ASHS 2024 Conference

High tunnel soil health is crucial for successful and sustainable crop production within protected environments. Soil microbial activity is highly temperature-dependent, and soils that are slightly warmer will foster increased metabolic rates within soil communities enhancing microbial diversity and enzymatic activity, promoting nutrient availability. However, little is understood about the potential for microbial activity during colder seasons in norther latitudes when high tunnels are taken out of production and soils are left fallow. Temperature variation in high tunnels could also create variation in microbial community activity, creating spatial nutrient variation with impacts on production the following season. To analyze soil temperature fluxes, we buried an array of 27 soil sensors four inches deep within the soil in a newly built, 30-foot-wideby 96-foot-long tunnel located in Brookings, South Dakota. The high tunnel was oriented east to west and soil was bare. Soil temperatures were recorded at 30-minute intervals from December 22 to March 15, (2023 – 2024). Air temperature and light (lux) data was also collected inside of the high tunnel as well as external weather data from a nearby (>1km) Mesonet weather station. We used multiple linear regression to model the relationship between average internal soil temperature and internal light and temperature data. We also compared sensor location (latitude, longitude, and Euclidean distance from the center of the high tunnel) on soil temperature within the high tunnel using an ANOVA and multiple linear regression to examine how sensor location was related to soil temperature. Our top model of internal soil temperature showed light, internal temperature, and the interaction between light and internal temperature explained a large amount of high tunnel soil temperature variation (R2 = 0.87, p < 0.0001). There was also significant variation in soil temperature throughout the high tunnel, with the daily mean difference of 3.12 degrees Celsius (p < 0.0001) observed between our sensor at the center of the high tunnel and our sensor near the northwest corner of the high tunnel. Our top model showed that latitude, the quadratic of longitude, and the Euclidean distance from the center of the high tunnel explained a moderate amount of high tunnel soil temperature variation (R2 = 0.44, p < 0.0001). This analysis demonstrates a need to further investigate how microbial communities react to temperature variation within high tunnels when they are not in production.

The study was conducted at two farmers’ fields in Bangladesh viz., Shibpur, Narshingdi (24.050º N Latitude and 90.718º E) and Chowara Bazar, Cumilla (23.408º N Latitude and 91.244º E), during Oct 2021 to Sep 2022. In this study, we evaluated the effects of five types of vegetables, viz., tomato, sweet pepper, cucumber, netted melon, and okra, under a protected polynet house. The cultivation of vegetables in protected conditions using transparent UV poly net houses played a better role in improving quality, advancing maturity, fruit size, and yield and reducing pest and disease infestation. Protected polynet houses allow better utilization of sunlight due to the manipulation of the spectra of radiation reaching the crops, thus promoting physiological responses in plant and fruit development, including leaf area index, chlorophyll and carotenoid content, tissue structure, fruit ripening, and physiological disorders. Under this evaluation, cultivation under UV Poly nethouse was found better in the Cumilla area compared to Narshingdi. There might be differences in management operations by different growers. For all crops, viz., tomato, sweet pepper, cucumber, netted melon, and okra, the production of the Cumilla area was very significant and higher. The Benefit-cost ratio was also higher [Tomato (2.05), sweet pepper (2.53), cucumber (1.42), netted melon (2.63) and okra (1.35) in Cumilla compared to Narshingdi [Tomato (1.75), sweet pepper (1.92), cucumber (1.21), netted melon (2.20), okra (1.22)], the lower BCR is due to the 1st year calculation. So, with UV poly nethouse technology, high value thermos-sensitive vegetables can be commercially grown year-round successfully to produce a safe and quality product, while higher fruit yield/unit area will be achieved in a protected nethouse than in a field.

Assessing the impact of cultivar on garlic growth and yield ensures satisfactory productivity and better management of genetic resources for growers in North Dakota. A field experiment was conducted at the NDSU Horticulture Research Farm, located near Absaraka, ND to evaluate the effect of cultivar on the growth and yield of garlic. Twenty-nine garlic cultivars were arranged in a randomized complete block design (RCBD) with 4 replications. The leaf number, bulb diameter, bulb weight, scape weight and length were recorded throughout the growing season. The results showed significant differences between cultivars for all the variables evaluated. The highest bulb diameter(60.5 cm) was recorded in ‘German White’, while the lowest diameter (38.9 cm) was recorded in ‘German Red’. The highest bulb weight(73.4 g) was with ‘German White’ while ‘Italian Loiacono’ resulted in the lowest bulb weight(21.2 g).The number of leaves was recorded at 30, 45, 60, and 80 days after sprouting (DAS). The average number of leaves was similar for all cultivars until 60 DAS when ‘Ukrainian Red’ had the highest number of leaves (11) and ‘German Red’ had the fewest leaves (7). ‘Dakota White’ produced the longest scapes while ‘Italian Loiacono’ and ‘White Spring’ did not produce any scapes. ‘German White’ recorded the heaviest scapes (13.8 g). In conclusion garlic cultivar affected the growth and yield when grown under North Dakota environmental conditions. ‘German White’ appeared to be the most adapted to North Dakota environmental conditions while ‘Italian Loiacono’ and ‘German Red’ were the least adapted.

The production of fast-growing vegetable crops (such as specialty type lettuces) in slightly modified environments using high tunnels are widely underutilized. These structures can be used in the Midwest for winter production of a wide variety of leafy greens, including specialty lettuce. These crops have potential to garner a market premium due to high demand when there are not many other local vegetables for sale. Therefore, a study was conducted in 2020 and 2021 to evaluate four butterhead lettuce varieties (‘Nancy’, ‘Rhapsody’, ‘Red Cross’ and ‘Skyphos’) to determine optimal density for maximum revenue generation on a 3 ft wide raised bed. Three rows per bed and at 9 in. between plants worked best for ‘Nancy’, ‘Rhapsody’ and ‘Skyphos’, while for ‘Red Cross’ (a small more erect growing variety), 4 rows per bed at 12-inch spacing between plants maximized productivity. Head diameters were also highest for ‘Nancy’, ‘Rhapsody’ and ‘Skyphos’ using the 3 row, 12 inch between plant spacings. Overall gross revenues obtained per high tunnel, depending on plant density and variety, ranged from $3,600 to $6,000 (sold per piece at $4 each) or $1,753 to $7,279 (sold by weight at $6/ lb) for a typical 26’ (wide) x 48’ (long) high tunnel. Although most revenues increased when sold by weight, some increased by 50% (e.g., Rhapsody when grown at 3 row and 12 in spacings). Additionally, ‘Nancy’ (green-leaf type) and ‘Skyphos’ (red-leaf type) tended to be of higher quality than the other varieties evaluated and would be the better varieties to grow in a lower Midwest high tunnel environment. Both ‘Nancy’ and ‘Skyphos’ had optimal gross revenues when grown at 3 rows per bed with 9 in-row spacings when sold by piece ($4,500) or weight ($6,979 and $6,426, respectively). Thus, it is important for growers to understand the importance of butterhead variety selection and plant density in a high tunnel, as well as the method sold to maximizes revenues.

Soilless growing systems (SGS) integrated into controlled environment agriculture (CEA) offer a viable solution for increasing food production in densely populated areas with limited land, water, and nutritional security. The design, components, inputs, and nutrient management of alternative SGS along with the plant genotype, directly impact crop yield, nutritional value, and resource use efficiency. As the adoption of CEA and SGS continues to expand, there is a growing need to compare and evaluate the performance of alternative SGS in terms of resource use efficiency, crop yield, and impact on crop nutritional quality. To this purpose, a study was undertaken to assess the performance of five alternative SGSs including Deep Water Culture (DWC), Nutrient Film Techniques (NFT), Ebb and Flow, Drip irrigation, and the Kratky system concerning yield, nutritional quality, and resource use efficiency, using green and red stripe amaranth cultivar as test crops. As expected, the Kratky system had the lowest dissolved oxygen levels in the nutrient solution compared to other SGSs. Among the growing systems, DWC and NFT exhibited higher fresh and dry biomass production compared to drip irrigation, ebb and flow, and the Kratky system. There was no distinct difference in leaf fresh and dry weight between cultivars, but green amaranth displayed higher stem fresh and dry weight than red stripe amaranth. Dry matter content remained unaffected by the SGS, while red stripe amaranth exhibited higher dry matter content compared to green amaranth. The Kratky and DWC systems utilized 34.2% and 25.6% less nutrient solution, respectively, compared to the ebb and flow system, which had the highest nutrient solution consumption compared to other methods. DWC had the highest water use efficiency (WUE, dry biomass produced per liter of water used). Nitrate content in amaranth leaves was higher when grown in NFT compared to drip irrigation, DWC, and ebb and flow, but was similar to Kratky. The red stripe cultivar displayed higher nitrate content than the green one. Regarding bioactive compounds, green amaranth exhibited higher total antioxidants and flavonoids, whereas DWC and NFT led to lower total phenols and flavonoids compared to the Kratky, ebb and flow, and drip irrigation systems. In conclusion, the DWC and NFT systems maximized yield, with DWC having higher water use efficiency, while Kratky, ebb and flow, and drip irrigation system resulted in higher nutritional quality of the amaranth grown as a summer leafy vegetable.

Microgreens, harvested within 7-21 days, are nutritionally dense and are rich sources of antioxidants, minerals, and vitamins required for body and mental health. However, poor germination, leading to poor establishment, seed-borne diseases, and high water consumption often limit microgreen production. Low-temperature plasma (LTP) is a partially ionized gas with unbound electrons, neutral particles, ions, reactive nitrogen and oxygen species, and ultraviolet light. LTP is emerging as a viable non-chemical tool for seed priming, improving crop productivity, and disinfecting seeds and foods, among other uses. Thus, LTP may address the concerns limiting microgreen production. The effects of LTP on imbibition, germination rate of germination, seedling biomass, and drought tolerance were assessed primarily using mustard greens and ten microgreen crops with or without Ar or He Plasma at different exposure times. The drought tolerance experiment induced drought stress using PEG 6000 at 0 (Control), 5, 10, and 15% at w/v. The treated or untreated seeds were placed in Petri dishes and later transplanted into pots containing soilless potting mix. The days to first seed germination, germination rate, seedling height, root length, seedling and root biomass were recorded. Ar and He LTP hastened seed germination and increased the total seed germination percentage over Control. Ar and He LTP enhanced seed germination by 12.7% and 5.6%, respectively. He LTP increased seedling length by 40% and doubled the seedling fresh biomass over the Control. Ar LTP at 30 s and He at 90 s increased the root length by nearly 17% and 71% over that of Control, respectively. In another study, seeds directly exposed to either LTP or plasma-activated water (PAW) showed a 36% increase in seed germination compared to Control. Plant height significantly increased by 98% in Ar30 seconds and 50% (all other treatments) compared to Control. Exposure of seeds directly to He and Ar plasma also increased seedling biomass. He30s, He 60s, He 90s, and Ar 90s significantly enhanced biomass by 250%, 200%, 215%, and 120%, respectively compared to Control. In another study, seeds of ten microgreen crops exposed to Ar LTP for 30 seconds or He LTP for 90 seconds significantly boosted imbibition and germination rates compared to untreated seeds within 24 hours of treatment. The study showed that Ar or He LTP could improve the drought tolerance of microgreens by shortening the crop growing cycle and increasing root length without compromising seedling biomass.

Radicchio (Cichorium intybus var. latifolium) is grown widely throughout Europe, especially northern Italy. This crop features several groups that differ in color, shape, and culinary use, and there is considerable phenotypic variation among and within groups and cultivars. The New England growing climate is very different from that of major production regions in Europe and the pacific northwestern U.S. The availability of varieties to commercial growers in the U.S. has expanded greatly, but there remains a need for regionally relevant information about performance of these varieties. In Durham, NH, USA we grew 30 (2022) and 34 (2023) cultivars of radicchio belonging to seven main groups (Chioggia, Castelfranco, Treviso, Sugarloaf, Verona, Rosa del Veneto, and Lusia). In both years, they were seeded on 20-21 June, and transplanted on 14-15 July. Plants were harvested and weighed as they reached market maturity, or considered unmarketable due to bolting, rot, tipburn, or failure to head. We used standard cultural practices for the region: plants were grown in double rows on 30-inch-wide raised beds covered with white-on-black plastic mulch with drip irrigation. The weather in 2022 and 2023 differed greatly, with 2022 experiencing warm and dry conditions, and 2023 much wetter and cooler. The percentage of heads that became marketable ranged from 0-94% in 2022, and from 10-95% in 2023. Several cultivars had very high percentages of unmarketable heads, due to tipburn, rot, bolting, or failure to head. We also observed cultivar differences in susceptibility to powdery mildew. In both years, the cv. Rubro developed powdery mildew early and developed severe symptoms, several others eventually developed symptoms, and some never did. For traditional round red Chioggia types, several cultivars had very high percentages of marketable heads, and appear to be well adapted to production in the northeast. We identified cultivars within both sugarloaf and Treviso types that were well adapted, with high percentages of marketable heads. The cultivars we evaluated within the Lusia and Rosa del Veneto types were especially interesting from a culinary and attractiveness point of view, but had high percentages of rot (Lusia types) and very long days to maturity required (Rosa del Veneto types).

Comparative analysis of biodegradable mulch use in hill-side strawberry production Plastic film (PF) is widely used in crop production, yet global environmental concerns urge for reduced plastic waste. Biodegradable and bio-based mulches emerge as promising alternatives, potentially crucial for sustainable agriculture. This significance is emphasized by the hypothesis that small farms prioritize sustainability and seek to reduce plastic waste in soil and food systems, especially if these alternatives match or exceed the benefits of plastic mulch. However, there is limited data available on the effectiveness of biodegradable paper (BP) and bio-based film (BB) in small-scale crop production, an area frequently affected by heat and drought stress. A field experiment was conducted on a strawberry field in Redlands, San Bernardino County, California during the seasons of 2022 and 2023, respectively. This study was conducted to identify the most appropriate alternative to plastic mulch in hill-side production systems under the Mediterranean climate as it relates to yield and fruit quality at harvest day. We used four common mulches in small farms in California, polyethylene mulch (PE), landscape paper mulch (PA), Coconut liner mulch (CL), Biodegradable plastic mulch (MB), and bare soil (control) with the most popular ever-bearing variety, ‘Albion’. To investigate the suitability and efficacy of his mulches, we recorded the soil properties (temperature, moisture, and pH) daily, fruit yield (fruit weight and fruits/plant) biweekly, and fruit quality (Soluble solid and color) at harvest considering farm stand or U-pick sale service. Our results indicate that the highest total yield in terms of total fruit weight and number of fruits per plant grows under MB, CL, and PF mulch respectively. No notable differences were observed among treatments in fruit quality parameters such as soluble solids and color. The soil under the coconut coir liner had the highest moisture content, compared to PE, BDM, and bare ground treatments. No significant difference was found among the treatments in weed control. By the end of the cropping period, all treatments adequately covered the soil surface. However, in the buried part of the mulches, the PA mulch exhibited considerable degradation before the end of the season, while the MB showed faster signs of biodegradation. Based on crop productivity and the different mulch efficacy observed in our study, this production system with CL and MB is a good alternative to compare to PE and PA mulches for ever-bearing hillside strawberry production in the Mediterranean climate.