Growth and Nutrient Partitioning of Containerized Malus trilobata Schneid. and Acer syriacum Boiss. and Gaill. Under Two Fertigation Regimes

The native flora of Lebanon is threatened. As part of an ex situ conservation strategy, this study was conducted to determine if Malus trilobata (Schneid.) and Acer syriacum (Boiss. and Gaill.), two native Lebanese trees, were amenable to container production. Therefore, these species' growth and nitrogen, phosphorus, and potassium uptake efficiency and distribution under two fertilizer rates were studied. Malus trilobata seedlings were obtained from seeds collected from two mother trees, whereas Acer syriacum seeds were collected from a single tree. Two-year-old seedlings raised from these seeds were planted in 11-L containers in a 3:1 pine bark:compost substrate. Half the seedlings within each source and species were assigned to either 25 or 100 mg·L−1 N from 21N–3.1P–5.9K water-soluble fertilizer treatments. Seedlings of both Malus trilobata sources grown under 25 mg·L−1 N were taller than those grown at 100 mg·L−1 N. Nitrogen loading occurred in plants of Malus trilobata under the high fertilizer rate, although total plant N, phosphorus, and potassium content was unaffected by fertilizer rate, because larger seedlings had lower nutrient concentrations. There were significant differences in growth among the two Malus trilobata seed sources, but there were no differences in mineral nutrient uptake or nutrient use efficiency. Growth, mineral nutrient uptake, and nutrient use efficiency of Acer syriacum seedlings were unaffected by fertilizer rate. Malus trilobata and Acer syriacum seedlings are amenable to container production. Using container production for these species with subsequent transplanting into managed landscapes might be a viable ex situ conservation method. Further studies are needed.