The Effect of Arbuscular Mycorrhizal Fungi Inoculation on the Quality of Seedlings for the National Greening Program in the Philippines Angela Ferraren, Nestor Gregorio, Lourdes Agne Mayet Avela and Arturo Pasa
Biliran, Philippines
Average erosion rate (tons ha -1 yr -1 )by region in the Philippines in 1993. Dotted line represents the average erosion rate. (FAO, 1998)
The National Greening Program is the Philippine government banner program for massive forest rehabilitation Target: 1.5 B trees in 1.5 M ha of public lands nationwide between 2011 to 2016.
Greening the Philippines NGP requirement: rapid production of high quality seedlings The successful establishment of seedlings after outplanting, especially in stressful sites, depends upon good seedling quality
Seedling Quality Physico- chemical characteristics of potting media are critical for the success in nursery seedling establishment and consequently in the field Growth and performance of nursery stock are oftentimes related to the nutrient supplying capacity of the potting media.
Seedling Quality Improving the fertility of nursery soils is essential to guarantee the production of high quality seedlings. Small scale tree seedling nurseries in the Philippines use the soils collected locally in raising seedlings and most often these soils are deficient in mineral nutrients
Seedling Quality Arbuscular mycorrhizal fungi (A MF) inoculation has been proposed and then adapted as a solution in attaining good growth performance of seedlings in the NGP reforestation sites
AMF in National Greening Program In 2013:The Department of Environment and Natural Resources (DENR) produced 155 tons of AMF inoculant and distributed them to different regions in the Philippines to ensure the supply of AMF inoculum for planting materials for the NGP
Why AMF inoculation? AMF can form mutualistic symbioses with most tropical forest species. AMF inoculation in the nursery may provide better growth, and vigour of seedlings to cope with transplantation stress. AMF population is low because the soils used in the nursery are often collected from barren surroundings and may have been stored for a long time.
Research Questions Will AMF inoculation improve the nursery growth performance of A. falcataria using a potting medium of low fertility? Will addition of small amount of chemical fertilizer improve the effectiveness of AMF inoculation in nursery seedlings with less fertile potting medium? Which will have the strongest effect (potting medium, fertilizer or AMF) on the growth, biomass production, photosynthetic rate, nutrient concentration and AMF infection of A. falcataria seedlings in the nursery?
Treatments & Experimental design 2x2x2 factorial in Randomized Complete Block Factor A Potting Mix : Soil alone, Soil + Rice Hull Factor B Fertilizer level: Distilled Water, Nutrient Solution - 8 mg N - 6 mg P 6 mg K/seedling Factor C AMF Inoculation: Without AMF, With AMF Replications:3 Test plant: Albizia falcataria
Measurements Biweekly seedling height and base diameter from two to 14 weeks after potting Photosynthetic potting, rate: at harvest, four months after Nodulation, biomass and nitrogen, phosphorus and potassium concentration, and AMF infection of harvested seedlings
Characteristics of Potting Mix Soil Alone Soil + rice hull ph 5.19 5.04 Total OC (%) 5.22 5.47 Total N (%) 0.40 0.43 Total P (%) 0.05 0.08 Total K (%) 0.06 0.08
Main effects: seedling height from two to 14 weeks after potting Source of variation Empirical Probability Values 2 4 6 8 10 12 14 Potting mix 0.730 ns 0.809 ns 0.359 ns 0.310 ns 0.310 ns 0.160 ns 0.121 ns Fertilizer 0.677 ns 0.524 ns 0.162 ns 0.141 ns 0.025* 0.060 ns 0.053* Inoculation 0.397 ns 0.357 ns 0.950 ns 0.650 ns 0.969 ns 0.985 ns 0.990 ns
Main Effects: seedling base diameter at two to 14 weeks after potting Source of variation Potting mix Empirical Probability Values 2 4 6 8 10 12 14 0.709 ns 0.561 ns 0.386 ns 0.524 ns 0.606 ns 0.954 ns 0.645 ns Fertilizer 0.958 ns 0.335 ns 0.065 ns 0.072 ns 0.010* 0.006* 0.006* Inoculation 0.571 ns 0.475 ns 0.848 ns 0.715 ns 0.630 ns 0.792 ns 0.977 ns
Fertilizer Effect: Height of A. falcataria from two to 14 weeks after potting 140 120 Unfertilized Fertilized Biweekly Plant height 100 cm 80 60 40 20 0 2 4 6 8 10 12 14 16 Weeks
Fertilizer Effect: Base diameter of A. falcataria from two to 14 weeks after potting 3.0 2.5 2.0 Unfertilized Fertilized Biweekly Base diameter mm 1.5 1.0 0.5 0 2 4 6 8 10 12 14 16 Weeks
Main effects: Ps rate, nodule number, nodule dry weight, shoot and root dry weight and root:shoot ratio Source of variation Ps rate Empirical Probability Values Nodule Number Nodule Dry Weight Root Dry Weight Shoot Dry weight Root: shoot ratio Potting mix 0.005** <0.001** 0.000** 0.804ns 0.019* 0.358 ns Fertilizer 0.190 ns <0.001** 0.007** 0.024* 0.005** 0.447 ns Inoculation 0.153 ns 0.925 ns 0.908 ns 0.577 ns 0.945 ns 0.605 ns
Main Effects: Shoot and root nutrient concentration, and mycorrhizal infection Source of variation Empirical Probability Values Shoot Root Total N Total P Total K Total N Total P Total K Mycorrhizal infection Potting mix 0.012* <0.001** 0.064 ns 0.007* <0.001** 0.260 ns 0.066 ns Fertilizer 0.280 ns 0.279 ns 0.050* 0.078 ns 0.855 ns 0.016* <0.001** Inoculation 0.213 ns 0.621 ns 0.082 ns 0.277 ns 0.606 ns 0.489 ns 0.785 ns
Potting Mix Effect: Ps rate, nodule number and dry weight, shoot dry weight Ps rate Nodule Number Dry Matter Yield Potting mix (mg plant -1 ) (g plant -1 ) Nodule Shoot Soil alone 7.90b 22.88 b 3.78 b 0.57b Soil + rice hull 9.17a 40.18 a 7.60 a 0.72a
Potting mix Effect : Nitrogen and phosphorus concentration in shoot and root Shoot Root Potting mix Total N Total P Total N Total P % % Soil alone 2.19b 0.09b 1.63b 0.65b Soil +rice hull 2.46a 0.12a 1.84a 0.93a
Fertilizer Effect: nodule number and dry weight, root dry weight and shoot dry weight Fertilizer level Nodule Number Dry Matter Yield (mg plant -1 ) (g plant -1 ) Nodule Root Shoot Unfertilized 21.25 b 4.83 b 0.38 b 0.57b Fertilized 41.82 a 6.56 a 0.76 a 0.72a
Fertilizer Effect : Shoot and root K concentration and mycorrhizal infection Total K Mycorrhizal Fertilizer level Shoot Root % infection Unfertilized 0.79b 0.43b 27.41b Fertilized 0.84a 0.48a 55.33 a
AMF Inoculation X Potting Mix Interaction effect: Ps rate 12 10 Without AMF With AMF umol-2s-1 8 6 4 2 0 Soil alone Soil + ricehull
Fertilizer X Potting Mix Interaction effect: Nodule number 70 60 50 Soil alone Soil + ricehull No. of nodules 40 30 20 10 0 Unfertilized Fertilized
Conclusion and Implications Potting mix of soil with organic amendment and application of small amount of chemical fertilizer enhance growth, nodulation, biomass production and shoot and root N, P and K of A. falcataria seedlings. The absence of positive influence of AMF on the growth performance of unfertilized A.falcataria seedlings grown in soil alone implies that AMF inoculation alone for growing seedlings in potting medium with low fertility should proceed with caution.
Conclusion and Implications Blanket recommendation of AMF inoculation of seedlings in the nursery for the NGP in lieu of fertilizer applications needs to be revisited. Is the fertility of the potting medium more limiting? Does the potting medium contain native AMF?
The forests of tomorrow depend on the seedlings of today