Optimizing planting density enhances light capture, improves air circulation, and promotes more efficient resource utilization, ultimately leading to increased crop productivity. It facilitates uniform growth, maximizes land use efficiency, reduces nutrient competition, and supports sustainable weed management, thereby improving yield and resource use efficiency. The wide and narrow row cropping (WNRC) system is an optimized planting method that adjusts the row spacing strategically to enhance crop growth and productivity. This study reviews the development and implementation of WNRC technology, focusing on its effects on crop growth, development, and environmental optimization. (1) Crop growth and environmental optimization: Modifying the row spacing in WNRC enhances light interception, air circulation, and the soil moisture distribution, creating an optimized growth environment that improves the photosynthetic efficiency and water use. (2) Genetic variation and yield performance: The performance of different crop varieties in WNRC systems varies, with specific varieties showing better adaptation to the altered spatial arrangement, leading to improved growth uniformity and higher yields. (3) Weed management: The planting density is optimized, reducing the need for herbicides and fostering more sustainable weed control methods. (4) Efficient input management: WNRC systems enhance the uniform application of fertilizers and pesticides, optimizing nutrient uptake, minimizing input wastage, and lowering the environmental impact. While WNRC offers substantial advantages in yield enhancement and resource optimization, challenges remain in adapting this technology to diverse cropping systems and environmental conditions. Further research is required to refine WNRC for specific regions and crops, ensuring its long-term agronomic and ecological benefits.

Rice blast caused by the pathogenic fungus Magnaporthe oryzae poses a significant threat to rice cultivation. The identification of robust resistance germplasm is crucial for breeding resistant varieties. In this study, we employed functional molecular markers for 10 rice blast resistance genes, namely Pi1, Pi2, Pi5, Pi9, Pia, Pid2, Pid3, Pigm, Pikh, and Pita, to assess blast resistance across 91 indica rice backbone varieties in South China. The results showed a spectrum of resistance levels ranging from highly resistant (HR) to highly susceptible (HS), with corresponding frequencies of 0, 19, 40, 27, 5, and 0, respectively. Yearly correlations in blast resistance genes among the 91 key indica rice progenitors revealed Pid2 (60.44%), Pia (50.55%), Pita (45.05%), Pi2 (32.97%), Pikh (4.4%), Pigm (2.2%), Pi9 (2.2%), and Pi1 (1.1%). Significant variations were observed in the distribution frequencies of these 10 resistance genes among these progenitors across different provinces. Furthermore, as the number of aggregated resistance genes increased, parental resistance levels correspondingly improved, though the efficacy of different gene combinations varied significantly. This study provides the initial steps toward strategically distributing varieties of resistant indica rice genotypes across South China.

The “Indica to Japonica” initiative in China focuses on adapting Japonica rice varieties from the northeast to the unique photoperiod and temperature conditions of lower latitudes. While breeders can select varieties for their adaptability, the sensitivity to light and temperature often complicates and prolongs the process. Addressing the challenge of cultivating high-yield, superior-quality Japonica rice over expanded latitudinal ranges swiftly, in the face of these sensitivities, is critical. Our approach harnesses the CRISPR-Cas9 technology to edit the EHD1 gene in the premium northeastern Japonica cultivars Jiyuanxiang 1 and Yinongxiang 12, which are distinguished by their exceptional grain quality—increased head rice rates, gel consistency, and reduced chalkiness and amylose content. Field trials showed that these new ehd1 mutants not only surpass the wild types in yield when grown at low latitudes but also retain the desirable traits of their progenitors. Additionally, we found that disabling Ehd1 boosts the activity of Hd3a and RFT1, postponing flowering by approximately one month in the ehd1 mutants. This research presents a viable strategy for the accelerated breeding of elite northeastern Japonica rice by integrating genomic insights with gene-editing techniques suitable for low-latitude cultivation.

Because of labor shortages or resource scarcity, direct seeding is the preferred method for rice (Oryza sativa. L) cultivation, and it necessitates direct seeding at the current density. In this study, two density of direct seeding with high and normal density were selected to identify the genes involved in shade-avoidance syndrome. Phenotypic and gene expression analysis showed that densely direct seeding (DDS) causes a set of acclimation responses that either induce shade avoidance or toleration. When compared to normal direct seeding (NDS), plants cultivated by DDS exhibit constitutive shade-avoidance syndrome (SAS), in which the accompanying solar radiation drops rapidly from the middle leaf to the base leaf during flowering. Simulation of shade causes rapid reduction in phytochrome gene expression, changes in the expression of multiple miR156 or miR172 genes and photoperiod-related genes, all of which leads to early flowering and alterations in the plant architecture. Furthermore, DDS causes senescence by downregulating the expression of chloroplast synthesis-related genes throughout almost the entire stage. Our findings revealed that DDS is linked to SAS, which can be employed to breed density-tolerant rice varieties more easily and widely.

The fertility conversion of photoperiod thermo-sensitive genic male sterility (P/TGMS) lines in rice is mostly regulated by the P/TGMS genes in different environmental conditions. A point mutation with G-C on the pms3 (p/tms12-1) gene regulates the pollen fertility of Nongken58S and a large amount of Nongken58S-derived lines. In this study, we developed and designed a functional co-dominant marker according to the SNP loci for the pms3 (p/tms12-1) gene. We can differentiate the SNP loci in pms3 (p/tms12-1) gene from another TGMS lines and inbred cultivars using the dpms3-54 marker. The results showed that 376 bp band was detected in the homozygous genotype for pms3 (p/tms12-1), while 359 bp band was detected in the homozygous genotype for non-pms3 (p/tms12-1), two bands with 376 and 359 bp were detected in the heterozygous genotype. The dpms3-54 marker can be used to test the purity of two-line hybrid rice seeds and to divide each of F₁ plant into homozygous and heterozygous genotypes at the seedling stage. Thus, this study provide a useful functional marker to detect pms3 (p/tms12-1) gene in different genetic resources and populations, which can be applied to the development and breeding of P/TGMS lines in two-line hybrid rice system with marker-assisted selection.

The utilization of heterosis is of great significance in improving rice yield. To explore the physiological and genetic basis for high yield in indica–japonica hybrid rice, Zheyou18 (z18) and Yongyou12 (y12) were used as materials and compared with indica hybrid rice, Zheyou12 (z12); japonica hybrid rice, Liangyoupeijiu (LYPJ); and the conventional lines zhe04B (04B) and zhehui818 (h818) under seedling growth vigor, functional leaf morphology, chlorophyll content, yield component, panicle trait, and InDel heterosis analysis. Z18 and y12 showed the largest increase in plant height 6 d and 9 d after germination; the root dry weight of z18 was 31.2% and 42.0% higher than its parents on the 12th d. The length of functional leaves ranked in the middle, while the width was the largest, resulting in z18 and y12 having the largest leaf area. Yield components showed that z18 and y12 had the highest number of primary branches, spikelets, and grains, and grain yield, which was 58.1 g in z18, increased by 29.8% and 8.7%, respectively, in comparison with h818 and LYPJ. The InDel genetic distance was significantly positively correlated with single spike weight, with r reaching 0.771, making it the only consistent and most correlated among the seven traits. Therefore, we speculated that as the InDel genetic distance expands, heterosis mainly manifests in the increase in single spike weight. This study comprehensively explored the physiological mechanism of yield improvement in indica–japonica-hybrid rice and used InDel genetic distances to study the genetic basis of heterosis, which will be helpful for future rice yield improvement.