The development of varieties with strong tolerance is one of the important strategies to diminish the negative impact of chilling stress during heading on the spikelet fertility and yield formation of late-season rice. However, whether such genetic improvement has been made in inbred late rice lines in China is not clear. In the present study, three late-season inbred rice varieties, Xiangwanxian2 (XWX2, released in 1988), Xiangwanxian8 (XWX8, released in 1998) and Xiangwanxian17 (XWX17, released in 2008) were subjected to moderate (20 °C) and extreme (17 °C) chilling stress during heading, and the grain yield components and flowering-related traits of the three varieties in response to different temperature were investigated. The results showed that the newly released inbred late rice variety XWX17, demonstrated better chilling tolerance during heading than the early released varieties with respect to higher grain filling percentage. The improved grain filling percentage in XWX17 might be the results of increased spikelet fertility, which was attributed to the increase in pollen viability, anther dehiscence length and anther volume. In addition, the SPAD value and the chlorophyll a content of the flag leaf can be used as indicators to predict the rice spikelet fertility when suffering from chilling stress during heading. The present study provides evidence that the genetic approach has been made to improve the chilling tolerance of inbred late rice lines during heading; however, further research is needed to explore the physiological and molecular mechanism underlying the relationship between leaf characteristics and function with rice spikelet fertility.

Background: Light availability governs plant growth and metabolism; however, the influence of shade intensity on metabolic allocation between leaves and corms in konjac (Amorphophallus konjac) remains unclear. Methods: Untargeted liquid chromatography-tandem mass spectrometry (LC–MS/MS) metabolomics was employed to profile metabolic responses in both tissues under three shading regimes (0%, 50%, and 75%). Results: A total of 1684 annotated metabolites were identified. Shading induced more pronounced changes in leaves (624 differentially accumulated metabolites) than in corms (227). These metabolites participated in oxylipin/jasmonate, lipid, flavonoid, amino acid, and organic acid metabolism. Linoleic acid metabolism was enriched in both tissues, whereas carbon/organic acid metabolism was more prominent in corms, and amino acid/flavonoid metabolism in leaves. Metabolites associated with oxylipins/jasmonates and lysophospholipids peaked at 50% shading, while flavonoids were more abundant under full light (0% shading). Among the three levels, 50% shading elicited the most significant metabolic response. Venn analysis identified 526 leaf-specific, 129 corm-specific, and 98 shared metabolites. Conclusions: This study establishes a metabolic framework for understanding shade responses in konjac and identifies candidate metabolites and pathways for future research on light-regulated growth and development.