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| DOI：10.13522/j.cnki.ggps.2025309 |
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| Effects of sowing date on growth and annual yield of medium-duration ratoon rice |
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Yi Jia, Zheng Huabin, Mao Ruiqing, Li Zheli, Zhang Ming,
Liu Longsheng, Fang Shengliang, Zou Dan, Gao Jing
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1. Hunan Agricultural University, Changsha 410128, China;
2. Hengyang Academy of Agricultural Sciences, Hengyang 421200, China;
3. Shashi Town Agricultural Comprehensive Service Center, Liuyang 410300, China
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| Abstract: |
| 【Objective】Ratooning rice can produce two harvests from a single planting, but its yield is strongly influenced by sowing date. This study investigated the effects of sowing date on annual yield and yield formation of a medium-duration ratoon rice.【Method】The field experiment was conducted in Changsha, central Hunan Province, from 2020 to 2021, using the ratooning rice variety Huiliangyou 898, a widely cultivar grown in the region. We compared six sowing dates: March 15 (B1), March 20 (B2), March 25 (B3), March 30 (B4), April 5 (B5), and April 10 (B6).【Result】Delayed sowing progressively shortened the annual growth duration, primarily because of the reduced vegetative growth period in the main crop, whereas the growth duration of the ratoon crop remained relatively stable. The growth duration of the main and ratoon crops was negatively correlated. Reproductive periods differed between years and were negatively correlated with mean temperature. For the main crop, the tillering rate increased with delayed sowing, resulting in earlier attainment of maximum tiller number. In the ratoon crop, seedling emergence was rapid within 5 days after main-crop harvest, subsequently slowing and stabilizing. Sowing on March 20 produced the greatest number of regenerated seedlings. Both main-crop and ratoon-crop yields showed unimodal responses to sowing date, with B2 producing the highest yields in both 2020 and 2021. Compared with other treatments, B2 increased main-crop yield by 6.31%-13.28% and ratoon-crop yield by 9.49%-69.55%. It also maintained slow post-heading decline in SPAD value, rapid ratoon regeneration, more regenerated seedlings, low sheath blight incidence, and significantly high harvest index and panicle number per unit area. In contrast, B6 had the lowest harvest index, panicle number per unit area, and seed-setting rate. Annual yield showed a unimodal response to sowing date, with B2 producing the highest yield in 2020 and B3 in 2021, representing an increase of 0.23%-8.70% and 9.49%-69.55%, respectively, compared with other treatments.【Conclusion】In central Hunan Province, the optimal sowing window for medium-duration ratoon rice is March 20–25, which maximizes annual yield. Both excessively early and late sowing reduced annual yield, with magnitude of the reduction depending on sowing date. |
| Key words: ratooning rice sowing date medium growth duration yield |
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