Evaluation of the response of Eucalyptus grandis seedlings grown on a nutrient deficient soil supplied with two different fertilizers

ESTEBAN TUBERT; VICTORIA VITALI; GABRIELA AMODEO

Providence, RI

Congreso; Plant Biology Meeting; 2013

American Society of Plant Biology

Eucalyptus grandis has become the main species used for wood and pulp production in Argentina, Brazil and Uruguay due to its rapid growth and good adaptation to different types of soils. Seedlings undergo a critical stage after being transferred to a final on-field destination, where the availability of water and nutrients at the rhizosphere determines survival of the specimens as well as health and future performance of the plantation. On the past years, the industry worldwide has focused on using nutrient and water deficient soils for tree plantation as these fields remain mainly unused by agriculture.  With the purpose of studying water relations and nutrition of E. grandis seedlings during the first 60 days after being transferred from greenhouse to a poor soil, we evaluated its response to different mixtures of minerals, using sand and a superabsorbent polymer as substrate. Physiological parameters including height, neck width and number of leaves were measured at 15, 30, 45 and 60 days. After the test was concluded, plants were collected so leaf area and dry matter accumulation in stem could be measured.  Specific Leaf Area, Relative Growth Rate (RGR) and Net Assimilation Coefficient (CAN) were calculated with the above mentioned data. All treatments showed a similar Water Content (WC). However Control plants (no fertilizer) showed a significantly lower WC (30%) probably due to reduced synthesis of fresh tissues. Our preliminary results indicate that  a mixture of salts with high contribution of N, K and low P (Bal), produces an increase in dry weight accumulation (600%) compared to Control and a lower but significant increase (70%)if compared against a treatment consisting in Monoamonium Phosphate (MAP) -a widespread fertilizer used in forestry- which delivers higher P but lower N. Moreover, CAN increases in plants treated with Bal compared with MAP treated plants, suggesting a higher photosynthetic efficiency. Significant improvement in all parameters was observed relative to MAP highlighting the potential importance of the choice of a start up fertilizer in Eucalyptus granids on poor soils.