Molecular Plant Breeding 2025, Vol.16, No.2, 119-124 http://genbreedpublisher.com/index.php/mpb 123 is vigorous. In the late growth period, the grains are well filled and mature, showing strong stable yield (Ni et al., 2021; Xu et al., 2022). It has a long growth period (136 days) and is suitable for promotion in areas with sufficient sunlight and good temperature conditions. In terms of quality, the rice quality of this variety meets the general edible quality standards, with a comprehensive rating of third grade, which can meet general market demand. However, it should be noted that Tailiangyou 217 has weak resistance to brown planthoppers, and pest and disease control needs to be strengthened during field management to ensure stable production and increased income. Overall, this study found that among the continuous cropping late rice varieties in Ruian City, Tailiangyou 217 had the highest yield and showed strong potential for yield increase; Tailiangyou 1332 had good adaptability and stronger adaptability to different environmental conditions; Huazheyou 261 was early-maturing and had better rice quality, suitable for planting patterns with shorter growth periods; Yongyou 1540 had a low number of effective panicles, which limited its overall yield. Although it had the most grains per panicle, it could not make up for the disadvantage in panicle number. The differences in yield and agronomic traits among different varieties show that when selecting varieties, we should not only look at yield, but also consider growth period, disease resistance, rice quality and local adaptability to find the most suitable variety combination. At the same time, the key to improving the stable yield and yield potential of continuous cropping late rice is to optimize the number of effective panicles, improve the disease resistance of the varieties, and enhance the growth performance of the plants through scientific and reasonable water and fertilizer management. 3 Materials and Methods 3.1 Experimental site The experiment was conducted at Tianjingyang Center, Lianfeng Village, Mayu Town, Rui’an City, Zhejiang Province. The site is located at 27°78′N latitude and 120°46′E longitude, falling within a subtropical monsoon climate zone characterized by warm and humid conditions. The annual precipitation ranges from 1110 to 2200 mm, with an average annual temperature of approximately 17.9 °C, making it highly suitable for rice cultivation. A late-season double-cropping rice field was selected for the study, with early-season rice as the previous crop. The field was leveled before planting, ensuring good drainage and irrigation conditions. The soil type is alluvial sandy loam, with a moderate-to-high fertility level, as indicated by an organic matter content ranging from 34.1 to 40.7 g/kg, which provides favorable conditions for rice growth. 3.2 Experimental design A large-plot comparative trial was used in this study, with each experimental plot covering an area of 2 mu (≈1333.3 m²). The field was managed under a unified cultivation system to ensure that all varieties were grown under similar conditions. The experiment included four treatment groups, corresponding to four rice varieties, but due to land limitations, no replication was set up. To minimize the impact of environmental variables on yield, all plots followed the same cultivation practices, fertilization plan, and water management regime. Throughout the experiment, key agronomic traits such as tillering ability, plant height, and heading date were recorded, and standardized yield measurements were conducted at maturity to ensure the reliability of the data. 3.3 Tested rice varieties Four rice varieties were selected for this study, including three indica hybrid late-season rice varieties and one indica-japonica hybrid late-season rice variety. The indica hybrid rice varieties were Teyou 1332, Huazheyou 261, and Teyou 217, while the indica-japonica hybrid variety was Yongyou 1540. All seeds were purchased from local seed companies in Rui’an City, and their quality met the requirements of the “Grain Crop Seeds - Part 1: Cereal Crops” (GB 4404.1-2008) standard, ensuring compliance in terms of germination rate, purity, cleanliness, and moisture content. 3.4 Field management To ensure a fair comparison of yield performance across different varieties, a unified cultivation and management approach was applied to all experimental plots. Fertilization was conducted in stages based on rice growth requirements, aiming to promote tillering, panicle development, and grain filling, thereby optimizing yield and grain quality. Before transplanting, 25 kg of compound fertilizer (N-P-K 15-15-15) per mu was applied as a basal fertilizer to enhance soil fertility. 5 to 7 days after transplanting, a topdressing of 20 kg urea (46% N) and 10 kg
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