Nghiên cứu ứng dụng kỹ thuật chiếu sáng LED (light emitting diodes) sản xuất rau ăn lá trong nhà tt tiếng anh

MINISTRY OF EDUCATION AND TRAINING CAN THO UNIVERSITY SUMMARY MAJOR: CROP SCIENCE Code: 62 62 01 10 PHAN NGOC NHI STUDY OF LED (Light-Emitting Diodes) LIGHTING TECHNOLOGY APPLICATION TO PRODUCE LEAFY VEGETABLES INDOOR Can Tho, 2020 WORRK DONE IN CAN THO UNIVERSITY Instructor 1: Assoc Prof Dr Tran Thi Ba Thesis seminar at: Dortoral Dissertation Defe, Can Tho University Time: Date: Reviewer 1: Reviewer 2: Confirmation of Chairman Further information of the dissertation could be found at: LIST OF PUBLISHING Phan Ngoc Nhi, Nguyen Thi Kieu Khuyen, Tran Thanh Hau, Vo Thi Bich Thuy and Tran Thi Ba, 2018 Effects of LED light spectrum on growth and yield of hydroponic lettuce Science and Technology Journal of Agriculture & Rural Development Ministry of Agriculture and Rural Development, Viet Nam (ISSN 1859-4581), Special issue 8/2018: 199-205 Phan Ngoc Nhi, Tran Thi Ba, Vo Thi Bich Thuy, Nguyen Binh Khang, Bui Thi Cam Thu and Ho Thi Cam Nhung, 2019 Effects of LED light intensities and photoperiod regimes on growth and yield of baby golden frills mustard greens (Brassica juncea L.) Journal of Vietnam Agricultural Science and Technology (ISSN 1859-1558), (2019): 54-59 Phan Ngoc Nhi, Tran Thi Ba, Vo Thi Bich Thuy, Mai Phuc Thanh, Nguyen Phuong Uyen and Nguyen Thi Anh Thu, 2019 Effects of photoperiod regimes supplemental LED lighting on growth and yield of lettuce (Lactuca sativa L.) under multilayer hydroponic cultivation in greenhouse Journal of Vietnam Agricultural Science and Technology (ISSN 1859-1558), (2019): 43-48 Chapter 1: INTRODUCTION 1.1 The urgency of the topic Since 2007, more than 50% of the world's population has lived in urbaning areas and it was estimated that by 2050, this number will rate more than 70% Therefore, more and more people were starting to tend about urban agricultural production (Despommier, 2010) Urban agriculture has two basic benefits that help people in the city to conduct farming as a hobby, an entertaining activity in their daily and create safe food sources for families as well or more which provided to nearby residents (Kozai, 2016) Facing these facts, many people in the city have taken in advanced the terrace or balcony to grow vegetables However, a small area of planting and lack of sunlight has caused many difficulties for growers LEDs are considered as an optimal artificial light source in replacing sunlight for photosynthetic (Shimizu et al., 2011) LED lamps have many advantages such as low power consumption, small size, long lifespan and lower releasing heat than fluorescent lamps and high-pressure lamps (Gupta and Jatothu, 2013, Tewolde et al., 2016) More importantly, the light-emitting diode technology (LED) is abled to produce the appropriate blue and red monochromatic wavelengths for maximum absorption of chlorophyll a and chlorophyll b in plant photosynthesis (Shimokawa et al., 2014) In Vietnam, the research and application of artificial LED lighting in agricultural production are progressively focused However, there have not been many LED studies that applied on vegetables, especially leafy vegetables Therefore, it is extremely necessary to conduct this study nowadays 1.2 Research objectives - Determine the suitable spectrum, intensity and photoperiod of LEDs light for growth, yield of baby radish greens, mustard greens and lettuce in dark room - Determine the suitable supplemental LED lighting time for growth and productivity of baby radish greens, mustard greens and mature lettuce under multitiers growing shelf in greenhouse condition 1.3 New contributions of the thesis - The thesis had identified: + LED had 80% red: 20% blue (spectrum) was approriate for growth, yield of baby radish greens, mustard greesn and mature lettuce + When used 80% red: 20% blue LED with intensity of 107 μmol.m-2.s-1 and lighting of 20 hours/day, the growth and yield of baby radish greens, mustard greens and mature lettuce were affectively better than other treatments + With multi-tiers growing shelf in greenhouse, baby radish greens, mustard greesn and mature lettuce were added 80% red: 20% blue LED with intensity of 107 μmol.m-2.s-1 in 16 hours/day so that gave the best efficiency - The thesis also showed the outstanding advantages of applying LED light in multi-tiers growing shelf of vegetable production compared to traditional way It was obviously a premise to build up and develop models of LED lamps for vegetable growing in commercial production 1.4 The scientific and practical significance of the thesis - The thesis has contributed the results of basic research on LED light application in farming The scientific basis diversity for future was opened in order to approach the trendy indoor vegetable farming development in advanced agricultural countries - This result can be also incorporated the curriculum and reference materials for further studies on the effect of artificial light for some leafy vegetables - Demanding self-production for some leafy vegetables in urban regions and big cities where are lack of farming space and natural light condition - Contributing an important part in building up the production process for baby greens and mature lettuce under multi-tiers growing shelf to increase vegetable production per unit area - It is a necessary foundation for appling LED in multi-tiers growing shelf vegetable production towards commercial production Chapter LITERATURE REVIEW 2.1.1 Overview of indoor plants production The term "plant factory" is used primarily in Asia, to describe an agricultural production base that operates as a typical industrial production facility These facilities are carefully designed, full of areas corresponding to each stage of plant development Internal environmental conditions in production facilities such as temperature, humidity, light, CO2 concentration and standards of nutrient solutions are always controlled according to requirements Facilities are also equipped with sensor systems that control the process of automating certain stages in the factory (Ting et al., 2016) Fluorescent lamps, high-pressure sodium lamps and LEDs are often used as single lighting sources or mixed lighting sources for crop plants (Zhang et al., 2015) In recent years, LED lamps have been the best choice in existing artificial light sources LEDs are able to reduce the cost of power consumption by converting energy efficiently to suitable light wavelengths for plants, while reducing cooling costs for manufacturing plants by the amount of heat emission is lower than other artificial light sources Besides, compact LED design is suitable for installation according to multi-stages plant design However, the high initial investment cost is currently a major obstacle to the development of LED applications in agricultural production (Ting et al., 2016) 2.2.2 Effect of light on plant morphogenesis According to Higuchi and Hisamatsu (2016), light was not only used for plant photosynthesis, but also a signal that regulates growth and development throughout their life cycle When the quality, the intensity and the time of lighting changes, it will lead to changes in the morphology of plants It can be seen through by the changing in the structure and shape of plants such as seed germination, flower initiation, leaf size expansion, avoiding neighboring plants, extending the body and synthesizing pigments Light signals are received by photoreceptors, affecting the circadian rhythms and directly activating the light response Different wavelengths of light influence each stage of plant growth The photosynthesis system reacted most clearly to red light (wavelength 600-680 nm) and blue light (wavelength 380- 480 nm) (Roberto, 2003) Therefore, when studying the effect of LED wavelengths on crop growth and productivity, most authors used red and blue light wavelengths 2.2.3.1 Blue light Blue light had a wavelength of 400-500 nm, capable of inhibiting the stem elongation of many crops (Cosgrove, 1981) The combination with red light was essential for plants to be not excessively prolonged (Randall and Lopez, 2014) Blue light with or without red light can affect the density and aperture of stomata However, when adding a certain amount of blue light to red light, the aperture of the stomata increased significantly compared to the monochromatic red light The increase in stomata opening increases CO2 uptake leading to increased photosynthetic activity (Kinoshita et al., 2001) The requirement for blue light is necessary for the normal development of plants that vary by species The plant's response to blue light was first introduced by Wheeler et al., (1991), at the same time proved a link of the length of soy stalks with a blue light content In addition, with a blue light intensity of about 30 μmol.m-2.s-1, it prevents stem growth and elongates slang Similar results were found by Yorio et al (1998), on wheat, potatoes, soybeans, lettuce and cabbage objects to ensure normal growth and development, the minimum blue light intensity of 30 μmol.m-2.s1 was required The 450 nm light spectrum allows cryptochrome and phototropin to react in plants Cryptochrome changes the circadian rhythm (changing from the respiratory cycle to the photosynthetic cycle) The protein phototropin stimulates plants to open stomata, bending towards light to help develop stems and form chlorophyll Blue light wavelength also stimulates plant growth through strong root formation and high intensity photosynthesis This spectrum of light is used in the period of seedling, sapling and growth If you want the plant to stop growing, this wavelength must be reduced or eliminated (Cosgrove, 1981) 2.2.3.2 Red light Red light has a wavelength of about 600-700 nm One of the most common roles of red light is to participate in the vital physiological activity of photosynthesis Specifically, the red light of the LED is at a wavelength of 660 nm, very close to the absorption peak of chlorophyll (Massa et al., 2008) Therefore, the red of LEDs are used to promote photosynthetic performance, resulting in increasing biomass and total yield However, the monochromatic red light is not enough to make the crop achieve optimum yield and quality Under the condition that only monochromatic red light is present, the eucalyptus axis in many dicotyledons extends excessively (Hoenecke et al., 1992) But when combined with blue light (400-500 nm) it is possible to control the elongation of the stem, petiole and prevent other morphological abnormalities when only using red light alone (Goins et al., 1998, Kigel and Cosgrove, 1991) The red light is the most important wavelength for photosynthesis, flowering and fruit setting It is used to extend the light cycle, stimulate flowering plants for long-day plants (dragon fruit, gladiolus, etc.) or prevent flowering in short-day plants (chrysanthemum ) Especially with red light emitted from high pressure sodium lamp is very good for flowering and fruit formation (Roberto, 2003) In order to create optimal conditions for plant growth, chossing the right light source for light intensity, lighting time and light color is the decisive factor (Roberto, 2003 and Sirtatutas et al., 2014) In some plants such as lettuce, tobacco, light is an important factor affecting seed germination process According to Borthwick et al (1952) demonstrated that red light (600-700 nm) promotes the germination of most lettuce varieties, while red light (700-800 nm) is the opposite Phytochrome is the main place to receive light affecting the germination process Classical physiology has hypothesized that there is a link between the gibberellin (GA) and abscisic acid (ABA) hormones within plants with seed germination The red light promotes seed germination by possible addition of GA to the seed In contrast, ABA supplementation will prevent germination Thus, the endogenous content of GA and ABA can be adjusted by light In fact, GA and ABA endogenous content are inverted in bright conditions Phytochrome regulates GA biosynthesis during germination ABA accumulation in the seeds triggers dormancy and prevents germination Chapter MATERIALS AND METHODS 3.1.1 Time and location: from May 2016 to January 2019 at the Fresh Vegetable Research Greenhouse, College of Agriculture, Can Tho University 3.1.2 Materials: Various types of LEDs with different wavelengths were provided by Rang Dong Thermos Bulb Joint Stock Company GN 63 lettuce variety was provided by Nguyen Nong Company Limited (Gino) The radish greens and mustard greens varieties were supplied by Trang Nong Trading Company Limited (b) (c) (a) (d) Figure 3.1 LEDs with different spectra were used in this study (a) LED light bar, (b) red LED, (c) blue LED and (d) 50% red: 50% blue LED Figure 3.2b 4-tiers shelf with LED light 3.2 Study content: contents with experiments (Ex), (4 experiments on baby greens and experiments on mature lettuce) (Fig 3.5) Effects of LED light spectrum Ex Baby radish and mustard greens Ex Mature lettuce Dark room condition Effects of LED light intensities and photoperiods Ex Baby radish and mustard greens Ex Mature lettuce Effects of supplemental LED lighting periods Ex Baby radish and mustard greens Ex Mature lettuce Greenhourse condition Effect of indoor growing models using LED lights with traditional production Ex Baby radish and mustard greens Ex Mature lettuce Figure 3.5 Step-conducting Diagram of the thesis 3.3 Study methods (1) Effect of LED spectrum: the experiments were arranged in a completely random with replications on baby radish greens and mustard greens and replications on mature lettuce Eight treatments included types of LED spectrum and natural light: (1) red LED (660 nm), (2) blue LED (450 nm), (3) white LED, (4) 50% red: 50% blue LED, (5) 60% red 40% blue LED, (6) 70% red: 30% blue LED, (7) 80% red: 20% blue LED and (8) natural light (control) (a) (b) (c) (d) (e) (f) (g) (h) Figure 3.6 Treatments of LED spectrum and natural light (a) red LED, (b) blue LED, (c) white LED, (d) 50% red:50% blue LED, (e) 60% red:40% blue LED, (f) 70% red:30% blue LED, (g) 80% red:20% blue LED and (h) natural light (2) Effect of LED light intensities and photoperiods: the experiments were in a completely randomized design with factors and replications Factor A consisted of photoperiod regimes: 14/10, 16/8, 18/6, 20/4, 22/2 and 24/0 (light/dark) Factor B consisted of levels of light intensity: 40, 66, 107 and 137 μmol.m-2.s-1 in corresponding with 1, 2, and bars of 80% red: 20% blue LEDs (chosen from content 1) Figure 3.7 b Baby greens under 3-tiers shelf Figure 3.8 Overview of the experimental layout of the supplementary LED lighting (3) Effect of supplemental LED lighting periods under 3-tier growing shelf in greenhouse: the experiments were completely randomized design with treatments and replications on baby radish greens and mustard greens and replications on mature lettuce Treatments included: (1) 10 hours, (2) 12 hours, (3) 14 hours, (4) 16 hours, (5) 18 hours and (6) 20 hours of supplemental LED lighting (80% red: 20% blue LEDs, light intensity of 107 μmol.m-2.s-1- chosen from content 2) 4.1.2 Hydroponic lettuce a The height of plants The height of lettuce under red LED always gave the highest results (3.9820.7 cm, respectively rate between 14-35 DAS), followed by 80% red: 20% blue LED, 70% red: 30% blue LED and blue LED (13.9-14.6 cm at harvesting time - 35 DAS) White LED, 50% red: 50% blue LED and control showed the lowest plant height (Table 4.15 and Figure 4.7) The stem elongation effect of the red LED was similarly explained on baby greens Table 4.15 The height of hydroponic lettuce effected by LED light spectrum at different DAS LED light spectrum Red LED Blue LED White LED 50% red:50% blue LED 60% red:60% blue LED 70% red:30% blue LED 80% red:20% blue LED Natural light – Control F CV (%) 14 3.98a 2.90b 2.60c 2.50c 2.55c 2.58c 2.98b 2.48c ** 8.53 Plant height (cm) at different DAS 21 28 35 10.1a 14.8a 20.7a 5.89b 9.39b 14.6b d cd 5.13 8.57 12.0d 4.90d 7.67e 12.2d cd d 5.23 8.36 13.4c b bc 5.89 9.05 13.9bc bc bc 5.56 9.02 13.9bc d cd 4.99 8.58 12.2d ** ** ** 6.52 4.75 4.58 The values in each column followed by different characters are significantly different (Duncan test, P < 0.05).**: Significant at P ≤ 0.01 b Number of leaves Table 4.16 showed that 80% red: 20% blue LED treatment always gave the highest number of leaves on lettuce (except at 14 DAS) At the harvesting time - 35 DAS, the lettuce under 80% red: 20% blue LED had the highest number of leaves (17.5 leaves/plant), was significantly different from control treatment (11.9 leaves/plant) The other combinations of red and blue LED (70:30, 60:40 and 50:50 ratios) gave the average number of leaves from 15.1 to 15.3 leaves /plant The lowest result was found under blue LED and white LED LED light spectrum inluenced on the number of leaves on lettuce The combinations of red and blue LED and red monochrome LED showed the leaves growth faster than under natural light condition (at 21-35 DAS), especially the best one was 80% red: 20% blue LED 14 Table 4.16 The leaves number of hydroponic lettuce affected by the LED spectrum at different DAS Number of leaves (leaves/plant) at different DAS 14 21 28 35 1.62b 5.40a 9.60bc 16.7b 1.13d 4.19bc 7.55d 10.9e cd c d 1.23 4.05 7.46 10.6e cd a c 1.24 5.08 9.58 15.2c bd a c 1.38 5.20 9.57 15.1c 1.40bd 5.21a 10.2ab 15.3c 1.46bc 5.09a 10.3a 17.5a a b d 1.91 4.45 8.06 11.9d ** ** ** ** 17.7 6.92 6.57 5.07 LED light spectrum Red LED Blue LED White LED 50% red:50% blue LED 60% red:60% blue LED 70% red:30% blue LED 80% red:20% blue LED Natural light - Control F CV (%) The values in each column followed by different characters are significantly different (Duncan test, P < 0.05).**: Significant at P ≤ 0.01 (a) (b) (c) (d) (e) (f) (g) (h) Figure 4.7 Lettuce under LED spectrum at 35 DAS (a) red LED, (b) blue LED, (c) white LED, (d) 50% red:50% blue LED, (e) 60% red:40% blue LED, (f) 70% red:30% blue LED, (g) 80% red:20% blue LED and (h) natural light c Fresh weight Growing hydroponic lettuce under 80% red: 20% blue LED and red monochromatic LED showed the highest fresh weight (30.5 and 31.0 g), followed by 70% red: 30% blue, 60% red: 40% blue and 50%: 50% blue LED (24.2, 21.2 and 20.0 g/plant, respectively), was significantly different from natural light (14.4 g/plant) The white LED treatment showed the lowest plant weight (9.23 g/plant) Despite the similar results in fresh weight, the lettuce under red monochromatic LED 15 Fresh weight (g/plant) proved the stem elongation, large and weak leaves, changed plant morphogenesis young leaves tended to arrange in a dense rosette that developed into a compact ball when mature of the GN 63 lettuce variety Growing lettuce under 80% red: 20% blue LED was nearly abled to retain the inherent characteristics of variety, liked planting under sunlight condition 36 31.0a 30.5a 24.2b 27 20.0c 18 21.2c 14.4d 13.8d 9.23e Red Blue White 50R:50B 60R:40B 70R:30B 80R:20B Control LED light spectrum Figure 4.9 Fresh weight of hydroponic lettuce affected by the LED spectrum at harvest time – 19 DAS d Total productivity and commercial productivity Productivity(kg/m2) Using 80% red: 20% blue LED and red LED gave the highest productivity of lettuce, was 111-114% higher than control When the ratio of red LED light decreased from 70% red: 30% blue to 50% red: 50% blue, the yield of lettuce also decreased, but it was still 38.5-67.5% higher than natural light Lettuce under white LED resulted the lowest yield, was equivalent 64.1% compared to control Total productivity Commercial productivity 2.51a 2.18a 2.47a 1.62c 1.12d 0.96e 0.75e 1.72c 1.38c 1.33c 1.96b 1.66b 2.08a 1.17d 1.08d 0.67f Red Blue White 50R:50B 60R:40B 70R:30B 80R:20B Control LED light spectrum Figure 4.10 Productivity of hydroponic lettuce affected by the LED spectrum at harvest time – 19 DAS 16 The similar result was also found on the commercial yield of lettuce (Figure 4.10) Thus, the result of this experiment showed that the fresh weight, total yield and commercial yield of hydroponic lettuce tended to increase with the one in the ratio of red LED light However, a combination of blue light needed controlling the stem elongation, petiole and detered other morphological abnormalities when only red light was used (Goins et al., 1998, Hoenecke et al., 1992) (Kigel and Cosgrove, 1991) This result was consistent with studies of Shin et al (2014) and Zhang et al (2017) when they assumed that red light combined blue light with the ratio of 80:20 increased the weight of the plant 4.2 Effect of LED light intensity and photoperiods 4.2.1 Baby radish greens and mustard greens a Fresh weight There was an interaction between two factors of LED light intensities and photoperiods to fresh weight of baby radish greens (Table 4.32), LED light intensities of 107 and 137 µmol.m-2.s-1 combined with 20/4 and 22/2 (light/dark) showed the highest fresh weight (1.12-1.15 g/plant) and the lowest results were found under 40 µmol.m-2.s-1 combined with 14/10, 16/8 and 18/6 (0.57-0.58 g/plant) Table 4.32 Fresh weight (g/plant) of baby radish greens under LED light intensities combined with different photoperiods at 19 DAS Photoperiod (light/dark) (A) 14/10 16/8 18/6 20/4 22/2 24/0 Average (B) F CV (%) = 3.46 LED light intensities (μmol.m-2.s-1) (B) 40 66 107 137 0.57k 0.80i 0.81hi 0.86g 0.58k 0.82gi 0.96f 1.01de k gi de 0.58 0.83 1.01 1.07c j f a 0.73 0.96 1.15 1.14a i ef a 0.79 0.98 1.14 1.12ab gh de bc 0.85 1.01 1.08 1.05cd c b a 0.68 0.90 1.03 1.04a ** ** F(A) , F(B) , F(A x B)** Average (A) 0.76d 0.84c 0.87b 1.00a 1.01a 1.00a The values in each column or row followed by different characters are significantly different (Duncan test, P < 0.05).**: Significant at P ≤ 0.01 The similar effects of LED light intensities and photoperiods to fresh weight were also found on baby mustard greens, the combinations of 107 and 137 µmol.m2 -1 s with 20/4, 22/2 and 24/0 resulted the highest fresh weight (0.36-0.37 g/plant), the lowest one was still at 40 µmol.m-2.s-1 combined with 14/10 and 16/8 (0.11 and 0.10 g/plant, respectively) (Table 4.33) For this experiment, under the high LED light intensity and long lighting time conditions, it increased the fresh weight of baby 17 radish greens and mustard greens The different effects on plant mass could lead to difference in productivity Table 4.33 Fresh weight (g/plant) of baby mustard greens under LED light intensities combined with different photoperiods at 19 DAS Photoperiod (light/dark) (A) 14/10 16/8 18/6 20/4 22/2 24/0 Average (B) F CV (%) = 0.09 LED light intensities (μmol.m-2.s-1) (B) 40 66 107 137 0.11kl 0.18h 0.26e 0.27e 0.10l 0.21g 0.31c 0.30cd j g d 0.13 0.21 0.29 0.30cd i f a 0.15 0.25 0.37 0.37a j d ab 0.13 0.29 0.36 0.36ab 0.15i 0.28e 0.36ab 0.37a 0.13c 0.24b 0.33a 0.33a ** ** F(A) , F(B) , F(A x B)** Average (A) 0.21c 0.23b 0.23b 0.28a 0.28a 0.29a The values in each column or row followed by different characters are significantly different (Duncan test, P < 0.05).**: Significant at P ≤ 0.01 b Commercial productivity The commercial yield of baby radish greens was effectted by the interaction between LED light intensities and photoperiods (Table 4.36) The highest commercial yield was found under combination of intensity of 107 µmol.m-2.s-1 with 20/4 and 22/2 (3.30 and 3.32 kg/m2), and 137 µmol.m-2.s-1 with 18/6, 22/2 and 24/0 (3.14-3.37 kg/m2) The lowest one was found at intensity of 40 µmol.m-2.s-1 combined with 14/10, 16/8 and 18/6 (1.85-2.01 kg/m2) Table 4.36 Commercial yield (kg/m2) of baby radish greens under LED light intensities combined with different photoperiods at 19 DAS Photoperiod (light/dark) (A) 14/10 16/8 18/6 20/4 22/2 24/0 Average (B) F CV (%) = 6.15 LED light intensities (μmol.m-2.s-1) (B) 40 66 107 137 1.85h 2.34fg 2.88de 2.95ce 1.99h 2.53f 2.98ce 3.12bd h e ce 2.01 2.82 2.99 3.14ac g ce ab 2.28 2.91 3.30 3.10bd g e ab 2.27 2.81 3.32 3.37a 2.25g 3.08bd 2.97ce 3.26ab 2.11c 2.75b 3.07a 3.16a ** ** F(A) , F(B) , F(A x B)** Average (A) 2.50c 2.66b 2.74b 2.90a 2.94a 2.89a The values in each column or row followed by different characters are significantly different (Duncan test, P < 0.05).**: Significant at P ≤ 0.01 18 (a) (b) (c) (d) (e) (f) Figure 4.11 Baby radish greens under different photoperiods (a) 14/10, (b) 16/8, (c) 20/4, (e) 22/2 and (f) 24/0 combined with 107 μmol.m-2s-1 of LED light intensities at harvest time-19 DAS There was an interaction between LED light intensities and photoperiods on the commercial yield of baby mustard greens (Table 4.37) The intensity of 137 µmol.m-2.s-1 combined with 20/4, 22/2 and 24/0 showed the highest results (2.102.25 kg/m2), were unsignificantly different from the combinations of 107 µmol.m2 -1 s with 20/4 and 22/2 (2.22 and 2.23 kg/m2) According to Michael (2015), most of the studies on LED application for planting used the light intensity less than 200 µmol.m-2.s-1 Table 4.37 Commercial yield (kg/m2) of baby mustard greens under LED light intensities combined with different photoperiods at 19 DAS LED light intensities (μmol.m-2.s-1) (B) Photoperiod Average (A) (light/dark) (A) 40 66 107 137 14/10 0.96j 1.33fh 1.76de 1.81de 1.47c ij f de de 16/8 1.04 1.49 1.87 1.85 1.56b hi f de de 18/6 1.16 1.48 1.87 1.85 1.59b gi e a ab 20/4 1.21 1.71 2.22 2.16 1.82a gi ce a a 22/2 1.22 1.92 2.23 2.25 1.90a 24/0 1.39fg 1.98bd 1.96bd 2.10ac 1.86a c b a a Average (B) 1.16 1.65 1.98 2.00 F F(A)**, F(B)**, F(A x B)* CV (%) = 8.92 The values in each column or row followed by different characters are significantly different (Duncan test, P < 0.05).** and *: Significant at P ≤ 0.01 and P ≤ 0.05 19 (a) (b) (c) (d) (e) (f) Figure 4.12 Baby mustard greens under different photoperiods (a) 14/10, (b) 16/8, (c) 20/4, (e) 22/2 (f) 24/0 combined with 107 μmol.m-2s-1 of LED light intensities at harvest time-19 DAS 4.2.2 Hydroponic lettuce a Fresh weight Table 4.50 showed that the fresh weight of lettuce was effectted by the interaction between LED light intensities and photoperiods, the intensity of 107 µmol.m-2.s-1 combined with 20/4 and 22/2 hours/day gave the same result (33.9 and 34.6 g/plant), were higher than all other combinations and the lowest one (5.30 g/plant) was found at the shortest lighting time (14/10) combined with lowest lighting intensity (40 µmol.m-2.s-1) Table 4.50 Fresh weight (g/plant) of hydroponic lettuce under LED light intensities combined with different photoperiods at 35 DAS Photoperiod (light/dark) (A) 14/10 16/8 18/6 20/4 22/2 24/0 Average (B) F CV (%) = 4.74 LED light intensities (μmol.m-2.s-1) (B) 40 66 107 137 5.30p 12.0n 17.7l 22.5gh 8.64o 14.8m 21.1ij 17.4l o k hi 8.45 19.4 21.5 20.0jk n gi a 13.1 22.2 33.9 25.1e l d a 16.8 27.7 34.6 23.2fg l ef c 17.6 24.0 29.4 30.8b d c a 11.6 20.0 26.4 23.1b ** ** F (A) , F (B) , F (A x B)** Average (A) 14.4d 15.5d 17.3c 23.6b 25.6a 25.5a The values in each column or row followed by different characters are significantly different (Duncan test, P < 0.05).**: Significant at P ≤ 0.01 20 b Commercial productivity The commercial yield of lettuce had an interaction between LED light intensities and photoperiods (Table 4.52), the highest one was found at a combination of 107 µmol.m-2.s-1 with 20/4 and 22/2 (2.53-2.57 kg/m2), followed by the combination of 137 with 24/0 (2.28 kg/m2) and 66 with 22/2 (2.01 kg/m2), were significant differences compared to other combinations The light intensity of 40 µmol.m-2.s-1 combined with any photoperiods (from 14/10 to 24/0) gave the low commercial yield (less than 1.50 kg/m2) Table 4.52 Commercial yield (kg/m2) of hydroponic lettuce under LED light intensities combined with different photoperiods at 35 DAS Photoperiod (light/dark) (A) 14/10 16/8 18/6 20/4 22/2 24/0 Average (B) F CV (%) = 5.30 LED light intensities (μmol.m-2.s-1) (B) 40 66 107 137 0.37n 0.91l 1.29ij 1.58fg 0.64m 1.04k 1.53fg 1.24j m hi gh 0.62 1.40 1.48 1.31ij kl gh a 0.97 1.48 2.53 1.82e j d a 1.27 2.01 2.57 1.61f ij e c 1.32 1.80 2.15 2.28b 0.86d 1.44c 1.93a 1.64b ** ** F (A) , F (B) , F (A x B)** Average (A) 1.04d 1.11d 1.20c 1.70b 1.86a 1.89a The values in each column or row followed by different characters are significantly different (Duncan test, P < 0.05).**: Significant at P ≤ 0.01 The reason for the highest yield of lettuce under combinations of 107 µmol.m-2.s-1 with 20/4 and 22/2 was the fresh weight and total yield in these two combinations were also the highest Beside that the growth of lettuce (plant height, number of leaves on plant) also had the same tendency 4.3 Effect of supplement LED lighting time 4.3.1 Baby radish greens and mustard greens * Total productivity and commercial productivity The highest yield of baby radish greens was found at supplemental periods of 18 and 20 hours/day (3.15-3.31 kg/m2), was not significantly different compared with 16 hours of additional lighting (3.05 kg/m2) and the lowest was found at 10 and 12 hours/day supplement (2.57-2.64 kg/m2) However, the commercial productivity under supplemental lighting periods of 16, 18 and 20 hours/day were similar (2.903.13 kg/m2) and significantly higher in comparison with 10, 12 and 10 hours/day (2.50-2.61 kg/m2) (Fig 4.13) 21 Productivity (kg/m2) Total productivity Commercial productivity 2.77bc 2.64c 2.57b 2.57d 2.61b 2.50b 3.05ab 2.90a 3.15 3.01a 3.31a 3.13a 10 12 14 16 18 Supplemental LED lighting period (hours/day) 20 Figure 4.13 Productivity of baby radish greens under supplemental LED lighting periods at 13 DAS The total yield and commercial yield of baby mustard greens were similar to that of baby radish greens (Figure 4.5) Supplementing long lighting time (16-20 hours/day) for total yield (2.81 to 2.95 kg/m2) and commercial yield (2.80-2.93 kg/m2) were significantly higher compared to short lighting time of 10, 12 and 14 hours (total yield from 2.17 to 2.32 kg/m2 and 2.17-2.29 kg/m2 of commercial yield) Productivity (kg/m2) Năng suất tổng Năng suất thương phẩm 2.17b 2.17b 2.17b 2.17b 2.81a 2.80a 2.81a 2.80a 2.95a 2.93a 2.32b 2.29b 10 12 14 16 18 20 Supplemental LED lighting period (hours/day) Figure 4.14 Productivity of baby mustard greens under supplemental LED lighting periods at 15 DAS 22 4.3.2 Hydroponic lettuce a Fresh weight The Figure 4.15 showed that growing lettuce under multi-storey shelves with additional lighting of 16, 18 and 20 hours/day always gave the highest fresh weight (20.4-22.0 g/plant at 25 DAS, 39.5-40.1 g/plant at 31 DAS), were significantly higher than additional lighting of 12 and 14 hours/day and the lowest one was under 10 hours supplementation (12.6, 18.1 and 20.6 g/plant at 25, 28 and 31 DAS) This result was completely consistent with the growth indicators Fresh weight (g/plant) 48 25 NKSG 28 NSKG 39.5a 34.1b 36 30.6a 27.0c 24 40.1a 31 NSKG 39.9a 20.6d 22.4c 18.1d 15.4c 12.6d 27.6b 22.0a 20.4a 18.4b 30.0a 30.1a 20.4a 12 10 12 14 16 18 20 Supplemental LED lighting period (hours/day) Figure 4.15 Fresh weight of lettuce under supplemental LED lighting periods at 25, 28 and 31 DAS b Commercial productivity The commercial yield of lettuce under supplemental LED lighting periods had the same tendency with total yield (Figure 4.17) Supplemental LED lighting for a long time of 16, 18 and 20 hours/day showed the highest commercial yield (1.611.73 kg/m2, 2.39-2.45 kg/m2 and 3.09-3.15 kg/m2 at 25, 28 and 31 DAS, respectively), and the lowest one was at 10 hour supplemental treatment (1.02, 1.45 and 1.62 kg/m2, respectively at 25, 28 and 31 DAS) 23 Commercial yield (kg/m2) 25 DAS 28 DAS 31 DAS 3.15a 3.15a 3.09a 2.68b 2.45a 1.62d 1.45d 1.02d 2.13c 1.79c 2.39a 2.20b 1.73a 1.61ab 1.46b 2.40a 1.60a 1.22c 10 12 14 16 18 20 Supplemental LED period (hours/day) Hình 4.17 Commercial productivity of lettuce under supplemental LED lighting periods at 25, 28 and 31 DAS 4.4 The effect of growing vegetable model using LED 4.4.1 Model of baby radish greens and mustard greens production a Total productivity and commercial productivity Total yield and commercial yield of baby radish greens were highest under open field condition (3.84 kg/m2 for total yield and 3.26 kg/m2 for commercial yield), but commercial productivity was not significantly different from statistical analysis compared to 3-tiers hydroponic shelf with LED lighting (2.89 kg/m2) which were significantly higher than hydroponic + natural light (2.09 kg/m2) (Fig 4.20) Productivity (kg/m2) Total productivity Commercial productivity 3.05b 3.26a 2.89a 3.84a 2.15c 2.09b 3-tiers hydroponic shelf + LED Hydroponic + Natural light Open field condition Growing method Figure 4.20 Productivity of baby radish greens under growing methods at 15 DAS The highest total yield and commercial yield of baby mustard greens were found under 3-tiers hydroponic shelf in greenhouse condition (2.81 kg/m 2/tier and 2.80kg/m2/tier, respectively for total yield and commercial yield), with the 24 commercial productivity/total yield rate was 99.8%, followed by hydroponic + natural light (1.39 kg/m2, 100% commercial product) The lowest commercial yield (1.10 kg/m2) was found under open field condition that was only 78.1% of commercial productivity/total yield rate (Fig 4.21) This result was consistent with plant height but contrary to plant weight, number of leaves on plant, leaf size (long and wide) and stem diameter The reason for the yield and commercial productivity was low because the seeds were so small that the seedlings were very small, to be affected by open field conditions Productivity (kg/m2) 2.81a 2.80a Total productivity 1.39b Commercial productivity 1.39b 1.41b 1.10c 3-tiers hydroponic shelf + LED Hydroponic + Natural light Open field condition Growing method Figure 4.21 Productivity of baby mustard greens under growing methods at 15 DAS Under open field conditions, baby radish greens and mustard greens were affected by many adverse conditions of the environment and harmful pests, thus reducing the seeds germination, number of plants in experimental plots, there was a loss due to increased impact of pests and pathogens from the soil environment It was these causes that could lead to a significant reduction in the commercial productivity of green vegetables This result once again showed that the advantages of growing hydroponic vegetables in the greenhouse and the disadvantages when cultivating baby vegetables in the traditional way under open field b Production Quantity Growing baby radish greens under 3-tiers hydroponic shelf with LED showed the highest total production quantity and commercial production quantity (9.14 and 8.69 kg/m2/crop, respectively), significantly higher than under open field (3.84 and 3.26 kg/m2/crop, respectively) The lowest one was found under hydroponic using natural light in greenhouse (2.15 and 2.09 kg/m2/crop) (Table 4.85) Similar result was found on baby mustard greens (Table 4.86) Growing baby mustard greens under 3-tiers hydroponic shelf with LED lighting gave the highest total production quantity and commercial production quantity (8.43 and 8.40 25 kg/m2/crop) Under open field and hydroponics + natural light in greenhouse conditions, the total production quantity (1.41 and 1.39 kg/m2/crop) and commercial production quantity (1.10 and 1.39 kg/m2/crop) were equivalent Table 4.85 Production quantity of baby radish green under growing methods at 13 DAS Growing method 3-tiers hydroponic shelf + LED Hydroponic + Natural light Open field condition F CV (%) Total production quantity (kg/m2/crop) 9.14a 2.15c 3.84b ** 9.02 Commercial production quantity (kg/m2/crop) 8.69a 2.09c 3.26b ** 9.68 The values in each column followed by different characters are significantly different (Duncan test, P < 0.05).**: Significant at P ≤ 0.01 Table 4.86 Production quantity of baby mustard green under growing methods at 15 DAS Total production Commercial production Growing method quantity (kg/m2/crop) quantity (kg/m2/crop) a 3-tiers hydroponic shelf + LED 8.43 8.40a b Hydroponic + Natural light 1.39 1.39b b Open field condition 1.41 1.10b F ** ** CV (%) 8.19 8.35 The values in each column or row followed by different characters are significantly different (Duncan test, P < 0.05).**: Significant at P ≤ 0.01 Thus, growing baby radish greens and mustard greens under 3-tiers hydroponic shelf with LED lighting were 167-664% higher of commercial output than under open field condition and 316-504% higher than hydroponics with natural light in the greenhouse This were the outstanding advantage of the multi-tier vegetable growing shelf (exploiting overhead space) Using artificial light (LED) for replacement or supplement for sunlight was more effective in improving vegetable yield per unit area 4.4.2 Lettuce production model a Commercial productivity Similar to the difference in total yield, the lettuce commercial production reached the highest under 3-tiers hydroponic shelf with additional LED lighting (1.61, 2.45 and 3.15 kg/m2, respectively at 25, 28 and 31 DAS), was significantly higher than under hydroponic with natural light in greenhouse (0.16, 0.30 and 0.39 kg/m2, respectively) and under open field condition (0.13, 0.30 and 0.44 kg/m2, respectively at harvest times) (Figure 4.8) 26 Commercial yield (kg/m2) 25 DAS 3.15a 28 DAS 31 DAS 2.45a 1.61a 0.39b 0.16b 0.30b 0.13b 0.30b 0.44b 3-tiers hydroponic shelf + Hydroponic + Natural light LED Open field condition Growing method Figure 4.25 Commercial productivity of lettuce under growing methods at 25, 28 and 31 DAS The reason for the highest total yield and commercial productivity of hydroponic lettuce under 3-tiers growing shelf were the fresh weight, plant height, number and size of leaves on the plant, and stem diameter of this treatment higher than under hydroponic + natural light and open field condition b Production Quantity Growing lettuce under a 3-tiers hydroponic shelf with LED lighting always gave the highest commercial production quantity at 25, 28 and 31 DAS (4.83, 7.34 and 9.44 kg/m2/crop, reaspectively) Meanwhile, growing hydroponic lettuce under greenhouse showed the commercial production quantity equal to under open field condition (0.39 and 0.44 kg/m2/crop, respectively, 31 DAS) The commercial production quantity of lettuce under 3-tiers hydroponic shelf with LED was 24-30 times higher than under hydroponic + natural light in greenhouse and 21-37 times higher than under open field at 25-31 DAS Table 4.96 Production quantity of lettuce under growing methods at harvest times Commercial production quantity (kg/m2/crop) at harvest times Growing method 25 28 31 3-tiers hydroponic shelf + LED 4.83a 7.34a 9.44a Hydroponic + Natural light 0.16b 0.30b 0.39b b b Open field condition 0.13 0.30 0.44b F ** ** ** CV (%) 20.6 14.3 16.1 The values in each column or row followed by different characters are significantly different (Duncan test, P < 0.05),**: Significant at P ≤ 0.01 27 Chapter 5: CONCLUSION AND SUGGESTION 5.1 Conclusion * In dark room condition - In terms of spectrum: LED light had 80% red spectrum: 20% blue was suitable for growth, productivity and quality of baby radish greens, mustard greens and lettuce - Regarding the intensity and lighting time: + Baby radish greens: LED light intensity of 107 μmol.m-2.s-1 combined with 20/4 and 22/2 gave the high commercial yield that was equivalent to the intensity of 137 μmol.m-2.s-1 combined with 18/6, 22.2 and 24/0, were 1.56-1.82 times higher than 40 μmol.m-2.s-1 with 14/10, 18/6 and 18/6 + Baby mustard greens: light intensity of 107 μmol.m-2.s-1 with photoperiod of 20/4 and 22/2 showed high commercial yield equivalent to 137 μmol.m-2.s-1 combined with 20/4, 22/2 and 24/0 + Lettuce: light intensity of 107 μmol.m-2.s-1 combined with 20/4, 22/2 and 137 μmol.m-2.s-1 with 24/0 for commercial productivity were 6.16-7.11 times higher than the combination of 40 μmol.m-2.s-1 with 14/10 * In greenhouse condition - Planting baby radish greens and mustard greens under 3-tiers growing shelf with supplemental LED lights (spectrum: 80% red: 20% blue, intensity: 107 μmol.m2 -1 s ) on 16, 18 and 20 hours/day gave the highest commercial yield, was 11-35 % higher than being under 10,12 and 14 hours/day - The remarkeble yield of muture lettuce under 3-tiers growing shelf with supplemental LED lights (spectrum: 80% red: 20% blue, intensity: 107 μmol.m-2.s1 ) on 16, 18 and 20 hours/day was 56,9-69,6%, 64,8-69,0%, 90,1-94,4% (respectively at 25, 28 and 31 DAS) higher than under 10 hours/day 5.2 Suggestion - Continue to study on and experiment on number of other high economic value crops in order to ensure economic efficiency of the model - Research, improve and reduce the cost of LED lamps so that is going to be widely used in commercial agricultural production 28 ... effected by LED light spectrum at different days affter sowing LED light spectrum Red LED Blue LED White LED 50% red:50% blue LED 60% red:60% blue LED 70% red:30% blue LED 80% red:20% blue LED Natural... greens affected by the LED spectrum at different DAS LED light spectrum Red LED Blue LED White LED 50% red:50% blue LED 60% red:60% blue LED 70% red:30% blue LED 80% red:20% blue LED Natural light... Figure 4.7 Lettuce under LED spectrum at 35 DAS (a) red LED, (b) blue LED, (c) white LED, (d) 50% red:50% blue LED, (e) 60% red:40% blue LED, (f) 70% red:30% blue LED, (g) 80% red:20% blue LED and