Understanding the yield attributes of the popular rice (Oryza sativa L.) hybrids can provide useful information for developing new hybrid rice varieties. Field experiments were conducted at two subtropical sites (Hengyang and Xingyi) in two years (2021 and 2022) to compare grain yield and yield attributes of three currently popular hybrid rice varieties (Jingliangyouhuazhan, Jingliangyou 534, and Longliangyouhuazhan) with three representative super hybrid rice varieties (Y-liangyou 1, Y-liangyou 2, and Y-liangyou 900). No significant differences in grain yield were observed between the group of popular hybrids and the group of super hybrids at Hengyang and Xingyi in 2021 or at Xingyi in 2022, but at Hengyang in 2022, the group of popular hybrids produced a 15% higher grain yield. The grain yield at Hengyang in 2022 was lower than that at Hengyang and Xingyi in 2021 and at Xingyi in 2022. At Hengyang in 2022, the group of popular hybrids had 9–15% higher panicles per m², spikelet filling percentage, and harvest index but similar spikelets per panicle and total biomass production and 12% lower grain weight compared to the group of super hybrids. Correlation plot analysis showed that grain yield was significantly related to panicles per m² but not other yield attributes across six varieties at Hengyang in 2022. These results indicated that the currently popular hybrid rice varieties had higher yield performance than the representative super hybrid rice varieties under the condition of relatively lower productivity, and the key factor for this higher yield performance in the popular hybrids was the higher panicles per m². This finding highlights that more attention should focus on the yield performance under medium- and low-productivity conditions in hybrid rice breeding programs, and an effective breeding strategy is to select the varieties with high panicle numbers.

The availability of commercially available portable photosynthesis systems has facilitated widespread photosynthetic research. Our study aimed to evaluate the reliability of a recently developed inexpensive portable photosynthesis system, Yaxin-1105, in measuring gas exchange in rice (Oryza sativa L.) leaves. Gas exchange parameters, including net photosynthetic rate (A_net), stomatal conductance (g_s), intercellular CO₂ concentration (C_i), and transpiration rate (E), were measured on 88 rice leaves across seven rice cultivars and three growth stages (panicle initiation, heading, and early ripening), using both Yaxin-1105 and LI-6400XT. There were significant difference between each gas exchange parameter at each growth stage measured by Yaxin-1105 and LI-6400XT, except C_i at the heading stage. Mean A_net, g_s, and E measured by Yaxin-1105 were 26–66% lower than those measured by LI-6400XT at panicle initiation, heading, and early ripening stages. Mean C_i measured by Yaxin-1105 was 13–22% higher than that measured by LI-6400XT at panicle initiation and early ripening stages. The coefficients of determination between each gas exchange parameter measured by Yaxin-1105 and by LI-6400XT at panicle initiation, heading, and early ripening stages ranged from only 0.0007 to 0.1889. These results indicate that the Yaxin-1105 is not a reliable tool for measuring gas exchange in rice leaves.

Background/Objectives: Sunflower (Helianthus annuus L.) is one of the four major oil crops worldwide and possesses strong stress tolerance. However, salt stress remains limiting in the improvement of sunflower yield and quality. Methods: In this study, the salt-tolerant cultivar P50 and salt-sensitive cultivar P29 were used as experimental materials to conduct transcriptome sequencing on root and leaf samples treated with NaCl. Subsequently, the molecular mechanisms underlying salt tolerance in sunflower were revealed through assembly and splicing, functional annotation, differential expression analysis, enrichment analysis, and transcription factors (TFs) prediction. Results: Results showed that 54,860,184 and 60,601,572 high-quality clean reads were obtained from the two cultivars, respectively. A total of 110,751 all-unigenes were generated after assembly and clustering, of which 77,536 were functionally annotated. A total of 21,332 differentially expressed genes (DEGs) were identified, including 10,306 upregulated and 11,026 downregulated genes. Quantitative real-time PCR validation of 15 DEGs showed a 93.33% consistency rate with the sequencing data. GO enrichment analysis indicated that DEGs were significantly enriched in pathways related to antioxidant enzyme activities. KEGG enrichment analysis demonstrated that DEGs were primarily involved in 15 carbohydrate metabolism pathways, especially starch and sucrose metabolism. In addition, 67 differentially expressed TF families containing 528 DEGs were identified, including bHLH, AP2/ERF-ERF, MYB, C3H, WRKY, EREBP, B3-ARF, and NAC. Conclusions: Our study constructed a comprehensive transcription map of the sunflower response to salt stress and systematically elucidated the molecular mechanisms underlying salt tolerance. The salt-tolerant sunflower cultivar P50 exhibits an efficient salt stress defense system via three core strategies: (i) activating the antioxidant system to rapidly scavenge excess reactive oxygen species and mitigate oxidative damage; (ii) regulating carbohydrate metabolism through starch and sucrose redistribution to provide energy and osmotic protection against physiological drought; and (iii) mobilizing multiple TF families to establish a complex regulatory network for the precise control of downstream functional genes.