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Effect of Light Intensity and Temperature on Yield of Salad Crops for Space Exploration
Abstract
The candidate crops that have been considered by NASA for providing moderate quantities of supplemental food for crew's consumption during near term or long duration missions include minimally processed "salad" species. Lettuce (cv. Flandria), radish (cv. Cherry Bomb II) and green onion (cv. Kinka) plants were grown under cool-white fluorescent (CWF) lamps with light intensities of 8.6, 17.2, or 25.8 mol m-2 d-1, at air temperatures of 25 and 28 °C, 50% relative humidity, and 1200 μmol mol-1 CO2. Following 35 days growth, final edible mass yields were recorded. All three species grown at 25°C showed an increase in edible fresh mass and growth rates as light intensity increased. When grown at 28°C however, the edible fresh mass and crop growth rate of radish, lettuce and onion was significantly reduced at all light intensities when compared to yields at 25°C. Overall, results indicated that all three crops were sensitive to changes in light intensity and temperature. Therefore understanding the interactions of these environmental factors on crop performance is crucial to the success of future missions which incorporate plant-based life support technologies.
... In both years, plant yields under shade were lower than in unshaded control treatments, except for onion in 2013. At 50% shade, our results agree with studies on vegetable crops that reported better performances when uncovered, or with not more than 30% shade (Caiyong et al., 2008;Richards et al., 2005). Average daily radiation, registered by our weather station in Efoetse, Table 4. F-probabilities of effects of seed origin, water quality, and interactions on seedling emergence rates and indices of carrot and onion seed lots sown in sand substrate under shaded field conditions (n = 4) in a field experiment in SW-Madagascar decreased gradually during the dry season (from 250 W·m −2 in March to 170 W·m −2 in July). ...
Agricultural production on the Mahafaly Plateau in SW-Madagascar has traditionally been based on subsistence rain-fed agriculture, with yields declining as a result of low soil fertility, recurrent droughts, and erratic rainfall. Market-oriented vegetable production in this area may help households improve their nutrition and diversify their income. In field trials between the 2013 and 2016 dry cropping seasons, the feasibility of carrot ( Daucus carota L.) and onion ( Allium cepa L.) production was assessed by testing effects of manure and charcoal amendments, shading, and seed quality on yields. Due to damage caused by cyclones and strong winds, only data from 2013 and 2016 are reported in this paper. Additionally to the field experiments, effects of salinity on seed germination were also examined under laboratory conditions and in the field. Carrot dry matter (DM) yields were 0.24 to 2.76 t·ha ⁻¹ while those of onion were 0.15 to 0.99 t·ha ⁻¹ DM. While the combination of manure and charcoal application had only minor effects on crop growth, manure alone increased carrot yield by 26% across years. After one cropping season, manure application reduced soil pH from 9.0 to 8.6 and increased soil C org from 0.87 to 1.76%, N from 0.08 to 0.14%, and P from 10.6 to 15.1 mg·kg ⁻¹ . Shading reduced carrot yields from 0.87 to 0.58 t·ha ⁻¹ DM in 2013 and from 1.87 to 0.85 t·ha ⁻¹ DM in 2016, but increased onion yield in 2013 from 0.24 to 0.62 t·ha ⁻¹ DM. Carrot seed procured locally performed better in the field than seed imported from the capital which translated into differences in seedling emergence. Saline irrigation water (electrical conductivity = 7.03 mS·cm ⁻¹ ) reduced seedling emergence rate of carrot from 73 to 20% and for onion from 44 to 28% and unprimed seeds performed better than primed ones. Using shading during the dry season is not advisable for carrot and onion production, but improving seed quality and targeted use of soil amendments (time of manure application, manure quality) may enhance vegetable yields.
Growth Temperatures And Lighting Intensity Are Key Factors That Directly Impact The Design, Engineering, And Horticultural Practices Of Sustainable Life-Support Systems For Future Long-Term Space Missions. The Effects Of Exposure Of Lettuce (Cv. Flandria), Radish (Cv. Cherry Bomb Ii). And Green Onion (Cv. Kinka) Plants To Controlled Environment Temperatures (Constant Day/Night Temperature Of 22, 25, Or 28 °C) And Lighting Intensities (8.6, 17.2, Or 25.8 Mol M-2 D-1 Photosynthetic Photon Flux [Ppf]) At Elevated Co2 (1200 μMol Mol-1) Was Investigated To Ascertain Overall Yield Responses. Following 35 Days Growth, The Yields Of Lettuce Indicated That Increasing The Growing Temperature From 22 To 28°C Slightly Increased The Edible Fresh Mass Of Individual Plants. However, Even Though Lettuce Plants Grown Under High Ppf Had The Highest Fresh Mass, The Resultant Increase In The Incidence And Severity Of Tipburn Reduced The Overall Quality Of The Lettuce Head. As A Result Of The Tipburn, The Quantum Efficiency (G Fm Mol-1 Ppf) Of Lettuce Plants Grown At The Highest Ppf Was Also Significantly Reduced. In Contrast, Radish Was More Sensitive To Higher Growth Temperatures, With Reductions In Fresh Mass Of The Storage Root As Growth Temperature Increased, Especially At Higher Daily Ppfs. As A Result, High Ppf And High Growing Temperatures Translated Into Lower Storage-Root Quality, As Surface Cracking And Hollow Heart Of Storage Roots Was Severe For Radish. Quantum Efficiencies Were Also Lowest At The Higher Growth Temperature. Yields Of Onion Were Significantly Enhanced By Increasing Growth Temperature And, More Importantly, Light Intensity. Unlike Lettuce And Radish, There Were No Indications Of Any Physical Deformities Of Onion At Any Ppf/Temperature Treatment.
Two studies were conducted in which 'Waldmann's Green' lettuce (Lactuca sativa L.) was grown hydroponically from seed to harvest in a large (20-m2), atmospherically closed growth chamber for the National Aeronautics and Space Administration's controlled ecological life support system (CELSS) program. The first study used metal-halide (MH) lamps [280 micromoles m-2 s-1 photosynthetic photon flux (PPF)], whereas the second used high-pressure sodium (HPS) lamps (293 micromoles m-2 s-1). Both studies used a 16-hour photoperiod, a constant air temperature (22 to 23C), and 1000 micromoles mol-1 CO2 during the light period. In each study, canopy photosynthesis and evapotranspiration (ET) rates were highly correlated to canopy cover, with absolute rates peaking at harvest (28 days after planting ) at 17 micromoles CO2/m2 per sec and 4 liters m-2 day-1, respectively. When normalized for actual canopy cover, photosynthesis and ET rates per unit canopy area decreased with age (between 15 and 28 days after planting). Canopy cover increased earlier during the study with HPS lamps, and final shoot yields averaged 183 g fresh mass (FM)/plant 8.8 g dry mass (DM)/plant. Shoot yields in the first study with MH lamps averaged 129 g FM/plant and 6.8 g DM/plant. Analysis of leaf tissue showed that ash levels from both studies averaged 22% and K levels ranged from 15% to 17% of tissue DM. Results suggest that lettuce should be easily adaptable to a CELSS with moderate lighting and that plant spacing or transplant schemes are needed to maximize canopy light interception and sustained efficient CO2 removal and water production.
The Spacelab-Mir-1 (SLM-1) mission is the first docking of the Space Shuttle Atlantis (STS-71) with the Orbital Station Mir in June 1995. The SLM-1 "Greenhouse-2" experiment will utilize the Russian-Bulgarian-developed plant growth unit (Svet). "Greenhouse-2" will include two plantings (1) designed to test the capability of Svet to grow a crop of Superdwarf wheat from seed to seed, and (2) to provide green plant material for post-flight analysis. Protocols, procedures, and equipment for the experiment have been developed by the US-Russian science team. "Greenhouse-2" will also provide the first orbital test of a new Svet Instrumentation System (SIS) developed by Utah State University to provide near real time data on plant environmental parameters and gas-exchange rates. SIS supplements the Svet control and monitoring system with additional sensors for substrate moisture, air temperature, IR leaf temperature, light, oxygen, pressure, humidity, and carbon-dioxide. SIS provides the capability to monitor canopy transpiration and net assimilation of the plants growing in each vegetation unit (root zone) by enclosing the canopy in separate, retractable, ventilated leaf chambers. Six times during the seed-to-seed experiment, plant samples will be collected, leaf area measured, and plant parts fixed and/or dried for ground analysis. A second planting initiated 30 days before the arrival of a U.S. Shuttle [originally planned to be STS-71] is designed to provide green material at the vegetative development stage for ground analysis. [As this paper is being edited, the experiment has been delayed until after the arrival of STS-71.]
ABSTRACT Knight, S. L. and Mitchell, C. A. 1988. Effects of CO2 and photosynthetic photon flux on yield, gas exchange and growth rate of Lactuca sativa L. ‘Waldmann’s Green'.—J. exp. Bot. 39: 317–328.
Enrichment of CO2 to 46 mmol m−3 (1 000 mm3 dm−3) at a moderate photosynthetic photon flux (PPF) of 450 μmol m−2 s−1 stimulated fresh and dry weight gain of lettuce leaves 39% to 75% relative to plants at 16 mmol m−3 CO2 (350 mm3 dm−3). Relative growth rate (RGR) was stimulated only during the first several days of exponential growth. Elevating CO2 above 46 mmol m−3 at moderate PPF had no further benefit. However, high PPF of 880–900 μmol m−2 s−1 gave further, substantial increases in growth, RGR, net assimilation rate (NAR) and photosynthetic rate (Pn), but a decrease
in leaf area ratio (LAR), at 46 or 69 mmol m−3 (1000 or 1500 mm3 dm−3) CO2, the differences being greater at the higher CO2 level. Enrichment of CO2 to a supraoptimal level of 92 mmol m−3 (2000 mm3 dm−3) at high PPF increased leaf area and LAR, decreased specific leaf weight, NAR and Pn and had no effect on leaf, stem and
root dry weight or RGR relative to plants grown at 69 mmol m−3 CO2 after 8 d of treatment. The results of the study indicate that leaf lettuce growth is most responsive to a combination of
high PPF and CO2 enrichment to 69 mmol m−3 for several days at the onset of exponential growth, after which optimizing resources might be conserved.
Given the constraints on physical space, energy supply, and labor availability, crop production efficiency must be maximized if a sustainable supply of food is to be produced on lunar and planetary space stations. In the modules designed for plant growth, crop production efficiency or the harvest index (HI, fruit weight/total plant weight) must be calculated on a cubic volume basis because the physical space allocated for plant growth will be limited in three dimensions. In order to increase HI, tomato plant architecture could be modified to reduce the extent of internode elongation and side shoot production. To test this hypothesis, plants were treated with the growth retardant paclobutrazol (PAC) and topped after the second flower cluster. PAC reduced plant height at harvest by 29% and total vegetative shoot growth by 28%. Fruit yield was reduced by 12%, although the greater reduction in vegetative growth by PAC resulted in an increased HI from 0.53 to 0.58 when calculated on a gram fresh weight basis. Yield/m3 of growing space utilized increased 23% with PAC treatment. The leaf axils of tomato plants grown in a single truss system were treated with the chemical pruning agent Off-Shoot-O (OSO), a mixture of short chain fatty acid methyl esters. OSO significantly reduced the number of side shoots/plant, increased fruit yield by 12%, and increased the HI from 0.71 to 0.77 compared to hand-pruned plants. Untreated plants required three manual pruning operations during the production period; plants treated with OSO were pruned only once at the time of application for a significant savings in labor. The results of both experiments clearly demonstrate that HI of tomato can be increased by reducing internode elongation and preventing side shoot development.