精量播种减免间定苗对棉花产量和产量构成因素的影响

间苗、定苗是黄河流域棉区十分普及却费工费时的棉田管理措施。通过精量播种减免间苗、定苗环节，将为黄河流域棉区棉花轻简化栽培提供新的技术途径。2011-2013年连续3年在山东省临清市、夏津县、惠民县和东营市4个地点，以常规播种保苗方式为对照，研究了精量播种保苗(播量11.25 kg hm–2，出苗放苗后不间苗、定苗)方式对棉花收获密度、籽棉产量和产量构成因素的影响。年份、地点和播种保苗方式对棉花收获密度、籽棉产量和铃数皆有显著的互作效应。12个点次(3年4个地点)中有10个点次精量播种保苗方式的收获密度达到4.5~8.5株 m–2，铃数和籽棉产量与常规播种保苗方式相当；2011年东营点和2012年惠民点精量播种保苗方式的密度分别只有3.53株 m–2和3.63株 m–2， 铃数比常规播种分别减少13.8%和9.7%，单铃重与各自的对照无显著差异，籽棉产量分别减少14.2%和5.5%。精量播种处理中2个点次减产的主要原因在于收获密度过低，导致铃数降低。通过提高播种质量确保较高的收获密度，精量播种减免间定苗能够实现省工节本不减产，可作为一项重要的简化栽培措施在黄河流域棉区推行。

Effects of Precision Seeding without Thinning Process on Yield and Yield Components of Cotton

Thinning is a considerably popular practice in cotton field management in the Yellow River valley of China, but such a traditional practice is currently facing a big challenge because of labor costs and time consuming. The objective of the present study was to determine the effects of precision seeding on seed cotton yield and yield components so as to provide a new alternative technique to simplify cotton cultivation in the Region. A three-year field experiment was conducted at four experimental sites (Linqing, Xiajin, Huimin and Dongying) to comparatively investigate the effects of precision seeding without thinning on plant population density, seed cotton yield and yield components, with conventional seeding with thinning (seeding rate of 22.5 kg hm^–2 and thinning seedlings two times after emergence) as the control. There existed significant interaction effects among planting years, experimental sites and planting patterns on plant density, seed cotton yield and number of bolls per unit area. In 2011–2013, the plant population reached 4.5–8.5 plants m^{–2 in precision seeding treatment at ten out of twelve sites, and number of bolls per unit area and seed cotton yield were equivalent to those of conventional seeding at these ten sites. However, the seed cotton yield of precision seeding treatment at Dongying in 2011 and at Huimin in 2012 was significantly reduced by 14.2% and 5.5% owing to the low density (3.53 and 3.63 plants m–2}) and their boll number was reduced by 13.8% and 9.7% relative to that of conventional seeding treatment. There was no significant difference in single boll weight between the two seeding patterns. The yield reduction of precision seeding treatment at two experimental sites was mainly attributed to the decrease in number of bolls per unit area as a result of reduced plant density. Therefore, costs saving without yield reduction can be realized through precision seeding under the support of improved seeding quality and a relatively high plant density. Precision seeding without seedling thinning can be one of the simplified cultivation measures of cotton production in the Yellow River valley of China.