The experiment occurred in a randomized, complete block design with five treatments and five replicates. The results showed that grafting the B74 scion onto the KP rootstock resulted in trees with reduced canopy area (65.76 ± 4.39b) and volume (48.43 ± 4.92b), indicating its suitability for narrow-planting distance to produce more mangoes in a smaller area. Grafting the B74 scion onto the KP resulted in a larger leaf area (6.52 ± 1.36), ultimately increasing nutrient resorption efficiency, which is beneficial in nutrient-deficient soils like in the NT. NMBP 4069 scions grafted onto the KP rootstock had a larger canopy area (87.47 ± 5.37a) and canopy volume (72.23 ± 6.21a). These trees need more space to grow and have lower nutrient resorption efficiency, owing to their smaller leaf area. The scions NMBP 1201 and NMBP 1243 displayed comparable growth metrics and nutrient resorption efficiency when grafted onto the KP. Scions of the B74 can be highly suitable to withstand diverse environmental conditions, optimize nutrient use, and increase fruit yield on a commercial level.

This study aimed to evaluate the effects of nanoparticle fertilizers and plant growth regulator (PGR) treatments on Catharanthus roseus (L.) plants under water-deficit stress. Plant growth and yield were evaluated in two consecutive years (2018-2019 and 2019-2020). This experiment was performed as a split factorial plot arranged in a randomized complete block design (RCBD) with three replications. The main factor was irrigation at three levels (full irrigation, mild, and severe water-deficit stress). The subfactors included priming with PGRs (not priming, auxin, gibberellic acid, and cytokinin) and foliar application of nanoparticles (water, nano Zn particles, nano Mg particles, and nano Zn particles + nano Mg particles). The results showed that water-deficit stress decreased total chlorophyll content, plant height, number of flowers, and shoot dry weight. However, plants primed with PGRs had higher plant height, lateral branches, and shoot dry weights than the control. The highest vinblastine (0.0091%) and agmatine content (0.667%) occurred in response to severe water-deficit stress and ZnO (1 mg L-1) + MgO (0.5 mg L-1). Moreover, stem diameter and lateral branches had the highest value without priming with plant growth regulators but with ZnO application (1 mg L-1) + MgO (0.5 mg L-1). In contrast, priming with gibberellic acid and foliar application of ZnO (1 mg L-1) + MgO (0.5 mg L-1) increased the agmatine content. The current study suggested nanoparticles and PGRs can enhance Catharanthus roseus tolerance to water-deficit conditions.

Catharanthus roseus L. is a valuable medicinal plant renowned for its potent anticancer compounds, i.e., vincristine and vinblastine. The efficient mass production of this plant can be challenging due to limitations in conventional propagation methods. Tissue culture techniques offer a promising alternative, and optimizing plant growth regulator (PGR) treatments can play a crucial role in achieving successful in vitro propagation. In this study, we investigated the effects of several PGR combinations, i.e., NAA, BAP, and 2,4-D, on the morpho-phytochemical attributes and antioxidant activity of in vitro grown Catharanthus roseus L. var. ‘Ocellata’. The plants were arranged in a completely randomized design with three replications. The results demonstrated that applying PGRs, either alone or in combination, significantly improved the morphological characteristics. The NAA treatment caused the highest plant height, number of branches and leaves, and root diameter. Notably, the treatment with 2,4-D resulted in the highest photosynthetic pigment content compared to the control. Moreover, the treatments with NAA + BAP and NAA + BAP + 2,4-D exhibited the highest levels of total phenolic compounds (TPC) and total flavonoid content (TFC) in both roots and leaves. Regarding antioxidant activity, the DPPH radical scavenging assay revealed the highest radical scavenging percentages, i.e., 74.21% (NAA + 2,4-D) in leaf samples and 78.08% (NAA + 2,4-D) in root samples. These findings emphasize the potency of PGRs in optimizing tissue culture protocols for Catharanthus roseus L., thus facilitating the production of superior-quality plants with enriched medicinal properties. This study contributes to the advancement of sustainable and efficient cultivation of bioactive compounds from Catharanthus roseus L. using tissue culture techniques.

In recent years, the application of deep learning models has significantly advanced the field of computer vision, enabling automated recognition and classification of various objects, including flowers. This research begins with exploring two distinct pre-trained convolutional neural networks (CNNs): VGG16 and Xception. Each model has architecture and performance characteristics that are analyzed and compared to establish a baseline for flower species classification. To enhance classification performance further, we introduce a hybrid model that fuses the extracted features from VGG16 and Xception. These features are concatenated and fed into a dense layer with ReLU activation, followed by a softmax classifier, which leverages the combined knowledge of hybrid models to classify various species of flowers accurately. Experimental results are presented on a benchmark flower dataset from Kaggle, demonstrating the effectiveness of the proposed hybrid model in achieving state-of-the-art classification accuracy. The results highlight the performance of the proposed hybrid model for 25 epochs with 512 dense layers, showcasing a remarkable state-of-the-art classification accuracy of 91.20% on the Kaggle flower dataset. The comprehensive evaluation includes quantitative metrics such as accuracy, precision, recall, and F1-score, highlighting how robust the model is and its generalization capabilities. The findings in this research can assist in developing deep learning-based flower species classification systems.

Light quality and intensity determine the synthesis of photosynthetic pigments and gas exchange, reflecting plant growth and yield. This study evaluated growth, photosynthetic pigments, and gas exchange in baby leaf kale on colored reflective cultivation benches. In a greenhouse, we evaluated five cultivation benches with colored laminated reflective materials (Fórmicas®), representing a control bench without reflective material and benches with bright white, yellow, red, and blue reflective laminates in two production cycles. The white bench was the most effective in increasing photosynthetic active radiation in both cycles. Cultivation benches with white, yellow, red, and blue reflective material increased the number of leaves, fresh matter, dry matter, and total aerial parts concerning the control bench in both production cycles. The reflective bright blue laminate on the cultivation bench increased the chlorophyll a, b, total (a + b), and carotenoid content of baby leaf kale plants in both cycles. Using reflective materials, regardless of color, during periods of lowerradiation or on a white bench at times of higher radiation increased growth, leaf productivity, and the production of photosynthetic pigments in baby leaf kale. In both cycles, the blue bench stimulated the production of photosynthetic pigments, especially carotenoids.

A high demand for lettuce, combined with a growing appeal for the sustainability of production processes, requires changes in production techniques. In such a context, no-till practices appear as a conservation alternative. The current work evaluated the development and productivity of lettuce crops in a no-tillage system. The experiment had four treatments, i.e., conventional management, millet, sunn hemp, and a combination of covers, comprising millet and sunn hemp. Two lettuce cultivars, Pira Roxa and Valentina, were used in this research. The experimental design was set in randomized blocks, with three replications. Physiological, biometric, and productive characteristics were considered, including net photosynthetic rate, stomatal conductance, CO2 concentration, transpiration, water use efficiency, relative chlorophyll content, head diameter, fresh weight, and productivity. In the Valentina cultivar, there was an increase in the photosynthetic rate when using straw, regardless of the cover plant species. In the cultivar Pira Roxa, the photosynthetic rate was higher without the presence of straw, causing an increase in water use efficiency in the presence of straw. Higher transpiration and head diameter were found in treatments that included all cover plant species in the soil. In addition, fresh weight, leaf count, and productivity increased when using millet straw and the combination for the Valentina cultivar. Regardless of the cover crop or the arrangement between cover plants, the presence of straw on the soil increased the gas exchange capacity in plants, resulting in productive gains.

Quality seedlings can guarantee the establishment of a productive crop, and, at the same time, light quality makes it possible to increase photosynthetic pigments. This study evaluated plant pigments along with the growth of Guaraci Cumari do Pará ornamental pepper seedlings on different-colored benches that emitted specific wavelengths. The wavelengths appeared from different reflective colored laminates (reflective bright blue laminate, reflective bright red laminate, reflective bright white laminate, reflective bright yellow laminate, and a control treatment without reflective material) on growth benches considered as treatments. The treatments were in a completely randomized design with six replications. The white laminate increased the photosynthetic-active radiation inside the experimental environment by 16.6%. The blue laminate promoted quality in pepper seedlings similar to the control bench regarding growth parameters, such as seedling height, stem diameter, and dry matter. However, the seedlings in the control bench had a higher quality index. The wavelengths promoted by the blue, red, and yellow laminates increased the production of chlorophyll a (41, 49, and 44%), chlorophyll b (36, 34, and 31%), and total chlorophyll (39, 45, and 40%) in the Guaraci Cumari do Pará pepper seedlings compared to the control. The color of laminates on the cultivation benches reflected different levels of photosynthetic-active radiation, influencing the traits of photosynthetic pigments in the Guaraci Cumari do Pará pepper seedlings.

Nacobbus aberrans is a phytoparasitic nematode responsible for significant losses in numerous horticultural crops. For this reason, it is considered a major economic pest in several countries. This work focuses on the morphological, biochemical, and physiological changes in pepper plants due to N. aberrans parasitism. The experiment was conducted under controlled conditions. A significant reduction in growth was observed in the inoculated plants, showing less accumulation of dry matter in aerial parts and roots. The leaves of the inoculated plants showed lower chlorophyll and soluble protein contents than the non-inoculated plants. Net photosynthesis and transpiration decreased, thus reducing water use efficiency in the inoculated plants. Stomatal conductance in the inoculated plants was also lower. The penetration of mobile forms of N. aberrans in the roots damaged cell membranes, as evidenced by a more profuse release of electrolytes that, in turn, increased relative conductivity. Malondialdehyde content was higher in the roots and leaves of inoculated plants than in plants without nematodes. An increase in the catalase activity and peroxidase enzymes was observed in plants infected by N. aberrans. The loss of functionality in inoculated roots caused drought stress and culminated in reduced plant growth. This was also confirmed by a greater accumulation of proline and sugars, metabolites used as osmoregulators in water-deficit situations.