播种期对2个不同类型棉花品种产量和产量构成的影响

 适期播种是棉花丰产的重要措施，品种类型常影响播种期。为确定不同类型棉花品种的适宜播期，采用裂区设计，以品种类型（早发型鲁棉研21号和后发型鲁棉研28号）为主区，播种期（4月上旬早播、4月下旬中播和5月上旬晚播）为副区，于2009—2010年在山东临清研究了品种类型和播种期对棉花产量和产量构成的影响。两年的试验结果表明：品种和播期对棉花产量有显著的互作效应，而且主要是由于铃数和衣分的变化所致；早发型品种4月下旬播种产量最高，比4月中旬播种增产6.3%，5月上旬播种与4月中旬播种产量相当；后发型品种4月中旬播种产量最高，比4月下旬和5月上旬播种分别增产4.8%和12%。在鲁西北棉区地膜覆盖栽培条件下，早发型品种以4月下旬播种为宜，可以适当晚播，直到5月上旬；后发型品种应适当早播，以4月中旬为宜，晚播会显著减产。

Effect of Planting Date on Yield and Yield Components of Two Different Cotton Genotypes

Selecting a suitable planting date is important for achieving high yield in cotton(Gossypium hirsutum L.), and is dependent upon cotton genotype. A two-year field experiment was conducted in Linqing, Shandong Province, to study the effects of cotton  genotype and planting date on yield, yield components, photosynthetic rate and harvest index. A split-plot design with three replicates was used for the study. The main plots comprised two cotton genotypes(the early-developing variety SCRC21 and late-developing cultivar SCRC28), while planting dates(early planting, mid planting and late planting) constituted the subplots. A significant interaction affecting economic yield was detected between genotype and planting date, mainly attributable to variation in boll numbers·m^-2 and lint percentage. For the early-developing cultivar SCRC21, plants sown in late April had the highest yield, 6.3% higher than those planted in mid-April; the yield was similar between plants sown in early and late April. For the late-developing cultivar SCRC28, plants sown in mid-April produced the highest cotton yield, which was 4.8% and 12% higher than for those planted in late April and early May, respectively. In the northwest of Shandong Province where film mulching is used, the early-developing variety is suitable for being delayed planted if no later than early May, and maximum yield can be obtained with being planted in late April. In terms of yield and economic index, the late-developing cultivar should be planted in mid-April, because later planting would significantly reduce cotton yield.