Impact of Pot Sizes on Seedlings Growth for Some Forest Trees Propagated in Forest Nursery

Seedlings of four species of Eucalyptus (E. gamophylla, E. eremophila, E. camaldulensis and E. oleosa), two species of Melaleuca (M .eleutherostachya and M. lateralis) and Casuarina obesa were grown in three different container volumes (1.6, 2.9 and 4.2 liter) under standard plastic greenhouse conditions. The effect of pot size on several growth parameters was evaluated, including final height increase, overall percentage of increase, relative height growth rate and accumulative increase in plant height. Eucalyptus camaldulensis had significantly better growth performance than other studied eucalypt seedlings. In general, M. eleutherostachya had significantly better growth performance than M. lateralis. The 2.9 liter pot provided sufficient root volume for growing seedlings of E. gamophylla, E. eremophila and E. oleosa. For E. camaldulensis, the 4.2 liter pot was the best for final height increase and overall percentage of increase in plant height and relative height growth rate. The 2.9 liter pot was the best for final height increase and overall percentage of increase in plant height. The 4.2 liter pot was the best for relative growth rates in M. eleutherostachya, M. lateralis and C. obesa. It was adequate to grow seedlings of E. gamophylla and E. eremophila for 181-240 days and E. camaldulensis and E. oleosa for 241-300 days using the smallest pot size (1.6 liter). In the largest pot size (4.2 liter), it was possible to grow the seedlings of E. gamophylla for 61-120 days, 121-180 days for E. eremophila and 181-240 days for E. camaldulensis and E. oleosa. It was adequate to grow seedlings of M. eleutherostachya and M. lateralis in the smallest pots (1.6 liter) for 301-365 days or in the medium pots (2.9 liter) for 241-300 days. C. obesa growth was possible for 301-365 days in the smallest pots (1.6 liter) or for 181-240 days in the medium pots (2.9 liter). In general, the time required for seedlings to reach an adequate size was decreased as the pot size increased. The best combination of pot size and time for growing seedlings for afforestation was species dependent