Category: Vegetables

+9.4% Yield Boost in Romaine Lettuce Trial AT A GLANCE</h4 Results Crop Farm Location +9.4% Wet Weight; +4.4% Dry Weight Lactuca sativa L. ‘Coastal Star’ Romaine Lettuce Santa Fe Community College Research Greenhouse Santa Fe, NM, USA DOWNLOAD CASE STUDY PDF ABOUT THE PROJECT Discover the future of agriculture with SFCC student Lydia Steinhoff’s groundbreaking study, guided by Professor Shultz and Manager Casas. Explore the growth of ‘Coastal Star’ romaine lettuce under UbiGro Inner 650 luminescent quantum dot (QD) greenhouse film versus a control film at Santa Fe Community College Research Greenhouse in 2022. Special thanks to UbiQD, Inc. for vital support. Uncover the potential of Controlled Environment Agriculture and advanced greenhouse cover in revolutionizing crop cultivation. Ready to shape the future? Join us on this journey. College Research Greenhouse in 2022. EXPERIMENT UbiGro QD greenhouse films emitting at 650 nm were installed above a 254 ft2 (23.6 m2) nutrient film technique (NFT) system inside the Santa Fe Community College Research Greenhouse (SolaWrap cover, 83% PAR transmission). An identical neighboring NFT area in the greenhouse was chosen to serve as the control group, over which a clear polyethylene film (K50 Clear 6 mil, RKW Klerks) was installed to balance the light intensities and diffusivities between the two areas (see Table 1 describing the haze and transmission of the QD film and the polyethylene control film). A reflective mylar barrier was hung between to the two areas to prevent light mixing between treatment areas. A Watchdog Plant Growth Micro Station with four quantum light sensors was installed to measure daily light integral (DLI) on each side of the experiment using five-minute measurement spacings. Crops were grown with Calcium Nitrate, Magnesium Sulfate, and Potassium Nitrate-rich nutrient salt solutions with targets of EC 1.7 and pH 5.8. In order to better achieve proper light intensity for lettuce, shade curtains were deployed over the crops in both treatments. Table 1. Optical properties of experimental films. Haze and PAR transmission of the QD film and the polyethylene control film. Over an 11-week period spanning July to October 2022, two seven-week crops were grown. Each crop consisted of 72 plants, including 36 plants per experimental group. Seeds were sown in Oasis Rootcubes on an ebb-and-flow seedling table inside the greenhouse. Each pair of plant groups was transplanted into the NFT system, under the QD film and control films, at approximately three weeks after sowing. The harvest times ranged from 45 days after sowing (DAS) to 50 DAS. The first harvest was completed on September 8, 2022, and the final harvest was completed on October 6, 2022. HARVEST DATA Due to labor scheduling, critical activities including sowing and harvesting were conducted ±4 days from the target nominal DAS, so days after treatment (DAT) were kept consistent between experimental repeats. The maturity time for this lettuce cultivar is 57 DAS, according to seed purveryer Johnny’s Seeds; however, this 57-day maturity time can vary with sunlight intensity, seasonality, climate, and other variables, which can be better controlled in a greenhouse. These maturities at harvest represent typical harvest times for a commercial greenhouse grower. Table 2. Average wet weights. Harvested wet weights, and % changes for lettuce harvests across experimental repeats. Positive % change values indicate greater performance under the treatment. Average wet weights for each harvest were compared across both crops, and are shown in Table 2 and in the form of bar plots in Figure 1. Harvest data outside of three standard deviations from the mean were consdired outliers; no data qualified as outliers by this definition, so all data collected were included in the analysis. Plants grown under the QD film exhibited larger wet weights in each experimental repeat. Greater yield differences (i.e., increases) were observed under the QD film treatment when plants overall were larger as in the first experimental repeat where +11% more fresh weight was accumulated under the QD film. The larger growth results represent the most impactful results of this experiment, as a commercial grower would grow out their crop to a marketable wet weight of ~100 to 150 g and would realize the yield benefit in terms of greater revenue (if selling by weight or size) or faster grow cycles (if selling by head count). This yield boost for the mature crop translated to the ability to harvest the same size crop 2-3 days earlier, which would compound to approximately one extra harvest cycle annually. Figure 1. Average wet weight. Average wet weights measured at 28 DAT in each experimental repeat and overall, with 1 standard deviation error bars. In this study, planting density was cut to approximately half-size from previous lettuce experiments in this NFT system to reduce shading by neighboring plants and thereby decrease variance; however, large variances remained, and larger variances were present in the treatment group in both experimental repeats. The persistent variance could have resulted from a number of factors, including the difference in cumulative light integral between experimental repeats. Harvest data from one week earlier indicated a lower magnitude of the treatment effects even one week earlier than these harvest data collected at maturity; more data on a larger scale could further clarify this result. The larger growth results represent the most impactful results of this experiment, as a commercial grower would grow out their crop to a marketable wet weight of ~100 to 150 g and would realize the yield benefit in terms of greater revenue (if selling by weight or size) or faster grow cycles (if selling by head count). This yield boost for the mature crop translated to the ability to harvest the same size crop 2-3 days earlier, which would compound to approximately one extra harvest cycle annually. Table 3. Average dry weights. Harvested dry weights and % changes for lettuce harvests across experimental repeats. Positive % change values indicate greater performance under the treatment. Average dry weights for each harvest were compared across both crops, and are shown in Table 3 and in the form of bar plots in Figure

+17% Yield Boost in Romaine Lettuce Trial AT A GLANCE</h4 Results Crop Farm Location +17 % Wet Weight at maturity; +6.1% average Leaf Length. Lactuca sativa L. ‘Coastal Star’ Romaine Lettuce. Santa Fe Community College Research Greenhouse. *This work was independently performed by SFCC students Jen Lein and Amanda Garcia with advising by Controlled Environment Agriculture professor Charlie Shultz and greenhouse manager Pedro Casas. Film donation and data analysis were provided by UbiQD, Inc. Santa Fe, NM, USA DOWNLOAD CASE STUDY PDF ABOUT THE PROJECT This study monitored the growth and development of ‘Coastal Star’ romaine lettuce crops grown under an orange-red UbiGro luminescent quantum dot (QD) greenhouse film, and identical crops grown under a colorless control film at the Santa Fe Community College Research Greenhouse in 2021. EXPERIMENT UbiGro QD greenhouse films emitting at 600 nm were installed above a 254 ft2 (23.6 m2) nutrient film technique (NFT) system inside the Santa Fe Community College Research Greenhouse (SolaWrap cover, 83% PAR transmission). An identical neighboring NFT area in the greenhouse was chosen to serve as the control group, over which a clear polyethylene film (K50 Clear 6 mil, RKW Klerks) was installed to balance the light intensities and diffusivities between the two areas (see Table 1 describing the haze and transmission of the QD film and the polyethylene control film). A reflective mylar barrier was hung between the two areas to prevent light mixing between treatment areas. A Watchdog Plant Growth Micro Station with four quantum light sensors was installed to measure daily light integral (DLI) on each side of the experiment using five-minute measurement spacings. Crops were grown with Calcium Nitrate, Magnesium Sulfate, and Potassium Nitrate-rich nutrient salt solutions with targets of EC 1.7 and pH 5.8. In order to better achieve proper light intensity for lettuce, shade curtains were deployed over the crops in both treatments until August 26 (covering the first three crops in this experiment), when they were removed. Table 1. Optical properties of the QD film and the polyethylene control film. Every week for 12 weeks starting in July 2021, two groups of 27 plants were seeded in Oasis Rootcubes on an ebb-and-flow seedling table inside the greenhouse. Each pair of plant groups was transplanted into the NFT system, under the QD film and control films, at 21 days after sowing (DAS). In order to explore differences in growth rates over time, each transplant group was split into three subgroups, where each subgroup consisted of 9 plants. Each subgroup was harvested a week apart from the others in order to explore all stages of growth – early to late (mature). The staggered harvest times ranged from 39 DAS to 59 DAS. Separating the staggered harvests into DAS ranges allows a better understanding how development changes over time under the altered QD film spectrum. Amongst 12 crop groups, a total of 35 individual harvests (subgroups) were made during the experiment. The first harvest was completed on August 20, 2021, and the final harvest was completed on November 23, 2021. HARVEST DATA Staggered harvests were grouped into similar DAS ranges, as indicated in Table 2, such that four growth stages were explored: very early growth (39 DAS), early growth (44-46 DAS), mid growth (51-53 DAS), and late growth (56-59 DAS). Due to labor scheduling, the harvests were conducted ±2 days from the target nominal DAS. The maturity time for this lettuce species is 57 DAS according to seed purveryer Johnny Seeds, so these ranges represent harvest times up to a typical harvest time for a commercial grower; however, this 57-day maturity time can vary with sunlight intensity, seasonality, climate and other variables. *Table 2. Harvested wet weights, % difference and p-value for lettuce harvests from four growth stages. * indicates that the difference is not significant beyond a 95% confidence threshold. Average wet weights for each harvest were compared across all crops, and are shown in Table 2 and in the form of growth curves in Figure 1 and bar plots in Figure 2. Harvest results outside of one standard deviation from the mean were excluded as outliers. Plants grown under the QD film exhibited larger wet weights for all DAS ranges. The largest yield increases were for the very early and early harvest windows, +20% and +28%, respectively. The mid stage showed a small yield increase of +4%. The late harvest showed a +17% yield improvement which represents the total growth during the full period. This late stage growth represents the most impactful result of this experiment, as a commercial grower would grow out their crop to full maturity and realize the yield benefit in terms of greater revenue (if selling by weight) or faster grow cycles (if selling by head count). This yield boost for the mature crop translated to the ability to harvest the same size crop 2-3 days earlier. *Figure 1. Top: Growth curves for lettuce grown under the QD film and under the control film, with 1 standard deviation error bars. Bottom: Average wet weight yield increases for different DAS ranges for staggered harvests. *Figure 2. Average wet weight yields for different DAS ranges for staggered harvests, with 1 standard deviation error bars. Plots marked with the same letter are not statistically significant beyond a 95% confidence threshold. Plots marked with different letters are statistically significant beyond a 95% confidence threshold. The harvest results were analyzed with a t-Test (two-sample assuming unequal variances) and corresponding p-values are show in Table 2. This analysis showed that the yield improvements observed for very early and early harvests were statistically significant beyond a 95% confidence threshold, meaning that the difference was highly likely to be a result of an existent relationship. For mid and late growth, yield enhacments were observed but the differences were not statistically significant. For mid growth, the difference was too small (+4%) to be significant beyond the variance in the dataset. For late growth, the enhancement reappears (+17%), but so was the variance in the dataset, leading to a p-value