Effects of super-absorbent polymer on dry matter accumulation and nutrient uptake of Pinus pinaster container seedlings

Super-absorbent polymer (SAP) is a widely studied cross-linked hydrophilic polymer used as water absorbent material. However, little information is available concerning the effects of SAPs on the growth and nutrient accumulation in forest container seedlings. The present study was conducted to quantify the effects of SAP applied with or without fertilizer on the dry matter and nutrient uptake of Pinus pinaster container seedlings. SAP addition with fertilizer increased dry matter along with increased seedling emergence time. However, no effect was found without fertilizer. Compared with fertilizer only, rapid accumulation time of nitrogen (N) and potassium (K) was 7 days longer resulting from SAP addition. The maximum daily N and K accumulations in the fertilized seedlings increased by 9.31 and 10.44 %, respectively, whereas those of the unfertilized seedlings did not differ significantly. SAP addition had little effect on phosphorous (P) uptake, except for an increase in the maximum daily P accumulation under fertilized conditions. The shoot and root of P. pinaster with SAP had 8.61 and 13.70 % higher yields, respectively, than those that received fertilizer only. Compared with fertilizer only, SAP addition with fertilizer increased the N and K contents by 7.15 and 10.04 %, respectively, whereas the P content did not differ significantly. Under fertilized conditions, N, P, and K uptake increased by 17.17, 10.13, and 20.33 %, respectively, from SAP addition. Hence, SAP could be used as a nutrient absorption enhancer (mainly N and K) in forest container seedlings, aside from being a water absorbent material.