Yield components of forage ramie ( Boehmeria nivea L.) and their effects on yield

Ramie (Boehmeria nivea L.) is a perennial herb and an ideal raw material for plant protein feed. Thus, the selection and breeding of high-yielding varieties of forage ramie have a considerable influence on livestock husbandry development. Although yield and yield components provide important indices for evaluating germplasm resources and breeding new varieties, only a few studies have examined ramie forage yield traits. In this study, we assessed the growth rate, node number, node length, ramet number, plant height, dry-fresh weight ratio, and yield of 24 ramie varieties harvested at 12 time points during the middle period of growing season in Yuanjiang, China, from 2016 to 2017. We determined correlations among these traits and their effects on yield. The forage yield and its components showed high phenotypic diversity. Five components (namely, growth rate, node number, node length, ramet number, and plant height) showed significant positive correlations with forage yield, whereas dry-fresh weight ratio showed a significant negative correlation with yield. The principal component analysis revealed that a plant type with rapid growth, more nodes, strong ramets, and dense leaves can significantly improve forage yield. Ramet number and plant height were found to be the most important yield indices, with ramet number presenting a slightly stronger influence on yield. We established a regression equation to represent the relationship between yield components and yield. This study provides important information that will facilitate the breeding and germplasm screening of high-yielding forage ramie for an ideal plant type.