Molecular Plant Breeding 2025, Vol.16, No.2, 119-124 http://genbreedpublisher.com/index.php/mpb 121 had relatively fewer effective panicles, with 167 700 and 159 100 per mu, respectively. These differences are likely influenced by both genetic characteristics and field management during the tillering stage. Regarding the number of grains per panicle, Yongyou 1540 had the highest grain count per panicle, reaching 207.3 grains, followed by Huazheyou 261 (204.7 grains per panicle). In comparison, Teyou 1332 (177.9 grains per panicle) and Teyou 217 (145.9 grains per panicle) had relatively lower grain counts. For thousand-grain weight, there was little variation among the four varieties, but some trends were still noticeable. Teyou 217 had the highest thousand-grain weight at 24.7 g, followed by Huazheyou 261 (23.4 g) and Yongyou 1540 (23.3 g), while Teyou 1332 had the lowest at only 22.7 g. Thousand-grain weight is closely related to grain plumpness and is mainly influenced by genetic factors and environmental conditions during the grain-filling stage. Overall, Teyou 217 achieved high yields primarily due to its large number of effective panicles, whereas Yongyou 1540, despite having the highest grains per panicle, was limited by its lower effective panicle count, which restricted its total yield. This suggests that different varieties adopt distinct “strategies” to achieve yield—some rely on increasing the number of effective panicles, while others focus on producing more grains per panicle. In future variety selection and field management, it will be essential to adjust cultivation strategies based on the characteristics of each variety to further enhance yield and rice quality. 1.3 Growth period and phenological stage analysis of tested varieties This study monitored and compared the growth period (from sowing to maturity) and key phenological stages (initial heading, full heading, and maturity) of the four tested rice varieties (Table 2). The results showed significant differences in growth duration, ranging from 120 to 136 days, with a maximum difference of 16 days, indicating varying adaptability to light and temperature conditions among these varieties. Table 2 Growth duration and phenological stages of the tested rice varieties Variety Name Growth duration (days) Phenological stages Sowing date (MM/DD) Transplanting date (MM/DD) Initial heading date (MM/DD) Full heading date (MM/DD) Maturity date (MM/DD) Teyou 1332 133 7/3 7/22 9/21 9/28 11/18 Huazheyou 261 130 6/30 7/21 9/20 9/27 11/15 Yongyou 1540 120 6/30 7/21 9/9 9/13 11/5 Teyou217 136 6/30 7/22 9/22 9/28 11/18 Among them, Yongyou 1540 had the shortest growth period, taking only 120 days from sowing on June 30 to maturity on November 5. Its initial heading occurred on September 9, and full heading was reached by September 13, earlier than the other varieties. This classifies Yongyou 1540 as an early-maturing variety, making it particularly suitable for fields with a short cropping cycle. Huazheyou 261 and Teyou 1332 had growth periods of 130 and 133 days, respectively, and their initial heading (September 20-21) and full heading (September 27-28) were quite similar, indicating that their growth patterns were largely consistent. In contrast, Teyou 217 had the longest growth period, reaching 136 days. Its initial heading (September 22) and full heading (September 28) were slightly later than those of Huazheyou 261 and Teyou 1332, while its maturity date (November 18) was the same as Teyou 1332. This suggests that Teyou 217 has a longer growth cycle, possibly due to a slower grain-filling rate or a stronger ability to continuously accumulate dry matter in the later stages. The length of the growth period for different varieties is mainly influenced by genetic traits, light and temperature conditions, and growth rate. Short-duration varieties like Yongyou 1540 are more suitable for double-cropping systems or regions with a shorter growing season, as their early maturity allows for timely field turnover for the next crop. On the other hand, long-duration varieties like Teyou 217 require ample sunlight and an extended growing period, utilizing a longer grain-filling stage to accumulate more nutrients and ultimately increase yield. 2 Discussion The yield of rice is mainly determined by three factors: the number of effective panicles per unit area, the number of grains per panicle, and the thousand-grain weight. The results of this study show that the more effective
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