A new technology for predicting the fiber content in hemp bast

Hemp (Cannabis sativa L.) is a traditional fiber crop, which is becoming one of the most important industrial fibers, with a promising future in many fields. To accelerate the breeding of hemp cultivars with increased fiber content, it is important to establish a pre-flowering method that can be used to predict the potential fiber content in hemp bast. This study investigated the correlation between fiber content in the stem bast portion and in the entire stem. In addition, the variation in the bast fiber content during the sampling period was studied in three hemp cultivars. It was clear that the bast fiber content in hemp stems was determined up to 40 d before emergence of the staminate buds. The fiber content of the bast (in a sample piece 30cm long and covering one-quarter of the stem girth, sampled at two-fifths of the plant height from the soil, 20 d before the staminate buds emerged) was shown to be representative of the fiber content of the entire stem. In conclusion, this new method would allow breeders to select the hemp plants for high bast fiber content during the early to middle growth periods, before the male buds emerged, potentially accelerating the genetic improvement of fiber content in industrial hemp.