Greenhouse Plant Production Journal

Abstract Salicylic acid (SA) is a key signaling molecule that regulates plant growth, flowering, and responses to abiotic and biotic stresses. This study evaluated the effects of different SA concentrations (0, 0.5, and 1.0 mM) and application frequencies (once and twice) on the growth, pigment composition, and yield of eggplant (Solanum melongena L.) under field conditions during the 2023–2024 growing season. Eggplant seeds were sown in a cocopeat and perlite growing medium at a ratio of 3:1 and the seedlings were watered daily in greenhouse. Foliar spraying was done in two stages before transplanting (four-leaf stage) in greenhouse and before flowering in farm. After the first foliar spray, the eggplant seeds were transferred to the field and the plants were irrigated every three days throughout the growth period. A factorial experiment arranged in a completely randomized design revealed significant SA effects on most measured traits, with 0.5 mM producing the most favorable outcomes. Compared with the control, this treatment increased relative water content by 11%, reduced electrolyte leakage by 30–35%, and enhanced SPAD values, total chlorophyll, and carotenoid contents by up to 120%. Plant height, fruit number, and total yield rose by 38.1%, 85.7%, and 88.6%, respectively. Two applications further improved growth and yield compared to a single spray, indicating that repeated applications amplify the physiological benefits of SA. In contrast, 1.0 mM SA provided no additional improvement, suggesting a threshold beyond which inhibitory effects are not observed. The observed enhancements were associated with improved water balance, enhanced photosynthetic efficiency, and increased membrane integrity. Overall, applying 0.5 mM SA twice during both the vegetative and reproductive stages proved to be an optimal, low-cost, and environmentally safe strategy for enhancing eggplant growth and productivity. Future studies should elucidate SA’s molecular mechanisms and interactions with other biostimulants and stresses to optimize its use across crops and production systems.

Abstract Heirloom tomatoes (Solanum lycopersicum L.) are highly valued for their superior quality, yet their potential as rootstocks remains largely unexplored. The experiment followed a 4×2factorial arrangement consisting of four rootstock levels (the commercial hybrid ‘Parisa’, two heirloom rootstocks, and a non-grafted control) and two scion cultivars (‘Sylviana’ and ‘E15B.50115’). Under this design, grafting success, vegetative vigor, yield, and fruit quality were assessed. The commercial rootstock ‘Parisa’ maximized total yield, reaching 1316.93 g/plant, while the Heirloom1 rootstock achieved a competitive marketable fruit percentage of 84.28%, comparable to the commercial hybrid. Beyond these primary yield components, heirloom rootstocks significantly improved fruit quality attributes compared to non-grafted controls, specifically increasing fruit firmness, titratable acidity (up to 4.12 mL), and total soluble solids (up to 4.87 °Brix), as well as enhancing morphometric traits such as larger fruit diameter (6.31 cm) and increased pericarp thickness. These reproductive and quality benefits were supported by enhanced vegetative vigor, with Heirloom1 producing the tallest plants (279.67 cm) and the highest root dry weight (13.72 g). Consequently, these findings demonstrate that while commercial rootstocks excel in total biomass production, heirloom rootstocks provide a superior strategy for optimizing marketable quality and physiological performance in greenhouse production. These findings demonstrate that locally adapted heirloom genotypes are valuable, under-utilized genetic resources. Their use as rootstocks offers a strategy to improve plant vigor, fruit quality, and sustainability in high-value greenhouse tomato production systems.

Abstract This study was conducted to evaluate the performance of four red raspberry cultivars, namely ‘Encore’, ‘Rosana’, ‘Polana’, and ‘Saanich’, under hydroponic cultivation in a greenhouse. Two-year-old plants were grown in 12-L pots containing a raspberry-specific substrate, using an open drip hydroponic system. The substrate consisted of 40–45% processed wood fiber, 20–25% processed pine bark fiber, 25–30% processed pumice, 1–2% hardening agent, and 0.5–1% wetting agent. Plants were fertigated with a standard nutrient solution formulated for raspberry production. ‘Encore’ exhibited superior vegetative growth, recording the highest plant height (142 cm), stem diameter (7.24 mm), internode length (3.25 cm), and number of suckers per plant (3.5), while ‘Rosana’ had the highest leaf number (38). ‘Encore’ significantly outperformed the other cultivars, with the highest number of fruits per plant (31), fruits per inflorescence (6), inflorescences per plant (5.25), fruit weight (1.4 g), and receptacle diameter (15.35 mm). ‘Polana’ flowered and fruited earlier than the other cultivars, whereas ‘Encore’ required a longer period to flowering and harvest. The highest TSS was recorded in ‘Polana’ (8.87). The highest total phenolic content among the evaluated cultivars was found in ‘Saanich’ (55.45) and ‘Polana’ (53.85), while the highest anthocyanin content was observed in ‘Rosana’ (30.83). The highest vitamin C content was recorded in ‘Encore’ and ‘Polana’ (11.66). ‘Polana’ showed earlier flowering and favorable biochemical characteristics, ‘Encore’ demonstrated the best vegetative growth and yield performance. Therefore, ‘Encore’ can be recommended as the most suitable cultivar for hydroponic greenhouse raspberry production.

Abstract This study investigated the allelopathic potential of Thymus kotschyanus Boiss. on the germination, growth, and photosynthetic performance of Cynodon dactylon and Convolvulus arvensis. Laboratory and greenhouse experiments were conducted in 2025 using a completely randomized design with four replications at a research farm in Shirvan, North Khorasan Province, Iran. Treatments consisted of aqueous root and shoot extracts of mountain thyme prepared by soaking plant material in distilled water and shaking for 24 h at room temperature under continuous agitation (200 rpm), at concentrations of 10 and 20 g L-1, with distilled water serving as the control. The results indicated that the highest extract concentration (20 g L-1) significantly reduced germination percentage in C. dactylon by 19.8% and 36.6% and in C. arvensis by 31.2% and 51.3% following application of shoot and root extracts, respectively, compared with the control. Under the same treatment conditions, germination rate decreased by 36.8% and 57.8% in C. dactylon and by 44.2% and 65.0% in C. arvensis, respectively. Application of the root extract at 20 g L-1 significantly reduced several growth and physiological traits in both weed species, including plant height (34.4% and 31.7%), leaf area (41.8% and 43.0%), shoot dry weight (29.4% and 34.9%), total chlorophyll content (30.4% and 36.0%), net photosynthetic rate (41.0% and 50.4%), and stomatal conductance (50.5% and 56.6%) in C. dactylon and C. arvensis, respectively (P ≤ 0.01). Overall, the findings demonstrated that root and shoot extracts of T. kotschyanus, likely containing water-soluble allelochemicals, markedly inhibited germination and growth of both weed species. These results suggest that T. kotschyanus may have potential for future development of bioherbicidal agents and could serve as a promising candidate for environmentally friendly weed management strategies.

Abstract Low and inconsistent rooting remains a major constraint to the vegetative propagation of Olea europaea L., owing to genotype-dependent rooting capacity and the influence of rooting substrate and beneficial micro-organisms. Therefore, this study evaluated the interactive effects of rooting substrate (perlite, cocopeat, perlite+ cocopeat), olive cultivar (Zard, Koroneiki, Roghani), and arbuscular mycorrhizal fungi (control, G. intraradices, G. mossaea, G. intraradices+ G. mossaea) on the rooting performance of olive stem cuttings under greenhouse conditions using a factorial experiment in a completely randomized design with three replications in Research Institute of Zabol on 2025. The results demonstrated that rooting performance was strongly influenced by the combined effects of cultivar, substrate, and mycorrhizal inoculation. Inoculation with Glomus intraradices consistently enhanced callus formation, rooting percentage, and the number of roots per cutting compared with the non-inoculated treatment suggesting that arbuscular mycorrhizal symbiosis promoted adventitious root formation through improved mineral nutrition, enhanced water relations, and increased root growth potential. Cocopeat promoted the highest callus formation, whereas perlite produced the greatest number of roots, indicating superior root development. Rooting responses also varied among cultivars, with the Zard cultivar exhibiting the highest root production, particularly when grown in perlite. The highest rooting percentage was achieved in the cocopeat–perlite substrate inoculated with G. intraradices. These findings demonstrate that integrating an appropriate rooting substrate with arbuscular mycorrhizal inoculation can substantially improve the vegetative propagation of olive, providing an effective strategy for producing high-quality nursery plants.

Abstract Greenhouse climate management is undergoing a paradigm shift from maintaining fixed environmental setpoints toward dynamic, plant-centered control strategies that optimize crop physiological performance while minimizing energy and water consumption. Despite remarkable advances in greenhouse technologies, most existing climate-control approaches remain environment-driven and frequently overlook the dynamic interactions among temperature, vapor pressure deficit (VPD), radiation, carbon dioxide concentration, and plant physiological responses. This review synthesizes recent advances in stress-aware greenhouse climate control by integrating plant physiology, environmental sensing, intelligent control algorithms, and energy-efficient engineering solutions into a unified conceptual framework. The analysis demonstrates that plant stress is more accurately characterized by physiological indicators including canopy temperature, stomatal conductance, transpiration, chlorophyll fluorescence, daily light integral, and VPD than by conventional environmental thresholds alone. Comparative synthesis further reveals that individual climate-control technologies effectively mitigate specific stress factors but inevitably introduce trade-offs among energy demand, water consumption, carbon retention, and disease risk. Emerging technologies, including artificial intelligence, digital twins, wireless sensor networks, and multi-objective predictive control, provide new opportunities to optimize greenhouse climate simultaneously for crop productivity, resource-use efficiency, and environmental sustainability. Based on this synthesis, we propose a stress-aware greenhouse climate-control framework in which environmental regulation is guided by real-time plant physiological status rather than fixed climatic setpoints. The framework supports adaptive decision-making across diverse greenhouse systems and provides a foundation for the next generation of intelligent, resilient, and low-carbon protected horticulture.