<p>Cotton seedlings were pre-treated with chilling stress for 3 days, then inoculated with <i>A. alternata</i> isolate A1, and removed to grow at optimal temperature of 28/20°C; Different letters behind the disease index indicate significant difference with the <i>P</i> value of 0.05. The first letters indicate the comparison among different temperatures of chilling stress pre-treatment and the second letters indicate the comparison between XLZ13 and XLZ33.</p>