Horticulturae

20 pages, 3398 KB

Open AccessArticle

SlbHLH113 Promotes Tomato Fruit Elongation by Restricting Radial Growth of the Columella and Interacting with SlIQD21a

by Xiaochen Wang, Hanru Hu, Benben Li, Lingyi Liu, Zhujun Zhu and Yuanyuan Liu

Horticulturae 2026, 12(6), 650; https://doi.org/10.3390/horticulturae12060650 (registering DOI) - 22 May 2026

Fruit shape is determined by patterns of cell division and expansion during early development, yet the upstream transcription factors coordinating cell wall dynamics and cytoskeletal organization remain largely unknown. Here, we report that SlbHLH113, a bHLH transcription factor, positively regulates tomato fruit elongation. Overexpression (OE) of SlbHLH113 produced elongated fruits with increased length/width ratio, whereas RNAi lines exhibited flattened fruits. Histological analysis revealed that SlbHLH113 alters columella cell polarity—promoting elongated cell morphology without affecting cell area—and reduces columella–placenta width and locule width, without altering pericarp thickness. Transcriptomic profiling identified 87 differentially expressed genes in OE lines, with enrichment in cell wall-related processes. Notably, a pectate lyase gene (PL5) and an expansin gene (EXT90) were down-regulated, while genes involved in oriented cellulose deposition (COBRA4) and ethylene signaling were up-regulated. Importantly, SlbHLH113 physically interacts with the microtubule-associated protein SlIQD21a, as demonstrated by yeast two-hybrid and luciferase complementation assays. Finally, SlbHLH113 did not affect major nutrient contents in red-ripe fruits. Collectively, our findings identify SlbHLH113 as a novel regulator of tomato fruit shape that might act through cell polarity control, cell wall remodeling, and interaction with a microtubule-associated protein, offering a potential target for improving fruit morphology without compromising nutritional quality. Full article

(This article belongs to the Section Developmental Physiology, Biochemistry, and Molecular Biology)

20 pages, 5578 KB

Open AccessArticle

Leaching Fraction Regulates Root-Zone Salinity, Gas Exchange, and Ornamental Quality in Off-Season Potted Curcuma cv. ‘Jasmine Pink’ Under Crop Coefficient-Based Irrigation

by Vannak Sour, Anoma Dongsansuk, Supat Isarangkool Na Ayutthaya, Soraya Ruamrungsri and Panupon Hongpakdee

Horticulturae 2026, 12(6), 647; https://doi.org/10.3390/horticulturae12060647 (registering DOI) - 22 May 2026

Abstract

Containerized ornamental plant production requires efficient irrigation strategies to balance plant quality with water and nutrient conservation. This study evaluated four leaching fraction (LF) levels (0%, 20%, 40%, and 60%) in a completely randomized design with three replications, each consisting of three pots, to determine their effects on plant growth, ornamental quality, gas exchange, water use efficiency (WUE), and macronutrient leaching in off-season potted Curcuma cv. ‘Jasmine Pink’. Irrigation volumes were determined using crop coefficient (Kc)-based estimates derived from evaporation pan measurements. The results showed that the highest LF level (60%) significantly improved several ornamental quality traits, including flower number per cluster, leaf greenness, specific leaf area, and compactness index, while also increasing aerial dry weight and improving gas exchange parameters during the flowering stage. These improvements were associated with reduced substrate electrical conductivity, indicating lower soluble salt accumulation in the root zone under higher LF treatments and more favorable conditions for plant growth. Leaching fraction is commonly used in containerized crop production to prevent excessive salt accumulation in the root zone by allowing excess irrigation water to drain from the substrate. However, increasing LF also resulted in greater irrigation water consumption and higher macronutrient losses through leachate, particularly potassium. In contrast, lower LF treatments (0–20%) improved water use efficiency and reduced nutrient losses but were associated with higher substrate electrical conductivity, suggesting greater soluble salt accumulation in the root zone. Overall, the results indicate that a higher LF (60%) provided the greatest improvement in plant growth and ornamental quality under the conditions of the present study for off-season potted Curcuma alismatifolia production, although integrated strategies may be required to reduce water and nutrient losses. These findings provide practical insights for optimizing irrigation management in container-grown ornamental crops. Full article

(This article belongs to the Section Floriculture, Nursery and Landscape, and Turf)

24 pages, 7410 KB

Open AccessFeature PaperArticle

Developmental Changes in Raceme Carbohydrates and Nutrients During Flowering and Fruit Set in Macadamia

by Suzy Y. Rogiers, Jean T. Page, Manisha Thapa, Gerhard C. Rossouw, Kwanho Jeong and Terry J. Rose

Horticulturae 2026, 12(6), 646; https://doi.org/10.3390/horticulturae12060646 (registering DOI) - 22 May 2026

Abstract

Daddow is a macadamia cultivar that yields poorly because flowers and fruitlets frequently abort early in development. The objective was to determine whether resource availability limits fruitlet retention in this cultivar. Racemes of Daddow and three other cultivars, 849, A38, and A203, were sampled weekly during flowering and fruit set, and trends in nutrients and non-structural carbohydrates were assessed. Starch concentrations in the flowers and rachis were lower in Daddow than in the other cultivars before fruit set. Rachis concentration of glucose, an important signalling molecule, was also lower in Daddow at flowering. Most flower and fruitlet nutrient concentrations in Daddow were comparable to those of the other cultivars. However, potassium concentrations were lower in both the rachis and leaves of Daddow, while boron concentration, important for pollen tube growth, was higher. These results suggest altered signalling mechanisms, inadequate carbohydrate supply and deficiencies in specific nutrients may have been contributing factors to the high flower and fruitlet abortion rates of Daddow. Full article

(This article belongs to the Section Plant Nutrition)

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22 pages, 7323 KB

Open AccessArticle

Dolomite-Loaded Vermicompost Improves Acidic Soil Health and Promotes Panax quinquefolius L. Growth in Pine Agroforestry Systems

by Azhi Yang, Guobing Tian, Weiye Tong, Yihang Ouyang, Junwen Chen, Shengchao Yang, Shuhui Zi, Ping Zhao, Wei Fan, Fuseini Issaka, Xiumei Shen, Yufei Jiang, Yuchun He and Shuran He

Horticulturae 2026, 12(6), 645; https://doi.org/10.3390/horticulturae12060645 - 22 May 2026

Abstract

Agriforestry systems are essential for improving the quality of medicinal herbs and ensuring the sustainable management of forests. Forest soil acidification inhibits the growth of medicinal plants. The application of novel dolomite-loaded vermicompost (DOVC) is considered a potential method for promoting plants growth. However, the mechanisms by which it promotes the growth of medicinal plants are poorly understood. This study combined observational analysis and field experimentation, to first elucidate the correlation between under-forest soil pH and root dry weight of American ginseng (Panax quinquefolius L.). Subsequently, the mechanisms by which DOVC promotes the growth of P. quinquefolius were analyzed from the perspectives of plant physiology and soil microbiome. The results indicate: (1) Field survey results demonstrated when the pH was between 5.28 and 5.99, the root dry weight of P. quinquefolius gradually increased with increasing soil pH. (2) Compared with Control, DOVC increased the soil pH by 1.48 units and promoted the growth of P. quinquefolius, with a net photosynthetic rate increase of 60.26%, malondialdehyde content decrease of 71.07%, and root dry weight increase of 50.33%. (3) Compared with Control, DOVC enhanced bacterial community diversity, with Ace and Chao 1 indices increasing significantly by 33.88% and 25.18%, respectively; and increased the relative abundance of Chloroflexi and Basidiomycota. (4) Partial Least Squares Path Modeling revealed that DOVC positively influenced P. quinquefolius growth via the improvement of soil health index and microbial community diversity. The development of this novel soil amendment offers a new approach to improving soil health in agroforestry systems. Full article

(This article belongs to the Special Issue Bioresource for Sustainable Cultivation of Medicinal Herbs)

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Horticulturae, Volume 12, Issue 6 (June 2026) – 4 articles

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