Critical daylength 长日植物 临界日长 (天仙手) Critical day length: the minimum daylength 24 for longday plant or 短日植物 要一 (苍耳) maximum daylength 临界日长 for shortday plant to 12 18 24 induce the flowering of these plants 日中性植物 18 每天光期长度(h)Critical day length:the minimum daylength for longday plant or maximum daylength for shortday plant to induce the flowering of these plants. Critical daylength