Salinity and soil water limitation frequently co-occur in semi-arid environments, yet their combined effects on plant water regulation remain insufficiently understood. In this study, we examined how soil moisture influences the physiological responses of beet (Beta vulgaris L.) to increasing salinity, focusing on water relations, osmotic adjustment, and leaf succulence. Beet (B. vulgaris L.) plants were grown in a controlled soil system under a 5 × 3 factorial arrangement with four replicates, combining five irrigation water salinity levels (0–8 dS m⁻¹) and three soil moisture conditions (100

El achachairu (Garcinia humilis) es un árbol frutal tropical de crecimiento lento que se desarrolla en el sotobosque de los bosques amazónicos de Bolivia y otras regiones de Sudamérica. Produce un fruto muy apreciado que se cosecha tanto de árboles cultivados como silvestres. Aunque es relativamente desconocido fuera de sus zonas endémicas, posee un importante potencial comercial, y su cultivo se ha expandido a países como Brasil, México y Australia. El achachairu puede cultivarse exitosamente en el sur de Florida. Este documento ofrece información detallada sobre las características, la botánica y las prácticas hortícolas recomendadas del achachairu para productores comerciales y para el personal de Extensión en el sur de Florida, y también es útil para propietarios de viviendas y estudiantes interesados en cultivar achachairu.

Sea level rise is increasing saltwater intrusion into soil and irrigation water in low-lying coastal agricultural regions, posing threat to crop performance and productivity. However, effects of increasing salinity on papaya (Carica papaya L.) grown in calcareous soils remain poorly understood. This study assessed physiological growth, and nutrient uptake responses of two commercial papaya cultivars (‘Exp 15′ and ‘Red Lady’) grown in an oolitic limestone soil (Krome very gravelly loam) to increasing salinity of the irrigation water. Increasing the electrical conductivity (EC) of the irrigation water to 3, 6, or 9 dS m⁻¹ resulted in declines in physiological parameters. At the highest salinity level (9 dS m⁻¹), net CO₂ assimilation (A) decreased by 81.4% in ‘Exp 15′ and 78.4% in ‘Red Lady’ relative to the control (no salt added to the irrigation water). Similar reductions were observed in stomatal conductance (gs) (95.5% and 93.5%), transpiration (Tr) (98.1% and 96.9%), the ratio of variable to maximum chlorophyll fluorescence (Fv/Fm) (21.6% and 20.5%), and the leaf chlorophyll index (LCI) (39.7% and 33.3%) in ‘Exp 15′ and ‘Red Lady’, respectively. Leaf water potential (Ψw) also declined with increasing EC, by 44.6% in ‘Exp 15′ and 73.5% in ‘Red Lady’, whereas osmotic potential (Ψo) and relative water content (RWC) remained unchanged, suggesting limited osmotic adjustment. Increased salinity altered leaf and root nutrient concentrations with most elements increasing as EC increased. High salinity also reduced leaf area and plant biomass accumulation. The normalized difference vegetative index (NDVI), determined from single multispectral images of all plants in the study, detected salinity stress only at the highest salinity level (9 dS m⁻¹) for ‘Exp 15′, but not for ‘Red Lady’. Overall, increased salinity of the irrigation water impaired physiology and growth of papaya in Krome very gravelly loam soil, apparently through stomatal limitation of carbon assimilation resulting in growth suppression.

Maprang (Bouea macrophylla Griff.), also known as gandaria, marian plum, or plum mango, is a tropical fruit tree in the family Anacardiaceae cultivated throughout Southeast Asia and increasingly recognized as a specialty fruit with potential in south Florida. The species produces aromatic yellow-to-orange fruit with a thin edible peel and sweet to sweet–tart flavor. Although commercial production is well established in Thailand and neighboring countries, cultivation in Florida is currently limited to small private plantings. This publication provides a comprehensive overview of maprang botany, phenology, fruit characteristics, environmental requirements, propagation methods, pest and disease pressures, and recommended horticultural practices to support growers, Extension personnel, homeowners, and students interested in establishing maprang for home landscapes and potential commercial production under south Florida conditions.

Commercial tropical fruit crop acreage is expanding in Florida outside the traditional extreme south Florida and coastal counties. This largely results from the significantly warmer climate, less frequent freezing events, and less severity and duration of freezing events throughout the state, especially south-central counties. In addition, as the loss of citrus acreage continues, citrus growers and entrepreneurs are seeking alternative crops to remain in business. The successful establishment and maintenance of tropical and subtropical fruit crops in Florida depend on the crop’s tolerance to critical abiotic factors, including tolerance to flooded or waterlogged soil conditions, its ability to withstand high soil and irrigation water salinity, and its high and low temperature ranges for growth, flowering, and production. This publication aims to provide an understanding of the impacts of environmental factors on subtropical and tropical fruit crops grown in Florida.

Silicon (Si) has been widely reported to enhance tolerance to abiotic stresses, including drought, in several crops. However, the long-term effects of soil-applied Si remain insufficiently explored. This study aimed to assess dry matter production, plant nutritional status, C:N:P:Si stoichiometry, and soil Si availability in ratoon sugarcane under water deficit and the residual effect of an amorphous silica-derived fertilizer (ASF). Ratoon sugarcane was grown under two levels, 40

Light management is a critical factor influencing growth and physiological performance of Vanilla planifolia , a shade-requiring plant, yet quantitative information on the minimum irradiance required for vegetative development under controlled environments remains limited. The objective of our study was to evaluate whether low light-emitting diode (LED)–supplied irradiance can sustain vegetative growth and to compare the response of two genotypes under those conditions. Two V. planifolia genotypes (AG3 and Painter) in a controlled environment were subjected to two low-light intensities (160 or 360 µmol·m –2 ·s –1 photons corresponding to 8% or 18% of full sunlight, respectively) supplied by LED lighting for 15 months. Vine length, leaf number, basal stem diameter, and leaf chlorophyll index (LCI) were measured monthly. The maximum quantum efficiency of photosystem II [the ratio of variable chlorophyll fluorescence (Fv) to maximum chlorophyll fluorescence (Fm)] was recorded at month 10. Genotype influenced vegetative growth significantly, with ‘AG3’ exhibiting greater vine length, leaf number, and basal stem diameter than ‘Painter’. Increasing irradiance from 8% to 18% of full sunlight did not affect growth variables significantly. However, plants grown under 8% light exhibited greater LCI values and a greater Fv-to-Fm ratio compared with those grown under 18% light, indicating greater photochemical efficiency under lower irradiance. These results suggest that the low irradiance levels provided by low-intensity LED lighting may be sufficient to sustain vegetative growth of V . planifolia in controlled-environment agriculture. Future research should evaluate a broader range of irradiance levels, extend monitoring into the reproductive phase, and assess yield and pod quality to refine irradiance recommendations for full-cycle indoor vanilla production on a commercial scale.

The University of California Riverside (UCR) avocado rootstock breeding program has recently developed five advanced clonal rootstocks (PP35, PP40, PP42, PP45, and PP80), selected for their resistance to Phytophthora root rot (PRR), the most widespread disease of avocados worldwide. Laurel wilt (LW), caused by the fungus Harringtonia lauricola, is a lethal vascular disease responsible for extensive mortality of forest trees throughout the southeastern United States. Although LW has been reported in avocado only in Florida within the United States, documented outbreaks in Taiwan and Myanmar demonstrate its potential to threaten avocado production globally. As LW continues to expand its range, its eventual introduction into major production regions such as California and Mexico is considered likely. Therefore, evaluating how these experimental PRR-resistant rootstocks influence LW susceptibility is critical before commercialization. We assessed LW susceptibility and physiological responses in two commercially available cultivars: 'Donnie' (widely grown in Florida) and GEMVR (grown in California). Each cultivar was grafted on each of the five UCR experimental rootstocks or 'Waldin' seedling rootstock, the dominant rootstock in Florida. Under temperature-controlled greenhouse conditions, trees were inoculated with H. lauricola or with deionized water as a control. External symptoms were rated on a 1 to 10 scale, and net CO2 assimilation and xylem sap flow were measured repeatedly. Infection was confirmed at harvest by plating stem sections on a selective medium. Both 'Donnie' and GEMVR were susceptible to LW on all rootstocks tested, but the symptom severity and progression rate varied by scion/rootstock combination. In 'Donnie', symptom progression was rapid and severe, although it was slightly reduced in PP40 and PP45. In contrast, GEMVR trees grafted on PP45, PP80, or 'Waldin' showed slower symptom progression and lower severity compared with those on PP35, PP40, or PP42. Net CO2 assimilation declined significantly after inoculation in all trees, but decreases were smaller in 'Donnie'/PP40 and in GEMVR grafted on PP45, PP80, or 'Waldin'. Daily xylem sap flow decreased after inoculation for all 'Donnie' combinations, but declines occurred only in some GEMVR combinations. Overall, 'Donnie' showed high susceptibility to LW regardless of the rootstock, whereas GEMVR grafted onto PP45, PP80, or 'Waldin' exhibited comparatively reduced susceptibility. These scion/rootstock combinations, which exhibit slower disease progression, likely due to reduced pathogen multiplication and movement within the xylem, may slow LW spread within orchards through root grafts and represent promising components of an integrated pest management strategy.

Anthracnose, caused by species of plant pathogenic fungi in the genus Colletotrichum, ranks among the most economically important diseases impacting production and marketing of avocado and mango fruits. Fruit infected with Colletotrichum suffer reduced shelf-life during postharvest, shipping and storage, resulting in lower grade fruit or even rejection by packinghouses due to fruit rot. Additionally, some species of Colletotrichum cause substantial damage to mango inflorescences, i.e., blossom blight, which results in loss of flowers and abortion of small fruit. Under high disease pressure, damage caused by Colletotrichum sp. to mango and avocado foliage can be observed in orchards but is seldom considered important compared to the damage caused to fruit. Nevertheless, infections on the foliage represent an inconspicuous source of inoculum that allows Colletotrichum to survive, reproduce, and persist in the field, making disease management challenging. Warm, humid, and rainy environmental conditions, predominant in the region during fruit set and development, are conducive for the spread and germination of Colletotrichum spores, frequently allowing quiescent fungal infections on the skin of fruit. Thus, to protect flowers and fruit against Colletotrichum infections, fungicide sprays usually start from the flower bud swelling stage in mango and from the fruit set stage in avocado.

Soil salinity and bacterial spot of tomato (BST), caused by Xanthomonas perforans, are major abiotic and biotic stresses limiting tomato production, particularly in Florida. While their individual effects are well documented, the impact of soil salinity on BST has not yet been investigated. This greenhouse study evaluated how increasing irrigation water salinity (electrical conductivity [EC] = 0.5, 3, 5, or 7 dS m-1) affected tomato growth, physiology, BST severity, fruit quality, and transcriptomic responses. Salinity reduced plant growth and BST severity but did not directly affect X. perforans populations. Results indicated that reduced plant physiological activity (net CO2 assimilation [A], transpiration [E], and stomatal conductance [gs]) contributes to lower disease levels. Increased salinity led to more solute concentrations, altered sugar metabolism, and improved perceived taste, as supported by taste panel, osmolality, and transcriptomic analyses. They also showed that transcriptional responses to salinity (EC = 7 dS m-1) and X. perforans infection were strongly time-dependent. Salt-treated plants exhibited fewer differentially expressed genes following inoculation, whereas comparisons between EC 7-treated and control plants revealed extensive salinity-induced reprogramming. KEGG analysis indicated enrichment of photosynthesis, carbon metabolism, amino acid biosynthesis, and ribosome pathways, while defense-related pathways, including MAPK signaling and plant-pathogen interaction, were downregulated, suggesting that tomato prioritized adaptation to salinity over pathogen defense.

Nitrogen (N) management is a critical factor influencing growth and physiological performance of vanilla. However, quantitative information on N requirements for Vanilla & times; tahitensis remains limited. This study evaluated six N application rates (0, 2, 4, 8, 16, and 32 g N plant-1 yr-1) on tissue N partitioning, leaf chlorophyll index (LCI), vegetative growth, and biomass under controlled container conditions. Plants were arranged in a randomized complete block design (RCBD), and final analyses were conducted on destructively sampled plants (three plants per treatment; total n = 18). N concentration increased in all tissues with increasing N supply, but responses differed among tissues. Stem N concentration exhibited the greatest proportional increase at high N rates, whereas leaf N increased more gradually. Growth traits and LCI followed curvilinear patterns, with intermediate N rates generally associated with improved vegetative performance. Quadratic models estimated optimal N rates between 13 and 21 g N plant-1 yr-1, with predicted leaf N concentrations of 1.5-2.2%. However, confidence intervals indicated substantial uncertainty for variables with low model fit. LCI was strongly correlated with leaf N concentration, supporting its use as a nondestructive indicator of plant N status. Because the study was conducted under controlled conditions, field validation is required before broader recommendations are made.

Rollinia (Annona mucosa Jacq.) (sometimes called biribá) is a fast-growing tropical fruit tree cultivated for its large, aromatic fruits. It is well adapted to the warm, humid conditions of south Florida, where it produces an extended warm-season crop, is generally unaffected by major pest and disease pressure, and shows potential for niche fresh and processing markets. Constraints include sensitivity to flooding and salinity, fruit fragility, and short postharvest life. This publication is intended for commercial growers, Extension personnel, and homeowners and students interested in growing this species. Drawing on published literature and field observations from south Florida, the publication addresses botany, phenology, fruit characteristics, pollination biology, environmental requirements, horticultural practices, propagation, orchard management, yields, and postharvest behavior.

Soil salinity affects large areas of the world and results in horticultural and biodiversity losses in tropical regions. Garcinia humilis (Vahl) C.D. Adams, fam. Clusiaceae, commonly known as achachairu, is a neotropical evergreen fruit tree native to the Amazonian forests in Bolivia. Its tolerance and responses to soil salinity exclusive of other stressors and within a range of salinity levels have not been reported. This study assessed the physiological, biochemical, and morphological responses of G. humilis to different levels of elevated soil salinity induced by saline irrigation. Physiological variables measured included net CO2 assimilation (An), stomatal conductance of H2O (gs), intercellular CO2 concentration, leaf chlorophyll index (LCI), and the ratio of variable to maximum chlorophyll fluorescence (Fv/Fm). Leaf and root nutrient analyses were performed to assess nutrient imbalances and the accumulation of toxic ions. Antioxidant responses, including superoxide dismutase, catalase, peroxidase, guaiacol peroxidase, ascorbate peroxidase, ascorbic acid, monodehydroascorbate reductase, dehydroascorbate reductase, glutathione, and glutathione reductase; reactive oxygen species (ROS) such as hydrogen peroxide and superoxide radical; and lipid peroxidation as indicated by malondialdehyde were also measured. The results indicate that G. humilis tolerates elevated soil salinity induced by saline irrigation with an electrical conductivity of at least 6 dS m−1, which results in stress responses without fatal consequences. Soil salinity induced by saline irrigation of 6 dS m−1 reduced An and gs by approximately 50% during a 30-day period, but there was no evidence of physiological damage based on the LCI or Fv/Fm. The levels of Na+ and Cl− did not reach toxic levels, and the plants were able to prevent damaging imbalances of plant nutrients, indicating an ion-avoidance strategy. Increased antioxidant response to soil salinity induced by saline irrigation possibly prevented ROS and lipid peroxidation damage. G. humilis appears to be moderately tolerant of soil salinity induced by saline irrigation of at least 30 days at 6 dS m−1.

Soil salinity poses a global threat to crop production. Early understanding of plant physiological responses to salinity stress can be critical to implementing timely stress management strategies. One of the initial plant physiological responses to salinity is a reduction of transpiration. This study used papaya as a model crop to better understand the effect of salinity on whole-plant transpiration using a greenhouse experiment. Treatments consisted of four electrical conductivity (EC_IR) levels of irrigation water: 0 (tap water), 2, 4, or 8 dS m− 1 were considered for the experiment. An automated phenotyping platform measured whole plant transpiration from the time of papaya transplanting until they reached approximately 15 weeks of age. Five machine learning models: extreme gradient boosting (XGBt), categorical boosting (CATBt), light gradient boosting (LAGBt), random forest (RF), and decision tree (DT) were fitted to the transpiration data and machine learning algorithms were deployed on a new data set. The impact of salinity on transpiration started to become evident 16 days after initiation of salinity treatments, where only the 8 dS m− 1 treatment induced a significant decline in transpiration. All machine learning models efficiently captured salinity-induced impacts on transpiration. The use of salinity as an input feature improved the performance of all machine learning models. Salinity contributed up to 32

In Florida, many agricultural soils contain up to 600 mg/kg of Mehlich-3 extractable phosphorus (P), yet potato growers continue to apply P fertilizers, indicating complex P dynamics that remain underexplored. Previous studies have mainly focused on P fertilizer trials, overlooking crucial factors like phosphatase activity and P sorption isotherms in high-legacy P systems. This study aimed to address this gap by examining acid phosphatase activity (AcPA) and P sorption dynamics in a potato field in northeastern Florida. Utilizing a split-block design, 24 plots were subjected to two P application rates (0 and 49 kg/ha) and three management treatments: a multispecies cover crop (MSCC), MSCC with Telone-C35 (a nematicide), and an untreated control. Significant increases in AcPA were observed during the tuber bulking stage, suggesting that applied P was insufficient for plant needs. P sorption isotherms indicated that the soil had reached maximum P sorption capacity, with applied P primarily fixed through chemical processes. These findings underscore the need for revised P fertilizer strategies in high-legacy P soils and highlight the importance of monitoring AcPA and sorption phases for effective nutrient management.

Efficient irrigation management relies on accurately estimating crop evapotranspiration (ETc), yet conventional methods often face limitations, such as cost, spatial coverage, data requirements, and the need for local calibration. This study had two main objectives: 1) to quantify daily ETc of sweet corn (SC) and green beans (GB) using crop water stress index (CWSI) calculated from canopy temperatures (Tc) and crop coefficient (Kc) estimated vegetation indices and 2) to evaluate the potential of machine learning (ML) models in estimating daily ETc and Tc. Irrigation experiments were conducted during the winter seasons of 2020-2021 and 2021-2022 at the University of Florida's Tropical Research and Education Center (TREC), Florida, USA. Networks of above-canopy infrared thermocouples (IRTs) and soil moisture (SM) sensors were used to collect Tc and SM. Multispectral images were also collected using an unmanned aerial vehicle (UAV)-based RedEdgeMX sensor. Sub-hourly changes in SM during dry periods were aggregated to estimate the daily measured ETc of SC and GB. Time series of CWSI were generated from Tc, while Kc was estimated using eleven vegetation indices (VIs) generated from drone imagery. Moreover, four ML models, i.e., CatBoost (CB), Random Forest (RF), k-Nearest Neighbors (kNN), and Extreme Gradient Boosting (XGB), were evaluated for simulating ETc. Six models, i.e., CB, kNN, RF, XGB, Light Gradient Boosting Machine (LGB), and Deep Learning (DL), were also evaluated for simulating the Tc of SC and GB. The results showed that the CWSI approach was acceptable in estimating ETc with an average MAE of 0.90 mm day-1 for SC and 0.62 mm day-1 for GB. Four out of eleven vegetation indices (VIs) demonstrated superior performance in estimating daily ETc, including the Soil Adjusted Vegetation Index (SAVI), Normalized Green-Red Difference Index (NGRDI), Red Edge Normalized Difference Vegetation Index (RENDVI), and NIR-RE normalized difference vegetation index (NIRRENDVI). The ML models captured ETc and Tc with better accuracy. Averaged root mean square error (RMSE) for ETc across the four models was 0.86 mm day-1 for SC and 0.89 mm day-1 for GB. The average RMSE of the ML models for simulating Tc was +1.1 degrees C for SC and +1.5 degrees C for GB. Overall, CWSI, spectral reflectance-based Kc, and ML models proved to be useful tools for estimating ETc at finer spatial and temporal scales with reasonable accuracy.

It was previously determined that G. humilis, a woody perennial species native to the Amazon and grown commercially as a tropical fruit tree, is tolerant of either flooding or high soil salinity and simultaneous exposure to flooding and high soil salinity, as evidenced by no visible signs of stress and continued vegetative growth. However, exposure to either stressor or to both stressors simultaneously, significantly reduced net CO2 assimilation (A) and stomatal conductance (gs), which can negatively impact plant growth and yield. This study tested the effects of 24-epibrassinolide (EB) priming on reducing the negative physiological responses of G. humilis to flooding and high soil salinity. G. humilis trees that were either flooded or non-flooded were each subjected to either low or high soil salinity levels and either primed with a solution of 1.0 mg l-1 EB or not primed prior to flooding and salinity treatments. Prior to the imposition of treatments and periodically during the treatment period, A, gs, internal CO2 content in the leaf (Ci), the leaf chlorophyll index (LCI), and the variable to maximum chlorophyll fluorescence ratio (Fv/Fm) were determined. At the end of the treatment period, nutrient element concentrations in the leaves and roots, as well as reactive oxygen species (ROS), antioxidants, and lipid peroxidation in the leaves were measured. Epibrassinolide priming decreased the negative impacts of salinity or flooding and simultaneous exposure to both stressors on G. humilis, apparently by reinforcing antioxidant responses which decreased ROS and lipid peroxidation.

Soil salinity affects crop growth and production, especially in arid and semi-arid regions of the world. The interactions between salt ions and soil particles vary depending on soil texture, mineralogy, and ion composition. The relationship between soil ions and particles and the effects of this interaction on crop plants remains underexplored. This study evaluated the plant water relations, growth, and yield of cowpea (Vigna unguiculata) as affected by the salinity of the irrigation water in two different soil types with varying weathering levels and contrasting mineralogies. The treatments consisted of six salinity levels based on the electrical conductivity (EC) of the irrigation water (0, 1.5, 3, 4, 5, 6.0, or 9 dS m−1) and were tested in Ultisol (well-weathered soil) and Alfisol (less-weathered soil). The experiment was conducted over 80 days with 4 repetitions. The results showed that the plant salinity tolerance, growth, and yield in response to salinity varied depending on the soil type. Irrigation with saline water exceeding an EC of 3 dS m−1 completely halted cowpea production in Ultisol, whereas in Alfisol, production ceased at an EC above 6 dS m−1. Although it accumulates more salts under saline irrigation, Alfisol promotes better cowpea growth and yield than Ultisol.

Avocado (Persea americana Mill.) trees are classified into three ecotypes: Mexican (M), Guatemalan (G), and West Indian (WI) based on their geographical center of origin. In southern Florida, avocado trees are grown on WI seedling rootstocks, mainly ‘Waldin’, generally with WI or WI × G hybrid scions. Flood tolerance is influenced by the rootstock, and ‘Waldin’ seedling rootstock is sensitive to short-term flooding. However, effects of rootstock ecotype on flood tolerance have not been reported. This study compared responses of a WI avocado scion (‘Simmonds’) among clonal avocado rootstocks of each ecotype. ‘Simmonds’ was grafted onto clonally propagated ‘Duke 7’ (M), ‘Reed’ (G), or ‘Waldin’ (WI) rootstocks and subjected to either short-term (1.5 days) of flooding or not flooded (control). As an indicator of plant stress, leaf gas exchange [net CO2 assimilation (A), stomatal conductance (gs), transpiration (Tr), and water use efficiency (WUE)] was measured during the flooding period and after trees were unflooded until flooded plants lost too many leaves to measure. After new leaves emerged on defoliated trees, leaf gas exchange was measured, and trees were harvested for dry weight determination. Flooding reduced leaf gas exchange and leaf dry weight of trees on clonal M or G rootstocks, but not on the clonal WI rootstock. All trees on the clonal WI rootstock survived flooding, whereas 87% of trees on clonal M and 50% of trees on clonal G rootstock survived flooding.