INTRODUCTION
Background
Jasmine rice is known as a most important aromatic rice originating in Thailand It was officially named as Khao Dawk Mali 105,
(KDML105) [1] In 1945, the best Jasmine rice local variety was discovered by a farmer in Lam
Pradoo district, Chonburi province, and in 1951,
199 panicles of the local variety were selected from a nearby district of Chachearngsoa province for pure line selection [2]
Figure 1.1 Long grain white Jasmine rice
(https://www.dreamstime.com/stock- photo-long-grain-uncooked-white- jasmine-rice-close-up-food-background- image65134089)
Jasmine rice originated in the Bang Khla District of Chachoengsao Province, known for its saline, sandy soil and absence of flooding Today, this region has evolved into a significant industrial and residential hub, renowned as the largest area for rice production in Northeast Thailand.
Jasmine rice is characterized by its long, slender grains, which are typically white in color Each grain measures at least 7.0 mm in length and 3.0 mm in width, ensuring a consistent quality Additionally, Jasmine rice contains an amylose content ranging from 12 to 19 percent at a humidity level of 14 percent These desirable traits make Jasmine rice a popular choice as a genetic resource in rice breeding programs.
Jasmine rice is a nutrient-rich grain that contains essential vitamins such as B1, B2, and niacin, along with carbohydrates, protein, and important minerals like iron, calcium, and phosphorus It can be enjoyed in various forms, including whole grain Cooking methods vary by culture; for instance, many Asian communities prepare rice with ample water for a desirable texture, while Western cultures often boil it in excess water until fully cooked In Thailand, Jasmine rice is not only a staple food for local consumers but also a key export that contributes significantly to the economy.
[8] It was produced annually at approximately 9.4 M ton of paddy rice from 4.3 M ha
[9] The annual export quantities of aromatic rice were as high as 1.06–1.45 million tons, which represented 20–27% of Thailand’s total rice export [10]
1.1.2.1 Life cycle of the rice plant
Figure 1.2 Growth phases and stages of the rice plant (https://nature-and- farming.blogspot.com/2014/10/rice-production-chapter-2-growth-stages.html)
The rice plant has a growth duration of 3-6 months, influenced by its variety and environmental conditions It undergoes three distinct growth phases: vegetative, reproductive, and ripening The vegetative phase includes germination, early seedling growth, and tillering, marked by active tillering, increasing plant height, and regular leaf emergence The reproductive phase features culm elongation, a decrease in tiller number, and the emergence of the flag leaf, culminating in heading and flowering Following fertilization, the ripening phase consists of milky, dough, yellow ripe, and maturity stages, which vary in length among different rice varieties based on the texture and color of the grains.
Jasmine rice, characterized by its tall and floppy structure, typically reaches an average height of 140 cm at harvest This photo-sensitive variety can only be cultivated once a year, specifically from August to December, with optimal planting occurring in December for the best growth and yield The paddy grain produced during this period meets high-quality standards Currently, the finest Hom Mali rice in Thailand is cultivated in the Northeast, covering approximately 7.6 million acres, yielding between 1,125 to 1,500 kg per acre.
Microbiota refers to the collection of microorganisms found in various environments, including soil, oceans, the atmosphere, and within the human body These microorganisms play a crucial role in sustaining life on Earth, as they significantly influence the health of humans, animals, and plants.
The human microbiota significantly influences host physiology, comprising diverse microbes such as bacteria, archaea, viruses, and eukaryotic organisms Research indicates that the microbiota is crucial for the maturation of immune cells and the development of immune functions However, not all microbiota are beneficial; they are also linked to various diseases, including infections, liver diseases, respiratory conditions, and autoimmune disorders Similarly, animal microbiota, found in the gut, oral cavity, and skin, communicate with the host's organ systems, contributing to homeostasis Additionally, microorganisms associated with plants are essential for shaping ecosystems, enhancing plant health, productivity, and community composition, while also offering protection against pathogens Thus, the plant microbiota is recognized as a vital component in promoting plant growth and resilience.
The rhizosphere is the soil zone around plant roots where biological and chemical factors are influenced by the roots Root exudates play a crucial role in this area, allowing plants to maintain their microbiota These exudates are categorized into two types: low molecular weight compounds, including amino acids, organic acids, sugars, and phenolics, which contribute to the diversity of root exudates, and high molecular weight exudates, such as mucilage and proteins, which, while less diverse, make up a significant portion of these compounds Additionally, the microbial communities in the soil include nitrogen-fixing bacteria that release nod factors to facilitate their attachment to plant roots, enhancing nutrient uptake and providing protection against pathogens through the release of antimicrobial compounds.
Figure 1.3 Root exudation in the rhizosphere
1.1.4 Microbiota application for plant growth promotion
The relationship between plants and microbes is essential for plant health, productivity, and overall condition, with interactions ranging from beneficial to pathogenic depending on factors like plant species and nutrient availability To enhance plant growth, microbiota is utilized, and microbiome engineering plays a crucial role in this process This experimental approach involves creating a microbial community, including both culturable and unculturable microbes, to improve host performance through selective breeding for specific microbial traits that benefit the host However, disruptions in these ecosystems can lead to negative consequences, such as reduced microbial diversity, increased disease rates, and diminished plant fitness and soil fertility Microbiome engineering aims to restore balance to these ecosystems, enhancing microbial functionality and promoting greater resistance to pathogens, ultimately improving plant phenotypes and productivity.
Figure 1.4 Microbiome engineering improves plant growth
Microbiome engineering is gaining global attention as a means to enhance plant growth and ecosystem diversity By optimizing plant-microbiome interactions, researchers aim to achieve beneficial outcomes that improve plant health However, the process can be hindered by the time-consuming nature of selection experiments.
1.1.5 The characteristics of silty, sandy and clay soil
Sand particles range from 0.05 to 2 mm in diameter, making them the largest among soil particles, while silt particles have a medium size of 0.002 to 0.05 mm In contrast, clay particles are the smallest, measuring less than 0.002 mm in diameter.
Figure 1.5 Soil particle size (a) Sandy soil (b) Silty soil (c) Clay soil
(https://support.rainmachine.com/hc/en-us/articles/228001248-Soil-
Sandy soil is characterized by large particle spaces, making it unable to retain water effectively In contrast, silty soil has a smoother texture and retains moisture longer, although it lacks the ability to hold many nutrients Clay soil, which feels sticky when wet and smooth when dry, drains slowly and is rich in nutrients, providing an ideal environment for plant growth.
Objectives
- To observe the effect of transition, chemical and intensive chemical soil to Jasmine rice growth
- To develop DNA extraction method suitable for silty, sandy and clay soil.
Scope of study
- Collect Jasmine rice seeds and the field soil samples, planting in pots
- Count the number of rice tillers once a week
- Compare the best rice plant and the worst rice plant (depend on the number of rice tillers) in each soil group and between 3 soil groups
- Collect the pictures of the rice plant
- Develop DNA extraction method from the field soil samples.
MATERIALS AND METHODS
Equipment and materials
No Name of device Type Country
3 Deep freezer VXE 380 Czech Republic
16 PCR machine T100 TM Thermal Singapore
A total of 27 soil samples were collected from the field, comprising three types: silty, sandy, and clay soils This collection included 9 chemical soil samples (refer to Table 2.2), 9 intensive chemical soil samples (see Table 2.3), and 9 transition soil samples (as shown in Table 2.4) All samples were preserved at a temperature of -80°C to maintain their integrity for analysis.
Table 2.2 9 samples of chemical soil
Malai Tongjarern, the owner of a chemical soil group in Bangkok, Kokpochai, Khon Kaen, Thailand, has been cultivating rice for over 20 years The soil, characterized as silt, is enhanced using green manure once and treated with chemical fertilizer (16-8-8) at a rate of 25 kg per 1.6 m², applied once.
Chemical soil group 2: Name of owner: Chuen Laokonka Address: Bankok, Kokpochai, Khon Kean, Thailand Grow rice more than 20 years Use: Green manure; Chemical fertilizer 15-15-15: 35 kg/1.6 m 2 (1 time) Soil type: silt
Chuen Laokonka, a seasoned rice grower from Bankok, Kokpochai, Khon Kean, Thailand, has been cultivating rice for over 20 years He utilizes green manure once and applies chemical fertilizer with a composition of 16-8-8 at a rate of 25 kg per 1.6 m² The soil in this area is classified as silt, contributing to the agricultural practices employed.
Table 2.3 9 samples of intensive chemical soil
Intensive chemical soil group 1: Name of owner: Soodjai Prajummueang Address:
In Bangkok, Kokpochai, Khon Kaen, Thailand, a rice farm has been operating for eight years, utilizing a combination of chemical fertilizer (15-15-15 at 50 kg per 1.6 m²), insecticides applied twice, and liquid bio-fertilizers used three times throughout the growing season Following the rice harvest, the farm transitions to corn planting, which also involves significant use of insecticides and chemical fertilizers The soil type on this farm is silt, supporting its agricultural practices.
Intensive chemical soil group 2: Name of owner: Sombul Wongchaileng Address:
Moolnak, Pochai Kokpochai, Khon Kean, Thailand Use: Weed killer (1 time); Herbicide (1 time); Insecticide (1 time); Urea: 12.5 kg/1.6 m 2 (1 time); Fertilizer formulate 15-15-15: 12.5 kg/1.6 m 2 Soil type: silt
Intensive chemical soil group 3: Name of owner: Jirapon Jaikachem Address:
Moolnak, Pochai Kokpochai, Khon Kean, Thailand Use: Herbicide (1 time);
Insecticide (1 time) Urea: 20 kg/1.6 m 2 (1 time); Fertilizer formulate 15-15-15: 20 kg/1.6 m 2 (1 time) Soil type: silt
Table 2.4 9 samples of transition soil
Transition soil group 1: Name of owner: Jongrak Jarupunngam Address: Jorakhe, Nongruea, Khon Kean, Thailand Start organic rice farm for 2 years Use insect dung: 30 kg/1.6 m 2 Soil type: clay
Transition soil group 2: Name of owner: Pattareeya Srisopon Address: Lerngphak,
Koodrung, Mahasarakam, Thailand Start organic rice farm for 1 year Use photosynthetic bacteria (1 time) Soil type: sand
Kidsanatchai Sawadsitung, the owner of an organic rice farm located in Tapra, Mueang, Khon Kaen, Thailand, has been cultivating this farm for three years The farm utilizes 150 kg of chicken dung per 1.6 m² and incorporates fermented banana shoots along with photosynthetic bacteria on a monthly basis The soil type on the farm is clay, which supports the organic farming practices.
Jasmine rice seeds were used in this study Seeds were collected from 25 Moo 11
Ban Pongchueag, Namakhuea, Sahadsakhan, Kalasin 46140, Thailand (Fig 2.1)
Figure 2.1 The seed of Jasmine rice
In this study, DNA was isolated using a DNA extraction buffer composed of 0.1 M Tris-HCl, 0.1 M EDTA (pH 8), and 1.5 M NaCl, which was sterilized by autoclaving at 121 °C for 20 minutes Three variations of the buffer were tested: the first included 10% SDS and 1% activated charcoal, the second contained only 1% activated charcoal, and the third had neither 10% SDS nor 1% activated charcoal.
Figure 2.2 Three types of DNA extraction buffer a b c
Methods
2.2.1 Preparing soil mixture for planting
In this study, a soil mixture was prepared using 4.5 kg of sterilized standard soil, 48 g of compost (comprised of rice bran and cow dung), and 300 g of field soil samples, each with varying water concentrations To standardize conditions, drying experiments were conducted on all field soil samples, with their actual weights for planting detailed in Table 2.5 The soil mixture was thoroughly combined and distributed into pots, with each pot containing 5 kg of the mixture and water added as needed A total of 30 pots were utilized, with 27 designated for planting and 3 serving as control pots that did not include field soil samples.
Table 2.5 The real weight of the field soil samples for planting (g)
Real weight soil for planting (g)
Real weight soil for planting (g)
Real weight soil for planting (g)
Before planting, jasmine rice seeds undergo a careful selection process, as illustrated in Fig 2.3, which outlines the steps for selecting and germinating rice seeds By placing the seeds in a water flask and waiting for 2-3 minutes, it becomes easy to distinguish between the bad seeds and the good seeds.
Figure 2.3 The process of germinating rice seeds
Jasmine rice seeds germinate within 3-4 days and continue to grow for an additional three weeks After this period, we selected the three healthiest plants based on leaf length, while removing the two least healthy ones The rice was cultivated for a total of 10 weeks, with water being the only addition during this time We maintained a consistent water level of 5 cm in each pot for optimal growth of the Jasmine rice.
2.2.3 Development of DNA extraction method
In this study, metagenomic DNA was extracted from field soil samples using three distinct methods, with method 1, sonication, being an innovative approach for soil DNA extraction (Table 2.6).
Take rice seeds into a water flask
Remove the bad seeds (above surface of water)
Select the good seeds (below surface of water)
Put 5 seeds for each pot (total: 27 pots)
Table 2.6 Metagenomic DNA extraction from soils using sonication
Weighed 5 g of soil sample and 5 g of small glass beads, transferred into 50 mL tube Added 5 mL of DNA extraction buffer, use two types of buffer: (1) added 1% of activated charcoal; (2) no added 10% of SDS and 1% of activated charcoal
Vortexed for 10 min and kept cool the soil samples for 10 min Sonicated at 30% amplitude, 40% amplitude, 50% amplitude and 60% amplitude, and duration of
5 times (the 30s for each time)
3 Centrifuged at 8000 rpm for 10 min at 4 o C Transferred 2.5 mL of the supernatant to 15 mL tube Repeated for 2 times
To prepare the sample, 500 µL of 3 M sodium acetate (CH3COONa) and 2 mL of PEG were added to the supernatant The mixture was precipitated at -20°C for 20 minutes in a deep freezer, followed by centrifugation at 8000 rpm for 15 minutes at 4°C After discarding the supernatant, the pellet was resuspended in 500 µL of distilled water and transferred to a fresh 1.5 mL Eppendorf tube.
Added 500 àL of phenol:chloroform: isoamyl alcohol (25:24:1) Centrifuged at
13500 rpm for 2 min at 4°C Collected the aqueous phase and transferred to a fresh 1.5 mL eppendorf Repeated for 2 times
Added 400 àL of chloroform: isoamyl alcohol (24:1) Centrifuged at 13500 rpm for 2 min at 4°C Collected the aqueous phase and transferred to a fresh 1.5 mL eppendorf Repeated for 3 times
Added 500 àL of ice-cold isopropanol Precipitated at 4°C for 10 minutes in a deep freezer Centrifuged at 13500 rpm for 15 min at 4°C Discarded the supernatant
8 The pellet was dried and dissolved in 30 àL of distilled water
Methods 2 and 3, which utilize big and small glass beads and small glass beads with three types of buffer respectively, were developed based on the principles of Method 1 Each method maintains a consistent weight for the field soil samples.
In Method 2, the process begins with the addition of large glass beads and a 0.85% sodium chloride (NaCl) solution, which are vortexed for 30 minutes Subsequently, small glass beads are incorporated, while sonication is omitted The remaining steps in Method 2 adhere to the protocol established in Method 1.
In Method 3, cell and nuclear disruption was achieved using small glass beads along with three different buffer compositions: (1) a mixture containing 10% SDS and 1% activated charcoal; (2) a buffer with 1% activated charcoal only; and (3) a control with no SDS or activated charcoal The samples were vortexed to ensure thorough mixing.
In the precipitation process, PEG was initially substituted with absolute ethanol In the subsequent step, isopropanol was replaced by a combination of 3 M sodium acetate (CH3COONa) and absolute ethanol Additionally, distilled water was changed to Nuclease-free water (NEB, UK) The remaining steps of method 3 adhered to the protocol outlined in method 1.
RESULTS
Compare the tiller number of the rice plant
In the analysis of chemical soil, the data presented in Fig 3.1 shows that the average number of tillers per pot increased for group 1 from week 4 to week 9, followed by a decrease at week 10 Similarly, groups 2 and 3 experienced an increase from week 4 to week 8, with a decline after week 9 Notably, the average tiller numbers among the three groups were comparable from week 4 to week 6, while group 2 reached the highest average at week 8 The error bars in the chart represent the standard errors of the means, calculated using Microsoft Excel 2010.
Figure 3.1 Averages of tiller number per pot in chemical soil
The analysis of tiller numbers in intensive chemical soil, as illustrated in Fig 3.2, shows an increase from week 4 to week 8, followed by a decline after week 9 across all samples Notably, group 1 exhibited a higher average tiller count compared to groups 2 and 3 after week 8 The error bars in the chart represent the standard errors of the means, calculated using Microsoft Excel 2010.
70.00 week 4 week 5 week 6 week 7 week 8 week 9 week 10
Figure 3.2 Averages of tiller number per pot in intensive chemical soil
In the analysis of tiller numbers across different groups, it was observed that the averages for groups 1 and 3 increased from week 4 to week 9, followed by a decline at week 10 Meanwhile, group 2 showed an increase in tiller numbers from week 4 to week 8, with a decrease after week 9 Initially, groups 1 and 3 outperformed group 2 in tiller numbers; however, by week 8 and week 10, group 3 surpassed both group 1 and group 2 The standard errors of the means were calculated and represented by error bars, generated using Microsoft Excel 2010.
Figure 3.3 Averages of tiller number per pot in transition soil
80 week 4 week 5 week 6 week 7 week 8 week 9 week 10
A v e ra g e o f ti ll er n u m b er
70 week 4 week 5 week 6 week 7 week 8 week 9 week 10
The analysis of tiller numbers across three soil groups reveals distinct trends over a ten-week period For transition soil, the average tiller count increased from week 4 to week 9, followed by a decline in week 10 Similarly, chemical soil showed an increase from week 4 to week 8, with a decrease noted after week 9 Initially, both intensive chemical soil and transition soil outperformed chemical soil in terms of tiller numbers However, by week 8, chemical soil recorded the highest average tiller count The error bars in the chart, generated using Microsoft Excel 2010, represent the standard errors of the means.
Figure 3.4 Averages of tiller number in three soil groups
Rice plants growth observation
To identify the best and worst rice plants in each group, we relied on the number of tillers produced Observations indicated that rice plants experienced rapid growth between weeks 4 and 8, but by week 10, the leaves began to yellow Comparative analysis of rice plants across different soil groups is presented in tables 3.1, 3.2, 3.3, and 3.4.
70 week 4 week 5 week 6 week 7 week 8 week 9 week 10
Table 3.1 Rice plants growth in chemical soil
Table 3.2 Rice plants growth in intensive chemical soil
Table 3.3 Rice plants growth in transition soil
Table 3.4 Rice plants growth in three soil groups
Extraction of metagenomic DNA from different methods
Metagenomic DNA was extracted from transition soil using three different methods: method 1 involved sonication, method 2 utilized both big and small glass beads, and method 3 employed small glass beads along with three types of buffer solutions In method 1, transition soil groups 1 and 2 were analyzed, while method 2 included all groups of transition soil.
In method 3, groups 1 and 3 were analyzed, with DNA quantity and quality assessed using a nanodrop spectrophotometer The A260/280 ratio indicates protein contamination, while the A260/230 ratio reflects the presence of other contaminants Results show that DNA quantity in method 1 is low for transition soil group 1 and better for group 2 (Table 3.5) Method 2 also yielded low DNA quantities for all samples (Table 3.6), whereas method 3 demonstrated improved DNA quantities (Table 3.7) However, the overall DNA quality remained low for all samples, with values falling below 1.8.
Table 3.5 DNA quantity and quality by method 1 for transition soil
Sample DNA concentration (ng/àL) A 260/280 A 260/230
Table 3.6 DNA quantity and quality by method 2 for transition soil
Sample DNA concentration (ng/àL) A 260/280 A 260/230
Table 3.7 DNA quantity and quality by method 3 for transition soil
Sample DNA concentration (ng/àL) A 260/280 A 260/230
Analysis of soil samples on 0.8% agarose gels revealed that Method 1 produced bright DNA bands for transition soil group 2, although significant DNA degradation was observed In contrast, Method 2 failed to yield bright bands for any samples Method 3 showed bright bands only for sample 1 of transition soil group 3, accompanied by light smearing and impurities, while sample 2 of transition soil group 1 also exhibited impurities, and no bright bands were detected for the remaining samples.
Figure 3.5 Metagenomic DNA was extracted from transition soil (a) Method 1;
Land 1: T1 was sonicated at 30% amplitude; Land 2: T1 was sonicated at 50% amplitude; Land 3: T2 was sonicated at 60% amplitude; Land 4: T2 was sonicated at 40% amplitude (b) Method 2 (c) Method 3 Land M: 1 Kb DNA ladder Samples were electrophoresed on 0.8% agarose in 1X TAE buffer
Metagenomic DNA was extracted from intensive chemical soil groups 2 and 3 using two different methods: method 2 with big and small glass beads for group 2, and method 3 with small glass beads and three types of buffer for group 3 The DNA quantity and quality were assessed using a Nanodrop spectrophotometer, where an A260/280 ratio indicates protein contamination and an A260/230 ratio reflects the presence of other contaminants All samples demonstrated satisfactory DNA quantity, exceeding 100 ng/µL; however, the DNA quality was found to be below the acceptable threshold of 1.7.
Table 3.8 DNA quantity and quality by method 2 for intensive chemical soil
Sample DNA concentration (ng/àL) A 260/280 A 260/230
Table 3.9 DNA quantity and quality by method 3 for intensive chemical soil
Sample DNA concentration (ng/àL) A 260/280 A 260/230
Analysis of soil samples on 0.8% agarose gels reveals that both method 2 and method 3 produce bright bands for all samples Method 2 exhibits tight bands with slight smearing, indicating high DNA concentration across all samples In contrast, method 3 displays tight bands with light smearing, showing high molecular weight for samples 1 and 3, while sample 2 exhibits low molecular weight Notably, RNA contamination remains present on the gel.
Figure 3.6 Metagenomic DNA was extracted from intensive chemical soil group 2 and group 3 (a) Method 2 (b) Method 3 Land M: 1 Kb
DNA ladder Samples were electrophoresed on 0.8% agarose in 1X
Metagenomic DNA was extracted from chemical soil groups 1 and 3, as well as transition soil group 2, utilizing method 3, which involves small glass beads and three types of buffer The quantity and quality of the extracted DNA were assessed using a nanodrop spectrophotometer, where the A260/280 ratio indicates protein contamination and the A260/230 ratio reveals the presence of other contaminants.
All of the samples have good DNA quantity (more than 200 ng/àL) However, DNA quality is lower than 1.5 (Table 3.10)
Table 3.10 DNA quantity and quality by method 3 for chemical soil and transition soil
Sample DNA concentration (ng/àL) A 260/280 A 260/230
Analysis of the extracted soil samples on 0.8% agarose gels revealed that method 3 produced bright bands with light smearing and high molecular weight across all samples (Fig 3.7), although RNA contamination was still present on the gel.
Figure 3.7 Metagenomic DNA was extracted by method 3 (a) Chemical soil group 1 and group 3 (b) Transition soil group 2 Land M: 1 Kb DNA ladder Samples were electrophoresed on 0.8% agarose in 1X TAE buffer.
CONCLUSIONS AND DISCUSSION
DNA extraction methods suitable for three types of soil
Most soil samples from transition soil groups 1 and 3 are unable to yield metagenomic DNA due to their clay composition, which retains significant water The high tension in these clay soils causes them to absorb organic matter, including DNA, making extraction challenging.
Method 2 (big and small glass beads) is suitable to extract metagenomic DNA for intensive chemical soil Method 3 (small glass beads and 3 types of buffer) that used
3 M sodium acetate and absolute ethanol to precipitate However, DNA quality wasn’t good (lower than 1.8) so it is necessary to purify
1 Vanavichit, A., Kamolsukyeunyong, W., Siangliw, M., Siangliw, J L., Traprab, S.,
Ruengphayak, S., & Tragoonrung, S (2018) Thai Hom Mali Rice: Origin and Breeding for Subsistence Rainfed Lowland Rice System Rice, 11(1), 20
2 Bureau of Rice Research and Development (2010) Khao Dawk Mali 105 Rice
3 Lin, S., Chantachon, S., & Laoakka, S (2014) Quality Control Management of
Traditional Jasmine Rice Production and Processing Methods Asian Culture and History, 7(1), 75
4 Department of Foreign Trade Rice in Thailand: Agriculture, history what makes jasmine rice so special Retrieved from: http://factsanddetails.com/southeast- asia/Thailand/sub5_8h/entry-3321.html (accessed on 18/10/2017)
5 Maksup, S., Pongpakpian, S., Roytrakul, S., Cha ‐ Um, S., & Supaibulwatana, K
(2018) Comparative proteomics and protein profile related to phenolic compounds and antioxidant activity in germinated Oryza sativa ‘KDML105’and Thai brown rice
‘Mali Daeng’for better nutritional value Journal of the Science of Food and Agriculture, 98(2), 566-573
6 Kaset Organic (2010) Thai Hom Mali Rice Organic Retrieved from: https://www.kasetorganic.com/thai-hom-mali-rice-organic.html (accessed on 12/03/2010)
7 Juliano, B O (1982) An international survey of methods used for evaluation of the cooking and eating qualities of milled rice
8 YOSHIHASHI, T., NGUYEN, T T H., & KABAKI, N (2004) Area dependency of
2-acetyl-1-pyrroline content in an aromatic rice variety, Khao Dawk Mali 105 Japan
9 Varinruk, B (2017, April) Thailand rice production and rice R&D on climate change
In Strengthening APEC cooperation on food security and climate change workshop, Hilton Hanoi opera hotel, Hanoi, Viet Nam (pp 19-21)
10 Pitiphunpong, S., & Suwannaporn, P (2009) Physicochemical properties of KDML
105 rice cultivar from different cultivated locations in Thailand Journal of the Science of Food and Agriculture, 89(13), 2186-2190
11 Maclean, J., Hardy, B., & Hettel, G (2013) Rice Almanac: Source book for one of the most important economic activities on earth IRRI
12 Summart, J., Panichajakul, S., Prathepha, P., & Thanonkeo, P (2008) Callus induction and influence of culture condition and culture medium on growth of Thai Aromatic rice, Khao Dawk Mali 105, cell culture World Applied Sciences Journal, 5(2), 246-251
13 Wangcharoen, W., Phanchaisri, C., Daengpok, W., Phuttawong, R., Hangsoongnern,
T., & Phanchaisri, B (2016) Consumer acceptance test and some related properties of selected KDML 105 rice mutants Journal of food science and technology, 53(9), 3550-3556
14 Chourwong, P., & Iaprasert, W (2018) The optimum conditions cultivated KDML
105 off season in Chachoengsao Province National and International Research conference, 1(9), 174-183
15 OK Nation (2014) The direction of Thai jasmine rice Retrieved from: http://www.oknation.net/blog/sonorwut/2014/01/04/entry-1 (accessed on 03/11/2015)
16 Sheth, R U., Cabral, V., Chen, S P., & Wang, H H (2016) Manipulating bacterial communities by in situ microbiome engineering Trends in Genetics, 32(4), 189-200
17 Ursell, L K., Haiser, H J., Van Treuren, W., Garg, N., Reddivari, L., Vanamala, J.,
& Knight, R (2014) The intestinal metabolome: an intersection between microbiota and host Gastroenterology, 146(6), 1470-1476
18 Bouskra, D., Brézillon, C., Bérard, M., Werts, C., Varona, R., Boneca, I G., & Eberl,
G (2008) Lymphoid tissue genesis induced by commensals through NOD1 regulates intestinal homeostasis Nature, 456(7221), 507
19 Wang, B., Yao, M., Lv, L., Ling, Z., & Li, L (2017) The human microbiota in health and disease Engineering, 3(1), 71-82
20 McFall-Ngai, M., Hadfield, M G., Bosch, T C., Carey, H V., Domazet-Lošo, T.,
Douglas, A E., & Hentschel, U (2013) Animals in a bacterial world, a new imperative for the life sciences Proceedings of the National Academy of
21 Berg, G., Grube, M., Schloter, M., & Smalla, K (2014) The plant microbiome and its importance for plant and human health Frontiers in microbiology, 5, 1
22 Müller, D B., Vogel, C., Bai, Y., & Vorholt, J A (2016) The plant microbiota: systems-level insights and perspectives annual review of genetics, 50, 211-234
23 Neeru, N., Kothe, E., & Behl, R K (2009) Role of root exudates in plant-microbe interactions Journal of Applied Botany and Food Quality, 82(2), 122-130
24 Dakora, F D., & Phillips, D A (2002) Root exudates as mediators of mineral acquisition in low-nutrient environments In Food Security in Nutrient-Stressed
Environments: Exploiting Plants’ Genetic Capabilities (pp 201-213) Springer,
25 Rougier, M (1981) Secretory activity of the root cap In Plant Carbohydrates II (pp
26 Walker, T S., Bais, H P., Grotewold, E., & Vivanco, J M (2003) Root exudation and rhizosphere biology Plant physiology, 132(1), 44-51
27 Rincon-Florez, V A., Carvalhais, L C., & Schenk, P M (2013) Culture-independent molecular tools for soil and rhizosphere microbiology Diversity, 5(3), 581-612
28 Glick, B R (2014) Bacteria with ACC deaminase can promote plant growth and help to feed the world Microbiological research, 169(1), 30-39
29 Quiza, L., St-Arnaud, M., & Yergeau, E (2015) Harnessing phytomicrobiome signaling for rhizosphere microbiome engineering Frontiers in plant science, 6, 507
30 Mueller, U G., & Sachs, J L (2015) Engineering microbiomes to improve plant and animal health Trends in microbiology, 23(10), 606-617
31 Foo, J L., Ling, H., Lee, Y S., & Chang, M W (2017) Microbiome engineering: curent applications and its future Biotechnology journal
32 Stephen How to Create Amazing Garden Soil from Clay, Silt or Sand Retrieved from: http://www.livingoffgridguide.com/gardening/how-to-create-amazing-garden- soil/ (accessed on 25/11/2015)
33 Leineriza 5 Different Soil Types – Know Your Soil Type Retrieved from: http://agverra.com/blog/soil-types/ (accessed on 07/04/2011)
1 Data of weight soil samples before and after drying
Soil sample Number of foil weight foil (g)
(Before) weight soil + foil+water (g) weight soil + water (g)
(After) weight soil + foil (g) weight soil (g)
Huminity (g) % huminity Real weight soil for using (g)
2 Data of tiller number in each week of planting (3 seeds per pot)