Effect of pot size and seedling age on growth and survival of Grevillea robusta (A. Cunn.) in the Eastern Amhara region of Ethiopia

Gravellia robusta was selected for this study because of its ecological and economic significance, as well as its potential for use in plantations, rehabilitation of degraded lands, and agroforestry purposes. The research aimed to assess the effects of different seedling ages in the nursery (4, 5, and 6 months) and various pot sizes (8 cm, 10 cm, and 12 cm) on the growth parameters and survival rate of G. robusta. In the nursery, we measured root length, shoot length, and the root: shoot ratio. In the field, we evaluated root collar diameter, diameter at breast height, height, survival rate, volume, and mean annual increment (MAI). The experiment was conducted using a factorial randomized complete block design in both the nursery and the field. The effect of different pot size and seedling age showed a significant effect on shoot length in the nursery at six months during destructing the seedling at (P < 0.05). The effect of pot size and seedling age at field also showed a significant effect on root collar diameter at 6 years and 2 months at (P < 0.05). These findings highlights, different pot size and seedling age showed significant effect not only in shoot length at the nursery but also in the root length at the field in mid-land Amhara, Northern Ethiopia. For others pecies with poor germination and slow seedling growth for field planting, more research is needed on the proper seedling age at nursery and pot size, including a benefit-cost ratio study.