Abstract The first attempts to establish energy crops in the tropical region using short rotation species are premised on the utilization of clones for wood production. Therefore, the present study is aimed at examining the growth aspects (survival, diameter and tree height), leaf architecture (leaf area index [LAI], number and angle of the branches and sylleptic branches), biomass production, as well as biomass flow at the age of 24 months of two clones of Gmelina arborea in short rotation crops within three spacings (1.0x1.0 m, 0.75x0.75 m and 1.0x0.5 m). The results showed an increment with age, as the diameter increased from 3.00 cm at six months to 8.0 cm at 24 months, whereas the total height increased from 2.00 m at six months to 10.00 m at 24 months. Clone survival varied from 20 to 60 %, whereas the LAI, branch angle and sylleptic branches increased with age. The differences between clones appeared after 12 months. Biomass production was similar between clones, from 6 ton/ha at six months to 67 ton/ha at 24 months, with clone 2 showing greater biomass flow than clone 1. On the basis of biomass production results and the development of diameter as well as height, clone 1 is recommended for spacing 1.0x1.0 m and clone 2 for spacings 0.75x0.75 m and 1.0x0.5 m.

中文翻译：

---

三行距林木无性系短轮作人工林的生物质产量及特性

摘要 在热带地区利用短轮作树种培育能源作物的首次尝试是以利用无性系进行木材生产为前提的。因此，本研究旨在检查生长方面（存活率、直径和树高）、叶结构（叶面积指数 [LAI]、分枝和音节分枝的数量和角度）、生物量生产以及生物量流量在 24 个月龄时，在三个间距（1.0x1.0 m、0.75x0.75 m 和 1.0x0.5 m）内短轮作作物中的两个 Gmelina arborea 克隆。结果显示，随着年龄的增长，直径从 6 个月时的 3.00 cm 增加到 24 个月时的 8.0 cm，而总高度从 6 个月时的 2.00 m 增加到 24 个月时的 10.00 m。克隆存活率从 20% 到 60% 不等，而 LAI、支角和音节支随年龄增加。克隆之间的差异在 12 个月后出现。克隆之间的生物质产量相似，从 6 个月的 6 吨/公顷到 24 个月的 67 吨/公顷，克隆 2 显示出比克隆 1 更大的生物量流量。高度，建议克隆 1 用于间距 1.0x1.0 m，克隆 2 用于间距 0.75x0.75 m 和 1.0x0.5 m。