GATRA FISIOLOGIS DAN AGRONOMIS PENGARUH PENGENDALIAN KERACUNAN BESI PADI SAWAH

DI LAHAN RAWA PASANG SURUT SULFAT MASAM

DISERTASI

Oleh : Izhar Khairullah

08/275488/SPN/352

PROGRAM PASCASARJANA FAKULTAS PERTANIAN

UNIVERSITAS GADJAH MADA YOGYAKARTA

2012

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RINGKASAN

GATRA FISIOLOGIS DAN AGRONOMIS PENGARUH PENGENDALIAN KERACUNAN BESI PADI SAWAH DI LAHAN RAWA

PASANG SURUT SULFAT MASAM

Padi merupakan komoditas pangan strategis yang produksinya perlu terus

ditingkatkan untuk mengimbangi laju pertumbuhan penduduk yang bertumpu

pada beras sebagai bahan makanan pokoknya. Produksi padi dari tahun ke tahun

mengalami pelandaian akibat berbagai hal termasuk alih fungsi lahan padi ke

nonpadi dan non pertanian, terutama di pulau Jawa. Untuk mengatasi hal tersebut

diperlukan ekstensifikasi areal sawah baru di berbagai ekosistem termasuk di

lahan rawa pasang surut yang tersedia cukup luas.

Lahan rawa pasang surut merupakan salah satu jenis lahan sub-optimal

yang kini dan ke depan semakin berperan penting untuk budidaya padi. Luas

lahan rawa pasang surut di Indonesia sekitar 20,1 juta ha, 33,3 % diantaranya

merupakan lahan sulfat masam. Kontribusi produksi padi pasang surut terhadap

produksi padi nasional cukup tinggi, yaitu sebanyak 3.684 juta ton padi dengan

melaksanakan intensifikasi melalui penerapan teknologi spesifik lokasi. Berbagai

hasil penelitian dan pengembangan mununjukkan bahwa lahan pasang surut

memiliki prospek yang besar untuk dikembangkan menjadi areal produktif

tanaman padi. Produktivitas padi di lahan pasang surut masih rendah, rerata

kurang dari 3 t ha-1 dengan intensitas pertanaman satu kali.

Pengembangan pertanian di lahan rawa pasang surut sulfat masam

menghadapi beberapa kendala antara lain tata air, kemasaman tanah, konsentrasi

Fe, Al, Mn tinggi, kahat hara, dan salinitas tinggi. Konsentrasi Fe2+ sebesar 300-

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400 mg kg-1 sangat meracuni tanaman padi. Teknologi pengelolaan air dan tanah

yang tepat akan mempercepat pemanfaatan lahan sulfat masam tersebut, terutama

untuk persawahan. Demikian juga dengan penggunaan varietas padi yang adaptif

dan tahan terhadap keracunan besi.

Keracunan besi menjadi masalah utama produksi padi di persawahan

pasang surut sulfat masam. Pertumbuhan dan hasil padi sawah di lahan sulfat

masam sangat dipengaruhi oleh keracunan besi. Penurunan hasil akibat

keracunan besi mencapai 30-100 % tergantung ketahanan varietas, intensitas

keracunan, dan status kesuburan tanah. Strategi ketahanan terhadap keracunan

besi telah diketahui, tetapi mekanisme fisiologisnya tidak dipahami dengan baik.

Pengendalian keracunan besi dapat dilakukan dengan menggunakan

varietas yang tahan keracunan besi dan menggunakan bahan organik in situ

seperti jerami dan tumbuhan purun tikus (Eleocharis dulcis). Varietas padi

berbeda-beda ketahanannya terhadap keracunan besi. Purun tikus adalah gulma

dominan di lahan rawa pasang surut sulfat masam, terutama di Kalimantan

Selatan dan Tengah. Penelitian mengenai peranan dan pengaruh bahan organik

dalam mengendalikan keracunan besi pada tanaman padi di lahan rawa pasang

surut sulfat masam belum banyak diungkap.

Atas dasar latar belakang tersebut perlu dilakukan serangkaian penelitian

untuk (1) mempelajari pengaruh konsentrasi Fe tanah terhadap serapan Fe

tanaman, pertumbuhan, dan hasil, serta memilih varietas padi yang tahan,

menghindar, dan rentan keracunan besi, (2) mempelajari perubahan serapan Fe,

karakter fisiologis dan agronomis akibat pemberian bahan organik, serta

menentukan aras optimum kompos jerami dan purun tikus dalam mengendalikan

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keracunan besi dan meningkatkan hasil padi, dan (3) mempelajari pengaruh

pemberian bahan amelioran dalam mengendalikan keracunan besi, meningkatkan

proses fisiologis, pertumbuhan, dan hasil padi, serta menentukan teknologi

ameliorasi terbaik dalam mengendalikan keracunan besi dan meningkatkan hasil

padi di lahan rawa pasang surut sulfat masam.

Telah dilakukan dua percobaan di rumah kaca dan satu percobaan

lapangan pada Januari 2010 sampai Agustus 2011. Percobaan pertama dan kedua

dilaksanakan di rumah kaca Balai Penelitian Pertanian Lahan Rawa (Balittra),

Banjarbaru. Percobaan ketiga di lapangan dilaksanakan di sawah pasang surut

sulfat masam Kebun Percobaan Belandean milik Balittra di Kabupaten Barito

Kuala, Kalimantan Selatan. Pengamatan meliputi karakter fisiologis dan

agronomis, pertumbuhan dan hasil, konsentrasi Fe tanah dan kadar Fe tanaman,

indeks bronzing daun, indeks ketahanan akar dan tajuk, dan gejala keracunan besi,

serta beberapa sifat kimia tanah sulfat masam rawa pasang surut.

Hasil penelitian menunjukkan bahwa peningkatan konsentrasi Fe tanah

meningkatkan kadar Fe akar dan Fe daun Inpara-2 dan Inpara-1 (padi rawa) paling

kecil, sedangkan IR64 (padi sawah beririgasi) paling besar. Penurunan

pertumbuhan dan hasil gabah Inpara-1 paling kecil diikuti Inpara-2, sedangkan

IR64 paling besar. Dari 15 varietas yang diuji pada empat konsentrasi Fe tanah

(229,44; 236,34; 564,15; dan 1277,50 mg kg-1 Fe), terpilih Inpara-1 sebagai

varietas tahan, Inpara-2 sebagai varietas menghindar, dan IR64 sebagai varietas

rentan keracunan besi. Pemilihan tersebut berdasarkan atas serapan Fe tanaman,

persamaan regresi linear, dan metode pembobotan terhadap pertumbuhan tanaman

(jumlah anakan, tinggi tanaman, bobot kering akar dan jerami), indeks ketahanan

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akar dan tajuk, indeks bronzing daun, gejala keracunan besi, komponen hasil dan

hasil gabah per rumpun serta indeks panen.

Inpara-1 memiliki kadar Fe akar dan Fe daun yang tinggi, tetapi

pertumbuhan baik dan hasil gabah tinggi. Inpara-2 dengan kadar Fe akar dan Fe

daun yang rendah, tetapi pertumbuhan baik dan hasilnya tinggi. IR64 dengan

kadar Fe akar dan Fe daun paling tinggi, tetapi pertumbuhan tidak baik dan hasil

gabahnya paling rendah. Inpara-1 menunjukkan slope paling rendah dari

persamaan regresi linear diikuti oleh Inpara-2, sedangkan IR64 dengan slope

paling besar. Inpara-1 juga menunjukkan skor akhir paling besar diikuti Inpara-2

pada metode pembobotan, sedangkan IR64 dengan skor paling kecil. Semakin

besar skor akhir semakin tahan suatu varietas terhadap keracunan besi.

Kadar Fe akar, Fe batang, dan Fe daun Inpara-1 lebih tinggi dibanding

Inpara-2, baik pada percobaan di rumah kaca maupun percobaan di sawah pasang

surut yang mengindikasikan adanya kemampuan meretensi Fe dalam jaringan

batang dari Inpara-2 yang lebih tinggi dibanding Inpara-1. Oleh karena itu Inpara-

2 dinyatakan sebagai varietas yang memiliki mekanisme ketahanan menghindar

(eksklusi dan inklusi). Inpara-1 dengan kadar Fe akar lebih tinggi disertai

aktivitas PPO rendah serta aktivitas POD tinggi yang mengindikasikan adanya

aktivitas enzim dalam mengendalikan kadar Fe tinggi dalam jaringan daun. Hal

ini mengarah pada mekanisme inklusi tahan, di mana tanaman mampu mentolelir

Fe2+ yang tinggi di dalam sel daun melalui detoksifikasi enzimatik, terutama POD.

Varietas IR64 memiliki kadar Fe akar, Fe batang, dan Fe daun yang lebih tinggi

dibanding Inpara-1 dan Inpara-2. IR64 dengan tingkat ketahanan paling rendah,

pertumbuhan dan hasil gabahnya juga paling rendah sehingga termasuk katagori

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varietas yang rentan terhadap keracunan Fe. Aktivitas POD IR64 lebih rendah,

sedangkan aktivitas PPO lebih tinggi dibanding Inpara-1 dan Inpara-2.

Varietas Inpara-2 yang memiliki mekanisme menghindar keracunan besi

mampu menekan konsentrasi Fe di daerah perakaran, menyerap Fe dalam jumlah

yang relatif sedikit, proses fisiologis dan pertumbuhan tanaman sedang, dan hasil

gabah per rumpun tinggi (19,56 g). Inpara-1 yang tahan keracunan besi cukup

mampu menekan konsentrasi Fe tanah di daerah perakaran, menyerap Fe dalam

jumlah relatif banyak, proses fisiologis dan pertumbuhan tanaman baik, dan hasil

gabah per rumpun tinggi (21,59 g). IR64 sebagai varietas rentan keracunan besi

tidak mampu menekan konsentrasi Fe tanah di daerah perakaran, menyerap Fe

dalam jumlah banyak, proses fisiologis dan pertumbuhan tanaman tidak baik, dan

hasil gabah per rumpun rendah (13,57 g).

Pemberian bahan organik kompos jerami dan purun tikus meningkatkan

pH tanah, indeks ketahanan akar dan tajuk, kadar P dan K daun, kandungan air

nisbi tanaman, kerapatan dan lebar bukaan stomata, laju transpirasi, aktivitas

enzim POD, kadar klorofil, panjang dan luas permukaan akar, pertumbuhan

tanaman (jumlah anakan maksimum, tinggi tanaman, bobot kering akar, batang,

dan daun, ILD, LPT, LPN, LAB, dan BDK), komponen hasil, hasil gabah per

rumpun serta indeks panen. Sebaliknya bahan organik kompos jerami dan purun

tikus ini menurunkan Fe dan Eh tanah, gejala keracunan besi, indeks bronzing

daun, aktivitas enzim PPO, kadar Fe akar, Fe batang, dan Fe daun varietas Inpara-

1, Inpara-2, dan IR64.

Pola peningkatan atau penurunan variabel tersebut akibat pemberian bahan

organik mengikuti persamaan regresi kuadratik. Peningkatan aras purun tikus

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pada 5 t ha-1 jerami menurunkan konsentrasi Fe tanah. Aras optimum purun tikus

Inpara-1, Inpara-2, dan IR64 adalah 5,37 t ha-1, 5,05 t ha-1, dan 5,91 t ha-1.

Penurunan Fe tanah sebesar 47,4 % dan 22,2 % dibanding cara petani dan

pemberian dolomit 2 t ha-1. Aras optimum purun tikus untuk mengurangi gejala

keracunan besi Inpara-1, Inpara-2, dan IR64 sebesar 5,45 t ha-1, 5,55 t ha-1, dan

5,55 t ha-1. Penurunan gejala keracunan besi dan indeks bronzing daun sebesar

90,6 % dan 27,0 % dibanding cara petani dan sebesar 47,6 % dan 16,2 %

dibanding pemberian dolomit 2 t ha-1. Peningkatan aras purun tikus menurunkan

kadar Fe daun 45,5 % dibanding cara petani dan sebesar 30,3 % dibanding

pemberian dolomit 2 t ha-1, serta meningkatkan kadar Fe gabah sebesar 22,2 %

dibanding cara petani dan 18,9 % dibanding pemberian dolomit 2 t ha-1.

Laju asimilasi bersih (LAB) meningkat sebesar 26,2 % dibanding cara

petani dan 17,4 % dibanding pemberian dolomit 2 t ha-1, sedangkan bobot kering

tanaman meningkat 27,3 % dibanding cara petani dan sebesar 13,9 % dibanding

pemberian dolomit 2 t ha-1.

Inpara-1 menunjukkan komponen hasil yang relatif lebih tinggi dibanding

Inpara-2, baik pada percobaan kedua di rumah kaca maupun percobaan ketiga di

sawah pasang surut. Jumlah malai, jumlah gabah, persentase gabah isi, dan bobot

1.000 gabah Inpara-1 dan Inpara-2 pada percobaan kedua berturut-turut adalah

17,1 dan 15,8 malai; 99,0 dan 96,1 butir; 64,4 dan 62,9 %; 23,56 dan 25,44 g.

Hasil gabah dan indeks panen Inpara-1 adalah 21,19 g dan 0,52, sedangkan

Inpara-2 dengan hasil 19,33 g dan indeks panen 0,48. Pada percobaan ketiga,

Inpara-1 dengan jumlah malai, jumlah gabah, persentase gabah isi, dan bobot

1.000 gabah masing-masing 16,62 malai, 145,65 butir, 75,72 %, dan 23,5 g,

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sedangkan Inpara-2 masing-masing 15,37 malai, 140,39 butir, 72,56 %, dan 25,3

g. Pemberian bahan organik kompos jerami dan purun tikus meningkatkan

komponen hasil padi. Hasil gabah Inpara-1 dan Inpara-2 masing-masing adalah

4,45 t ha-1 dan 4,17 t ha-1 dengan indeks panen 0,58 dan 0,47.

Pemberian bahan organik kompos jerami dan purun tikus meningkatkan

komponen hasil, hasil gabah, dan indeks panen. Penambahan aras kompos purun

tikus sampai 5 t ha-1 masih menunjukkan peningkatan, setelah itu menurun. Aras

optimum kompos purun tikus yang ditambahkan pada kompos jerami 5 t ha-1 dari

Inpara-1 adalah 5,29 t ha-1 untuk mencapai jumlah malai per rumpun maksimum

26,84 malai; 4,89 t ha-1 untuk mencapai jumlah gabah per malai maksimum

sebesar 140,85 butir; 5,27 t ha-1 untuk mencapai persentase gabah isi maksimum

sebesar 97,28 %; 5,27 t ha-1 untuk mencapai bobot 1.000 gabah maksimum

sebesar 25,82 g; 5,14 t ha-1 untuk mencapai hasil gabah maksimum sebesar 47,80

g; dan 5,38 t ha-1 untuk mencapai indeks panen maksimum sebesar 0,85.

Pemberian kompos jerami 5 t ha-1 ditambah purun tikus 5 t ha-1

meningkatkan jumlah malai per rumpun, jumlah gabah per malai, persentase

gabah isi, dan bobot 1000 gabah, hasil, dan indeks panen masing-masing sebesar

29,1 %, 12,8 %, 28,5 %, 6,3 %, 34,5 %, dan 17,8 % dibanding cara petani dan

sebesar 13,3 %, 5,4 %, 13,6 %, 4,5 %, 16,4 %, dan 8,2 % dibanding pemberian

dolomit 2 t ha-1.

Keracunan besi menurunkan komponen hasil, hasil gabah, dan indeks

panen. Bahan organik kompos aerob dan anaerob jerami dan purun tikus serta

dolomit mampu menurunkan gejala keracunan besi, indeks bronzing daun,

konsentrasi Fe tanah, kadar Fe akar, Fe batang, dan Fe daun, serta meningkatkan

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proses fisiologis, pertumbuhan, komponen hasil, dan hasil gabah Inpara-1, Inpara-

2, dan IR64. Hasil gabah Inpara-1 (4,45 t ha-1) sebanding dengan Inpara-2 dan

lebih tinggi 42,9% dibanding IR64 (3,12 t ha-1), tetapi IR64 lebih tanggap

terhadap pemberian bahan amelioran tersebut dibanding Inpara-1 dan Inpara-2.

Kompos aerob jerami 5 t ha-1 ditambah purun tikus 5 t ha-1 merupakan

teknologi ameliorasi terbaik dalam mengendalikan keracunan besi, meningkatkan

proses fisiologis, pertumbuhan, dan hasil. Hasil gabah pada kombinasi tersebut

sebesar 4,83 t ha-1 dan meningkat sebesar 73,4%, 34,5%, dan 14,6 % masing-

masing dibanding tanpa pemberian bahan amelioran, pemberian kompos jerami

dan purun tikus secara anaerob cara petani dan pemberian dolomit 2 t ha-1.

Varietas Inpara-1 yang tahan keracunan besi dan Inpara-2 yang

menghindar keracunan besi dapat ditanam pada sawah pasang surut sulfat masam

yang memiliki konsentrasi Fe tanah tinggi. Bahan organik berupa jerami dan

purun tikus yang dikomposkan secara aerob dapat digunakan pada sawah pasang

surut sulfat masam yang berpotensi keracunan besi dengan inovasi teknologi cara

pembuatan kompos aerob yang efisien di sawah pasang surut sulfat masam.

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SUMMARY

PHYSIOLOGICAL AND AGRONOMIC ASPECTS OF THE EFFECT OF IRON TOXICITY CONTROL TO WETLAND RICE AT ACID SULFATE

SOILS OF TIDAL SWAMPLANDS

Rice is a strategic food commodity for Indonesian people because it is a

staple food. It’s production should be increased to keep pace with population

growth. Rice production from year to year has decreased due to conversion of

paddy filed to non-paddy and non-agricultural land, especially in Java. To solve

the problem, it is required to extens the paddy field to other areas including tidal

swamplands that is quite wide.

Tidal swamplands is one type of sub-optimal lands which become

potential areas for rice cultivation in this time and future. Tidal swamplands areas

in Indonesia are around 20.1 million hectares and 33.3% of them are areas with

acid sulfate soils. Contribution of tidal swamps rice production to national rice

production is quite high, i.e. 3,684 million tons of rice with implement

intensification of application of site-specific technologies. Various research and

development at tidal swamplands proved that tidal swamplands has high potential

as field for rice plantation. Productivity of rice in tidal swamplands is still low in

average less than 3 t ha-1 for cultivation per year.

Agricultural development at acid sulfate soil of tidal swamplands may

meet some problems in water management, soil acidity, high concentration of Fe,

Al, Mn, nutrients deficiency, and high salinity. Concentration of 300-400 mg kg-

1 Fe is toxic concentration to rice plants. Technologies of soil and water

management will accellerate appropriate acid sulfate soils of tidal swamplands,

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especially for rice. Moreover, using tolerant rice varieties to iron toxicity will

contribute to increase the rice production at tidal swamplands.

Iron toxicity is a major problem of rice production at acid sulfate soils of

tidal swampland. Rice growth and yield at acid sulfate soil is affected by iron

toxicity. Iron toxicity can decrease rice production among 30-100% depends on

variety, intensity of toxicity and soil fertility status. Strategy of resistance to iron

toxicity has been identified, but the physiological mechanisms are not determined.

One method to control iron toxicity is development resistant varieties to

iron toxicity and using in situ organic matter such as straw and purun tikus plants

(Eleocharis dulcis). The resistance of each rice varieties to iron toxicity is

different. Purun tikus is a dominant weed at acid sulfate soils of tidal swamplands,

especially in South and Central Kalimantan. The research of role and effect of

organic matter compost in controlling iron toxicity at acid sulfate soils of tidal

swamplands has not been studied.

Based on the background needs to be conducted a series of researches to (1)

study the effect of Fe concentration in soil to Fe uptake by plant, growth and yield, as

well as to select resistant, avoidant, and susceptibility varieties to iron toxicity, (2) study

the changes in Fe uptake, physiological and agronomic characters due to application of

organic matter, and to determine the optimum rate of straw and purun tikus compost in

controlling iron toxicity and increasing rice yields, and (3) study the effect of ameliorant

in controlling iron toxicity, improving physiological processes, rice growth and yield, and

determine the best amelioration technologies in controlling iron toxicity and increasing

rice yields at acid sulfate soils of tidal swamplands.

The research have been conducted in greenhouse (two experiments) and at paddy

field (one experiment) in January 2010 up to August 2011. The first and second

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experiments were conducted in the greenhouse of Indonesian Swampland Agricultural

Research Institute (ISARI), Banjarbaru. The third experiment was conducted at the paddy

field of acid sulfate soils of tidal swamplands, Experimental Station, Belandean, ISARI

in Barito Kuala District, South Kalimantan. Observations were done on physiological

and agronomic characters, growth and yield, soil concentrations of Fe and Fe content in

plants, leaf bronzing index, root and shoot resistance index, iron toxicity symptoms, and

some soil chemical properties of acid sulfate soils of tidal swamplands.

The results showed that increasing of soil Fe concentration increased Fe

content in roots and leaves of Inpara-2 and Inpara-1 (swamps rice) were the

smallest, whereas IR64 (irrigated rice) was the most. Decreasing in growth and

yield of Inpara-1 was the smallest followed by Inpara-2, whereas of IR64 was the

greatest. Of the 15 varieties were tested at four Fe concentrations of soils (229.44,

236.34, 564.15, and 1277.50 mg kg-1 Fe), Inpara-1 was determined as resistant

variety, Inpara-2 as avoidant variety, and IR64 as susceptible variety to iron

toxicity. The selection based on Fe uptake of plants, a simple regression analysis

and weighting methods on plant growth (number of tillers, plant height, dry

weight of root and shoot), root and shoot resistance index, leaf bronzing index,

iron toxicity symptom, yield components, grain yield per hill and harvest index.

Inpara-1 as resistant variety to iron toxicity had high Fe content in roots

and leaves, but its growth was very good and had high grain yield. Inpara-2 as

avoidant variety to iron toxicity had low Fe content in roots and leaves, but its

growth was good and had high yield. IR64 as susceptible variety to iron toxicity

had the highest Fe content in roots and leaves, but its growth was poor and had the

lowest yield. Inpara-1 showed the lowest slope of the regression equation,

followed by Inpara-2, whereas IR64 showed the greatest slope. In weighting

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method, Inpara-1 also showed the most average score, followed by Inpara-2,

whereas IR64 shoed the smallest average score. Variety with the greater average

score was identified as more resistant variety to iron toxicity.

Iron content in roots, stems, and leaves of Inpara-1 was higher than Inpara-

2 both in greenhouse and field experiments. That indicated had a Fe retention

power in stems tissue of Inpara-2 which higher than Inpara-1. Therefore Inpara-2

can be expressed as avoidant variety (exclusion and inclusion mechanism).

Inpara-1 had higher Fe content in roots and low PPO activity but high POD

activity. That indicated had enzymatic activity in controlling high Fe content in

leaves tissue. This led to inclusion mechanism, in which plants could tolerate

high Fe in leaves cells through enzymatic detoxification, especially POD. Variety

IR64 had higher Fe content in roots, stems, and leaves than Inpara-1 and Inpara-2.

IR64 showed the lowest level of resistance and had the lowest growth and yield,

therefore it was categoried as susceptible variety to iron toxicity.

Inpara-2 could reduce Fe concentration in root zone, absorb Fe in small

quantities, medium physiological processes and plant growth, and had high grain

yield per hill (19.56 g). Inpara-1 was quite capable to suppress Fe concentration in

root zone, absorbed Fe in large amounts, good physiological processes and plant

growth, and had higher yield per hill (21.59 g). IR64 was not able to decrease Fe

concentration in soil root zone, absorbed Fe in large amounts, poor physiological

processes and plant growth, and had low yield per hill (13.57 g).

Application of straw and purun tikus compost organic matter increased

soil pH, root and shoot resistance index, P and K content in leaves, relative plant

water content, density and width of stomata, transpiration, POD activity,

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chlorophyl content, length and surface area of root, plant growth (maximum

number of tillers, plant height, dry weight of roots, stems, and leaves, leaf area

index (LAI), crop growth rate (CGR), relative growth rate (RGR), net assimilation

rate (NAR), and specific leaf weight (SLW), yield components, grain yield per

hill and harvest index. Instead of organic matter of straw and purun tikus compost

decreased soil Fe and Eh, iron toxicity symptoms, leaf bronzing index, PPO

activity, Fe content in roots, stems and leaves of Inpara-1, Inpara-2 and IR64.

The pattern of increasing or decreasing in all variables due to application

of organic matter were following quadratic regression equation. Increasing in rate

of purun tikus at 5 t ha-1 straw reduced soil Fe concentration. Optimum rate of

purun tikus of Inpara-1, Inpara-2 and IR64 were 5.37 t ha-1, 5.05 t ha-1, and 5.91 t

ha-1. Decreasing in soil Fe concentration about 47.4% and 22.2% compared to

farmers way and application of dolomite 2 t ha-1. Optimum rate of purun tikus to

reduce iron toxicity symptoms of Inpara-1, Inpara-2 and IR64 were 5.45 ha-1, 5.55

ha-1, and 5.55 ha-1. Decreasing in iron toxicity symptoms and leaf bronzing index

about 90.6% and 27.0% compared to farmers way and about 47.6% and 16.2%

compared to application of dolomite 2 t ha-1. Increasing in rate of purun tikus

decreased leaves Fe content about 45.5% and 30.3% compared to farmers way

and dolomite application 2 t ha-1, and increased Fe content in grain about 22.2%

and 18.9% compared to farmers way and application of dolomitr 2 t ha-1.

Net assimilation rate (NAR) increased about 26.2% and 17.4% compared

to farmers way and application of dolomite 2 t ha-1, whereas plant dry weight

increased about 27.3% compared to farmers way and about 13.9% compared to

application of dolomite 2 t ha-1.

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Inpara-1 showed yield components that were relatively higher than Inpara-

2, both in experiment in greenhouse and in the field at acid sulfate soil of tidal

swamplands. The number of panicles and grain, percentage of fertile grain, and

1000 grain weight of Inpara-1 and Inpara-2 in greenhouse experiment were 17.1

and 15.8 panicles; 99.0 and 96.1 grains; 64.4 and 62.9%, 23.56 and 25.44 grams,

respectively. Grain yield and harvest index of Inpara-1 was 21.19 grams and

0.52, while of Inpara-2 was 19.33 grams and 0.48. In the field experiment,

Inpara-1 had number of panicles and number, percentage of fertile grain and 1000

grain weight were 16.62 panicles, 145.65 grains, 75.72%, and 23.5 grams, while

Inpara-2 was 15.37 panicles, 140.39 grains, 72.56%, and 25.3 grams. Application

of straw and purun tikus compost increased rice yield components. Grain yield of

Inpara-1 and Inpara-2 were 4.45 t ha-1 and 4.17 t ha-1, and harvest index of 0.58

and 0.47, respectively.

Application of straw and purun tikus compost increased yield components,

grain yield and harvest index. The addition of purun tikus up to 5 t ha-1 showed it

increased, over which it decreased. Optimum rate of purun tikus which were

added to the straw 5 t ha-1 of Inpara-1 was 5.29 t ha-1 to reach the maximum

number of panicles per hill (26.84 panicles); 4.89 t ha-1 to reach the maximum

number of grains per panicle (140.85 grains); 5.27 t ha-1 to reach the maximum

percentage of fertile grain (97.28%), 5.27 t ha-1 to reach the maximum 1000 grains

weight (25.82 grams); 5.14 t ha-1 to reach the maximum grain yield (47.80 grams)

and 5.38 t ha-1 to reach the maximum harrvest index (0.85).

Application of straw 5 t ha-1 and purun tikus 5 t ha-1 compost increased

number of panicles per hill, number of grains per panicle, percentage of fertile

269

grain, and 1000 grain weight, grain yield and harvest index, i.e. 29.1%, 12.8%,

28.5%, 6.3%, 34.5%, and 17.8% compared to farmers way and 13.3%, 5.4%,

13.6%, 4.5%, 16.4%, and 8.2% compared to application of dolomite 2 t ha-1.

Iron toxicity decreased yield components, grain yield and harvest index.

Organic matter in form of aerobic and anaerobic compost of straw and purun tikus

and dolomite could reduce iron toxicity symptoms, leaf bronzing index, soil Fe

concentrations, Fe content in roots, stems and leaves, and increased physiological

processes, growth, yield components, and yield of Inpara-1, Inpara-2, and IR64.

Grain yield of Inpara-1 (4.45 t ha-1) was not msignificantly different with Inpara-

2, but it was 42.9% higher than IR64 (3.12 t ha-1). Variety IR64 was greater

responsive to application of these ameliorant than Inpara-1 and Inpara-2.

Aerobic compost of straw 5 t ha-1 and purun tikus 5 t ha-1 was the best

technology amelioration in controlling iron toxicity, improved physiological

processes, growth and grain yield. Grain yield at the rate was 4.83 t ha-1 and

increased 73.4%, 34.5%, and 14.6%, respectively compared to no application

ameliorant, application of straw and purun tikus compost, farmers way and

application of dolomite 2 t ha-1.

Inpara-1 and Inpara-2 can be grew at acid sulfate soils of tidal swamplands

with high Fe concentrations in soil. Organic matter of straw and purun tikus in

form aerobic compost can be used at acid sulfate soil that potential to iron toxicity

with technological innovation to efficient aerobic composting at acid sulfate soil

of tidal swamplands.

270

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