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Acta Prataculturae Sinica ›› 2020, Vol. 29 ›› Issue (5): 132-140.DOI: 10.11686/cyxb2019421

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Effects of different direct seeding methods and weed control timing on weed occurrence and grain yield of early indica rice

ZHOU Yan-zhi, CHEN Li-ming, WANG Wen-xia, LI Zu-jun, ZENG Yong-jun, TAN Xue-ming, HU Shui-xiu, SHI Qing-hua, PAN Xiao-hua, ZENG Yan-hua*   

  1. Collaborative Innovation Center for the Modernization Production of Double Cropping Rice, Key Laboratory of Crop Physiology Ecology and Genetic Breeding Ministry of Education, Jiangxi Key Laboratory of Crop Physiology Ecology and Genetic Breeding, Jiangxi Agricultural University, Nanchang 330045, China
  • Received:2019-09-29 Online:2020-05-20 Published:2020-05-20
  • Contact: * E-mail: zyh74049501@163.com

Abstract: This research aimed to identify the optimal timing of weed control in rice paddy fields. Hybrid early indica rice Qiliangyou 2012 was planted in pot experiments with three sowing methods [dry direct seeding (DDS), wet direct seeding (WDS) and flooding direct seeding (FDS)] and four manual weeding treatments [from sowing to three leaves (C1), from three leaves to four leaves (C2), weeding for the whole growth period (C3) and no weeding over the entire growth period (CK)], to study the effects of the different seeding methods and weed control options on weed occurrence and grain yield. It was found that in the DDS treatment, the seeding emergence rate was significantly increased compared to FDS and WDS. Weeds such as Echinochloa crusgalli and Euphorbia lathyris were a serious problem in DDS, while aquatic weeds including Juncellus serotinus and Monochoria vaginalis were relatively serious in FDS and WDS. The weed occurrence in the DDS treatment was serious in early crop development (3-29 days after sowing), but was significantly lower than that of FDS and WDS after 43 days. For the whole rice growing period, the weed density in DDS was decreased by 12.57%-15.72%, and the biomass of weeds was significantly lower than that of FDS and WDS, while the fresh weight of weeds in DDS was decreased by 65.83% and 57.45%, while the dry weight was decreased by 69.73% and 59.04%, respectively, compared to FDS and WDS. Correlation analysis showed that weed biomass was negatively correlated with grain yield and its components for direct seeding rice, and the occurrence of weeds 15-22 days after sowing significantly reduced yield. Compared with CK, the grain yield of early indica rice was significantly increased by all weed control treatments, with the ranking for yield being C3>C1>C2>CK, and the average yield increase being 17.91%-31.21%. The best among the weed control treatments was C1; while the yield of DDS was higher than the yields of FDS and WDS, and the increase in grain yield was mainly due to an increase in number of effective panicles per unit area. The peak occurrence of weeds occurred at different times in the different sowing treatments. DDS has potential to reduce the occurrence of weeds in direct seeded paddy fields, and used with weed control from sowing to the three leaf stage, could enhance rice crop yield.

Key words: direct-seeded rice, direct seeding pattern, the occurrence of weeds, the period of weed control, grain yield