Growth response of Podocarpus blumei seedling to slow-release fertilizer in the nursery

Podocarpus blumei which is known as local adaptive species that produce high biomass and is suitable for rehabilitation, especially in the gold mining area. One of the factors that support of plantation is availability of the seedlings. The good quality of seedlings depends not only on plant genetics but also on seedlings’ treatment. The research aims to determine the effect on plants after being given slow-release NPK fertilizer. The design used in this research is a complete randomized design with a single factor and continued with variance statistic test and Duncan’s Multiple Range Test (DMRT). There are five experimental units with three repetitions. In general plant growth varies, and the effect of NPK slow-release fertilizer is not significantly different from the control. The Research results of P3 (1,5 gram) showed the best performance of Podocarpus blumei with parameters height (3,41 cm), diameter (0,42 cm), and leaves number (6,67). In conclusion, slow-release fertilizer could stimulate the growth of Podocarpus blumei seedling in the nursery.


Introduction
The Podocarpaceae family has been widely used for landscaping in tropical and sub-tropical areas because of high ecological, aestethical and pharmacological values [1].Podocarpus blumei which is known as local adaptive species that suitable for rehabilitation.Adaptive types of local species, with fast growth and have the ability to produce high biomass, are species that can be used in developing strategies rehabilitation and restoration.Podocarpus sp is one of local species that suitable for rehabilitation of ex-gold mining land [2].Restoration and revegetation become a mandatory activity on mining land.Land rehabilitation strategy former gold mines, can be done by improving soil conditions, choosing the type of vegetation, seedling, planting and maintain.The challenge of revegetation is the preference for vegetation that adaptive to soil condition after mining [3].
One of the factors that support of plantation is availability of the seedlings.The good quality of seedlings depends not only on plant genetics but also on seedlings' treatment.The Appropriate fertilizers must be applied in order to obtain healthy seeds with optimal growth.The application of slow-release fertilizers has many potential benefits for plant production.Slow-release fertilizer can control the release of the elements in it slowly or gradually.Characteristic of the slow-release 1315 (2024) 012076 IOP Publishing doi:10.1088/1755-1315/1315/1/012076 2 fertilizer in releasing nutrients to plants is expected similar to the pattern of nutrient uptake by plants.The slow-release fertilizer properties help reduce the loss of nutrients due to the movement of existing water, such as evaporation.Slow-release fertilizers can be applied as a preplant application, production costs could be lessened, eliminating the need for multiple applications of fertilizer [4].
There are six macronutrients: Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S).The macronutrients, N, P, and K, are often classified as 'primary' macronutrients.Macro elements caused increase the number of traits such as plant height, leaf area, yield seed, and oil content [5].The application of slow-release NPK can reduce loss of nutrients from fertilizers, as well as increase the efficiency of fertilization.The research aims to determine the effect on plants after being given slow-release NPK fertilizer.

Methods
This research was conducted at the R&D Centre for Forest Nursery, Bogor.Materials for this research: Podocarpus blumei seedlings, slow-release fertilizer (NPK), husk charcoal and topsoil.The design used in this research is a complete randomized design with a single factor (slow-release fertilizer (NPK) doses) with 5 treatments: 1) P0 = 0 g (control) 2) P1= 0,5 g slow-release fertilizer (NPK) /seedling 3) P2= 1 g slow-release fertilizer (NPK) /seedling 4) P3=1,5 g slow-release fertilizer (NPK) /seedling 5) P4= 2 g slow-release fertilizer (NPK) /seedling Experiments were arranged in three replications; each treatment consisted of 10 seedlings, hence resulting in 4 x 3 x 10 = 120 seedlings in total.The total observation time was 6 months.Media for this research is top soil and husk charcoal (2:1).The media of seedlings were analyzed at the Soil Laboratory, IPB University.
Parameters of this research were height of seedling (cm), diameter of seedling (cm), and leaves number, shoot dry weight (gr), root dry weight (gr) total shoot root dry weight (gr).Height and diameter were measured monthly for 6 months.Shoots were separated from root parts restricted by media surface (root neck) at the 6 months age of seedlings.Each part was then put in the oven for 48 hours to remove the water contents.
The collected data were then analyzed using ANOVA test, treatments with significant impact then were further analyzed using Duncan's Multiple Random Test (DMRT) at the level of confidence 95% (α = 0.05), with the application of SPSS Program 16.0.

Result and Discussion
The slow-release fertilizer used in this study contains elements the main nutrients N, P, and K which play a very important role in the growth of seedling.The effect of slow-release fertilizer treatment is presented in Table 1.Based on the results of observations, it was shown that the slow-release NPK fertilizer application did not have a significant effect on the growth of Podocarpus blumei seedlings until the age of 6 months in the nursery.In general plant growth variables, the effect of NPK slowrelease fertilizer is not significantly different from the control.The result of analysis of variance of application of slow release NPK fertilizer only significant to P. blumei seedlings height (Table 1).

The Growth variables increment of Podocarpus blumei seedling
The best height of P. blumei seedlings was found in the treatment P3(1.5 gram of slow-release NPK) with an increase of seedling height of 3.41 cm.The least growth of P. blumei seedlings' height is found in P0 treatment as a control without applying slow-release NPK with a seedling height value of 2.34 cm.The application of NPK fertilizer can increase the growth of plant seeds [6].Generally the dose used is 5 grams per plant [7].The dose of NPK in this study was lower when compared to the results of the study [7] but with a dose of 1.5 grams.it could be seen an increase in the growth of P. blumei seedlings in the nursery.
The slow-release fertilizer can control to realease of the elements (N.P. K) slowly or gradually.but this fertilizer difficult to dissolve in water.N. P. and K. are primary macronutrients that increased of plant height [4].Nitrogen (N) plays a critical role in the structure of chlorophyll.the primary lightharvesting compound of photosynthesis.and is related to the structural function of nitrogen in amino acids.The plants require large amounts of nitrogen for growth.Phosphorus (P) has important functions in plants.Adenosine diphosphate (ADP) and adenosine triphosphate (ATP) are high-energy phosphate compounds that control most processes in plants including photosynthesis.respiration.protein and nucleic acid synthesis.and nutrient transport through the plant's cells.Potassium or Kalium (K) is the primary osmolyte and ion involved in plant cell membrane dynamics.including the regulation of stomata and the maintenance of turgor and osmotic equilibrium [5].
The best diameter of P. blumei seedlings was found in the treatment P3(1.5 grams of slow-release NPK) with an increase of seedling diameter of 0.42 cm.Providing slow-release fertilizer at a dose of 1.5 grams per seedling is thought to be sufficient for the diameter growth of podocarpus seedlings.The presence of the element N is very important for vegetative growth plants because they can stimulate plant growth whole.Element K works strengthens plant vigor can affect the diameter stem [8].The least growth of P. blumei seedlings' diameter is found in P0 treatment as a control without applying slowrelease NPK with a seedling diameter value of 0.35 cm.However. the effect of different treatment to the diameter growth was not significant.The application of compound fertilizer in Elaeis guinensis seedlings at a dose of 2.5 grams per plant also did not make a significant difference in the diameter growth of seedlings [7].The application of 15 grams of NPK fertilizer to Terminalia catappa seedlings had a significant effect on diameter growth [3].
The best leaves growth of P. blumei seedlings was found in the treatment P3(1.5 grams of slowrelease NPK) with an increase of leaves of 6.67.The application of slow-release fertilizer at a dose of 1.5 grams per seedling is thought to be sufficient for leaves growth performance of P. blumei seedlings.Providing slow-release fertilizer at 1,5 grams per seedling able to contribute nutrients for plants (N and K) and can increase of photosynthesis that supports the work of tissue cells plants in differentiation, and will speed up growth and development of leaf.The N element can be stimulating vegetative growth of plants including growth in leaf width and the green colors on leaves [8].The least of P. blumei seedlings' leaves growth is found in P4 treatment (2.0 grams of slow-release NPK) with a seedling leaves number value of 5.3.However. the effect of different treatments on the leaf's growth was not significant.

The Response of slow-release NPK to Podocarpus blumei seedling Biomass
Observation of the biomass of Podocarpus blumei seedlings to determine the adaptation success of the seedlings.Shoot dry weight, root dry weight, and total dry weight in Podocarpus blumei were not significantly different by applying the treatment of slow-release NPK (Table 2).However. the highest growth of total dry weight (including shoot and root dry weight) was obtained by treatment P4 at a dose of slow-release NPK (2 grams).While the lowest value was in the P0 (control) treatment (2.83 grams).The higher root weight is expected to absorb more nutrients for growth [9] This shows that the photosynthesis process in A. polystachya seedling runs effectively.The organic compounds produced through the photosynthesis process will cause an increase in the dry weight of the seedling [10].The application fertilizers could stimulate the growth of plants by increasing the chlorophyll content and enhancing the photosynthetic rate and root vigor [11].The application of slow-release NPK has increased total root dry weight more than the control.

Conclusion
The application of slow-release NPK fertilizer could stimulate the growth of Podocarpus blumei seedling in the nursery.The application of slow-release NPK fertilizer with 1.5 grams has generated the best growth performance of P. blumei seedling for height, diameter and biomass.

Table 1 .
The Effect of application of slow-release NPK to growth variables.Different letters indicate statistically significant differences at the 0.05 level according to Duncan's multiple range test

Table 2 .
The Effect of application of slow-release NPK to Biomass variables.Different letters indicate statistically significant differences at the 0.05 level according to Duncan's multiple range test