Rice is an important food crop. Rice seedlings are mainly composed of root, coleoptile, mesocotyl and euphylla. The elongation of coleoptile and mesocotyl promotes the emergence of rice seedlings. Therefore, analyzing the mechanism of coleoptile and mesocotyl elongation is important for the cultivation of rice varieties. Due to global warming, heat stress is threatening rice yields. Betaine plays an important role in plant resistance to heat stress; however, we lack research on its regulation mechanism of rice seed germination under heat stress. Therefore, we explored the effects of soaking seeds with betaine at different concentrations on rice seed germination under heat stress. According to the results, soaking seeds with 10 mM of betaine could effectively improve the seeds’ germination potential and rate under heat stress to promote the germination of rice seeds. To clarify the mitigation mechanism of betaine in heat stress, we measured the antioxidant enzyme activity, malondialdehyde content, soluble protein content and endogenous hormone content of seed protrusion under heat stress. We constructed the cDNA library for transcriptome sequencing. According to the results, 10 mM of betaine improved the activities of the superoxide dismutase, peroxidase and catalase of seed protrusion under heat stress to reduce the malondialdehyde content and increase the soluble protein content to alleviate the effect of heat stress on rice seed germination. The detection of the endogenous hormone content showed that soaking seeds with 10 mM of betaine increased the content of gibberellin and decreased the contents of auxin and abscisic acid of seed protrusion under heat stress. According to the transcriptome analysis, betaine can induce the expressions of key genes in the biosynthesis and metabolism of auxin, abscisic acid and gibberellins in the seed coleoptile and mesocotyl elongation stage, regulate the signal transduction of three hormones and promote the germination of rice seeds under heat stress. This study revealed, for the first time, the physiological and molecular regulation mechanism of betaine promotion of seed germination under heat stress.

The storage period of paddy is a critical factor affecting rice quality, and it is still unclear how fresh rice noodles, primarily made from paddy, respond to changes in the storage period. To elucidate the relationship between the paddy storage period and the quality of fresh rice noodles, this study used fourteen rice varieties as materials and set up three paddy storage periods (six months, nine months, and twelve months). It explored the quality variation patterns of fresh rice noodles processed from these paddies and analyzed the relationship between the two in conjunction with rice quality. The results indicated that fresh rice noodles produced from paddies stored for nine months exhibited superior quality compared to the other two storage periods. Grey relational analysis and correlation analysis confirmed that this was primarily attributed to changes in the gel consistency of the paddy. When the paddy was stored for nine months and the rice gel consistency was approximately 32 mm, the quality of the fresh rice noodles produced was optimal, serving as an important basis for selecting raw materials for fresh rice noodles.

To sustain agricultural productivity and safeguard global food security, and confront the escalating challenges posed by climate change and water scarcity, it is essential to enhance the growth and productivity of rice under water stress. This study investigated the effects of lanthanum chloride on the chlorophyll fluorescence characteristics and grain yield of rice under different irrigation modes. The rice cultivar H You 518 was selected and sprayed 20, 100, or 200 mg·L⁻¹ lanthanum chloride at the booting and heading stages under deficit irrigation (where no rewatering was applied after the initiation of stress, allowing the water layer to evaporate naturally under high temperatures) or conventional irrigation (with daily rewatering to maintain a consistent water level). The results showed that the application of low concentrations lanthanum chloride promoted the chlorophyll content, whereas high concentrations decreased the chlorophyll content, under deficit irrigation, the effect of lanthanum chloride on the green fluorescence parameters of rice leaves at the booting stage was greater than that at the heading stage, and the booting stage was more sensitive to water deficit. The application of 100 mg·L⁻¹ lanthanum chloride reduced the initial fluorescence (F0) and the non-photochemical quenching coefficient (qN); promoted the activity of leaf photosynthetic system II (PSII); and maximized the photochemical quantum yield (Fv/Fm), photochemical quenching coefficient (qP), and PSII relative electron transfer efficiency (ETR). Under deficit irrigation, this treatment significantly enhanced grain yield by increasing the thousand-grain weight, spikelet filling rate, and number of grains per panicle. These results suggest that spraying 100 mg·L⁻¹ lanthanum chloride at the booting stage under deficit irrigation can effectively increase the chlorophyll content, thereby increasing the light energy conversion efficiency of the PS II reaction center, ultimately resulting in increased spikelet filling rate and grain yields.

In early rice cultivation, the age of seedlings plays a crucial role in ensuring the annual safety production of double-cropping rice. When sowing staging and transplanting are performed simultaneously, it is still necessary to gather more data about the effects of seedling age on the growth period and grain yield of early rice machines transplanted. Two years ago, field experiments were conducted on machine-transplanted rice seedlings in the early season to compare the growth duration, crop growth characteristics, and yield attributes between the 18-day-old seedlings (SA18) and 32-day-old seedlings (SA32) of two rice cultivars. As a result of the study, it was found that SA18 reduced the total crop duration by between 11 and 12 days but delayed the maturity date by 2–3 days compared to SA32. SA18 had 14.5% fewer panicles per m² and 3.6% less harvest index but 7.5% more spikelets per panicle higher than SA32. The grain yield of SA18 was 3.4% less than that of SA32, but there was no significant difference between the two seedling ages. The machine-transplanted seedlings for early rice production are more efficient in reducing seedling management time without affecting harvesting time and yields. The authors provide a new cultivation management scheme for farmers who are interested in planting double-cropping rice at the same time.