关键词: 毛竹, 变温处理, 种子萌发, 幼苗生长发育

Abstract:

【Objective】The germination characteristics of moso bamboo seeds and the development law of seedlings with the 1-5 leaves were comprehensively studied after being cultivated in varying temperatures. This provided a theoretical and practical basis for the study of bamboo seedlings.【Method】The seeds were collected from Dajing Town, Lingchuan County, Guilin City in Guangxi Province. The seedlings were cultured in a laboratory incubator and seven different temperature treatments (two different temperature combinations within 24 hours) were set: 29 ℃/15 ℃ (T1), 28 ℃/16 ℃ (T2), 27 ℃/17 ℃ (T3), 26 ℃/18 ℃ (T4), 25 ℃/19 ℃ (T5), 24 ℃/20 ℃ (T6), 23 ℃/21 ℃ (T7), and one constant temperature environment 22 ℃/22 ℃ (T8). The temperature change period was 12 / 12 h. Every 12 hours, the germination time of each seed, the leaf development time of 1-5 leaves, and the leaf height under each environment of a different temperature were observed and recorded in detail. The leaf area, fresh and dry weights of the aboveground and underground parts, root morphology, leaf surface micromorphology, stomatal length and stomatal density were also measured.【Result】 ① The germination rate of P. edulis seeds was more than 50% under different temperature conditions. Combined with the germination potential of seeds, it was found that the germination potential of T4-T7 treatments was higher than 30%. In T1-T8 treatments, the mean germination time of the seeds was gradually shor-tened. ② Under different temperature conditions, the leaf development time of seedlings gradually extended from the first leaf to the fifth leaf. The time and quantity of leaf development were relatively concentrated in the T6-T8 treatments; meanwhile, leaf height and area of seedlings in the same culture environment gradually increased from the first leaf to the fifth leaf. Notably, the higher the temperature difference was, so did the leaf height increase. The development rate of leaves after the third leaf tended to be stable and it was observed that the larger the temperature difference, the larger the biomass of seedlings. In general, the root system developed better in T3-T6 treatments. ③ With the decrease in tempe-rature differences, the number of mastoid and epidermal hairs on the abaxial epidermis of P. edulis leaves gradually increased. From the first to the fifth leaf in the same treatments, the number of mastoid and epidermal hairs on the abaxial epidermis also gradually increased. In T1-T8 treatments, the stomata on the abaxial epidermis were arranged in rows. Although there was no significant difference in the appearance of the stomata, the length and density of the stomata ge-nerally increased first and then decreased, and the highest stomatal density was mainly concentrated in T5. 【Conclusion】The variable temperature treatments at 26 ℃/18 ℃ (T4), 25 ℃/19 ℃ (T5), and 24 ℃/20 ℃ (T6) were more conducive to improving the germination rate and germination potential of P. edulis seeds. Furthermore, the overall growth and development of the seedlings, including leaf height, leaf area, growth rate, biomass, root system and stomatal densities, were more suitable under these three different temperatures.

Key words: Phyllostachys edulis, variable temperature, seed germination, seedling growth and development