Nursery fertilization of oaks: consequences for plant quality and outplanting
Pedro Villar Salvador
Forest Ecology and Restoration Group Departamento de Ciencias de la Vida, Universidad de Alcalá, Spain
Vancouver, WA, USA, November 27-28, 2012 Introduction Introduction
ISI Web of knowledge: (Fertilization, Nursery) and main (conifer genera)
90
80 Conifers
70 Oaks
60
50 45% are oaks 40 of the 30 Mediterranean
20 basin Number of studies of Number
10
0
<1960 1960-19651965-19701970-19751975-19801980-19851985-19901990-19951995-20002000-2005
2006 to present Introduction Objectives
1)Why should Mediterranean oak seedlings be fertilized?
Importance of (nitrogen) fertilization on seedling quality and out-planting performance of Mediterranean oaks
• How much N should be supplied to fertilize oak seedlings?
• When should we start N supply?
• Several future research lines Why should we fertilize oaks in the nursery? Methodology
Experiment 1 Quercus coccifera
0 mg N 30 mg N 75 mg N 150 mg N 200 mg N
Quercus faginea
0 mg N 30 mg N 75 mg N 150 mg N 200 mg N
•Container: 300 ml •P and K constant: 40 and 75 mg plant-1, respectively • Weekly constant fertilization regime (June-October) Planting sites
Terrace 4
Terrace 3
Rincón de Ademuz (Eastern Spain) Planted Quercus coccifera Terrace 2 species 4 terraces on Previous use abandoned cropland Continental Climate Mediterranean Soil 50 cm deep holes preparation Why should we fertilize oaks in the nursery?
-4.4 MPa -3.6 MPa -2.4 MPa -2.3 MPa Quercus coccifera 100 Terrace
Fertilization P=0.60 80
60
40 Surival Surival after 7 years (%) 20
0 0 30 75 150 200 0 30 75 150 200 0 30 75 150 200 0 30 75 150 200 Terrace 1 Terrace 2 Terrace 3 Terrace 4 Why should we fertilize oaks in the nursery?
22 -4.4 MPa -3.6 MPa -2.4 MPa -2.3 MPa 20 Quercus coccifera
18 Terrace × Fertilization P=0.18 16 14 12 10 8 6 4
Volume increase after 4 years (ml) after increase 4 years Volume 2
0 0 30 75 150 200 0 30 75 150 200 0 30 75 150 200 0 30 75 150 200 Terrace 1 Terrace 2 Terrace 3 Terrace 4 Why should we fertilize oaks in the nursery?
1.0
0.8 P<0.001
0.6
0.4
7-year survival chance survival 7-year 0.2
0.0
0.0 0.4 0.8 1.2 1.6 2.0 2.4 Stem volume at planting (ml) Methodology
Experiment 2
Quercus ilex
Quercus suber 55% incident light
Low High Low High Unfertilized fertilized fertilized Unfertilized fertilized fertilized 34 mg N 154 mg N 34 mg N 154 mg N
•Container: 300 ml •P and K constant: 16 and 34 mg plant-1, respectively • Weekly, constant fertilization regime (June-mid September) Planting sites
Santorcaz (Central Spain) Planted Quercus ilex species Abandoned Previous use cropland Continental Climate Mediterranean Soil Subsoiling preparation Why should we fertilize oaks in the nursery?
100 Quercus ilex 4 years after planting 90 Fertilization P<0.001 80 Shade P=0.20 70 60 50 40 Survival (%) 30 20 10 0 0 34 154 Nitrogen fertilization rate (mg N plant-1) N fertilization and oak seedling quality N fertilization effect on plant quality: Root growth capacity
Tm=15 -16ºC Duration 1 month
Quercus coccifera Container: 3000 ml Tm=9 -10 ºC Duration 1.5 months Growing medium: Perlite
RGC= New roots mass / time (mg d-1) N fertilization effect on plant quality: Root growth capacity
Quercus coccifera 2.0 Outside (low temperature) Greenhouse (high temperature)
Environment P=0.002 ) 1.5 -1 Fertilization P<0.001 Env. Fert. P=0.5
1.0 RGC(mg d
0.5
0.0 0 30 75 150 200 N fertilization (mg N plant-1) N fertilization effect on plant quality: cold tolerance
Quercus coccifera Test temperature: -13ºC Fertilization P=0.013 32
28 Does N fertilization affect cold and drought 24 tolerance of oak seedlings?
Electrolyte leakage (%) leakage Electrolyte 20
16 0 0 30 75 150 200 N fertilization (mg N plant-1) N fertilization effect on plant quality: cold tolerance
Quercus ilex Location Fertilization 1.0 P<0.05 1.0 -12 ºC Low N Constant rate 0.86 High N Exponential rate 0.8 0.75
0.62
0.6 0.5 Survival 0.4 0.37 0.37
0.2 0 0.0 Mild fall Cold fall Mild fall Cold fall nursery nursery nursery nursery September November
Heredia et al. in preparation N fertilization effect on plant quality: drought tolerance
Quercus ilex + Quercus suber Unfertilized High N fertilization Shade P=0.023 (154 mg N plant-1) Shade Fertilization P=0.08 3.9
3.6
3.3
Osmotic potential at turgor loss point(-MPa) loss potential at turgor Osmotic 3.0 0.0 Shade Sun How much nitrogen should we supply to fertilize oaks? How much nitrogen should we supply to fertilize oaks?
Deficiency Luxury consumption Toxicity
Sufficiency level growth Plant
N supply How much nitrogen should we supply to fertilize oaks?
Quercus 100 coccifera Pinus pinea Pinus sylvestris Quercus suber
80 Quercus Pinus faginea pinaster
60 Ceratonia siliqua
Quercus ilex 40 Juniperus Pinus thurifera halepensis Standardized growth rate (%) rate growth Standardized 20 Mediterranean oaks have low N yield so they need to receive high N fertilization rates to maximize growth 0 0 20 40 60 80 100 120 140 Nitrogen supply rate (mg N plant-1) How much nitrogen should we supply to fertilize oaks?
7 c Quercus coccifera c Quercus faginea 6 b b
5 b b
ab 4 a a a
3 Plant mass (g) 2
0 0 30 75 150 200 Nitrogen fertilization rate (mg N plant-1) How much nitrogen should we supply to fertilize oaks?
720 18 Quercus coccifera Salifu and Jacobs 2006 616 Quercus faginea 14 Quercus ilex Jacobs et al. 2009Q. coccifera 512 Q. faginea 10 Q. ilex 7 Q. rubra 46 5 Plant mass (g) mass Plant Plant mass (g) mass Plant 34 3 22 1 00 00 2525 5050 7575 100100 125125 150150 175175 200200 NN fertilization fertilization rate rate (mg (mg N N planta plant-1-1)) When should we start oak fertilization? When should we start oak fertilization? Acorn N Soil N 24 P<0.001 20 Quercus ilex 16 12 8 15 4 Acorn N Soil N (Labeled N) N content (mg) 24 0 High N Low N Acorn N Soil N 21 12 P=0.19
9 18 6 15 3
N N content (mg) 0 12 High N Low N
9 N content (mg) N content
6
3
0 Only 1st shoot flush 1st shoot flush 2nd shoot flush 2nd shoot flush roots in progress completed in progress completed
Villar-Salvador et al. 2010 Tree Physiol. Future research Future research: can foliar fertilization help N loading?
40 mM N sprayed 6 times along two days 14
) Quercus ilex -1 13
12
11
10
9 PlantNconcentration (mg g 8 0 Control Urea NH4+ Glycine NO3-
N source Uscola et al. in preparation Future research: N sources
20 NH + 18 4 - NO3
) 16 Glycine -1 h
-1 14 Ng
15 12
10
8
6
N uptake rate (µg (µg rate uptake N 4
2
0 Quercus faginea Quercus ilex
Uscola et al. in preparation Conclusions
Why should Mediterranean oak seedlings be fertilized?
Because out-planting performance of Mediterranean oak seedlings is strongly improved by nursery fertilization.
Moderate to high N fertilization increases seedling vigor as measured by root growth capacity
Very low N fertilization hinders stress tolerance of oak seedlings. High N fertilization does not necessary reduce stress tolerance of oak seedlings in cold winter nurseries, although it might reduce it in mild winter ones. Conclusions
How much N should be supplied to fertilize oak seedlings?
Mediterranean oaks have low N yield when compared with other Mediterranean woody species. Consequently, N sufficiency levels are high (75-150 mg N plant-1), but this probably is not a specific trait of oaks from other biomes.
When should we start N supply?
To improve fertilizer use efficiency, early fertilization should be avoided in oak seedlings because dependence on N acorn is very high. For instance, Q. ilex fertilization should start at the beginning of the second shoot flush of growth Thank you!