Khao Dawk Mali Research Articles

Phosphoprotein Profile of Rice (Oryza sativa L.) Seedlings under Osmotic Stress after Pretreatment with Chitosan.

This study aims to identify novel chitosan (CTS)-responsive phosphoproteins in Leung Pratew 123 (LPT123) and Khao Dawk Mali 105 (KDML105) as drought-sensitive rice cultivars and differences in the CTS response. Rice seeds were soaked in CTS solution before germination, and 2- and 4-week-old rice seedlings sprayed with CTS before osmotic stress comprised the following four groups: (1) seedlings treated with distilled water; (2) seedlings treated with CTS; (3) seedlings pretreated with distilled water and subjected to osmotic stress; and (4) seedlings pretreated with CTS and subjected to osmotic stress. Phosphoproteins of leaf tissues were enriched using immobilized metal affinity chromatography (IMAC) before tryptic digestion and analysis via LC-MS. Phosphoprotein profiling analyses led to the identification of 4721 phosphoproteins representing 1052 and 1040 unique phosphoproteins in the LPT123 and KDML105 seedlings, respectively. In response to CTS pretreatment before osmotic stress, 22 differently expressed proteins were discovered, of which 10 and 12 were identified in the LPT123 and KDML105, respectively. These proteins are typically involved in signaling, transport, protein folding, protein degradation, and metabolism. This study provides fruitful data to understand the signal transduction mechanisms of rice seedlings pretreated with CTS before exposure to osmotic stress.

In vitro and in silico studies of salicylic acid on systemic induced resistance against bacterial leaf blight disease and enhancement of crop yield

Salicylic acid (SA) is an effective elicitor to promote plant defenses and growth. This study aimed to investigate rice (Oryza sativa L.) cv. Khao Dawk Mali 105 treated with salicylic acid (SA)-Ricemate as an enhanced plant protection mechanism against bacterial leaf blight (BLB) disease caused by Xanthomonas oryzae pv. oryzae (Xoo). Results indicated that the use of SA-Ricemate as a foliar spray at concentrations of more than 100 mg L−1 can reduce the severity of BLB disease by 71%. SA-Ricemate treatment also increased the hydrogen peroxide (H2O2) content of rice leaf tissues over untreated samples by 39–61%. Malondialdehyde (MDA) in rice leaves treated with SA-Ricemate also showed an increase of 50–65% when comparing to non-treated samples. The differential development of these defense compounds was faster and distinct when the SA-Ricemate-treated rice was infected with Xoo, indicating plant-induced resistance. Besides, SA-Ricemate elicitor at a concentration of 50–250 mg L−1 was correlated with a substantial increase in the accumulation of total chlorophyll content at 2.53–2.73 mg g−1 of fresh weight which suggests that plant growth is activated by SA-Ricemate. The catalase- and aldehyde dehydrogenase-binding sites were searched for using the CASTp server, and the findings were compared to the template. Chemsketch was used to design and optimize SA, which was then docked to the catalase and aldehyde dehydrogenase-binding domains of the enzymes using the GOLD 3.0.1 Software. SA is shown in several docked conformations with the enzymes catalase and aldehyde dehydrogenase. All three catalase amino acids (GLN7, VAL27, and GLU38) were discovered to be involved in the creation of a strong hydrogen bond with SA when SA was present. In this mechanism, the aldehyde dehydrogenase amino acids LYS5, HIS6, and ASP2 were all implicated, and these amino acids created strong hydrogen bonds with SA. In field conditions, SA-Ricemate significantly reduced disease severity by 78% and the total grain yield was significantly increased which was an increase of plant height, tiller per hill, and panicle in three field trials during Aug–Nov 2017 and 2018. Therefore, SA-Ricemate can be used as an alternative elicitor on replacing harmful pesticides to control BLB disease with a high potential of increasing rice defenses, growth, and yield components.

Phosphoproteome analysis reveals chitosan-induced resistance to osmotic stress in rice (Oryza sativa L.) seedlings

ABSTRACT This study sought to identify the mechanism underlying the response to chitosan at the posttranslational level. Khao Dawk Mali 105 seeds were soaked in 40 mg l−1 of chitosan, and leaves of 2- and 4-week-old seedlings were sprayed with chitosan before starting osmotic stress conditions. Chitosan induced resistance to osmotic stress by enhancing shoot fresh and dry weights and maintained increased photosynthetic pigments. Leaf phosphoproteomes were examined using gel-free LC-MS/MS. Of the 60 phosphoproteins showed a significant difference in protein expressions under osmotically-stressed plants treated with chitosan. More than 40% of the phosphoproteins involved in signaling pathways, including OsCML12 calmodulin-related calcium sensor protein, ubiquitin carboxyl-terminal hydrolase 15, U-box domain-containing protein 45, HEAT repeat family protein, BRCA1 C terminus domain-containing protein, pectinesterase, protein kinase domain-containing protein, and receptor-like protein kinase. Chitosan enhanced rice seedling growth and drought resistance via multiple complex networks, including metabolism, transport, transcription, and signaling under osmotic stress.

Effects of micronutrients on Khao Dawk Mali 105 rice in Thai paddy soils and assessment of their availability indices

AbstractBackgroundMicronutrient deficiency is currently the major cause of declining productivity in rice‐growing countries, including Thailand. A pot experiment was conducted to determine limiting micronutrients (Fe, Mn, Zn, and Cu) for Khao Dawk Mali 105 (KDML 105) rice, in four soil types. Soil micronutrient speciation and in‐soil extracts were examined to identify the species controlling the availability to the plant and the efficiency of soil extract to assess the availability indices of multi‐micronutrients for KDML 105 rice.ResultsMicronutrients in the studied soils were in the order Fe > Mn > Cu > Zn, mostly in stable forms accounting for 96.8%–99.7%, 81.3%–96.5%, 95.6%–97.6%, and 83.3%–98.0%, respectively, and in available fractions of only 0.32%–3.2%, 3.55%–18.66%, 2.44%–4.42%, and 2.03%–16.74% respectively. The omitted Fe had the greatest effect on limiting the rice grain yield with a significant reduction of 24.12%–46.46%, whereas the omitted Zn had the least effect. To assess the availability for KDML 105 rice, DTPApH 7.3 was the most suitable multipurpose extractant for Fe, Mn, and Cu, while HCl was superior to other extractants for Zn. All oxide fractions were responsible for supplying available Fe, Mn, and Cu, while Zn was generated from the organic and exchangeable fractions.ConclusionsThe yield of KDML 105 rice can be increased by adding each of these micronutrients but yield magnitude was different depending upon their deficient levels in soils. The oxide‐bonded micronutrients were the species controlling its availability and DTPApH 7.3 was suggested as the multipurpose extractant for micronutrient availability indices indicators.

Measuring sustainability performance of rice cultivation in Thailand using Sustainable Rice Platform indicators

ABSTRACT The sustainability level of current rice farming practices in Thailand was assessed based on in-field data from interviewing 2000 farmers covering six rice varieties and their different production systems. Data were collected on farmers’ characteristics and farming activities according to the 41 requirements of the Sustainable Rice Platform (SRP) standard. The SRP scores ranged from 53 to 81%, with the best performance by Khao Dawk Mali 105 cultivated in rainfed, organic production systems. The key success factors were linked to the formation of a farmer group resulting in very good performance on farm management, Integrated Pest Management, health and safety, and water use. The proposed 12 performance indicators (PIs) interconnected with the 41 requirements are considered appropriate to measure and monitor progress toward sustainable rice cultivation for policy makers. PIs for good governance, affordability of living costs, energy-use efficiency, and life satisfaction could potentially be added, considering the local context in relation to sustainable agriculture goals. The successful cases of SRP-certified rice farms and the benefits from SRP implementation should be conveyed to with other rice farmers to induce wider implementation. The SRP scores and PIs were useful to identify areas requiring priority interventions to make progress toward sustainability.

Comparative proteomic analysis of chromosome segment substitution lines of Thai jasmine rice KDML105 under short-term salinity stress.

Heat shock proteins, ROS detoxifying enzymes, and ion homeostasis proteins, together with proteins in carbohydrate metabolism, cell structure, brassinosteroids, and carotenoid biosynthesis pathway were up-regulated in CSSLs under salinity stress. Rice is one of the most consumed staple foods worldwide. Salinity stress is a serious global problem affecting rice productivity. Many attempts have been made to select or produce salinity-tolerant rice varieties. Genetics and biochemical approaches were used to study the salinity-responsive pathway in rice to develop salinity tolerant strains. This study investigated the proteomic profiles of chromosome segment substitution lines (CSSLs) developed from KDML105 (Khao Dawk Mali 105, a Thai jasmine rice cultivar) under salinity stress. The CSSLs showed a clear resistant phenotype in response to 150mM NaCl treatment compared to the salinity-sensitive line, IR29. Liquid chromatography-tandem mass spectrometry using the Ultimate 3000 Nano/Capillary LC System coupled to a Hybrid Quadrupole Q-Tof Impact II™ equipped with a nano-captive spray ion source was applied for proteomic analysis. Based on our criteria, 178 proteins were identified as differentially expressed proteins under salinity stress. Protein functions in DNA replication and transcription, and stress and defense accounted for the highest proportions in response to salinity stress, followed by protein transport and trafficking, carbohydrate metabolic process, signal transduction, and cell structure. The protein interaction network among the 75 up-regulated proteins showed connections between proteins involved in cell wall synthesis, transcription, translation, and in defense responses.

Influence of Seed Quality Stimulation in “Khao Dawk Mali 105” Rough Rice during the Deterioration Period Using an Automatic Soaking and Germination Accelerator Unit and Infrared Radiation Treatment

This study aimed to improve the seed quality during the deterioration period of rough rice (Oryza sativa L.), cultivar ‘Khoa Dawk Mali 105’ (KDML 105), using an automatic soaking and germination accelerator unit (ASGA) together with stimulation via infrared radiation treatment (IRT) to stimulate seed quality (germination rate and γ-aminobutyric acid (GABA) content). This study used a general full factorial design, and the independent variables were the storage period (10, 11 and 12 months), methods of germinated rough rice preparation (conventional method (CM) and an automatic soaking and germination accelerator unit (ASGA)), and stimulation with IRT. The initial grain moisture content did not exceed 14% (wet basis (wb)). The germination rate of the rough rice by CM and ASGA with stimulation with IRT was significantly higher than non-stimulated rice, by 6.56 and 8.11%, respectively, in each storage period. The GABA contents of the germinated rough rice using CM and ASGA stimulated with IRT were significantly higher than ungerminated rough rice, by 19.52 and 21.24% (10 months), respectively; 16.36 and 23.58% (11 months), respectively; and 69.88 and 67.69% (12 months), respectively.

Cognitive spectroscopy for the classification of rice varieties: A comparison of machine learning and deep learning approaches in analysing long-wave near-infrared hyperspectral images of brown and milled samples

Rapid and non-destructive detection of genuine Thai Jasmine rice (Khao Dawk Mali 105 (KDML105)) from Pathum Thani1 (PTT1) and Phitsanulok2 (PSL2) under either milled or brown conditions is required to disrupt fraudulent. This study aimed to resolve this real issue using long-wave near infrared hyperspectral imaging (NIR-HSI) coupled with machine learning and deep learning approaches. The best classification accuracy for the milled rice was achieved using the spectral imaging-based analysis on the NIR-HSI data with selected wavelength, approximately 95% for the test set either by convolutional neural network or support vector machine (SVM), whereas for the brown rice, the SVM model based on the averaged NIR spectra could achieve the best classification accuracy of 95.4%. It suggests the chemical component difference and its spatial distribution in the milled rice could contribute higher classification accuracy. Additionally, the surface bran effects of brown rice could be reduced by using averaged spectral data coupled with the SVM method.

Effects of aqueous Moringa oleifera leaf extract on growth performance and accumulation of cadmium in a Thai jasmine rice-Khao Dawk Mali 105 variety.

The contamination of paddy fields and rice grains by cadmium (Cd) adversely affects human health. Thus, many approaches have been proposed to reduce the accumulation of Cd in rice. Here, we investigate the potential of aqueous Moringa oleifera leaf extract (AMOLE) in decreasing uptake and toxicity of Cd in a popular Thai jasmine rice variety, Khao Dawk Mali 105 (KDML105). Plants were grown in Petri dishes, a hydroponic system, and a pot system under different concentrations of Cd, in the presence and absence of AMOLE. In Petri dishes, Cd reduced the percentage of germination by 79%, but the treatment with 0.5mgmL-1 AMOLE significantly increased the germination percentage. Moreover, AMOLE significantly decreased Cd accumulation in rice seedlings by 97%. In the hydroponics system, 0.5mgmL-1 AMOLE decreased Cd content in shoots by 48%. Although no significant physiological changes in response to Cd treatments were observed in the pot system, a large amount of Cd was accumulated in rice roots. The AMOLE treatments significantly reduced Cd accumulation in rice shoots and decreased Cd content in milled grain by half compared to those without AMOLE treatment. We conclude that AMOLE reduced Cd toxicity, enhanced seedling growth, and reduced Cd accumulation in rice grains.

Application of mild-subcritical alkaline water extraction: optimum condition for phenolic antioxidant extracted from cold-pressed defatted KDML 105 rice bran and its phenolic profile

This research was aimed at optimizing the process of the mild-subcritical alkaline water (pH 9.5) extraction (mild SAW) of cold-pressed defatted Khao Dawk Mali 105 rice bran (CDRB) in order to achieve the maximum antioxidants with minimal brown colour. Response surface methodology and central composite design were performed with two variables: extraction temperature (107-129°C) and time (21-149 mins). The elucidated optimum conditions were 119°C and 85 mins with predicted response values: the total phenolic content of 16.9 mg gallic acid/g; protein of 64.3 mg/g; an ABTS radical scavenging activity of 14.4 mg Trolox/g; a browning index of 0.41; and reducing sugar of 62.0 mg/g. Proto-catechuic acid and p-coumaric acid were major phenolic compounds in the CDRB, while trans-ferulic acid, proto-catechuic acid, and p-coumaric acid were all abundant in the mild SAW extract. The results confirmed that the mild SAW extraction process for antioxidants is an environmentally friendly approach, which can increase the release of value-added compounds from rice bran residues.

Screening for P- and K-solubilizing, and siderophore producing capacity of rhizobacteria from Khao Dawk Mali 105 Aromatic Rice

Low nutrient status and high salinity have been identified as significant constraints for KDML105 aromatic rice production in the TKR region, Northeastern, Thailand. The use of PGPR can provides green alternatives to synthetic fertilizer in this region. In this study, therefore, rhizobacteria were isolated from KDML105 rice and evaluated for their potential in P and K solubilization, and siderophore production. The results indicated that 52.0, 21.5, 17.9, and 21.1% of 629 tested isolates, were able to solubilize P, K-mica, K-feldspar, and produce siderophore, respectively. At 0% NaCl the highest amount of solubilized P (35.6 mg L-1), K (49.5 mg L-1), and hydroxamate-type siderophore (618.3 μg L-1), were obtained from isolates ORF4-13, ORF15-23, and CRF16-3, respectively. Under salt stress, the amount of solubilized P of almost all the isolates increased with salt concentration up to 0.5% NaCl and declined thereafter, as compared to the control. In contrast, the amount of solubilized K progressively decreased with NaCl concentration. On the average, ORF15-23 exhibited promising ability in P and K solubilization under salt stress. The promising isolates obtained in this study should be evaluated for their effects on rice nutrients uptake and growth before developing them as biofertilizer.

Combining Genome and Gene Co-expression Network Analyses for the Identification of Genes Potentially Regulating Salt Tolerance in Rice.

Salinity stress tolerance is a complex polygenic trait involving multi-molecular pathways. This study aims to demonstrate an effective transcriptomic approach for identifying genes regulating salt tolerance in rice. The chromosome segment substitution lines (CSSLs) of “Khao Dawk Mali 105 (KDML105)” rice containing various regions of DH212 between markers RM1003 and RM3362 displayed differential salt tolerance at the booting stage. CSSL16 and its nearly isogenic parent, KDML105, were used for transcriptome analysis. Differentially expressed genes in the leaves of seedlings, flag leaves, and second leaves of CSSL16 and KDML105 under normal and salt stress conditions were subjected to analyses based on gene co-expression network (GCN), on two-state co-expression with clustering coefficient (CC), and on weighted gene co-expression network (WGCN). GCN identified 57 genes, while 30 and 59 genes were identified using CC and WGCN, respectively. With the three methods, some of the identified genes overlapped, bringing the maximum number of predicted salt tolerance genes to 92. Among the 92 genes, nine genes, OsNodulin, OsBTBZ1, OsPSB28, OsERD, OsSub34, peroxidase precursor genes, and three expressed protein genes, displayed SNPs between CSSL16 and KDML105. The nine genes were differentially expressed in CSSL16 and KDML105 under normal and salt stress conditions. OsBTBZ1 and OsERD were identified by the three methods. These results suggest that the transcriptomic approach described here effectively identified the genes regulating salt tolerance in rice and support the identification of appropriate QTL for salt tolerance improvement.

Alternative economic and shortened method for the production of dried germinated rice

Since germination creates chalky grain around the entire surface of the kernel, it is commonly eliminated by steaming germinated paddy before drying. In this work, a continuous fluidized bed with a capacity of 100 kg/h was therefore used to treat the chalkiness with high-temperature hot air. The performance of this dryer in terms of water evaporation capacity and energy consumption along with the quality attributes was determined quantitatively. Two crops of Khao Dawk Mali 105 stored for 1 month and 8 and 9 months were used as the raw material. Hot air at temperatures of 130–150 °C with full recycling of the exhaust air was able to eliminate the chalkiness perfectly. The best performance, as indicated by higher water evaporation capacity and lower energy consumption, was obtained at a higher feed rate, higher bed depth and higher drying temperature. The higher bed depth and drying temperature provided a higher degree of starch gelatinization and the correspondingly higher head brown rice yield and hardness of the cooked germinated brown rice except for stickiness. Within the studied drying temperature range, the amount of accumulated gamma-aminobutyric acid after drying the rice which had been stored for 1 month decreased slightly compared to that of the sun-dried product, in a range of 11.4–12.6 mg per 100 g, and decreased significantly for the rice which had been stored for 8 and 9 months. The storage period also influenced the texture after cooking. It is recommended that to obtain the premium quality from the germinated product, the paddy should be stored for 1 month, and a drying temperature of approximately 130˚C should be applied. Under the recommended conditions, the energy consumption was about 1.13 MJ/kg of paddy, and the operating cost of the continuous fluidized bed was 0.17 USD/kg, which was more economical than that of the conventional method.

Bioaccessibility and antioxidant activity of phenolic acids, flavonoids, and anthocyanins of encapsulated Thai rice bran extracts during in vitro gastrointestinal digestion

Encapsulation technique was applied to improve the stability of bioactive compounds in bran extracts from Thai rice cultivars (Khao Dawk Mali 105, Kiaw Ngu, Hom Nil, and Leum Pua), using three carriers including gelatin, gum Arabic, and the mixture of gelatin and gum Arabic. The microcapsules obtained using gelatin provided a higher production yield of 76.08, 85.63, 85.63 and 85.59%, respectively. A greater encapsulation efficiency was also observed in the extracts encapsulated with gelatin (93.45, 95.91, 91.19 and 95.09%, respectively). After simulated gastric and intestinal digestion, the microcapsules formed by using gelatin exhibited the higher release of bioactive compounds and antioxidant activity than unencapsulated extracts. However, the extracts encapsulated using gelatin and gum Arabic complex yielded the lowest release of bioactive compounds and their antioxidant activity after simulated digestion. The overall results showed that gelatin was an appropriate carrier that could protect bioactive compounds from the digestion conditions.

Effects of hydrogen peroxide application on agronomic traits of rice (Oryza sativa L.) under drought stress

Drought stress is a major environmental factor limiting crop growth and productivity. Hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) plays an essential role during stress response by acting as a signal molecule that activates multiple stress tolerance mechanisms. In this study, the effects of H<sub>2</sub>O<sub>2</sub> on agronomic traits were studied in rice (Oryza sativa L.) cv. Khao Dawk Mali 105 (KDML 105) was subjected to drought stress. H<sub>2</sub>O<sub>2</sub> was applied by either seed priming or foliar application method with a concentration of 1, 5, and 15 mmol/L. The results showed that both seed priming and foliar application with H<sub>2</sub>O<sub>2</sub> improved some yield components. The tiller numbers, number of panicles, number of filled grains, filled grain weight, and harvest index were improved approximately 1.13, 1.04, 1.23, 1.21, and 1.1 times compared to the untreated plants. Foliar application, however, helps the plant by reducing yield loss as indicated by a 0.5-time reduction in the number of unfilled grain and lower unfilled grain weight. It was suggested that 5 mmol/L H<sub>2</sub>O<sub>2</sub> was the most effective concentration to alleviate the effect of drought stress during the reproductive stage in rice.

Physicochemical Characterization of Broken Rice and Analysis of Its Volatile Compounds

The term “broken rice” refers to fragments of rice grains broken during the milling process. Broken rice is generally classified into 3 sizes: large, medium, and small. Broken rice can be widely used for the pet food industry, livestock feeding, aquaculture, laundry starch, cosmetics, and textile manufacture. The purpose of this study was to determine certain properties of raw large broken rice (LBR) and small broken rice (SBR) of 4 commercially important varieties: Khao Dawk Mali105 (KDML105), Pathumtani1 (PTT1), Chainat1 (CN1), and Kor-khor6 (RD6). The properties analyzed were pasting properties, alkali spreading value, gel consistency, chemical composition, and amylose content. Volatile components of the LBR and SBR samples were also identified. Results revealed that each rice variety had different rheological characteristics. SBR of KDML105, PTT1, and CN1 had alkaline spreading value (ASV) in the range of 3 - 7. The rice flour gel of the glutinous rice variety RD6 showed the highest flow distance in both LBR and SBR forms. CN1 had the highest amylose content in both LBR and SBR forms, while RD6 had the lowest. Among all the samples, the 6 most abundant volatile components detected were alcohols, aldehydes, furans, ketones, sulfur, and terpenes. The 3 volatile compounds with the highest odor active values (OAV) in both LBR and SBR forms were hexanal, heptanal, and 3-methylbutanal.

Principal Component Analysis Application on Nutritional, Bioactive Compound and Antioxidant Activities of Pigmented Dough Grain

The dough stage of rice plant is a critical stage during the grain development. The rice endosperm continues to expand and the color of the seed coat develops in accordance with rice variety, so it is called as dough grain. This research was carried out to examine nutritional value, bioactive compound and antioxidant activity of Thai dough grain. Ten varieties of pigmented dough grain including non-glutinous and glutinous rice were studied. Principal component analysis (PCA) was conducted to visualize the difference in nutrition amongst ten rice varieties. Hierarchical cluster analysis was used to identify the unique characteristics of each rice variety. Three principal components (PC1-PC3) showed 82.04% of the total variance and could divide pigmented dough grain varieties into 3 groups. Group 1 consisted of a red dough grain (Red Hom Mali). It had the highest total phenolic content as well as high protein and antioxidant activities. Group 2 consisted of two red dough grains (Thabthim Chumphae and Niao Daeng) and two black dough grains (Riceberry and Niaodum Kumbaikeaw), which had moderate antioxidant activities. Group 3 consisted of two green dough grains (Khao Dawk Mali 105 and Kor Khor 6) and three black dough grains (Black Hom Mali, Mali Black Sulin and Niaodum Kumnoiy), exhibiting high gamma oryzanol value but, low total phenolic content. Hence, red and black dough grains had higher nutritional value, total phenolic content, total anthocyanin and antioxidant activities than green dough grains. In addition, dough grains from non-glutinous rice had higher protein and lower fat than those from glutinous rice. Therefore, the data from this research could benefit the utilization of these pigmented dough grain as functional food ingredients and healthy food product.

Low-energy heavy-ion-beam-induced mutation of novel high-yielding drought-tolerant Thai Jasmine rice

To respond to the global warming challenge to local agriculture, we applied a low-energy heavy ion beam as novel biotechnology to improve crop drought tolerance. Dehulled seeds of Thai Jasmine rice, Khao Dawk Mali 105 (KDML105), a popular Thai rice variety, were bombarded by a nitrogen ion beam with energy of tens-keV and fluences in an order of 1016 ions/cm2. The resulting mutagenized rice was obtained, selected, and further advanced until phenotypically stable. Mutagenized lines were screened for drought tolerance in the seedling and reproductive stages under an artificially created drought condition in comparison with KDML105 and the drought-tolerant reference variety, CT9993, using both subjective and quantitative parameters. We advanced the mutants up to M8 generation for stabilization and found a mutant line named HyKOS22, which displayed higher tolerance to the drought condition than KDML105 and CT9993 and produced a higher crop yield than KDML105. Genetic changes in HyKOS22 were confirmed by molecular biology analysis.

Development of a Universal Calibration Model for Quantification of Adulteration in Thai Jasmine Rice Using Near-infrared Spectroscopy

In the event the substituent rice variety present in adulterated Thai jasmine rice cannot be identified, the adulterant rice in unknown samples could be inconsistent with that used to establish the calibration model resulting in inaccurate quantitative prediction of the adulteration level. In this research study, near-infrared (NIR) spectroscopy was applied to quantify the adulteration level of Thai jasmine or Khao Dawk Mali 105 (KDML105) rice based on the use of partial least squares (PLS) regression. To cope with the inconsistency between the training and test rice samples, a chemometric technique known as orthogonal projection (OP) was applied to extract variation of the target KDML105 rice, which then was exclusively used for establishing the prediction model. Furthermore, calibration transfer (CT) was used to adjust the NIR spectra of the adulterated samples to comply with the prediction of the calibrated model. The predictive abilities of the developed models were improved resulting in relatively lower root mean square error of prediction (RMSEP) values with higher determination of coefficient (Q2) values. In addition, the combined uses of the preprocessing methods provided a data treatment strategy that yielded a more stable model in the subsequent calibration step with the lowest standard deviation of RMSEP. This development was allowed for the quantitative prediction of the adulterations in the rice without the need for information pertaining to the blended rice.

Influences of Farming Practices on Soil Properties and the 2-Acetyl-1-pyrroline Content of Khao Dawk Mali 105 Rice Grains

Khao Dawk Mali 105 (KDML105) is a premium fragrant rice variety and is widely grown in Thung Kula Rong Hai (TKR), northeast Thailand. In the present study, the influence of organic and conventional rice farming (ORF and CRF, respectively) in TKR farmers’ paddy fields on soil properties and their relationship with 2-acetyl-1-pyrroline (2AP) in KDML105 rice grains were investigated. The results indicated that the ORF system had a strong positive effect on major soil quality indicators and the 2AP content in the rice grains. The soil organic matter (SOM) was approximately twice as much in the ORF than in the CRF system, thus leading to much higher total nitrogen (TN), humic acid (HA), and microbial populations in the ORF system. The higher SOM in the ORF system not only enhanced the soil quality indicators but also contributed to approximately 3.5 times higher 2AP than in the CRF system. Principle component analysis indicated a close correlation among SOM, TN, HA, and microbial population under the ORF system; these variables exhibited strong correlations with the 2AP contents in KDML105 rice grains.