Characteristics of Seedling Raising and Mechanized Transplanting of Hybrid Rice with a Low Seeding Rate by Precise Seeding Method |
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| Authors: | WANG Yaliang ZHU Defeng XIANG Jing CHEN Huizhe ZHANG Yuping XU Yicheng ZHANG Yikai |
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| Institution: | State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China |
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| Abstract: | 【Objective】 The purpose of the study is to ascertain the effect of precise hill-sowing and drill-sowing methods on seedling raising and the characteristics of mechanized transplanting of hybrid rice with a low seed sowing rate below 70 g, and to further break the current technical bottleneck in mechanized transplanting process of hybrid rice. 【Method】 In this study, Zhongzheyou 1 and Yongyou 1540 were mechanically hill-sowed and drill-sowed in standard seedling raising trays with mechanized broadcasting as the control. The hill-sowing specification was 16×34 hill, and 16 drills were set in longitudinal direction for drill sowing. The seed sowing rates were 5 seeds, 3 seeds, and 2 seeds per hill for hill sowing, and the same seed rates were set in drill sowing. The effects of different sowing methods on the growth of seedlings and their mechanical transplanting characteristics were investigated. 【Results】 1) Sowing methods presented no significant effect on seedling percentage with a reduction in seeding rate. 2) A reduction in seeding rate improved rice seedling consistency, especially in hill sowing and drill sowing as compared with broadcasting. 3) In comparison with seed broadcasting, under hill seeding and drill seeding, seedling roots were more entwined as seedling mats. Under hill-sowing and drill sowing, Zhongzheyou 1 and Yongyou 1540 had 75.4% and 81.0% higher intertwining force than that of broadcasting, respectively. Precise hill- and drill-sowing generated effective seedling blanket without significant difference between the two treatments, while broadcast sowing did not. 4) Hill sowing and drill sowing significantly reduced the missed hill percent of machine transplanting. The missed hill percent of Zhongzheyou 1 and Yongyou 1540 under hill sowing and drill sowing were 76.3% and 74.6% lower than that of broadcast sowing in average, respectively. The missed hill percent for hill-seeding and drill-seeding with 3 seeds per hill was below 1%, 10% lower than that of broadcast sowing. 5) The uniformity of machine-transplanted seedling under hill sowing and drill sowing were better than that of broadcast sowing. And the proportion of the treatments with expected seedling-catching number in mechanized transplanting (2 to 5 seedlings with 5 seeds per hill, 1 to 3 seedlings with 3 seeds per hill and 1 to 2 seedlings with 2 seeds per hill) for the two cultivars were all above 80% in hill-sowing and drill-sowing in combination with machine transplanting, and the seedling uniformity of machine-transplanted Zhongzheyou 1 and Yongyou 1540 was 121.2% and 67.0% higher than that under broadcast sowing. Meanwhile hill sowing had a better result than drill sowing. 【Conclusion】 Precision hill seeding and drill seeding provide an alternative measure to current problems such as large amount of seeds, high missed hill percent and uneven seedling taking in the process of machine transplanting of rice. |
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| Keywords: | hybrid rice seed sowing rate precise seeding method machine transplanting |
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