The effects of seaweed fertilizer on the growth and productivity of upland rice, maize and oil palm grown in green house Pengaruh pupuk rumput laut terhadap pertumbuhan dan produktivitas padi gogo, jagung dan kelapa sawit di rumah kaca

Abstrak Sebagai negara kepulauan di daerah tropis, Indonesia kaya akan sumberdaya alam untuk swasembada pangan. Berjuta-juta hektar lahan di Indonesia ditanami tanaman perkebunan, tanaman tahunan yang memiliki masa juvenil yang relatif lama, terutama tanaman kelapa sawit dan karet. Sementara itu, upaya untuk meningkatkan produksi pangan terkendala oleh terbatasnya lahan subur. Penelitian yang mengeksplorasi bioregulator alami mampu meningkatkan produktivitas tanaman, menemukan bahwa Sargasum sp., rumput laut tipe liar yang di sepanjang pantai beberapa wilayah Indonesia, menunjukkan kemampuannya meningkat- kan pertumbuhan dan produktivitas tanaman seperti padi, jagung, tomat dan pertumbuhan kelapa sawit tanpa penambahan pupuk kimia. Percobaan pada padi gogo varietas Batutegi yang ditanam di rumah kaca, menunjuk- kan bahwa bioregulator alami tersebut meningkatkan produktivitasnya 50% lebih tinggi daripada kontrolnya. Percobaan menggunakan jagung var. Arjuna, tanaman yang telah diperlakukan dengan bioregulator tersebut mem- produksi dua hingga tiga tongkol, sementara pada tanaman kontrol hanya satu tongkol. Percobaan pada tanaman kelapa sawit di rumahkaca memperlihatkan bahwa bio- regulator tersebut menginduksi pertumbuhan vegetatifnya secara signifikan, lebih baik daripada kontrol dengan atau tanpa pupuk kimia. Intercropping tanaman kelapa sawit TBM dengan tanaman pangan seperti padi gogo atau jagung, diharapkan lebih menguntungkan bagi usaha perkebunan. Abstract Being a tropical archipelago, Indonesia is rich with natural resources enabling more production for food. Millions hectares of Indonesian lands is now planted with estate crops, perennial crops with relatively lengthen juvenile phase mainly oil palm and rubber. Meanwhile, attempts to increase national food production have been limited by availability of fertile lands. Our research exploring natural bioregulator capable of improving crop productivity, found that Sargasum sp., a wild sea weed grown mostly along the coast line in Indonesia, indicated its ability to improve the growth and productivity of crops like rice, maize, tomato and oil palm even though with no chemical fertilizers added. The experiment on upland rice of local variety Batutegi planted in greenhouse, demonstrated the natural bioregulator has increased the rice productivity by at least 50% over the control. The experiment using maize var. Arjuna, the bioregulator treated plants has made two to three corncobs instead of only one corncob on the control plants. The experiment on the oil palm grown in the nursery showed that the bioregulator has significantly induced vegetative growth better than the control with or without chemical fertilizers. Intercropping the food crops, rice or maize in the juvenile phase of the oil palm plantations, should be beneficial to the productivity of the plantation.


Introduction
To secure food availability with cheap price requires an improved production of the corresponding food.One of the limiting factors in improving the production the staple foods such as rice and corn has been the availability of fertile lands for the food crops to grow.Being located in tropical region, Indonesia has natural resources, including fertile lands, enabling to be world producer for foods.Some of the fertile lands in the country have however, been planted with estate crops such as oil palm, rubber and cacao trees, which are perennial crops with lengthen juvenile phase, three to five years.The area of oil palm plantation in Indonesia is almost 8 millions hectares (Ditjenbun, 2010).During the juvenile periods, the canopies of the neighboring trees have not yet overlapped each others so that enable planting annual crops like rice and maize in between.
This research aimed to study the effect of seaweed organic fertilizer on some agronomical characters of local varieties of upland (gogo) rice of Batutegi, Arjuna maize, and Tenera hybrid of oil palm.The experiments for each crop were conducted in green house for one harvest cycle except for the oil palm, which has been performed for a year period of nursery.The parameters observed were the vegetative growths of the rice, maize and oil palm, and the reproductive developments for the rice and maize.
The effects of seaweed fertilizer on the growth and productivity …… (Santoso et al.)The chlorophyll content was examined in the leaves of oil palm as the greenish color intensity visually distinctive among the treatments.
The result of the experiments demonstrated that the seaweeds organic fertilizer formulae were significantly improved the vegetative growths of the three tested crops.As a consequence, this improvement positively affected the reproductive development of the rice and the maize as well, leading to the increase of the seeds or fruits productivity of the two crops.Because of lengthen juvenile phase, an improved reproductive growth would predictably increase productivity of oil palm later during the productive phase.

Materials and Methods
The Batutegi gogo rice and Arjuna corn seeds were kindly provided by Dr.

Preparation of seaweeds organic fertilizer
See weeds of Sargasum sp freshly collected from Gunung Kidul Yogyakarta, were rinsed two to three times with clean water to remove salt.After drained to remove the excess water, the cleaned sea weeds were sundried for 2 to 3 days or until the remaining water content was 5 to10 %.The dried sea weeds were stored until the next usages or ground with powdering machine just before the following uses.

Planting the seeds and treatments
Top soil media were mixed with 2 or 5 % (v/v) of freshly seaweed powder.After contained in 25 liter polybags, the media were used to germinate and grow two good seedlings of rice, one good seedling of corn and one good seedling of oil palm.To keep the humidity under control, the planted media were watered once a day in the early morning or the afternoon.After 1 to 2 weeks, the growing seedling of rice or maize was selected for the best one to grow further.During the growing cycle the pertinent agronomical traits were recorded.Two types of control treatments were seedlings grown on top soil media with or without conventional fertilizers NPK or compost.Additional exogenous hormonal formulations for plant were applied periodically through foliar sprays of the tested plants.

Determination of the chlorophyll contents
Analysis of chlorophyll content in the leaves was determined using the Arnon method as described by Parman & Harnina (2008).The contents of chlorophyll-a were calculated from the OD at 665 nm multiply by 5.76, and chlorophyll-b equals to 25.8 times (the OD 649 -7.7 OD 665).

Results and Discussion
There are several types of sea weeds available in local markets.Table 1 lists five of them that can be purchased from a local supplier residing in southern coastal of Java island.Based on the high availability and the low price, Sargasum can most likely be used as organic fertilizer in plantation.The only limitation is that it is scarily cultivated so that seasonally dependence.Sargasum of the powder form was then utilized in the following experiments.
The first experiment was to examine the effects of the sea weed organic fertilizer in a form of relatively fresh powder, to the vegetative growth and reproductive development of maize of Arjuna variety.The results are presented in Table 2.With (Fisca BiH, Fisca BiF1 and Fisca BiF2) or without (Fisca BiM) additional plant hormone, both their vegetative growth and the reproductive development of the tested maize plants were better than those of the control plants.Additional plant hormones were able to induce more corncobs even though they did not always reflect to end productivity or the total seed weight.
These results are in line with the research reporting that seaweed was mostly already contained several types of plant hormones (Eswaran at al., 2005).This might be the reason why Sargasum with or without additional exogenous plant hormone did not differ significantly on the effect to the growth and development of maize compared to those of the control plants.Similar responses were also found in the following experiment on non-arid land of gogo rice type, as shown the results below (Figure 1).The application of the seaweed organic fertilizer was able to improve the vegetative growth of the rice by regenerating more shoots of varying stages in a ratoon.These shoots enabling the rice crops were harvested at least twice in one planting.In control plants however, the harvest is only one time.Figure 1 indicates that after one harvest the control rice ratoon in the polybags did not regenerated any shoots.In treated rice however the negative rice ratoon made more shoots.Later, these newly formed shoots would grow and produced good rice seeds.
The number and quality of rice seeds produced in this experiment is summarized in Table 3.In control ratoons, growing shoots was only once, but the treated ratoons, the shoots were regenerated twice.In the rice However, the quality of the seeds produced was inferior.In the rice treated with Sargasum, the number of shoots regenerated in second cycle was higher than those in the first cycle but lower than either those in the first cycle or the second cycle of NPK treatment.Nevertheless the quality of the seeds produced in Sargasum treatment is better than that in NPK treatment as indicated by the weight of 100 seeds, which were 1.74 g versus empty.The productivity of the second harvest cycle is around (2.5 x 1.74) / (1.55 x 1.41) = 199%.If the cycle 1 needs 110 days, because started at the mid of the first cycle, the second cycle start needs only 55 days after the end of the first cycle.
With regard to the time, the improved productivity from the use of Sargasum organic fertilizer should be around 199% times 110d/165d, equals to 133%.Improving national food security through intercropping of the plantations with food crops using organic fertilizer of seaweeds, needs to examine the effects of the primary input, the fertilizer, to the primary crops.Plantation in Indonesia is largely composed of oil palm, which is now covered an area of around 8 millions hectares (Ditjenbun, 2010).The result of the experiment to examine the effect of Sargasum on the growth of juvenile oil palm is shown Table 4. Compared to the control plants, the plants grown in the soil containing 2% (v/v) of Sargasum powder had the best vegetative growth.Even they were better than those fertilized with NPK.It was averaging around 7.4 % taller than control with NPK and 23.6 % taller than control with only top soil.They have made more leaves with better appearance (Figure 2). Figure 2 shows the appearance of oil palm growing in polybags with top soil media supplemented with various types of fertilizer.In addition to taller, the oil palm a seedling growing with 2% seaweeds organic fertilizer has leaves greener than the control with none and equally green as control with NPK.In most cases, the green color of leaves may represent the functionality of the leaves, which are performing photosynthesis.Photosynthesis in leaf molecularly depends on the presence of chlorophyll.To relate the greenish appearance with the chlorophyll content, analyses to determine the chlorophyll content were Table 3. Productivity gogo rice var Batutegi grown in polybags the green house.The numbers are the averages of 5 to 7 data.Tabel 3. Produktivitas padi gogo var.Batutegi yang ditumbuhkan dalam polibag di rumah kaca.

Growing shoots Jumlah anakan
Weight 100 seeds (g) Berat 100 biji (g)  conducted.The results indicates that there is positive correlation between the intensity of the green color with both chlorophyll-a and chlorophyll-b contents in the leaves (data not shown).In addition sewed fertilizer has become a preferred organic substance to add nutrion to plant.Seaweed absorbs the vitamin, minerals and enzymes present in the sea and retains more than 70 of the vital nutrients (Carpenter, 2011), which also useful to plants.
To estimate how much rice may be produced from intercropping of oil palm plantation with gogo rice some assumption are made.According to Ditjenbun (2010) the total area of oil palm plantation in Indonesia is almost 8 millions hectares (7,824,623 Ha).The first assumption is that as much as 25% of those areas are juvenile oil palm which can be used for intercropping with gogo rice.The productivity of gogo rice planted as intercrops between oil palm is assumed 25% than that in open field, which was reported as much as 5.9 ton per hectare (Humas, 2011), therefore total rice that might be produced through the intercropping would be around 11.5 millions ton per year.This is from 0.25 x 7824623 x 0.25 x 5.9 x 2 = 11.5 million ton per year.Assuming that the use of Sargasum organic fertilizer is able to improve productivity of the gogo rice by 133%, the total rice production by this technology in the oil palm plantation theoretically could be 11.5 times 233% = 26.8 million ton per annum.With this number, almost 50% of national need for rice would be satisfied.The national need for the rice was estimated equal to rice seed (Gabah) 54.905 million ton annually (Anonym, 2010).An additional advantage is that the application of the seaweed fertilizer was also able to improve vegetative growth of juvenile oil palm.A better growth during juvenile phase is expected to improve productivity during the next phase (Santoso & Widiastuti, 2011).The productivity of oil palm in Indonesian plantation is significantly lower than its potency, around 20 ton FFBOP (fresh fruit bunches of oil palm) per ha per year (Suryana et al., 2007) compared to 40 ton FFBOP per ha per year of its potency.Experimental result on these monocotyledonous species is in agreement with reports in some horticultural crops such as Allium cepa L., Garlic (Allium sativum L.), Peper (Capsicum L.) and Sweet potato (Ipomoea batatas (L.) Lamk) (Anonym, 2011) that Sargasum can be used as fertilizer.

Conclusion
Application of Sargasum organic fertilizer with or without additional exogenous plant hormones was able to improve significantly the vegetative growth of Batutegi gogo rice, Arjuna maize and Tenera hybrid of oil palm in green house.This sequentially improves the reproductive development of the annual food crops by around twice higher.Theoretically, intercropping of the juvenile oil palm plantations with the food crop of gogo rice using Sargasum organic fertilizer may significantly improve national food security.

Table 1 .
The relative availability and price of some seaweeds at local supplier.Tabel 1. Tipe dan harga seaweed yang tersedia di pasar lokal

Table 2 .
The effects of seaweed organic fertilizer formulae on the growth and productivity of maize.The numbers are the averages of 5 to 7 data Tabel 2. Pengaruh formula pupuk organik rumput laut terhadap pertumbuhan dan produksi Jagung.Data adalah rata-rata dari 5-7 data pengamatan.

Table 4 .
The growth of oil palm on the polybag in the green house.The numbers are the averages of 5 to 7 data.Tabel 4. Pertumbuhan sawit dalam polibag di rumah kaca.Data adalah rata-rata dari 5-7 data pengamatan.