Peat moss is an organic substance corroded by sphagnum moss and has a pH of 3.0–4.0. Elemental sulfur is sulfated and oxidized by the action of bacteria to become sulfuric acid. These biological factors can alter the soil environment. Blueberries require soil with a pH of 4.5–5.2 and high organic matter content. In this experiment, we investigated whether different treatment rates of peat moss, elemental sulfur, and sulfur-oxidizing bacteria affect changes in soil pH, physicochemical properties, and electrical conductivity. We detected strong changes in soil pH as a reaction to the supply of peat moss, elemental sulfur, and sulfur-oxidizing bacteria. The pH of the soil when peat moss and elemental sulfur each were supplied was reduced. In addition, the pH decreased faster when elemental sulfur and sulfur-oxidizing bacteria were supplied together than elemental sulfur alone, satisfying an acidic soil environment suitable for blueberry cultivation. In this experiment, it is shown that peat moss, elemental sulfur, and sulfur-oxidizing bacteria are suitable for lowering soil pH. It was demonstrated that when elemental sulfur and sulfur-oxidizing bacteria were treated together, the pH decreased faster than when treated with peat moss. It could be economically beneficial to farmers to use elemental sulfur and sulfur-oxidizing bacteria, which are cheaper than peat moss, to reduce the pH of the soil.

Rice is a source of food for the majority of the global population. Currently, the rice yield is declining owing to extreme climate change. Farmers use nitrogen fertilizers to increase the yield; however, excessive nitrogen fertilizer application has a negative impact on plants and the environment. Nitrogen fertilizer is necessary for the growth of rice, but it is an important cause of environ-mental pollution. Carbon monoxide (CO) emitted from rice fields due to nitrogen fertilizer reacts with greenhouse gases such as carbon dioxide or methane, affecting global warming. Although CO does not directly affect global warming, it is a gas that needs attention because it reacts with various other gases. In this study, a chamber was designed and manufactured to collect the CO emitted from the paddy field after nitrogen fertilizer application in 2021 and 2022. In paddy fields, nitrogen fertilizer treatment affected the pH, EC, and soil temperature, and affected various agricultural traits. Various agricultural characteristics and the number of spikes, number of tillers, and chlorophyll content increased with nitrogen fertilizer application, whereas the amylose content decreased. Adequate nitrogen fertilizer should be applied to increase the rice yield; however, excessive nitrogen fertilizer application has a serious negative effect on grain quality and can accelerate global warming by releasing CO from paddy fields. The appropriate application of nitrogen fertilizer can have a positive effect on farmers by increasing yield. However, caution should be exercised in the application of excessive nitrogen fertilizers, as excessive nitrogen fertilizers increase the emission of CO, which affects greenhouse gases.

Background: Recent temperature increases due to rapid climate change have negatively affected rice yield and grain quality. Particularly, high temperatures during right after the flowering stage reduce spikelet fertility, while interfering with sugar energy transport, and cause severe damage to grain quality by forming chalkiness grains. The effect of high-temperature on spikelet fertility and grain quality during grain filling stage was evaluated using a double haploid line derived from another culture of F₁ by crossing Cheongcheong and Nagdong cultivars. Quantitative trait locus (QTL) mapping identifies candidate genes significantly associated with spikelet fertility and grain quality at high temperatures. Results: Our analysis screened OsSFq3 that contributes to spikelet fertility and grain quality at high-temperature. OsSFq3 was fine-mapped in the region RM15749-RM15689 on chromosome 3, wherein four candidate genes related to the synthesis and decomposition of amylose, a starch component, were predicted. Four major candidate genes, including OsSFq3, and 10 different genes involved in the synthesis and decomposition of amylose and amylopectin, which are starch constituents, together with relative expression levels were analyzed. OsSFq3 was highly expressed during the initial stage of high-temperature treatment. It exhibited high homology with FLOURY ENDOSPERM 6 in Gramineae plants and is therefore expected to function similarly. Conclusion: The QTL, major candidate genes, and OsSFq3 identified herein could be effectively used in breeding rice varieties to improve grain quality, while tolerating high temperatures, to cope with climate changes. Furthermore, linked markers can aid in marker-assisted selection of high-quality and -yield rice varieties tolerant to high temperatures.

Whitebacked planthopper (WBPH) is a pest that causes serious damage to rice in Asian countries with a mild climate. WBPH causes severely rice yield losses and grain poor quality each year so needs biological control. Plants resist biotic and abiotic stress using expressing variety genes, such as kinase, phytohormones, transcription factors, and especially secondary metabolites. In this research, quantitative trait locus (QTL) mapping was performed by assigning the WBPH resistance score in the Cheongcheong/Nagdong doubled haploid (CNDH) line in 2018 and 2019. The RM280-RM6909 on chromosome 4 was detected as a duplicate in 2018, 2019, and derived from Cheongcheong. This region includes cell function, kinase, signaling, transcription factors, and secondary metabolites that protect plants from the stress of WBPH. The RM280-RM6909 on chromosome 4 contains candidate genes that are similar to the flavanone 3-hydroxylase (F3H) of rice. The F3H are homologous genes, which play an important role in biosynthesis defending against biotic stress in plants. After WBPH inoculation, the relative expression level of F3H was higher in resistant line than in a susceptible line. The newly identified WBPH resistance gene F3H by QTL mapping can be used for the breeding of rice cultivars that are resistant against WBPH.

The overall effects of gibberellic acid (GA3) with NaCl on different rice genotypes are inadequately understood. The present study determines the effect of different GA3 (50 and 100 µM) concentrations on the morphophysiological, molecular and biochemical effects of 120 mM NaCl salt stress in rice seedlings. Salt stress reduced germination percentages and seedling growth and decreased bioactive GA content. It also downregulated the relative expression of α-amylase-related genes – OsAmy1A, OsAmy1C, and OsAmy3C in the salt-sensitive IR28 cultivar. Salt stress differentially regulated the expression of GA biosynthetic genes. Salt stress increased antioxidant activity in all rice genotypes tested, except in IR28. GA3 mitigates the effect of salt stress, rescuing seed germination and growth attributes. GA3 significantly increased bioactive GA content in Nagdong and pokkali (50 µM) and Cheongcheong and IR28 (100 µM) cultivars. The α-amylase genes were also significantly upregulated by GA3. Similarly, GA3 upregulated OsGA2ox1 and OsGA2ox9 expression in the Cheongcheong and salt-sensitive IR28 cultivars. The present study demonstrated that salt stress inactivates bioactive GA – inhibiting germination and seedlings growth – and decreases bioactive GA content and GSH activity in IR28 and Pokkali cultivars. Further, GA3 significantly reversed the effects of 120 mM NaCl salt stress in different rice genotypes. The current study suggested that the known coastal area salinity concentration can be significantly recovered with the application of exogenous GA3. Thus, it could be possible to grow eco-friendly rice close to the coastal zone in order to reduce the damage caused by salinity.

The white-backed planthopper (WBPH) is a major pest of rice crops and causes severe loss of yield. We previously developed the WBPH-resistant rice cultivar “OxF3H” by overexpressing the OsF3H gene. Although there was a higher accumulation of the flavonoids kaempferol (Kr) and quercetin (Qu) as well as salicylic acid (SA) in OxF3H transgenic (OsF3H or Trans) plants compared to the wild type (WT), it is still unclear how OsF3H overexpression affects these WBPH resistant-related changes in gene expression in OxF3H plants. In this study, we analyze RNA-seq data from OxF3H and WT at several points (0 h, 3 h, 12 h, and 24 h) after WBPH infection to explain how overall changes in gene expression happen in these two cultivars. RT-qPCR further validated a number of the genes. Results revealed that the highest number of DEGs (4735) between the two genotypes was detected after 24 h of infection. Interestingly, it was found that several of the DEGs between the WT and OsF3H under control conditions were also differentially expressed in OsF3H in response to WBPH infestation. These results indicate that significant differences in gene expression between the “OxF3H” and “WT” exist as the infection time increases. Many of these DEGs were related to oxidoreductase activity, response to stress, salicylic acid biosynthesis, metabolic process, defense response to pathogen, cellular response to toxic substance, and regulation of hormone levels. Moreover, genes involved in salicylic acid (SA) and ethylene (Et) biosynthesis were upregulated in OxF3H plants, while jasmonic acid (JA), brassinosteroid (Br), and abscisic acid (ABA) signaling pathways were found downregulated in OxF3H plants during WBPH infestation. Interestingly, many DEGs related to pathogenesis, such as OsPR1, OsPR1b, OsNPR1, OsNPR3, and OsNPR5, were found to be significantly upregulated in OxF3H plants. Additionally, genes related to the MAPKs pathway and about 30 WRKY genes involved in different pathways were upregulated in OxF3H plants after WBPH infestation. This suggests that overexpression of the OxF3H gene leads to multiple transcriptomic changes and impacts plant hormones and pathogenic-related and secondary-metabolites-related genes, enhancing the plant’s resistance to WBPH infestation.