In the North China Plain, the excessive application of nitrogen (N) fertilizer for ensuring high yield and a single application at sowing for simplifying management in farmer practice lead to low N use efficiency and environmental risk in maize (Zea mays L.) production. However, it is unclear whether and how late split application with a lower level of N fertilizer influences maize yield. To address this question, a two-year field experiment was conducted with two commercial maize cultivars (Zhengdan 958 and Denghai 605) using a lower level of N input (180 kg ha⁻¹) by setting up single application at sowing and split application at sowing and later stages (V12, R1, and R2) with four different ratios, respectively. The maize yield with split-applied 180 kg ha⁻¹ N did not decrease compared to the average yield with 240 kg ha⁻¹ N input in farmer practice, while it increased by 6.7% to 11.5% in the four N split-application treatments compared with that of the single-application control. Morphological and physiological analyses demonstrated that late split application of N (i) increased the net photosynthetic rate and chlorophyll content and thus promoted the photosynthetic efficiency during the reproductive stages; (ii) promoted the sink capacity via improved kernel number, endosperm cells division, and grain-filling rate; and (iii) increased the final N content and N efficiency in the plant. Therefore, we propose that late split application of N could reduce N fertilizer input and coordinately improve N efficiency and grain yield in summer maize production, which are likely achieved by optimizing the source–sink relations during the grain-filling stage.

Anthocyanins (ACNs) are flavonoid pigments that accumulate in plants and respond to environmental stimuli, including low phosphorus (LP). The synthesis and stable accumulation of ACNs rely on substantial carbohydrate investment, implying a potential role in carbon partitioning-mediated growth and resistance, in addition to the well-established antioxidant activity. To investigate cultivar-dependent differences in ACN accumulation and their relationship with photo-assimilate partitioning and growth adaptation under LP stress, seedlings of six representative maize cultivars were hydroponically cultured under both control and LP conditions. ACNs content, photosynthetic parameters, plant relative growth ratio, and tissue-specific carbohydrates were quantified. The results showed that LP reduced photosynthesis and biomass, while stimulating ACNs biosynthesis in leaves and sheaths. Cultivars were then classified as ACN-sensitive and -insensitive groups based on the ACNs accumulation in the newly unfolded leaves and corresponding sheaths. ACN-sensitive cultivars exhibited higher ACNs levels, which correlated positively with soluble sugars but negatively with starch reserves, suggesting preferential carbon partitioning to ACNs precursors rather than to starch. These cultivars also maintained higher relative growth ratios under LP, associated with less photosynthesis decline and starch accumulation compared with ACN-insensitive cultivars. We hypothesize that ACNs synthesis function as a diversion of photo-assimilates into secondary metabolism under LP, thereby improving photosynthetic efficiency by mitigating excess sugar accumulation that could impair plant growth. This carbon-partitioning adaptation could be exploited by selecting for ACNs accumulation as a breeding trait to enhance maize resilience to LP.

Ustiloxins are the main mycotoxin in rice false smut, a devastating disease caused by Ustilaginoidea virens. A typical phytotoxicity of ustiloxins is strong inhibition of seed germination, but the physiological mechanism is not clear. Here, we show that the inhibition of rice germination by ustiloxin A (UA) is dose-dependent. The sugar availability in UA-treated embryo was lower while the starch residue in endosperm was higher. The transcripts and metabolites responsive to typical UA treatment were investigated. The expression of several SWEET genes responsible for sugar transport in embryo was down-regulated by UA. Glycolysis and pentose phosphate processes in embryo were transcriptionally repressed. Most of the amino acids detected in endosperm and embryo were variously decreased. Ribosomal RNAs for growth were inhibited while the secondary metabolite salicylic acid was also decreased under UA. Hence, we propose that the inhibition of seed germination by UA involves the block of sugar transport from endosperm to embryo, leading to altered carbon metabolism and amino acid utilization in rice plants. Our analysis provides a framework for understanding of the molecular mechanisms of ustiloxins on rice growth and in pathogen infection.

The densification of cereal crops increases population but simultaneously reduces the grain number per individual plant, constraining harvest index and overall yield. Since asynchronous pollination within spike/ear is conserved among cereals, its role in determining yield formation under densification remains unclear. Here, we varied pollination time gaps (PTG, defined as the duration required for all silks in an ear to emerge and be pollinated) to examine how PTG affects grain development and overall yield as planting density increases. Results showed that densification exacerbated PTG and increased grain abortion. Eliminating PTG through synchronous pollination (SP) recovered more than 20% of density-induced grain loss per ear and increased harvest index by 3.7∼3.9% and total yield by 4.9∼11.7%, along with higher optimal density. Using 13C-labeling to quantify daily carbon assimilates, SP increased carbon allocation to the ear and grains, while significantly decreasing carbon stored in vegetative tissues. Surprisingly, photosynthesis rates were also enhanced during the subsequent filling stage. These findings suggest a synergistic enhancement of sink and source capacities under densified populations with SP. Additionally, removing early pollinated grains at the grain set stage increased carbon availability to later-pollinated grains and prevented their abortion, confirming PTG’s role in carbon allocation within the ear for determining grain number. Validated across different varieties and years, we propose PTG as a new trait for breeding and management to enhance harvest index and yield potential in densified populations. This sink modulation approach complements existing strategies focused on improving source capacity and may be applicable across various cereals with asynchronous flowering.

Objective This study aims to determine the suitable sowing date for the cultivation of ordinary maize in red soil dryland of Jiangxi Province. Method The experimental materials used in this study were Zhengdan 958 and Xianyu 335 maize varieties.The sowing date treatments were set between May and July in 2021 and 2022.The study investigated the changes of maize yield and its contributing factors under different sowing date.The aim of this study was to provide theoretical reference for high-yield maize cultivation in Jiangxi Province. Result The adjustment of the sowing date significantly impacted the growth process，pre- and post-silking material accumulation，and the final yield of maize.Planting maize in early May yielded the highest （5529.99 kg/hm²），with a downward trend observed with delayed sowing dates.Ear grain number emerged as the primary factor influencing production with changes in sowing dates.Furthermore，grain weight was notably affected by adjustments in the sowing date and exhibited a significant positive correlation with grain weight during the maximum grain filling rate.In terms of hybrid comparison，Zhengdan 958 showed a higher overall yield than that of Xianyu 335. Conclusion In order to achieve a higher yield in common maize cultivation in the red soil dryland of Jiangxi，it is recommended to select suitable varieties and sow them before early/mid-May，while ensuring that it does not interfere with the cultivation of winter crops such as rapeseed.