Formula Fertilization Promotes Phoebe bournei Robust Seedling Cultivation

Abstract

Phoebe bournei is a rare and endangered woody species and the success of its plantation development is dependent upon proper seedling cultivation. This study explored the regulation of N, P and K fertilizer and the interaction of these macronutrients on the growth of Phoebe bournei seedlings. To determine the optimum rate and ratio of N–P–K fertilizer in seedling cultivation, we used the unique “3414” incomplete orthogonal regression design to evaluate the effects of N–P–K fertilization on seedling morphological development. One-year-old Phoebe bournei bareroot seedlings were grown for one growing season under the defined fertilization regime, with their morphological development determined by measuring seedling attributes—root, stem, leaves and total biomass, root collar diameter and seedling height. These attributes were then combined to calculate the following indices: height-diameter ratio, shoot-root ratio and the seedling quality index (QI). Results showed that the N–P–K fertilizer had significant and beneficial effect on seedling cultivation. N effect was highest, followed by K and P. The three-way N×P×K interaction effect was strong, and the two-way interactions effect was highest for N×P, followed by P×K and N×K. At the “2” level of N (0.532 g·plant−1), P (P2O5, 0.133 g·plant−1), and K fertilizer (K2O, 0.356 g·plant−1), seedling growth and biomass accumulation were at their maximum. Unary, binary, and ternary quadratic fertilizer effect function equations of QI were established. Through comparative analysis, the ternary quadratic model was the optimal model and through a simulation–optimization, the optimal N–P–K fertilizer rates were 0.373~0.420 g·plant−1 (N), 0.086~0.106 g·plant−1 (P2O5), 0.243~0.280 g·plant−1 (K2O), with a N–P–K ratio of 1:0.20:0.43~1:0.65:0.75.

Soil Bacteria to Regulate Phoebe bournei Seedling Growth and Sustainable Soil Utilization under NPK Fertilization

“…The average height of the seedlings was 20.2 ± 0.9 cm, and the average diameter was 2.3 ± 1.0 mm. Seedlings had total N, P, and K contents of 1.219, 1.555, and 14.022 g•Kg −1 , respectively, at the start of the experiment [48].…”

“…Plastic-potgrown seedlings (diameter × height: 25 × 25 cm) had 6.0 kg of dry soil. The fertilizers used were urea (N: 47%), superphosphate (P 2 O 5 : 12%), and potassium chloride (K 2 O: 60%) [48].…”

“…The experiment site was at a field nursery of the Fujian Agriculture and Forestry University, China (119 • 23 E, 26 • 09 N). The annual average temperature is 19.6 • C, the minimum temperature is −2.5, and the maximum temperature is 42.3 • C. Effective accumulated temperature ≥10 • C is 5880 • C, with 326 days >0 • C. Annual precipitation is 1490 mm, and annual average humidity is 77% [48].…”

“…The experiment had 14 treatments, with each treatment replicated three times, and 1260 seedlings, with 30 seedlings at each treatment replication. Random arrangement (complete randomized design) was used for the fertilizer replications to minimize any environmental effects [48]. Table 6.…”

“…P. bournei seedlings need a light intensity equivalent of 75% natural light, and a 2.7 m high shed was equipped in the nursery. Seedlings were watered on a varying schedule determined by the empirical method of topsoil coloration, resulting in watering at~7 days during March to April, 15 days during May to July, not watered in August,~10 days during September to November, and~15 days in December, to maintain the desired soil water status of~75% field capacity [48].…”