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Soil salinity is a limitation factor for rice cultivation in the north-eastern Thailand. Understanding the mechanisms of salt stress tolerance is critical for maintaining or improving crop yield under salt stress. Over the past ten years, many landrace rice varieties have been examined for genetic diversity. To utilize the richness of natural resources and to explore novel genetic resources for developing a new variety, evaluating local rice varieties for salinity is still needed. This study investigated the physiological and biochemical responses of 8 landrace rice varieties in comparison to ‘Pokkali’, the standard salt-tolerant rice genotype, to clarify the major salt tolerance mechanisms in the landraces found in Thailand. After being exposed to 120 mM NaCl for 7 days, ‘Pokkali’ expressed physiological parameters in response to salt stress which are indicative of salt tolerance ability including low growth reduction, low Na+/K+ ratio, low chlorophyll degradation and low membrane integrity. In contrast, the landrace varieties displayed varying patterns of response. No landrace variety showed an outstanding ion exclusion mechanism as ‘Pokkali’, as evidenced by the fact that all landrace varieties showed approximately two times higher Na+/K+ ratios than ‘Pokkali’. However, it was found that ‘Surin’ had a similar salt stress response to ‘Pokkali’ (low growth reduction, low chlorophyll degradation, low membrane integrity), except for the markedly increased proline and sugar accumulation, suggesting an osmotic adjustment mechanism. Therefore, this variety could be a potential genetic resource to be developed as a donor for the osmotic adjustment trait to improve salt-tolerant rice in the future.

Rice varieties with high anthocyanin content are often recognized for their vibrant colors and health benefits. The demand for rice with high anthocyanin is increasing domestically and internationally due to consumers becoming more health-conscious. However, the current increase in yield might not raise the anthocyanin content due to its location in the grain pericarp and seed coat, which are relative to the grain surface area. This study aims to develop rice lines to increase anthocyanin yield per production area by improving rice varieties with small, black, and three grains per spikelet. Accordingly, six rice recombinant inbred lines (RILs) were bred by crossing Niaw Dam Chaw Mai Pai 49 (NDCMP49) with Khao Nok (LLR059). The grain color, size, and number of grains per spikelet were selected from the F1 to the F4 population through the pedigree selection method. Six RILs and their parents were assigned in a randomized complete block design (RCBD) with three replications under field conditions during the rainy season of 2021 and 2022 in four locations. The results showed statistically significant differences in environmental conditions, affecting productivity and the yield components of rice lines. Consequently, the rice lines adapted to a specific environment, and there were significant differences in genotype. This study identified three RILs with higher yield performance (13-1 (3842 kg/ha), 374-1 (3699 kg/ha), and 903-3 (3550 kg/ha)) compared with the parent NDCMP49 (1996 kg/ha). However, the grain yields were unstable in the three top-yielding RILs due to varying environmental conditions, indicating that selective breeding requires a specific, narrow environment. Based on grain yield and grain size, the RILs performed better in the grain surface area than in the parent NDCMP49. Moreover, only two RILs (374-1 and 903-3) produced the highest anthocyanin content and yield, although this was lower than in the parent NDCMP49. However, the 374-1 and 903-3 RILs produced more grains, black grains, and three grains per spikelet with high yield and moderate anthocyanin content. They can, therefore, be backcrossed to the parent NDCMP49 to increase the accumulated anthocyanin content with a stable, high yield. This work provides a resource of small grains, black grains, and three grains per spikelet in the rice breeding line for breeding programs in the future.

RD6, the most popular glutinous rice in Thailand, is high in quality but susceptible to blast and bacterial blight disease. It was thus improved for disease resistance through marker-assisted backcross selection (MAS). The objective of this study was to evaluate the performance of improved near isogenic lines. Eight RD6 rice near isogenic lines (NILs) derived from MAS were selected for evaluation with RD6, a standard susceptible check variety, as well as recurrent parent for a total of nine genotypes. The experiment was conducted during the wet season under six environments at three locations, Khon Kaen, Nong Khai, and Roi Et, which was repeated at two years from 2019 to 2020. Nine genotypes, including eight RD6 rice near isogenic lines (NILs) selected from two in-tandem breeding programs and the standard check variety RD6, were evaluated to select the high-performance new improved lines. The first group, including four NILs G1–G4, was gene pyramiding of blast and BB resistance genes, and the second group, including another four NILs G5–G8, was gene pyramiding of blast resistance and salt tolerance genes. Field disease screening was observed for all environments. Two disease occurrences, blast (leaf blast) and bacterial blight, were found during the rainy season of all environments. The NILs containing blast resistance genes were excellent in gene expression. On the other hand, the improved lines containing the xa5 gene were not highly resistant under the severe stress of bacterial blight (Nong Khai 2020). Notwithstanding, G2 was greater among the NILs for yield maintenance than the other genotypes. The agronomic traits of most NILs were the same as RD6. Interestingly, the traits of G2 were different in plant type from RD6, specifically photosensitivity and plant height. Promising rice RD6 NILs with high yield stability, good agronomic traits, and disease resistance were identified in the genotypes G1, G2, and G7. The high yield stability G1 and G7 are recommended for widespread use in rain-fed areas. The G2 is specifically recommended for use in the bacterial blight (BB) disease prone areas.

The winged bean is only one of the members of the leguminous species that has the potential for duo-purpose for its pod and tuber yields. The protein and nutritional content in the tuber can be used as alternative crops for animal feed. Previous studies identified the winged bean varieties as having high potential for tuber production, although their tuber development remains unclear. This study aims to elucidate the development of winged bean tubers based on their size and weight during eight months of growth. Tuber yields of high-potential winged bean varieties (W018 and W099) were compared to commercial varieties (Ratchaburi) under field conditions over two years. The experiments were laid out in randomized complete block design with three replications in the 2021–2022 and 2022–2023 growing seasons. The tuber formation of winged bean exhibited a significant increase in tuber weight and size in the fourth month of growth in all varieties, with a gradual change from fibrous roots to tubers. Particularly in the W018 and W099 varieties, tuber development persisted up to eight months after transplanting. On the other hand, the Ratchaburi variety had small tuber size, resulting in the tubers weighing less than in the W018 and W099 varieties. The results indicated that winged bean varieties had different tuber development, with the W018 and W099 varieties being suitable for tuber harvesting at eight months. The large tuber size can be an appropriate alternative to animal feed materials. At the same time, the Ratchaburi variety requires only five months since it is cultivated primarily for tuber consumption, which is concerned with size and shape. Moreover, the yields of the W018 and W099 varieties were significantly higher compared to Ratchaburi at 22.4, 19.3, and 7.423 T/ha in the 2021–2022 growing season and 8.4, 7.9, and 5.6 T/ha in the growing season of 2022–2023, respectively. The protein content in the winged bean tubers increased to 13.00% at eight months. The years (Y) and genotypes (G) differed considerably for tuber formation. The variation in both Y and G and the shoot/root ratio are also discussed in this study.

Bacterial blight (BB) caused by Xanthomonas oryzae pv. Oryzae (Xoo) is a serious disease of rice worldwide that can reduce crop yield and affect food insecurity. A rice resistance variety is an alternate way to solve this problem. The broad-spectrum resistance (BSR) of ULR207 is important for durable resistance to several of the Xoo isolates. However, the inheritance of this resistance gene in ULR207 must be known before it can be utilized. Thus, this study aimed to survey the BB resistance gene with reference to the BB resistance gene for identification of non-analogous or analogous genes and confirmation of a broad-spectrum resistance, to investigate the gene effect, the number of genes, and the heritability of the BB resistance gene in the ULR207 variety. Six populations of two crosses (Maled Phai × ULR207 and RD6 × ULR207), i.e., ULR207 (Donor parent), Maled Phai and RD6 (Recurrent parent), F1, F2, BC1P1, and BC1P2 were constructed. These materials were evaluated for BB resistance by clipping methods under greenhouse conditions using a virulence isolate of a pathogen in Thailand. The results showed that ULR207 exhibited the strongest against BB with 0.8 of BSR with low area under the disease progress curve (AUDPC). Molecular screening for surveying of the BB resistance gene in ULR207 revealed a non-analogous resistance gene with resistance check varieties. The phenotype of the disease lesion length of F2 and BC1P2 populations exhibited a ratio of 1:3 and 1:1 (resistant: susceptible), respectively, revealing a single recessive gene in both crosses. The scaling test parameters A, B, and C were non-significant (p < 0.01), indicating that variation in data was sufficiently explained by additive (d) and dominance (h) components. The gene action of ULR207 was controlled by additive gene action. Heritability of the two crosses, Maled Phai x ULR207 and RD6 x ULR207, exhibited high values with 0.817 and 0.716, whereas the numbers of the genes were 1.4 and 1.2, respectively. The result indicated that the breeding strategy could be employed in early generations when using ULR207 as a new source of bacterial blight resistance.

Winged bean [Psophocarpus tetragonolobus (L.) DC.] is a neglected and underutilized crop in Thailand, and yet is locally important throughout much of Asia and in some parts of Africa. In Thailand, winged bean cultivars are landrace selections that are mainly grown in home gardens across the country. In this study, the genetic diversity and population structure of 60 domestic (Thai) and 64 imported winged bean accessions were assessed via their comparative morphological traits and 13 gene-based simple sequence repeat (SSR) markers. The 13 markers generated 36 alleles in total with an average of 2.77 alleles per marker, and overall gene diversity of 0.47. The gene diversity of the Thai and imported winged bean accessions was comparable with values of 0.42 and 0.49, respectively. The estimated out-crossing rate was relatively high, at 16.28%. STRUCTURE, phylogenetic, and principal coordinate analyses consistently revealed the separate yet intermingled attributes of several accessions, which demonstrated their similar genetic diversity of the Thai and imported winged beans. The Thai and imported winged bean populations were comparable in days to flowering, pod length and seed size. Majority of the Thai and imported winged bean accessions showed the same qualitative traits, including leaf shape, flower color, pod color and pod shape. These suggested the winged bean growers' similar preferences and selection of winged beans in different geographical regions. The admixture within the genetic base of the winged bean indicates the need for the management of future breeding programs.

There is an increasing interest in finding eco-friendly and safe approaches to increase agricultural productivity and deliver healthy foods. Arbuscular mycorrhizal fungi (AMF) and endophytic fungi (EPF) are important components of sustainable agriculture in view of their ability to increase productivity and various plant secondary metabolites with health-promoting effects. In a pot experiment, our main research question was to evaluate the additive and synergistic effects of an AMF and four root-endophytic fungi on plant performance and on the accumulation of health-promoting secondary compounds. Plant growth varied between the treatments with both single inoculants and co-inoculation of an AMF and four EPF strains. We found that inoculation with a single EPF positively affected the growth and biomass production of most of the plant-endophyte consortia examined. The introduction of AMF into this experiment (dual inoculation) had a beneficial effect on plant growth and yield. AMF, Rhizophagus variabilis KS-02 co-inoculated with EPF, Trichoderma zelobreve PBMP16 increased the highest biomass, exceeding the growth rate of non-inoculated plants. Co-inoculated R. variabilis KS-02 and T. zelobreve PBMP16 had significantly greater beneficial effects on almost all aspects of plant growth, photosynthesis-related parameters, and yield. It also promoted root growth quality and plant nutrient uptake. The phenolic compounds, anthocyanin, and antioxidant capacity in rice seeds harvested from plants co-inoculated with AMF and EPF were dramatically increased compared with those from non-inoculated plants. In conclusion, our results indicated that EPF and AMF contributed to symbiosis in Maled Phai cultivar and were coordinately involved in promoting plant growth performance under a pot trial.

Rice provides 70% of dietary carbohydrates and other essential nutrients. Breeding for consumer preferences and health benefits are the main considerations. Rice with a low amylose content offers a good cooking quality with its soft and sticky texture but fast starch digestibility with a high sugar release. Therefore, to provide health benefits, it is important to identify rice varieties with slow starch digestibility and a low amylose content. A total of 167 indigenous upland rice germplasms were analysed for amylose content (AC) and in vitro starch digestibility. The results showed that 167 upland rice genotypes were mostly low in AC, which was related to a soft and sticky texture during cooking. Based on the glutinous and non-glutinous types, thirteen and nine indigenous upland rice germplasms were selected with a lower AC than RD6 and KDML105 (check varieties). The in vitro starch digestibility and the hydrolysis were different at each time point and different in each variety. In the glutinous group, ULR155, ULR138, ULR308, and ULR241 released less sugar and had slower starch digestibility than RD6. In the non-glutinous group, ULR219 and ULR264 showed lower AC, slower digestion, and lower sugar release than KDML105. The results suggest that six indigenous upland rice varieties will provide a rice source to accommodate consumer preferences while also offering health benefits.

Rice (Oryza sativa L.) is one of the most popular cereal crops, being consumed by almost half of the world’s population. Among several cultivars widely distributed in Thailand, Maled Phai is a Thai pigmented-upland rice with exceptionally high nutritional value and high demand in the local Thai market. This study aimed to investigate the feasibility of producing plant growth-promoting properties (PGP) and enhancing the accumulation of phytochemicals in Maled Phai rice seeds of endophytic fungi isolated from upland black rice. Among a total of 56 isolates, the 4 most effective PGP isolates were identified as Trichoderma zelobreve PBMP16, Talaromyces pinophilus PBMP28, Aspergillus flavus KKMP34, and Trichoderma sp. PBMP4 based on their morphological characteristics and multigene (ITS, rpb2, tef-1, CaM, and BenA) phylogenetic analyses. These four endophytic fungi could promote plant growth parameters under greenhouse conditions. Outstandingly, upland rice inoculated with Tr. zelobreve PBMP16 had a significant increase in total seed weight, root length, phenolic compounds, anthocyanin, antioxidants, and N uptake, which were higher than those of the noninoculated control, and even better than the chemical fertilizer. Overall, this report shows that endophytic fungi efficiently promoted growth and increased the phenolic compounds, anthocyanin, and antioxidants of Maled Phai rice.

Indigenous upland rice is a staple food for local people in the North and Northeast regions of Thailand. As a result, variations of grain yield and GxE interactions have been utilized for wider adaptability of upland rice varieties. A high yielding genotype that performs well under a good yielding environment as well as in poor environments is greatly needed. Our experiment, therefore, aimed to identify high potential indigenous upland rice varieties for grain yield and yield stability under rainfed conditions. Fifty upland rice genotypes were evaluated from 2013 to 2015, in which a randomized complete block design with three replications was laid out over the three years. Based on grain yield, eight indigenous upland rice varieties, including ULR026, ULR042, ULR075, ULR078, ULR080, ULR081, ULR089 and ULR105; demonstrated superior performance, high yield stability, and greater adaptability over the other varieties, including the Sew Mae Jan check variety. Additional qualities of the superior varieties included high amylose content (ULR081 and ULR075), high aroma (ULR078), and intermediate gelatinization temperature test (GT) (ULR078, ULR026, and ULR105). The participatory varietal selection (PVS) test for farmer(s) acceptance, and promotion of these varieties under rainfed conditions will be further studied.

Bacterial blight (BB) has caused significant reductions in yield and quality of rice. The use of genetically resistant cultivars has proven to be one of the most effective methods used to address this problem. This study screened a total of 333 Thai lowland indigenous rice germplasms against four Xanthomonas oryzae pv. oryzae (Xoo) isolates under greenhouse conditions in the rainy and dry seasons of 2017. The ten varieties demonstrating the greatest BB resistance in the lower five centimeters of the lesion lengths in both experiment years were further investigated and validated for their agronomic performances in field conditions at the Udon Thani Rice Research Center in 2018. Our findings revealed that of the ten BB resistant lowland rice varieties, five varieties; LLR023, LLR134, LLR137, LLR205 and LLR207, exhibited high performances of agronomic traits in field conditions; as found in the plant height, tiller number, panicle number, panicle length, seeds per panicle, grain yield and harvest index when compared with the KDML105 check varieties. These five selected rice varieties may further serve as new genetic resources for future BB resistance and agronomic trait improvement programs.

Black rice (Oryza sativa L.) contains high concentrations of bioactive compounds that are associated with human-health benefits. Arbuscular mycorrhizal fungi (AMF) can increase plant performance and concentrations of these bioactive compounds. In a pot experiment, the effects of four different species of AMF (Claroideoglomus etunicatum; Rhizophagus variabilis; Rhizophagus nov. spec.; Acaulospora longula) were assessed on growth performance, grain yield, concentrations of phenolic compounds and anthocyanin, and antioxidant activity of two black-rice cultivars. The experiment was a completely randomized factorial design with two factors, viz. cultivar (Niew Dam Hmong and Maled Phai) and treatment (four different species of AMF and two non-inoculated treatments, without and with mineral fertilizer). Results showed that cultivar, treatment, and their interaction were almost always significant sources of variation for both plant performance parameters and concentrations of bioactive compounds. Maled Phai showed higher performance and higher concentrations of phenolics and anthocyanins but lower antioxidant activity than Niew Dam Hmong. The non-inoculated treatment without mineral fertilizer showed the lowest performance. The non-inoculated treatment with mineral fertilizer resulted in larger root and shoot biomass than the mycorrhizal treatments, but grain yield was higher in the mycorrhizal treatments. Inoculation with R. variabilis resulted in the highest concentration of phenolics and anthocyanins. We conclude that R. variabilis was the best inoculum for increasing grain yield and bioactive compounds, especially in Maled Phai.

Rice is an important and main staple food crop. Rice in Thailand grows in both the on- and off-seasons. The problem of growing rice in the off-season is that it is dry and the temperature tends to be high. To evaluate the effects of high temperatures on their phenology, yield and seed quality, three rice varieties were cultivated off-season in 2018 and 2019. Rice plants were grown in cement pots on planting date I (PDI; off-season; mid-January) and planting date II (PDII; late off-season; beginning of February). The results showed that rice plants were exposed to higher temperatures in 2019 (than 2018), as indicated by a higher accumulated growing degree day (AGDD). The high AGDD affected the phenology of the rice by shortening the duration of its development from sowing to physiological maturity (PM) from 106.8 DAS in 2018 to 86.0 DAS in 2019. The high AGDD shortened the development duration of the embryo and endosperm, resulting in reductions in the size and growth rates of the embryo and endosperm, and eventually reduced the yield and the yield components. Moreover, the high AGDD reduced the seed quality, as indicated by a decline in the seedling growth rate (SGR) and an increase in chalkiness. Among the varieties, the high temperature in 2019 caused the smallest phenological shift in Chai Nat 1 (CN1), while the shift was largest in Pathum Thani 1 (PTT1). In addition, CN1 exhibited a significantly higher total seed weight/panicle, 1000-seed weight and percentage of filled seed/pot than SP1 and PPT1. It was suggested that CN1 could be described as heat tolerant, and PTT1 as heat sensitive. It was also suggested that farmers should select appropriate rice varieties to grow in the off-season due to the risk of a high-temperature-induced reduction in the seed yield and quality.

Rice blast (BL) caused by Magnaporthe oryzae is a fungal disease causing significant yield losses in rice production worldwide. To overcome the breakdown of resistance by the rapid adaptation of pathogens, identifying resistance (R) genes or QTLs in indigenous rice, which harbors the R genes that co-evolved with the local pathogen race, is necessary. In this study, a recombinant inbred line (RIL) population derived from a cross between RD6 and Phaladum (PLD) was used to map quantitative trait loci (QTL) for BL resistance through a QTL-seq approach. A single QTL (qBLchr4) associated with BL resistance at the seedling and maximum tillering stages was mapped on the long arm of chromosome 4. Five genes, LOC_Os04g0616600, LOC_Os04g0617900 (OsGLP4-1), LOC_Os04g0619600 (OsRLCK161), LOC_Os04g0620800 (Pi63), and LOC_Os04g0621500, were considered the candidate genes representing qBLchr4. Subsequently, the Kompetitive Allele-Specific PCR (KASP) markers specific for the SNP variant and position of each gene were designed for validation in the mapping population. These markers showed the high phenotypic variance explained (PVE) values in all testing methods and/or environments, signifying the major effect of qBLchr4. Among these markers, the Pi63-KASP marker explained the highest and most stable phenotypic variation across all testing methods and/or environments, with 84.18%, 80.34%, and 23.43% in the upland short row (USR) method, Sila environment, and Mueang environment, respectively. Therefore, Pi63 was suggested to be the strongest candidate gene. These results represent the potential utility of future BL resistance breeding and/or pyramiding using marker-assisted selection (MAS).

Bacterial blight (BB) disease, caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most devastating diseases of rice worldwide. Breeding for BB resistance has been utilized to overcome this constraint of rice production; however, limited genetic resources of BB resistance or non-desirable genetic linkage between BB disease resistance and agronomic traits have become major obstacles. Interestingly, indigenous upland rice cultivars cultivated across Thailand are considered to be novel genetic resources of BB resistance for rice cultivar improvement through breeding programs. In this study, we screened for BB disease resistance among 256 indigenous upland rice cultivars using individual inoculation of two virulent Xoo isolates; NY1-1 and MS1-2, under greenhouse conditions. The results showed that 19 indigenous rice cultivars demonstrated BB disease resistance abilities after inoculation. These 19 upland rice cultivars were further examined for broad-spectrum resistance (BSR) performance through five individual Xoo isolate inoculations, under greenhouse conditions. Moreover, a mixed five Xoo isolate inoculation, including NB7-8, CM3-1, CN2-1, MS1-2, and NY1-1, was conducted to assess the BSR for BB resistance of those 19 cultivars under field conditions. Simultaneously, independent plants of the 19 varieties were grown without inoculation in the field to observe the disease reactions from the natural infection caused by local Xoo isolates. The results of the three experiments herein showed that five indigenous upland rice cultivars—ULR024, ULR029, ULR172, ULR207, and ULR356—consistently expressed 100% BSR to BB disease, as well as the resistance check varieties, IRBB5. This further illustrated that ULR024, ULR029, ULR172, ULR207, and ULR356 upland rice cultivars were phenotypically resistant to five Xoo isolates, within those (a) inoculated with five individual isolates under greenhouse conditions or (b) inoculation with five mixed isolates under field conditions. Moreover, the ULR024, ULR029, ULR172, ULR207, and ULR356 revealed BB disease-resistance abilities to natural infection. These results present novel genetic resources from indigenous upland rice cultivars in further breeding program of BB resistance in varied rice cultivars.

Indigenous upland rice (Oryza sativa L.) is an important staple food for people. The productivity of upland rice is generally lower than lowland rice since crop yield depends on the amount of rainfall. Climate change is a major problem in rice production due to the unpredictable rainfall. The flowering time, maturity days, growth duration, and photoperiod sensitivity in rice are important for determining productivity. Therefore, in this study, indigenous upland rice germplasm was classified according to their flowering-related traits in the basic vegetative phase (BVP), photoperiod sensitivity index (PSI), grain yield (GY), and yield components. The results reveal that the BVP ranges from 12 to 76 days (mainly less than 30 days) while the PSI ranges from −0.14 to 0.89. Classification of the three groups was based on the PSI: 24 insensitivities (G1; PSI = −0.14–0.30), 214 weakly sensitive (G2; PSI = 0.31–0.70), and 63 strongly sensitive (G3; PSI = 0.71–0.89). Grain yield showed different correlations with day to flowering (DTF), PSI, and BVP in each group. The results suggest that the selection criteria were not only based on GY and DTF but also PSI and BVP. The new ideotypes for upland rice selection under unpredictable conditions such as rainfall and light duration are weakly sensitive (PSI range 0.30–0.60), low BVP (20–30 days), and less than 105 days of DTF, such as ULR189, ULR039, ULR036, ULR403, ULR364, ULR342, and ULR245 genotypes.

Upland rice usually gives poor germination under rainfed upland environement. To improve the seed germination, seed priming technique was assessed in this study. Seed of three upland rice (Oryza sativa L.) varieties (Leum Pua, ULR038 and Sakon Nakhon1, SKN) were primed with three different seed priming agents; distilled water, CaCl2 and 300-fold diluted wood vinegar. Compared to untreated dry seeds, wood vinegar improved field emergence and improved drought tolerance of the rice seeds better than other priming agents, which 50 % for Leum Pua, 20 % for ULR038 and 16% for SKN, when watering was delayed for 7 days. All three priming agents increased the field emergence percentage by similar amounts when watering was delayed for 14 days. To understand how priming helped improvement of germination, antioxidation mechanism and sugar metabolism were examined. Level of malondialdehyde was markedly reduced in all three rice varieties in response to priming, which were associated with increased activity of antioxidant enzymes, guaiacol peroxidase and ascorbate peroxidase. Wood vinegar also accelerated amylase activity in ULR038 and SKN, but not the sugar content. The results suggest that wood vinegar is a potent priming agent for achieving rapid and uniform seed germination in upland rice.

Winged bean [Psophocarpus tetragonolobus (L.) DC.] (2n = 2× = 18) is a tropical legume crop with multipurpose usages. Recently, the winged bean has regained attention from scientists as a food protein source. Currently, there is no breeding program for winged bean cultivars. All winged bean cultivars are landraces or selections from landraces. Molecular markers and genetic linkage maps are pre-requisites for molecular plant breeding. The aim of this study was to develop a high-density linkage map and identify quantitative trait loci (QTLs) for pod and seed-related traits of the winged bean. An F2 population of 86 plants was developed from a cross between winged bean accessions W054 and TPT9 showing contrasting pod length, and pod, flower and seed colors. A genetic linkage map of 1384 single nucleotide polymorphism (SNP) markers generated from restriction site-associated DNA sequencing was constructed. The map resolved nine haploid chromosomes of the winged bean and spanned the cumulative length of 4552.8 cM with the number of SNPs per linkage ranging from 36 to 218 with an average of 153.78. QTL analysis in the F2 population revealed 31 QTLs controlling pod length, pod color, pod anthocyanin content, flower color, and seed color. The number of QTLs per trait varied between 1 (seed length) to 7 (banner color). Interestingly, the major QTLs for pod color, anthocyanin content, and calyx color, and for seed color and flower wing color were located at the same position. The high-density linkage map QTLs reported in this study will be useful for molecular breeding of winged beans.

The planting of upland rice is one cropping option in area with limited water availability and low soil fertility in North and Northeast Thailand. The varietal selection was determined by grain yield potential, wide adaptation, and good stability. This study was aimed at evaluation of indigenous upland rice germplasm for yield and yield stability in multi-locations. Thirty-six upland rice genotypes collected from six provinces of the North and Northeast Thailand and one check variety (Sewmaejan) were assessed under five locations in the rainy seasons of 2009 and 2010. The experiment was laid out in a randomized complete block design with three replications. The genotype grain yield was highly affected by location (59.90%), followed by genotypes (G)×location (L) interaction (12.80%) and genotype (6.79%). The most suitable location for the genotype evaluation was L3 (Khon Kaen-KKU10) which associated with stability of grain yield for all genotypes. Furthermore, biplot and regression analysis indicated that genotype numbers 6 (Jaowmong 1), 10 (Neawmong 1), 18 (Neawdum 1), 19 (Leamna), 20 (Prayaleamkang), 32 (Kunwang 2), and 33 (Kunwang 3) showed great yield stability over five locations. The genotypes will be applicant for upland rice production area and parental base in breeding program.

The study aimed to improve the small-ear waxy corn populations for prolificacy, high total carotenoid content and resistance to downy mildew. Three cycles of modified mass selection were carried out for population improvement. Forty-four genotypes derived from eight C3 populations and six check varieties were evaluated for agronomic traits and yield at Khon Kaen and screened for downy mildew resistance in the rainy season 2020 at two experimental sites in Ban Phang district of Khon Kaen province. Fifty genotypes were clustered into six major groups based on color parameter (h°) and total ear number. Two selected groups (C and E) with two populations of small-ear waxy corn including Nei9008/BK-24-9-B and TY/TF-33-1-B were selected as they were resistant to downy mildew, prolific ears, and intense orange kernel color. Modified mass selection was effective for improvement of multiple traits in waxy corn.

Taeng-Thai is the Thai name for oriental pickling melon or muskmelon (Cucumis melo L.) which is a Cucumis species. Based on consumption as Thai traditional dessert, fruit characters at ripening stage are very important to improve the muskmelon cultivar. Understanding the genetic control of fruit traits is the key to a successful for crop improvement. Research aimed to determine the genetic effects, number of genes and heritability of fruit characters in muskmelon. The results have shown that both additive and dominant effects governed for fruit weight, fruit length, fruit width and fruit thickness with the number of gene as 40.26, 1.55, 10.70 and 11.10 genes, respectively. Simple phenotypic correlation coefficients shown, had a significant positive correlation among the four fruit traits. Due to the quantitative inheritance of fruit characters, quantitative traits loci (QTL) mapping of those traits were necessary to identify all controlling genes of fruit traits in further muskmelon improvement.

Thai rice cultivar RD6 is well known for its cooking and eating qualities. However it is susceptible to blast disease, a major rice disease caused by the fungus Magnaporthe oryzae. This study focused on the pyramiding of four QTLs for blast resistance located on chromosomes 1, 2, 11 and 12, from two RD6 introgression lines. Marker-assisted selection was performed and facilitated the selection with 8 microsatellite flanking markers to enable the selection in BC2F2:3 lines. All possible combinations of the four QTL alleles were assessed for blast resistance by artificial inoculation using 8 diverse isolates in a greenhouse and under field conditions using the upland short row method. The results showed that the RD6 introgression lines carrying a high number of QTLs for blast resitance achieved from pyramiding have high levels of blast resistance and broad spectrum of resistance to the blast pathogens prevalent in the region. Only one of the M. oryzae isolates, THL185, was virulent to all the breeding lines, suggesting that the identification of new blast resistance genes or QTLs and pyramiding them into RD6 for durable blast resistance and no yield penalty should be the focus of further research.

Waxy corn is a popular, alternative staple food in most Asian countries including Thailand. The availability of small-ear waxy corn genotypes with prolific ears and a high level of carotenoids is expected to benefit growers and consumers. Integrated evaluation among source germplasm is essential before performing further breeding efforts for enhancing prolific ears and high-carotenoid content. Thus, the present study explored the variability of ear prolificacy, total carotenoids, lutein, zeaxanthin, and beta-carotene among yellow small-ear waxy corn accessions. About 44 corn accessions and 4 check varieties were evaluated for agronomic traits and yield components under multienvironment trials in a randomized complete block design (RCBD). The immature seed sample of these genotypes was analyzed to quantify the content of total carotenoids and some carotenoid fractions. All traits showed that low GXE interaction and significant genotypic diversity existed among all tested accessions with the predominant contribution of genotype to total phenotypic variation and beta-carotene. Accessions were clustered into four major groups based on the similarity of multiple carotenoids profiles. Three selected accessions (UT121001, KKU-WX112087, and KKU-WX212001) had higher values of total carotenoids, lutein, zeaxanthin, and beta-carotene than those of all check varieties. High and positive correlations among second-emerged ears, marketable second-emerged ears, and total ear number indicate that a higher chance of secondary ears becomes marketable ears with an increase of total ears per plant per hectare. Lutein and zeaxanthin had positive, strong correlations with total carotenoids. The implications and breeding strategies are discussed prior to promoting yellow small-ear waxy corn as a biofortified crop.

Winged beans (Psophocarpus tetragonolobus (L.) DC.) are grown as a vegetable legume crop in Thailand. All parts of the plant, including pods, seeds, leaves, flowers, and tubers are edible and are rich in protein and nutrients. Although the major consumption of winged bean is based on pod and tuber yields, only the people of Myanmar and Indonesia utilize winged bean tubers as food materials. The usefulness of the winged bean as an alternative crop for staple food and feed can shed some light on the impact of winged bean. Therefore, the evaluation of the dual purpose of the winged bean based on pod tuber yields is the objective of this study. In this study, ten-winged bean accessions—six accessions obtained from introduced sources and four accessions obtained from local Thai varieties—were laid out in randomized complete block design (RCBD) with three replications at the Agronomy Field Crop Station, Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand from September 2019 to April 2020 and from October 2020 to April 2021. Data, including total pod weight, number of pods, pod length, 10-pod weight, and tuber weight were recorded, and the proximate nutrient and mineral contents in the tubers were also determined. The results revealed that the principal effects of year (Y) and genotype (G) were significant for total pod weight and the number of pods. Moreover, the Y × G interactions were principal effects upon the total pod weights and tuber weights. The results indicated that superior genotype and appropriate environmental conditions are key elements in successful winged bean production for both pod and tuber yields. The winged bean accessions W099 and W018 were consistent in both experimental years for pod and tuber yields at 23.6 and 18.36 T/ha and 15.20 and 15.5 T/ha, respectively. Each accession also proved high in tuber protein content at 20.92% and 21.04%, respectively, as well as significant in fiber, energy, and minerals. The results suggest that the winged bean accessions W099 and W018 can be used for dual-purpose winged bean production in Thailand.

The soybean (Glycine max (L.) Merrill) is one of the world’s most important sources of food, feed, and fuel due to its high protein value and oil content. However, there exists a lack of soybean genotypes suitable for growth in diverse conditions as soybean breeders have developed their own varieties for specific purposes within their own unique environments. This, therefore, creates the need for soybean genotypes for different environments. The objectives of the experiment described herein were to determine the genotype magnitude through the environment interaction (GxE) of new soybean breeding lines, thereby identifying widely and/or specifically adapted genotypes under ten of Northeast Thailand’s typical environmental conditions from 2017 to 2019. Analyses of the environment (E) and GxE captured a large portion of the total sum of squares of grain yield and related traits, which demonstrated the influence of the two factors in evaluating soybean genotypes, thereby identifying the need for response analysis to identify superior genotypes in each environment. Based on the grain yields of three environments, four genotype groups were clustered. Within the high grain yield environment (EG1), we identified five genotypes with higher yield performance (35*sj-32 (3356 kg/ha), 38D*a-16 (3138 kg/ha), 42*Ly-50-2 (3122 kg/ha), 35*Lh-7 (3116 kg/ha), and 223*Lh-85 (3073 kg/ha)) of KK (3132 kg/ha), the recommended soybean variety for Northeast Thailand, than that of the CM60 (2606 kg/ha). These five top-yielding genotypes, however, produced unstable grain yields through varied environments as they were each narrowly adapted to a specific environment. Moreover, those genotypes may be grown within a rotational cropping system in a duo-environment (wet and dry season) of soybean production in Thailand’s northeast region.

RD6 is one of the most favorable glutinous rice varieties consumed throughout the north and northeast of Thailand because of its aroma and softness. However, blast disease and salt stress cause decreases in both yield quantity and quality during cultivation. Here, gene pyramiding via marker-assisted backcrossing (MAB) using combined blast resistance QTLs (qBl 1, 2, 11, and 12) and Saltol QTL was employed in solving the problem. To pursue our goal, the RD6 introgression line (RGD07005-12-165-1), containing four blast-resistant QTLs, were crossed with the Pokkali salt tolerant variety. Blast resistance evaluation was thoroughly carried out in the fields, from BC2F2:3 to BC4F4, using the upland short-row and natural field infection methods. Additionally, salt tolerance was validated in both greenhouse and field conditions. We found that the RD6 “BC4F4 132-12-61” resulting from our breeding programme successfully resisted blast disease and tolerated salt stress, while it maintained the desirable agronomic traits of the original RD6 variety. This finding may provide a new improved rice variety to overcome blast disease and salt stress in Northeast Thailand.

Pigmented rice is receiving much attention due to the large amounts of bioactive compounds and various health benefits.However, little information is available on its agronomic and physiological aspects. This research aimed to explore the effects of salinity on yield and grain quality of pigmented rice and the modulation of salinity responses by exogenous application of spermidine (Spd). Four cultivars of rice were grown in pots until the early booting stage. Thereafter, the plants were sprayed with 1 mM Spd for 7 successive days before being irrigated with 25 mM NaCl instead of tap water until maturity. Grain yield, yield components and harvest index in all rice cultivars were negatively affected by this salinity stress. Pretreatment with Spd dramatically improved yield and yield components of salt-treated plants, particularly the salt-sensitive cultivar. The major yield components which were improved and contributed most to the dramatic increase in seed yield were the number of filled grains per panicle and panicle fertility. Moreover, Spd pretreatment resulted in an increase in K+/Na+ ratio in rice grains. Salt stress increased nutritional quality of mature grains, i.e., total phenolic content, anthocyanins, proanthocyanins and antioxidant activities (evaluated by FRAP, DPPH and ABTS assays) in all rice cultivars. Furthermore, all aspects of health-promoting nutritional characters were further enhanced by Spd pretreatment. Thus foliar spraying of Spd to rice plants prior to salt application improved grain yield as well as nutritional quality of colored rice grains in relation to total phenolics, flavonoid pigments and antioxidant capacities.

This study was carried out to elucidate the spermidine (Spd) and gibberellic acid (GA3) priming-induced physiological and biochemical changes responsible for induction of salinity tolerance in two rice (Oryza sativa L.) cultivars, namely ‘Niewdam Gs. no. 00621’ (salt tolerant) and ‘KKU-LLR-039’ (salt sensitive). The seeds of the two cultivars were primed separately with distilled water, 1 mM Spd or 0.43 mM GA3. Primed seeds were germinated and the resultant seedlings were hydroponically grown for 14 days before being exposed to salinity stress (150 mM NaCl) for 10 days. Seed priming with Spd or GA3 slightly improved salt-induced reductions in growth, anthocyanin and chlorophyll contents of the seedlings. Salt stress induced pronounced increases in Na+/K+ ratio, proline and H2O2 contents, particularly in the sensitive cultivar. The levels of these salt-sensitivity physiological indicators tended to be mitigated by priming with Spd and GA3. Salt-stressed seedlings grown from seeds primed with these growth regulators also possessed higher phenolic contents and greater antioxidant capacity than the control seedlings. Based on all growth and physiological data, Spd tended to be more effective than A3 in improving salt tolerance in both rice cultivars.

The objectives of this study were to verify the use of LW7 marker in identifying maintainer lines (B-lines) and restorer lines (R-lines) in grain sorghum and sweet sorghum, and to identify B-lines in the F2, BC1F2 and BC2F2 generations. Twenty five accessions of sorghum were evaluated, and LW7 marker correctly identified accessions which presented male sterility gene (rf4) in Suphan Buri1 and 03B cultivars; moreover, these genotypes did not show 779 bp band. The cross between Suphan Buri1 and a male-sterile line (A-line) 03A resulted in a sterilized male, confirming the usefulness of the marker in breeding programs. B-lines in the F2, BC1F2 and BC2F2 generations were identified by LW7 marker. The segregation ratio of 3:1 for male fertility and male sterility in the progenies of the three generations supported the one-gene model of Mendelian segregation. The use of marker assisted selection was successful for line development of sweet sorghum with male sterility

The Sakon Nakhon (SKN) rice cultivar is non-photosensitive, rich in aroma, and an excellent choice for cooking quality; which adapts well to both upland and lowland conditions. Furthermore, it has been adopted by Thailand’s sugarcane growers, as it has proved fit for an upland crop preceding the sugarcane cropping system. However, SKN is very susceptible to blast disease caused by Pyricularia oryzae. The purpose of this study was to breed SKN for blast resistance, using marker-assisted backcrossing, together with phenotypic selection. The breeding population was constructed by crossing the SKN (recurrent) with the RD6 introgression line (donor), which contained four blast resistant quantitative trait loci (QTLs). Franking microsatellite markers for blast resistance QTLs on chromosomes 1, 2, 11 and 12 were used for selection through BC2F2. Thirteen BC2F3 selected lines were evaluated under greenhouse conditions, and seven lines of BC2F4 were evaluated against blast, along with their agronomic traits, under field conditions (upland and lowland). SKN 39-10-19-29-12 and SKN 39-10-19-29-13 presented high resistance to leaf and neck blast; and were non-photosensitive, with the same agronomic traits as the SKN. This study successfully demonstrates the improvement of the recommended SKN variety blast resistance, while maintaining similar agronomic traits.

Phosphorus (P) deficiency is a major factor limiting rice yield throughout the world. Fortunately, some rice accessions are tolerant and can thrive well, even in soils with low P content. The ability to uptake P is heritable, and thus can be incorporated into rice cultivars through standard breeding methods. The objective of this study was to screen for tolerance to phosphorus deficiency and validate the tolerant accessions with phosphorus uptake 1 (Pup1) gene-linked markers in Thai indigenous upland rice germplasm. One hundred sixty-eight rice varieties were screened in a solution culture and assigned a phosphorus deficiency tolerance index and plant symptom score. Eleven upland rice accessions (ULR026, ULR031, ULR124, ULR145, ULR180, ULR183, ULR185, ULR186, ULR213, ULR260, and ULR305), together with the lowland rice cultivar (PLD), were classified as tolerant. They were each validated by nine markers linked to the Pup1 locus and observed for the expected polymerase chain reaction (PCR) product of 0 to 9 markers. The presence or absence of the tolerant allele at the Pup1 locus showed only a slight relationship with the tolerance. Moreover, some lines such as ULR183 and ULR213 expressed high tolerance without the Pup1-linked gene product. Both accessions are useful for the exploration of novel genes conferring tolerance to phosphorus deficiency.