The environment is the main factor affecting variations in phytochemicals and antioxidant activity in rice. The objective of this study was to evaluate the stability of grain yield, phytochemicals and antioxidant capacity of six rice genotypes. Six rice genotypes were evaluated in a randomized complete block design with three replicates at three locations in Trat, Bangkok and Sakon Nakhon provinces in July–October 2019. Data on grain yield, yield components, total phenolic content, ferulic acid and antioxidant capacity were recorded. Grain yield was highest for crops grown in Bangkok, whereas antioxidant activity was highest for crops grown in Bangkok and Sakon Nakhon. Hom Nang Nual 1 and Mali Nil Boran had the highest grain yield. Riceberry had the highest grain yield in Trat; it also had high levels of total phenolic compounds, ferulic acid and antioxidant activity. Mali Nil Boran, Mali Nil Surin and Riceberry had the most stable total phenolic content, ferulic acid and antioxidant activity, respectively. Information on the levels and variability of phytochemicals in rice enables the selection of genotypes with high and stabile phytochemicals for production and rice breeding.

Parboiling influences chemical compositions in rice grains. The objectives of this study were to evaluate the change in chemical content, total phenolic content and antioxidant capacity of landrace rice genotypes under parboiling conditions and to identify the genotypes suitable for production of parboiled rice. Landrace rice varieties used in this study consisted of Glam Feang, Glam Tonkeaw, Kawgum, Glam Luem Phua, Medmakham, Deang Sakonnakhon, Sang Yod, Kawniewd-eang, Mali Deang, KDML105 and RD6. Parboiling reduced fiber content, total phenolic content and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity in rice grains. Fiber contents were 1.46% in brown rice (unpolished rice) and 1.40% in parboiled rice (24 h of soaking and 48 h of incubation). Total phenolic contents were 205.67 mg/100 g seed in brown rice and 35.34 mg/100 g seed in parboiled rice. Antioxidant capacity (DPPH) reduced from 68.45% in brown rice to 26.23% in parboiled rice. Ash content and protein content were not significantly affected by the parboiling process. Medmakham cv. had the highest total phenolic content and antioxidant capacity in brown rice and parboiled rice. Gum Leamphea cv. and Medmakham cv. were the best genotypes for ash content, protein content, total phenolic content and antioxidant capacity (DPPH) in brown rice and parboiled rice. Glam Feang cv. had the highest protein contents in brown rice and parboiled rice although it had low total phenolic content and antioxidant capacity. Cluster analysis further showed variation among genotypes, revealing distinct groupings in brown rice and parboiled rice based on chemical properties, phenolic content and antioxidant capacity. This research significantly contributes to a better understanding on how parboiling affects rice compositions and nutritional values. It emphasizes the importance of nuanced comprehension of how different rice varieties respond to parboiling, aiding informed decisions in rice processing and selection to meet specific nutritional needs.

Mid-season drought is increasingly recognized as a major constraint on tuber production in Jerusalem artichoke. The ability of different genotypes to maintain high yields under such conditions is a critical component of drought tolerance. This study aimed to investigate the effects of mid-season drought on tuber yield, biomass, harvest index, tuber water-use efficiency (WUEt), and biomass water-use efficiency (WUEb) across various Jerusalem artichoke genotypes with differing levels of drought tolerance. The experiment was conducted in pots using a 2 × 5 factorial combination in a randomized complete block design with four replications over two years. Factor A consisted of two water regimes: field capacity (FC) and mid-season drought. Factor B included five genotypes: JA 3, JA 125, JA 15, JA 89, and CN 52867. Mid-season drought significantly reduced tuber dry weight, biomass, WUEt, and WUEb, while increasing the harvest index. Significant differences were observed among genotypes for tuber dry weight, biomass, harvest index, WUEt, and WUEb under both water regimes. CN 52867 and JA 89 were characterized as drought-tolerant genotypes with high water-use efficiency and high yield potential. JA 3 was also noted for its lower yield reduction under stress. These three genotypes serve as valuable genetic resources for breeding programs aimed at developing progeny populations with enhanced yield potential and drought tolerance, particularly for mid-season drought-prone environments.

It is often stated that organic rice has a higher content of healthy phytochemicals than ordinary rice, and the facts on this claim obtained experimentally are rare. Riceberry is a new rice variety in Thailand. This study aimed to evaluate the effects of organic practice and conventional practice on the content of chemical composition and bioactive compounds in Riceberry rice. The results showed that agricultural practices were not significantly different for grain yield in the first year, but they were different in the second year. Rice produced by organic practice had a higher content of iron, gamma-aminobutyric acid, total phenolic and anthocyanin (4.15, 1.67, 41.3 and 20.1 mg/100 g dry weight in the first year, and 4.06, 3.37, 89.7 and 14.7 mg/100 g dry weight in the second year) than that produced by conventional practice (2.25, 1.11, 38.8 and 6.89 mg/100 g dry in the first year, and 1.96, 2.77, 54.1 and 5.71 mg/100 g dry in the second year). Rice produced by organic practice also had lower sugar content (2.92 g/100 g dry weight in the first year, and 1.99 g/100 g dry weight in the second year) than that produced by conventional practice (3.46 g/100 g dry weight in the first year, and 2.81 g/100 g dry weight in the second year). Gamma oryzanol and antioxidant capacity were also lower in organic rice compared to conventional rice. This study indicated that organic Riceberry rice had a higher quality compared to non-organic rice.

Drought is the one primary issue limiting peanut growth and productivity. The study aimed to investigate the effects of arbuscular mycorrhizal fungi (AMF), rhizobium (Rhi), and their combinations on phenolic content, proline content, growth, and yield of peanut under different soil water regimes. The pot experiments were carried out for two growing seasons under greenhouse conditions and designed based on a 2×3 factorial in randomized complete block design (RCBD) with four replications. Factor A comprised two soil water regimes: field capacity (FC) and 1/3 available soil water (1/3 AW), whereas factor B included three different types of microorganisms: (i) uninoculated control, (ii) arbuscular mycorrhiza (AMF), and (iii) a combination of AMF and rhizobium (Rhi) inoculations. Data were collected for growth, proline content, phenolic content, yield, and yield components. Drought stress significantly reduced in relative water content, leaf area, biomass, yield, and yield components of peanut, whereas leaf phenolic content was increased under drought stress. Higher pod dry weight was achieved under FC conditions (28.87 g plant^-1), and it was reduced to 16.06 g plant^-1 under 1/3 FC. Interestingly, AMF+Rhi synergistically increased the leaf area compared with non-incubated peanut under 1/3 FC conditions. AMF-inoculated peanut tended to increase biomass, while the combination of AMF+Rhi tended to have higher yield components compared with uninoculated control, especially for the weight of 100 seeds.