关键词: 玉米, 主要产区, 种植密度, 变化趋势

Abstract: 【Objective】Enhancing the maize plant population has undergone a constant evolution over the years, with the purpose of increasing the crop yield. However, the rational density range was determined by environmental condition, varieties and management. The objective of this work was to reveal the approach of enhancing maize yield in the future by analyzing the change trend of planting density and its influencing factors in major producing regions. 【Method】 The research data have been obtained over the Project of Sending Agricultural Technology into Farmers’ Homes and National Maize Industrial Technology System from 2005 to 2016, including 23 provinces, more than 267 counties. From this investigation, 117 960 farmer production investigation data samples were obtained from the Northern China spring maize planting region (NM), the Northwest China maize planting region (NWM), the Huang-Huai-Hai Plain summer maize planting region (HPM), the Southwest China maize planting region(SM) and the Southern China sweet-waxy maize planting region (SWM). The number of harvested plants surveyed in nationwide investigation was used to analyze the planting density of maize main producing region and different ecological regions. The sample data were verified and complemented by averaging the values of 5 neighboring points. According to the regional environmental condition and planting patterns, the main maize producing regions have divided into 25 typical ecological regions. Boxplot analysis and Tukey’s honestly significant difference (HSD) test method were used to compare the planting density difference and its significance in different regions. Evolutionary trends of county-scale planting density in different ecological regions were subjected to the fitting linear model to analyze inter-annual trend of planting density and its significance.【Result】The results showed that there were significant differences of planting densities in different regions. At present (2014-2016), the planting density of the main producing region respectively were 6.77×10⁴, 6.19×10⁴, 5.91×10⁴, 5.13×10⁴ and 4.80×10⁴ plants/hm² in NWM, HPM, NM, SWM and SM. The planting density in NWM was significantly higher (P＜0.01) than other regions. Furthermore, planting density in SWM and SM was significantly lower (P＜0.01) than that in NWM, HPM and NM. From 2005 to 2016, the inter-annual variability of planting density showed a significant increase in NM. In NWM and SM, the planting density kept it steady between 2009 and 2016. The planting density in HPM increased obviously from 2005 to 2009 and remained stable after 2009. Planting density in SWM showed a significant decreasing trend.【Conclusion】Dense planting cultivation is commonly acknowledged by both the government and the academic researchers. However, the planting density evolution in the main production regions and different ecological regions is not uniform. Regional environmental condition is the key factor for determining the planting density, and reasonable cultivation techniques and appropriate density-resistant varieties are effective approaches to overcome environmental constraints and increase planting density. Consequently, further analysis of the promotion and restriction increase planting density factors, including environmental condition, varieties and management, will provide a theoretical foundation for establishing regional dense planting management mode.

Key words: maize, main producing region, planting density, variation trend