International Journal of Horticultural Science and Technology
Volume:12 Issue: 1, Winter 2025

Arbuscular mycorrhizal fungi (AMF) are associated with plant roots and exhibit beneficial impacts such as stress tolerance, better nutrient uptake, and water absorption. These functions have opened the door to research opportunities for considering other fungi associated with AMF on the root rhizosphere. This study aimed to characterize fungal isolates associated with rhizospheric indigenous AMF from different plant species, i.e., banana, grass, and papaya, in three agroecologies, i.e., Mwea, Mitunguu, and Juja in Central Kenya. A total of 30 fungal isolates were isolated from soil samples through the pour plate technique. The isolates had diverse microscopic morphological characteristics, describable in form, margin, color, size, and surface. Physiochemical parameters showed varied growth at different pH values, temperatures, and salinity levels. Optimal growth appeared at pH 7.0, 30-35 °C, and 0-0.5 M NaCl salinity. The internal transcribed spacer (ITS) and AMF subunit sequences showed a level of diversity similar to Aspergillus spp. Ajellomyces spp., Fusarium spp., Trichoderma spp., Penicillium spp., Glomus spp., and Diversispora spp. In conclusion, there was a symbiotic relationship between AMF and other fungal isolates.

The current research applied four methods of supplementary pollination from male flowers of kiwifruit (cv. Tomori). These methods were open pollination, hand pollination, spray pollination with pure pollen, and spray pollination with impure pollen, collected from the entrance of bee hives at the time of male kiwifruit flower opening and arranged in three replications in 2021. The fruits were harvestable after reaching the maturity stage (6.2 °Brix) and stored for 90 days at 0 °C. The results showed that kiwifruit decay (1.70%), weight loss (3.14%), total soluble solids (TSS) (149.62%), and TSS: titratable acidity (TA) ratio (TSS/TA) (333.04%) significantly (P≤0.01) increased during 90 days of cold storage. However, fruit firmness (38.24%), TA (42.10%), total chlorophyll (53.72%), carotenoid (18.65%), vitamin C (10.34%), flavonoid (12.87%), and antioxidant activity (13.29%) significantly decreased through storage time. Furthermore, total phenolic content (TPC) increased substantially after 30 days of cold storage but then decreased. Generally, fruits from vines sprayed with impure pollen had higher firmness, bioactive compounds, and sensory attributes. They had lower decay and less weight loss after 90 days of cold storage. Overall, spraying kiwifruit vines with impure pollen could be recommended as a practical supplementary pollination in kiwifruits, cv. Hayward, regarding postharvest quality maintenance.

Fruit ripening involves marked physiological and biochemical changes that affect fruit color, taste, aroma, texture, and nutritional value. A significant amount of research has shown that chitosan interacts with other postharvest treatments, which can enhance the impact of the chitosan coating. This study considered the effects of chitosan coating and melatonin on banana shelf-life and fruit quality at the green mature stage. The studied variables had three levels of melatonin 0, 75, and 150 mg L-1, two levels of chitosan coating 0, 0.25, and 0.5%, and three storage durations 3, 6, and 9 days. Fruits were harvested at the green mature stage and stored at 25 °C and 80% RH for 9 days. The results showed that melatonin and chitosan coating interacted and significantly affected green mature banana quality and shelf-life during the storage time. Chitosan and melatonin interaction delayed the decrease in chlorophyll and the increase in carotenoids, fruit maturity, and color change. Our results showed that on the ninth day of storage under chitosan (0.5%) treatment along with melatonin at a concentration of 150 mg L-1, the total chlorophyll content became 3.89% lower than that under control conditions. The level of antioxidant enzyme activity in the treated samples after 3, 6, and 9 days of storage was more than in the control sample. The results showed that chitosan (0.5%) and melatonin (150 mg L-1) successfully increased the shelf life of banana fruits.

The current research explored the biocontrol ability of two strains of Trichoderma fungi on infected Freesia corm by Fusarium disease. Enhancements in plant growth and performance were evaluated in response to the Trichoderma fungi in laboratory and greenhouse conditions. Laboratory experiments included five Trichoderma strains, i.e., T1, T20, and Th4, related to T. harzianum species, T2 related to T. atroviride species, and Tvi related to T. virens species. A dual culture test and investigation of the inhibition and colonization rate were carried out with 11 treatments in three replications. Results revealed that strains T1 and T2 completely covered the pathogen in 96 h of culture by 70.02% and 68.98% and successfully inhibited the colonization of the disease agent by 84.53% and 82.72%, respectively, compared to the other strains. Then, a greenhouse experiment was performed with eight treatments, using suspensions of Trichoderma strains separately or combined with the presence of Fusarium fungus isolate on Freesia cultivation. The results showed that the strains at different levels were able to increase the growth and yield of Freesia plants and control Fusarium disease. In general, the T2 strain was more effective in increasing plant growth and flower stem height in Freesia. The T1 strain specifically improved the corm diameter. Both T1 and T2 strains demonstrated effectiveness in controlling and reducing the severity of Fusarium disease and enhancing the growth quality of Freesia.

Ethrel®, which contains ethylene, is used as a fruit ripening treatment. However, no information is available on its application as an artificial ripening agent for cacao pods. This study aimed to evaluate the effects of varying ethephon concentrations (0, 1000, 2500, and 5000 ppm) on cacao ripening in a completely randomized design with three replications. Unripe cacao pods, containing fully developed embryos, were utilized in this study. Cacao pods treated with 5000 ppm ethephon ripened five days earlier than untreated samples. In 1000 to 2500 ppm ethephon treatments, the day count required for ripening was three days after treatment (DAT). By 7 DAT, 100% of cacao pods treated with 2500 to 5000 ppm ethephon had ripened. The control treatment had the lowest percentage of ripened pods (50%) at 7 DAT. Total soluble solids (TSS) and titratable acidity (TA) of ripened cacao pods at 7 DAT were not altered substantially in response to ethephon concentrations. The highest TSS/TA ratio (29.13) was recorded in cacaos treated with 2500 ppm ethephon. In contrast, untreated cacao pods had the lowest TSS/TA ratio (23.49). Our findings suggest that ethephon can be used as a plant growth regulator (PGR) for cacao growers to accelerate the ripening of cacao pods.

White savory (Satureja mutica Fisch.) is an oil-bearing plant with applications in traditional medicine, pharmaceutical industries, and food additives in homemade dishes. The current research comprised a greenhouse experiment in a factorial arrangement based on a completely randomized design (CRD). It included four salinity levels (0, 50, 100, and 150 mM NaCl), two salicylic acid (SA) levels (0 and 2 mM), and three replicates. By increasing the NaCl concentration, the content of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid significantly declined. Increasing NaCl up to 100 mM caused a significant increase in proline and soluble protein content. The amount of proline at 150 mM NaCl showed no significant change compared to 100 mM NaCl, but the soluble protein sharply decreased at 150 mM NaCl. The enzymatic activities of superoxide dismutase, catalase, and peroxidase significantly increased in response to higher NaCl concentrations. Saturated water deficiency increased significantly, and leaf fresh and dry weights decreased substantially at 100 and 150 mM NaCl. SA enhanced chlorophyll a, chlorophyll b, total chlorophyll, carotenoid content, and leaf fresh and dry weight, depending on the NaCl treatments. SA applications considerably boosted peroxidase and catalase activities despite the presence of NaCl at any concentration. Also, SA significantly improved superoxide dismutase activity at 50 and 100 mM NaCl but could not counter its decrease when the NaCl level was 150 mM. SA significantly reduced saturated water deficiency and proline content despite any of the NaCl treatments. SA mitigated the adverse effects of NaCl on S. mutica by improving antioxidant activity, photosynthetic pigments, and physiological characteristics.

Medicinal plants have been used historically for various treatments and in human nutrition. Due to their natural occurrence and biodegradability, medicinal plants can be an eco-friendly alternative to toxic chemicals such as pesticides, fungicides, and herbicides. An in vitro experiment was conducted to test the impact of six medicinal plant extracts on tomato growth and callus induction. Two concentrations of each extract (50 and 100 mg L-1) were added to the Murashige and Skoog (MS) medium culture. Results showed that Juniperus sabina extract (50 mg L-1) accelerated tomato seed germination by 100% in vitro, compared to the control group in MS basal medium. Callus growth index (CGI) and callus weight (CW) increased by 50% and by more than 200% when using Taraxacum officinale (100 mg L-1) and Conocarpus erectus (50 mg L-1) extracts, respectively. Biochemical analysis revealed that the extracts were rich in phenolic compounds (348 mg g-1 of total phenol), flavonoids (162 mg g-1), antioxidants (61%), and auxin. A rise in antioxidant activity, plant growth regulators (PGR), and plant defense elicitation probably contributed to these outcomes. Plant extracts also affected the biochemical content of calluses, except for their total phenol. We recommend using these plant extracts to increase growth, accelerate seed germination, and promote callus induction. Optimizing concentrations and combinations of medicinal plant extracts require further research to maximize their benefits to different plant species and their growth-related values.

Yield quality and quantity in hydroponic greenhouses usually rely on optimum crop root health and effective nutrient mobility. This study evaluated the effects of applying arbuscular mycorrhizal fungi and biochar on different growth characteristics of commercial rose cultivars in a hydroponic cultivation system. In this experiment, Rosa hybrida cultivars were ‘Angelina’ and ‘Dolce Vita’. Treatments included concentrations of 0, 1.5, 3 and 6 g L-1 biochar, and 0 and 7 g L-1 of arbuscular mycorrhizal fungi as organic biofertilizers for the growth of rose plants. Biofertilizer application at 3 g L-1 biochar and 7 g L-1 arbuscular mycorrhizal fungi optimally increased flowering shoot diameter, flower diameter, flowering shoot length, and leaf phosphorus content. The ‘Dolce Vita’ cultivar responded more favorably to higher concentrations of arbuscular mycorrhizal fungi and biochar than the ‘Angelina’ cultivar in the hydroponic culture medium. Stem diameter, stem length, and flower diameter in both cultivars improved in response to higher biochar concentrations. The increased flowering shoot length resulted from root colonization by arbuscular mycorrhizal fungi and an enhanced nutrient uptake, especially phosphorus. A higher nutrient supply increased cell division and shoot growth.

Indicators for predicting the quality and vigor of fruit tree seedlings can be worthwhile if they are conveniently and visually assessable in various climatic regions. Since allometric relationships exist between plum seedling vigor index and morphological traits, this study evaluated morphological features in plum seedlings while determining their quality and vigor. The samples were of major commercial varieties from several regions of Iran, and the assessments followed path analysis and multiple linear regression. Plum seedlings of 8 commercial cultivars were harvested in three replicates from 11 nurseries in four provinces. Morphological indicators included seedling height, diameter above the graft line (DAGL) and at root-collar (RCD), root length, number of roots and branches, seedling vigor, dry weights of aerial parts and roots (ADW and RDW, respectively), and ratio of height to DAGL and seedling height to ADW. Simple correlations among these variables appeared diverse, and the correlation coefficients broke down into direct and indirect effects through path analysis, with vigor as the dependent variable. This variable increased with some of its components, including DAGL and dry weight. However, the ratio of height to DAGL decreased when the accumulated growing degree-days (AGDD) increased from 2700 to about 4500 °C per day in the various regions. Average vigor values of certified and uncertified seedlings were 11.7 and 19.2, respectively. Among the visually assessable traits in the nursery, DAGL showed a higher correlation with the vigor variable and other morphological features, thus making it the most important index for plum seedling evaluation.

Sweet gourd (Cucurbita moschata Duch ex Poir) has a high production volume in Bangladesh and holds third rank next to eggplant and radish. Salinity affects almost all growth and physiological aspects of the plant development and eventually reduces yield. Identifying salt tolerance among genetic resources and breeding populations is a valuable study for solving salinity problems. This research aimed to find sweet gourd hybrids tolerant to salinity. Sixteen sweet gourd hybrids (F1) were used for testing salt stress tolerance levels. Salinity stress was induced in pot soil by adding NaCl solutions (4, 8, 12, 16, and control 0.35 dS m-1). The experiment was conducted from October 2019 to March 2020 in a randomized complete block design with three replications. The research was conducted at the Horticulture Research Centre, Bangladesh Agricultural Research Institute (BARI), Gazipur. The measurements included changes in gas exchange parameters against photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (E), quantum yield (Fv/Fm), and relative water content (RWC). Results showed that the gas exchange traits and RWC in all hybrids decreased under stress compared to the control. Photosynthetic parameters in sweet gourd hybrids responded susceptibly to salt stress, thus suppressing overall growth under salinity stress. The reduction of gaseous exchange traits and RWC were minimal in P11 × P12 and P6 × P14. The highest Fv/Fm and RWC occurred in P11 × P12 at 8 dS m-1 salinity stress. The highest Fv/Fm and RWC appeared in P6 × P14 and P11 × P12 hybrids at 12 and 16 dS m-1 salinity stress, so the hybrid P11 × P12 appeared salt tolerant.