Preliminary Study on Optimizing Rice Production in Cold Regions: Yield and Nutritional Trade-Offs Between Transplanting and Mechanical Hill-Drop Seeding

Direct seeding of rice reduces labor intensity and cost, helping alleviate labor shortages in cold-region rice production. To investigate the effects of mechanical precision hill-direct seeding versus mechanical transplanting on yield and nutrient accumulation in cold regions, a set of field split-plot experiments were conducted with cultivation method as the main plot and rice variety as the sub-plot. Our comprehensive measurement results indicate that transplanting significantly increased yield by enhancing tiller number, filled grains per panicle, and grain weight per hill, with significant varietal differences observed. No significant difference in 1000-grain weight was found between the two cultivation methods. Except for Zn content, different cultivation methods have no significant effect on other measured nutrients such as N, P, K, Fe, starch, and fat. Transplanting significantly increased effective tiller number (an increase of 2.6 tillers per hill) and filled grains per panicle (an increase of 12.4 grains), with a significant variety–cultivation method interaction. Qijing 2 (QJ2) and Tiandao 261 (TD261) were more suitable for transplanting to achieve high yield potential, whereas Longgeng 3038 (LG3038) and Tianxiangdao 9 (TXD9) obtained relatively high yields under direct seeding. Therefore, appropriate cultivation methods should be selected based on varietal characteristics: transplanting is recommended for high-yield-potential varieties, while simplified direct seeding is advised for varieties tolerant to direct seeding. Overall, this is a comprehensive consideration and rational strategy based on balancing rice yield, revenue, and benefit, as well as ensuring both food security and farmer income of the entire country and society.