The Effects of Photoperiod on Phenological Development and Yields of Industrial Hemp

摘要

短光照引起提早开花，限制了工业大麻的产量(大麻L.)。试验是在昆士兰的班达伯格用不同光照制度下进行的。在植物成熟期，当光照低于13小时40分钟时，影响不大，但当光周期超过14小时40分钟时出现明显延迟。延长光照会使株髙显著增加。在自然光照期下株髙为1188毫米和1161毫米，在处理3(13小时40分钟的光照期)株髙为1286毫米。而用处理4(14小时40分钟)株髙为1395毫米。而且经过延长光照的植物干厚度增加，最终收获的茎和根的产量也最大。一个平行的田间试验作为单独的实验种植在同一位置在五个连续的日期(PD1至九月15，十月25,十一月25，十二月16,一月23),实验表明，从最髙株髙和干物质产量相比，跟其它种植日期相比十一月25日是最佳种植日期。从这些实验的结果清楚地表明，在此试验品种若获得髙产麻，在生长期一天的曰照长度必须至少超过13小时40分钟。%Shorter photoperiod cause early flowering, restricting yields in Industrial hemp (Cannabis sativa L.). Trials were conducted under different light regimes tinder the protected structure in Bundaberg, QLD, Australia. Little difference was observed in plant maturity when photoperiod was at or below 13 h 40 min but was significantly delayed when photoperiods exceeded 14 h 40 min. Plant heights at harvest increased significantly with extended light. Plant heights at harvest were 1,188 mm and 1,161 mm for natural light treatments, 1,286 mm in treatment 3 (13 h and 40 min light period) and 1,395 mm in treatment 4 (14 h and 40 min). Stem thickness increased, whereas stem and root yields at final harvest were greater with extended photoperiod. A parallel field trial as separate experiment was also planted at the same location over five consecutive dates (PD1- September 15, October 25, November 25, December 16, and January 23), which showed that November 25 as an optimum timing as evidenced by highest plant height and thy matter yield compared to other planting dates. Results from these trials clearly indicated that day length must exceed at least 13 b and 40 min during the growing season to produce high yielding hemp for the tested variety.