New marking method by electrical stimulation for studying xylem formation [of Japanese fir, Abies sachalinensis]

abies abies sachalinensis anatomy cell division conifers crops economic plants electricity energy energy sources experiments forest trees growth rings gymnosperms injurious factors lesions natural resources physics physiological functions physiology pinaceae plant anatomy plant vascular system plants research resources stimulation structural crops timber trees trees vascular bundles vascular tissues wood xylem