Sugar metabolism influences the quality of sweet corn (Zea mays var. saccharate Sturt) kernels, which is a major goal for maize breeding. In this study, the genome-wide transcriptomes from two supersweet corn cultivars (cv. Xuetian 7401 and Zhetian 11) with a nearly two-fold difference in kernel sugar content were carried out to explore the genes related to kernel sugar metabolism. In total, 45,748 differentially expressed genes (DEGs) in kernels and 596 DEGs in leaves were identified. PsbS, photosynthetic system II subunit S, showed two isoforms with different expression levels in leaf tissue between two cultivars, indicating that this gene might influence sugar accumulation in the kernel. On the other hand, hexokinases and beta-glucosidase genes involved in glycolysis, starch and sucrose metabolism were found in developing kernels with a genome-wide transcriptome analysis of developing kernels, which might contribute to the overaccumulation of water-soluble polysaccharides and an increase in the sweetness in the kernels of Xuetian 7401. These results indicated that kernel sugar accumulation in sweet corn might be influenced by both photosynthesis efficiency and the sugar metabolism rate. Our study supplied a new insight for breeding new cultivars with high sugar content and laid the foundation for exploring the regulatory mechanisms of kernel sugar content in corn.

Crop growth and development can be impeded by salt stress, leading to a significant decline in crop yield and quality. This investigation performed a comparative analysis of the physiological responses of two maize inbred lines, namely L318 (CML115) and L323 (GEMS58), under salt-stress conditions. The results elucidated that CML115 exhibited higher salt tolerance compared with GEMS58. Transcriptome analysis of the root system revealed that DEGs shared by the two inbred lines were significantly enriched in the MAPK signaling pathway–plant and plant hormone signal transduction, which wield an instrumental role in orchestrating the maize response to salt-induced stress. Furthermore, the DEGs’ exclusivity to salt-tolerant genotypes was associated with sugar metabolism pathways, and these unique DEGs may account for the disparities in salt tolerance between the two genotypes. Meanwhile, we investigated the dynamic global transcriptome in the root systems of seedlings at five time points after salt treatment and compared transcriptome data from different genotypes to examine the similarities and differences in salt tolerance mechanisms of different germplasms.

Clarifying the genetic basis of trace element accumulation is of great significance to breed new maize varieties with high quality. In this study, an integrated variant map with 1.25 million (M) SNPs and 489 inbred lines was used for a genome-wide association study on the accumulation of iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), cadmium (Cd) and Arsenic (As) in maize kernels. Seventeen SNPs linked with six genes were overlapped by different trace elements. After further analysis, 65 SNPs located in 28 genes with a p-value lower than 10⁻¹⁰ were associated with Cd content by genome-wide association studies (GWAS). There was a 3.1-fold difference in Cd content between different groups, which was divided by SNP haplotype in chr2.S_160782359, chr2.S_161045498 and chr2.S_161273716. The amino acid sequences of GRMZM2G150608 and GRMZM2G051367 only shared 68.85% and 88.16% similarity between B73 and Mo17, and the Cd content of Mo17 was 2.2-fold that of B73. In addition, 19 lines with higher contents of Fe, Zn, Cu, Mn and fewer contents of As and Cd were screened from GWAS associated populations. This study will lay a foundation for revealing the molecular mechanism of trace element accumulation in maize kernels and provide candidate genes for breeding new maize varieties with high nutritional quality.

Duckweed growing in paddy fields (DGP) has substantially increased because of the effects of climate warming and/or eutrophication in irrigated water. Previous studies have primarily focused on investigating the effects of DGP as a nonchemical agent for enhancing rice productivity on nitrogen utilization in rice paddy fields. However, how DGP impacts rice yield remains poorly understood. Therefore, a field experiment with three representative rice cultivars was conducted to determine the effects of DGP on rice yield, considering ecological factors, photosynthetic capacity, spectral changes, and plant growth. The results showed that DGP significantly reduced the pH value by 0.6 and the daily water temperature by 0.6 °C, accelerated rice heading by 1.6 days and increased the soil and plant analyzer development (SPAD) and photosynthetic rate of leaves by 10.8% and 14.4% on average, respectively. DGP also markedly enhanced the values of various vegetation indices such as RARSc, MTCI, GCI, NDVI₇₀₅, CI, CIrededge, mND₇₀₅, SR₇₀₅, and GM, and the first derivative curve of the rice canopy reflectance spectrum exhibited a ‘red shift’ phenomenon upon DGP treatment. Changes in the aforementioned factors may lead to average increases of 4.7% in plant height, 15.0% in dry matter weight, 10.6% in panicles m⁻², 2.3% in 1000-grain weight, and ultimately a 10.2% increase in grain yield. The correlation observed suggested that the DGP-induced enhancement in grain yield can be achieved by reducing the pH and temperature of the paddy water, thus enhancing the SPAD value and photosynthesis of leaves and stimulating rice plant growth. These results could offer valuable theoretical support for the future sustainable development of agriculture and the environment through the biological synergy between rice and duckweed.

The Contribution of Exotic Varieties to Maize Genetic Improvement

In the waxy maize production of Zhejiang Province, China, conventional straw management often causes planting difficulties and nutrient competition. Although no-till with straw retention is known to benefit soil structure, its long-term impacts on local soil health and productivity remain poorly understood. Hence, a six-year field experiment (2016–2021) was conducted with four treatments, i.e., no-till with residue retention (NTRR), no-till with residue removal (NTR0), plow tillage with residue incorporation (PTRR), and plow tillage with residue removal (PTR0), to investigate the long-term effects of tillage and residue management. The results demonstrated that plow tillage (PT) significantly improved soil physical properties, reducing soil compaction and decreasing bulk density compared to no-till (NT) practices. Meanwhile, residue retention (RR) enhanced soil chemical fertility, increasing soil organic matter by 7.8–9.8% and substantially improving available potassium levels. The PTRR treatment achieved the most favorable soil conditions with the lowest compaction and bulk density values among all treatments. PTRR consistently yielded the highest maize production, showing a 1.7–6.9% advantage over PTR0 and a substantial 15.4% yield increase in spring maize compared to residue removal (R0) treatments. Correlation analyses revealed significant relationships between soil quality and productivity, with the Soil Quality Index (SQI) showing strong positive correlations with both yield (r = 0.74, p < 0.01) and economic returns (r = 0.67, p < 0.05). These findings demonstrate that PTRR represents an optimal agricultural management strategy for simultaneously enhancing soil health and ensuring sustainable crop production in fresh maize cultivation.