Abstract:

【Objective】This study focused on the growing regularity and model fitting of module biomass of a dwarf ornamental bamboo species, Pleioblastus pygmaeus (one-and-a-half year old seedlings), and will provide a theoretical basis for rapid propagation and centralization of small-sized bamboo seedlings.【Method】During the approximately one-and-a-half year growth process after sowing, we conducted a follow-up investigation on P. pygmaeus seedlings, including the plant height and ground diameter of the mother plants, emergence time, plant height and ground diameter of tillering seedlings, and appearance and development of bamboo rhizomes. Multiple morphological indicators, including dry weight of leaves and culms, plant height of tillering seedlings, and length of bamboo rhizomes, etc. were fitted by a logistic model and polynomial function. The relative growth curves of plant modules with time were analyzed. The relationship between plant height, ground diameter and biomass was investigated. The ratio of dry weight between aboveground and underground areas was examined.【Result】The seedlings were unearthed about 1 week after sowing. On the 11th day after sowing, the first leaf was fully expanded. The first generation of tillering seedlings appeared approximately three months after sowing. Primary bamboo rhizomes were generated approximately six months after sowing. One year after sowing, the culms on the primary bamboo rhrizome system grew vigorously. In one and a half year after sowing, the second and third-grade bamboo rhrizomes began to differentiate and grow. The ground diameter and plant height of tillering seedlings increased gradually with their differentiation. The module biomass of P. pygmaeus seedlings increased with time. With the same ground diameter, dry weight of culms increased with plant height. Within three months after sowing, the aboveground biomass of seedlings was greater than the underground biomass of seedlings, and their ratio showed an upward trend. Within three to seven months after sowing, the aboveground biomass was lighter than the underground biomass, and their ratio tended to show an upward trend. Within 10 months to one year after sowing, the aboveground part was heavier than the underground part, but the dry weight ratio of the former to the latter was initially increased and then decreased. In one year after sowing, the ratio of aboveground and underground dry weight showed a downward trend, but it gradually tended to be stable. 【Conclusion】This study systematically revealed the growth mechanism and dynamic growth process of various modules of P. pygmaeus seedlings between the period of sowing and stem elongation. The increase in module biomass of P. pygmaeus seedlings fitted into the logistic model with time during the growth process. When the ground diameter of P. pygmaeus seedlings was the same, there was a significant linear relationship between plant height and biomass. For most of the time during the growth process, the aboveground biomass of P. pygmaeus seedlings was greater than the underground biomass of P. pygmaeus seedlings.

Key words: Pleioblastus pygmaeus, seed seedlings, growth mechanisms, biomass model