This study investigates how the ripening stage at harvest and fertilization rate impact tomato fruit quality. Tomato plants (cv. HM1823) were grown during the Fall 2023 season under four levels of fertilization (75%, 100%, 125%, and 150% of the recommended UF/IFAS rate, which is 200 lb/A nitrogen and potassium). Fruit were harvested at four distinct ripening stages: mature green (MG), turning (T), pink (P), and red (R), as assessed visually and stored at 25°C. Color, firmness, soluble solids content (SSC), pH, and titratable acidity (TA) were measured every 4 days until 12 or 16 days (for MG fruit). According to the analysis of variance, all factors (fertilization rate-FR, ripening stage at harvest- RS and shelf life period- SL), as well as the interaction RSSL significantly (P
Pepper (Capsicum annuum L.) as a non-climacteric fruit is usually harvested at either mature green or ripe stage, and fruit quality including texture, color, and nutritive values is different according to the fruit developmental stages. Understanding molecular mechanisms of fruit ripening and senescence processes is crucial to control the fruit quality and reduce the postharvest loss. This study was aimed to identify NAC transcription factors (TFs) involved in the ripening and senescence of pepper fruit by analyzing gene expressions and protein-protein interactions. To identify NAC genes related to the ripening, transcript levels of total 104 NAC TFs were investigated using publicly available transcriptome data. Among them, transcript levels of 8 genes significantly increased during the ripening and senescence. Their phylogenetic analysis also showed that they are closely associated with NAC TFs which play a role in ripening or senescence in other crop species. Among them, 4 genes showing abundant transcript levels at the ripening stage were selected, including CaNAC14, 45, 84, and 92, to further investigate their roles. In pepper (C. annuum var. ‘Gyeonggiyangpyeiong’) fruit, their expressions clearly increased during the ripening or induced by exogenous ABA, the major phytohormone regulating non-climacteric fruit ripening. To reveal a relationship between the CaNACs and ABA signaling, protein-protein interactions between the CaNACs and ABA receptors were analyzed through yeast- two-hybrid and bimolecular-fluorescence complementation assays. Among them, CaNAC92 and CaPYL12, the ABA receptor, interacted each other in a nucleus with an ABA-dependent manner. This result indicated that their interaction may affect the ABA signaling or the transcriptional regulation during the ripening. We identified CaNAC TFs involved in the pepper fruit ripening and suggested CaNAC92 as a putative molecule functioning in the ripening. These findings will provide genetic information to control the ripening and to improve pepper fruit quality.
This study investigates the volatile organic compounds (VOCs) of eight microgreens in the Brassicaceae family, known for their robust flavors and potential health benefits, including detoxification properties and anti-cancer effects. The microgreens analyzed included five Brassica species—B. juncea (mustard), B. napus (kale), B. rapa (mizuna), B. oleracea L. var. capitata (red cabbage), and B. oleracea L. var. italica (broccoli)—as well as Eruca sativa (arugula), Lepidium sativum (cress), and Raphanus sativus (radish). The above-ground plant tissues were homogenized in saturated salt water and the VOCs were examined using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GCMS). A total of 117 VOCs were identified across all tested species, with individual species VOC counts ranging from 42 to 67. Radish showed the highest total ion current at 676 million (mTIC), with other species varying down to 190 mTIC in arugula. Notably, sulfur and/or nitrogen-containing compounds (SCCs and/or NCCs) constituted over 90% of the total VOCs collected from all species, with Brassica species containing more than 96% SCCs and 93% NCCs. Conversely, radish and arugula had less than 88% NCCs, and cress contained only 66% SCCs. Dominant compounds were primarily isothiocyanates, with significant variability in major VOCs across different species. For instance, allyl isothiocyanate was prevalent in mustard, mizuna, and red cabbage; 4-isothiocyanato-1-butene in kale and mizuna; isothiocyanatomethyl-benzene in cress; 1-isothiocyanato-4-(methylthio)-butane in arugula and broccoli; and (E)-4-isothiocyanato-1-(methylthio)-1-butene in radish. The reduced SCCs in cress were attributed to the higher presence of benzyl nitrile and benzyl isocyanate, while the lower NCCs in radish were linked to increased levels of dimethyl disulfide and dimethyl trisulfide. This diversity in SCCs and NCCs contributes to the varied volatile flavors and potential health benefits of these microgreens.
Lettuce (Lactuca sativa) is cultivated in controlled environment agriculture via vertical production or hydroponic well systems. To extend shelf-life, growers harvest “living lettuce” by keeping roots intact, but there is limited data supporting this harvesting technique. The objective of this study was to assess the use of clamshell and root treatments on the shelf-life and nutritional quality of lettuce. Treatments included storage either inside or outside of plastic clamshells and with roots removed or intact. Lettuce was stored for 28 days at 4 oC, 85% relative humidity. Percent weight loss (%weight loss), visual ratings (1 to 5 scale, 1 = poor and 5 = excellent), and colorimeter analysis (L*, a*, b*, c*, hue angle) were measured every 3 days. Total assays of chlorophyll, carotenoids, anthocyanins, flavonoids and phenolic activity were analyzed via UV VIS spectrophotometry every 7 days throughout storage. Few differences were seen in root treatment. As days in storage progressed, %weight loss progressed to 16.9%. Closed clamshells decreased %weight loss (5.5%) compared to open (18.1%). Visual ratings of yellowing/nutrient deficiency, relative greenness, wilt/head looseness, and salability decreased through storage. Lettuce stored in closed clamshells decreased %weight loss by 12% and delayed wilt/head looseness by 11 days. Similarly, lettuce stored in closed clamshells with roots were salable until 18 days in storage, while open clamshells were no longer salable after 7 days. Short root length (~4 cm) may be the dominant factor for the lack of significance as previous research suggested harvesting “living lettuce” with 9 cm roots increased storage and quality. Color data differed, and lettuce stored in closed clamshells with roots had more intense red color a* (-3.7 vs. -2.7), blue color b* (12.6 vs 10.1), and were purer in color c* (13.3 vs. 10.5) compared to open clamshells with roots. No differences were seen in total anthocyanin (mg/L), total chlorophyll (g/g) or total carotenoid (g/g) content in clamshell or root treatment (p > 0.05). Through 14 days of storage, total anthocyanins degraded by 7.55 mg/L (Day 0 = 10.78 vs. Day 14 = 3.22), while no loss of total chlorophyll (9204.84 g/g) or total carotenoids (1947.25 g/g) were seen. Anthocyanins are water soluble pigments and with increased weight/water loss, anthocyanins solubilize leading to degradation. Chlorophylls and carotenoids were not lost, potentially due to low enzyme activity of chlorophyllase. This experiment indicates consumers should eat lettuce within 7-10 days of harvest for highest nutritional and postharvest quality.
Lettuce is a popular leafy vegetable that can play an important role in human nutrition and diets with regular consumption. Lettuce cultivars can vary considerably in their postharvest nutritional composition. It is critically important to determine which lettuce cultivars have the highest nutritional quality to allow growers to select those that are best for their market. The objectives of this experiment were twofold, to determine differences in the phytonutrient content of two butterhead lettuce cultivars, ‘Nancy’ (green butterhead) and ‘Skyphos’ (red butterhead), and if leaf location within the head (lower or mid leaves) differs in nutritional composition. The experiment was conducted in the spring of 2023 in a high tunnel, and setup as a completely randomized design with 4 replications. At horticultural maturity (40 days after germination), the lower and mid leaves were harvested. Lettuce samples were frozen and shipped to Auburn University where samples were assayed for total chlorophyll, carotenoids, anthocyanins, flavonoids, phenolics and antioxidant activity via UV VIS spectrophotometry. Carotenoids of violaxanthin, neoxanthin, lutein and -carotene were quantitated by UPLC/MS. The interaction of leaf location*cultivar (P < 0.05) indicated that the lower leaves of ‘Skyphos’ lettuce had the highest total anthocyanin content at 2.94 mg/L compared to ‘Nancy’ at 0.05 mg/L, respectively. No other differences (P > 0.05) were detected between the cultivars. Sample location differed in total carotenoids (mg/g) and total chlorophyll (mg/g) with the lower leaves having the highest nutritional composition at 1380.18 and 5973.58 mg/g, respectively compared to the mid leaves (509.02 and 1684.42 mg/g, respectively). Chlorophyll a (4399.67 mg/g) and b (1573.90 mg/g) was also highest in the lower leaves of both cultivars compared to the mid leaves. Our results indicate that both butterhead lettuce cultivar and leaf location strongly impacts human health. ‘Skyphos’, a red butterhead lettuce, had the high highest total anthocyanin content in the lower leaves. Anthocyanins are critical phytochemicals known for many health promoting properties such as free radical scavenging, and anti-cancer and anti-diabetic properties. This experiment also indicated the lower leaves of both cultivars had the highest amount of total chlorophyll and carotenoids. The lower leaves of red butterhead lettuces, such as ‘Skyphos’, should be eaten to obtain the highest nutrition for their diet.
Lettuce is one of the most widely consumed vegetables in the world and can provide various health benefits to consumers. The type of production system, such as high tunnel, green roof or open field environments, can influence the nutritional composition of lettuce. To determine the extent of phytonutrient content change, ‘Skyphos’ lettuce was grown in these various production environments to compare phytonutrient content at harvest. The production experiment was conducted at Southern Illinois University-Carbondale and set up with three treatment locations and four replications. Two production systems used organic fertility practices (high tunnel and green roof), while the field production system used conventional fertilizers. At horticultural maturity (40 days after germination), the lower and mid leaves were harvested to determine phytonutrient content. Lettuce samples were frozen and shipped to Auburn University where samples were assayed for total chlorophyll, carotenoids, anthocyanins, flavonoids, phenolics and antioxidant activity via UV VIS spectrophotometry. Carotenoids of violaxanthin, neoxanthin, lutein and b-carotene were quantitated by UPLC/MS. The interaction of production system*leaf sampling location differed (P < 0.05) in total anthocyanins, total carotenoids and total chlorophyll. Total anthocyanins were highest in the lower leaves of ‘Skyphos’ lettuce cultivated on the green roof at 3.57 mg/L. In comparison, total carotenoids, total chlorophyll and chlorophyll a were highest in the lower leaves of lettuce cultivated in the high tunnel at 1316.48, 6093.45 and 4401. 97 mg/g, respectively. Cultivating lettuce in the high tunnel provided the highest Chlorophyll b content (1638.37 mg/g) compared to the field (888.80 mg/g) or green roof (893.43 mg/g). The phytonutrient content of lettuce can be influenced by location, temperature, soil type, humidity and UV radiation. The green roof increased total anthocyanin content which may be due to the higher temperatures and irradiation levels on compared to the field or high tunnel. Total Chlorophyll and carotenoid content was increased in the high tunnel likely due to increases of UV-A and UV-B exposure from the poly film leading to an increase in photosystem response. This experiment suggests the specific phytonutrient content (e.g., anthocyanin or carotenoids) in a red lettuce like ‘Skyphos’ differs based on production system and can be used in market development to increase consumer consumption by highlighting the specific phytonutrients highest in each production system.
Florida is home to the largest caladium production in the world, supplying essentially all the global caladium tuber demand. These plants are famous for their vibrant leaf colors and patterns and are asexually propagated through tubers. Following plant development, tubers are harvested and stored for a few months before being forced from March to September for potted plant production and direct landscape planting. During extended postharvest storage, caladium tubers risk severe weight loss, tissue decay, and Fusarium tuber rot. The current storage practices under ambient conditions with high temperatures and high relative humidity exacerbate weight loss and tuber rot. The challenges of long-term tuber storage make it difficult to produce pot caladium plants for winter holidays, including Thanksgiving, Christmas, and New Year. These challenges also affect the commercialization of tubers in the Southern Hemisphere during the summer. Opening these marketing opportunities can allow growers to extend and increase their production. Additionally, identifying caladium tubers suitable for late-season production will give Florida growers a competitive advantage. To identify caladium varieties with long-term tuber storage potential and late-season production, 12 varieties were evaluated to target Thanksgiving and Valentine’s Day. No.1-sized tubers were potted in 5-inch containers and grown in a greenhouse. For each variety, 10 tubers were monitored for sprouting and leaf expansion and later evaluated for plant quality using a rating scale from 1 to 5. Potted tubers from all cultivars achieved suitable market quality standards when targeting Thanksgiving, with the higher ratings obtained by cultivars ‘Splash of Wine’, ‘Classic Pink’, and ‘Lemon Blush’. The higher number of leaves and height were obtained by cultivars ‘Classic Pink’, ‘Desert Sunset’, and ‘White Wonder’, and ‘Party Punch’, ‘Ballet Slipper’, and ‘Classic Pink’, respectively. For Valentine’s Day, despite sprouting decreasing, cultivars ‘Splash of Wine’, ‘Hot 2 Trot’, ‘Desert Sunset’, ‘Party Punch’, ‘Classic Pink’, ‘White Wonder’, and ‘Lemon Blush’ reached suitable market quality standards. Overall, the number of leaves and height decreased compared to plants targeting Thanksgiving, however, cultivars with a more desirable number of leaves were ‘Classic Pink’ and ‘Lemon Blush’ whereas cultivars with higher height were ‘Party Punch’ and ‘Ballet Slipper’. Identifying cultivars suitable for late-season production will allow growers to expand their commercialization window for major holidays and to supply tuber demand to the Southern Hemisphere.
Preservation of nutritional and market qualities of potato tubers during postharvest storage is essential for optimum economic return. Protecting tubers from unintended sprouting during storage is one of the major postharvest challenges that potato growers and stakeholders encounter. Storage environment, particularly storage temperature, significantly impacts dormancy progression and sprouting and effect overall marketability. Potato tubers carry significant amount of microbiome in different tissues of tubers from field to storage, which might contribute to overall storage qualities. However, how storage temperature impacts overall potato tuber microbiome and how changes in microbiome influence tuber dormancy are largely unknown. Therefore, the primary objective of this study was to investigate the impact of different storage temperatures on tuber microbiome and monitor the dormancy progression and sprout growth during long-term storage. Certified seed tubers of Russet Burbank were cured after harvest following industry practices. Then, one subset of tubers was stored at constant 8°C, and a second subset was stored at constant 21°C. Three types of tuber tissues (primary meristem, secondary meristem, and tuber flesh) were collected after 4, 8, 12, 17, and 24 weeks of storage for microbiome profiling and sugar and protein analysis. Additionally, a third subset was generated by moving tubers from 8°C to 21°C three days before sampling time of 8, 12, and 17 weeks. Tuber dormancy progression was monitored using additional subsets for each storage condition. As expected, the subset of tubers stored at 8°C had delayed sprouting compare to 21°C, and rapid sprout growth was observed when tubers were moved from 8°C to 21°C. Increase in reducing sugar content was observed in meristem tissues, while it decreased in tuber flesh with progression of storage duration. Interestingly, higher protein content was determined in secondary meristem tissues compare to primary meristems and tuber flesh. Overall, greater bacterial and fungal diversity and abundance were observed in meristem tissues when compared to tuber flesh. Additionally, storage temperatures, storage time, and tuber tissue types significantly impacted tuber microbial profile. In tuber tissues, Ascomycota and Basidiomycota were predominant fungal phyla, while Actinobacteria, Proteobacteria, and Cyanobacteria were the predominant bacterial phyla. Our results suggested that storage temperature and storage duration significantly impact both dormancy progression and tuber microbiome and subsequently contribute to postharvest qualities of potato tubers.
The anthocyanin pigments have antioxidant activities and play critical roles in plant and human health. They are abundant in flowers, vegetables, and fruits and are soluble in water, methanol, and nonpolar solvents such as chloroform. Extracting stable pigments with higher concentrations has been the research community's and industries' goal. Spectrophotometric methods can easily measure the total anthocyanin content. Other complex and more expensive methods, such as high-pressure liquid chromatography and ultrasound-assisted methods, are also available to identify and quantify the anthocyanin pigment. Strawberry color affects the appearance, fruit quality after harvest, and consumers' decision-making process. A large group of factors, such as sample type, temperature, pH, solvent type, and the ratio of its components, affect strawberry anthocyanin yield. We studied the effect of some of these variables on the anthocyanin yield, profile, and color of strawberries. Extraction solvents significantly changed the anthocyanin yield. The results suggest that acidified chloroform-methanol extracted the highest anthocyanin content compared to water-based solvents. Methanol-water-based solvents also performed better than water alone. Processing time (incubation time) was lowest in the pH differential method; however, the haze produced in this method may interfere with the spectrophotometry. Chloroform-methanol solvent with higher pH extracted pelargonidin as the main anthocyanin, and methanol and water-based solvents extracted delphinidin in UHPLC. Chloroform extracts reduced the redness and increased the extracts' brightness mainly due to higher pelargonidin content. Less redness and increased brightness indicated some level of color degradation of the extracts after storage for 48h at 4 °C.
Many fungal endophytes have the ability to promote plant growth, as well as increase the host plant’s tolerance to abiotic and biotic stresses. Most endophytic species of Trichoderma are well known biocontrol agents and have been used to control diseases caused by phytopathogens of the genera Rhizoctonia, Fusarium, and Phytophthora. However, our recent research has isolated a strain of Trichoderma from sweetpotato storage roots purchased from a local farm, which was shown to develop root rot symptoms. Therefore, the objective of this project was to evaluate this isolate, especially for its potentially pathogenic nature. In the laboratory, the ITS region of the isolate was amplified, and gene sequencing placed it to T. atroviride with 99% homology. However, T. atroviride has never been identified as a disease-causing agent for sweetpotato in literature so far. Pathogenicity test was carried out accordingly, by inoculating this isolate onto healthy, symptomless sweetpotato storage roots. Two weeks post-inoculation, the storage roots were cut in half to reveal necrotic lesion development between 1.7 and 2.1cm in diameter based on three replications. The necrotic tissue was sampled and cultured on PDA, and the re-isolated fungal specimen was confirmed to be T. atroviride through gene sequencing. This result demonstrated that under environmental conditions conducive for pathogen development, this strain of T. atroviride is capable of causing root rot disease in sweetpotatoes. This finding is particularly significant as farmers typically store sweetpotatoes for an extended time, sometimes up to a year, which increases the possibilities for disease occurrence. Dual-culture assays are still ongoing to determine if this strain of T. atroviride could be a beneficial endophyte under different storage conditions, especially when other fungal endophytes are co-existing in the same storage root.
