PERTUMBUHAN Arachis hypogaea L. DAN Jussiaea repens L. PADA KONDISI TERGENANG DENGAN APLIKASI Bradyrhizobium sp.

NUGRAHENI LINTANG PRIMASARI, Prof (emr). Dr. Santosa

2015 | Tesis | S2 Biologi

dan sensitif sehingga diperlukan metode untuk meningkatkan ketahan tumbuhan terhadap genangan. Penelitian ini bertujuan untuk mengevaluasi pertumbuhan serta adaptasi Arachis hypogaea dan Jussiaea repens pada kondisi tergenang dan kemampuan Bradyrhizobium sp. mempengaruhi pertumbuhan A. hypogaea dan J. repens pada kondisi tergenang. Penelitian menggunakan rancangan acak lengkap (RAL) pola faktorial. Faktor pertama adalah tinggi genangan yaitu tanpa genangan, genangan setinggi medium tumbuh, dan genangan setinggi 5 cm di atas medium tumbuh dan faktor kedua adalah aplikasi Bradyrhizobium sp. yaitu tanpa Bradyrhizobium sp. dan penambahan Bradyrhizobium sp. masing-masing perlakuan dengan empat ulangan. Parameter yang diukur meliputi potensial redoks (Eh) dan pH medium tumbuh, tinggi tanaman, jumlah daun, jumlah akar adventif, luas daun, berat kering tajuk, berat kering akar, rasio tajuk akar, persentase aerenkim, diameter akar, tebal korteks, diameter stele, diameter trakea akar, tebal lamina, tebal palisade, tebal spons, tebal trakea daun, kandungan klorofil, kadar etilen, laktat, dan etanol akar. Data dianalisis menggunakan Anava dan Duncan’s Multiple Range Test dengan taraf uji α=5%. Hasil penelitian menunjukkan bahwa perlakuan genangan dan aplikasi Bradyrhizobium sp. menurunkan Eh dan meningkatkan pH medium tumbuh A. hypogaea tetapi perlakuan tersebut hanya menurunkan pH medium tumbuh J. repens. Genangan menurunkan tinggi tanaman, berat kering tajuk, rasio tajuk akar, diameter akar, tebal korteks, diameter stele, dan diameter trakea akar serta meningkatkan jumlah akar adventif dan berat kering akar A. hypogaea sebaliknya genangan meningkatkan tinggi tanaman, jumlah daun, jumlah akar adventif, berat kering tajuk, berat kering akar, rasio tajuk akar, tebal lamina, tebal palisade, dan tebal spons serta menurunkan diameter akar dan tebal korteks J. repens. Bradyrhizobium sp. meningkatkan tinggi tanaman, jumlah akar adventif, berat kering tajuk, rasio tajuk akar, tebal lamina, dan tebal trakea daun A. hypogaea serta menghambat tinggi tanaman, jumlah daun, jumlah akar adventif, berat kering tajuk, dan berat kering akar dan meningkatkan diameter akar, diameter trakea akar, tebal lamina, tebal palisade, dan tebal spons J. repens. Adaptasi fisiologis antara lain kandungan klorofil, etanol, dan laktat tidak menunjukkan perbedaan pada A. hypogaea dan J. repens sebaliknya kandungan etilen dipengaruhi oleh perlakuan genangan dimana genangan memacu terbentuknya etilen dan Bradyrhizobium sp. menghambat terbentuknya etilen.

Plant can be categorized into tolerant and intolerant to waterlogged condition so that the necessary method to improve plant’s survival rate on waterlogging. The objectives of this research were to be evaluated the growth and adaptation of Arachis hypogaea and Jussiaea repens in waterlogged condition and Bradyrhizobium sp. ability to affect the growth of A. hypogaea and J. repens in waterlogged conditions. The study was carried out using factorial completely randomized design. The first factor was water levels i.e. without waterlogging, waterlogging at soil surface, and waterlogging at 5 cm above the surface of the growing medium and the second was application of Bradyrhizobium sp. i.e. with and without Bradyrhizobium sp. Four replications were made for each combination treatment. Parameters measured included the Eh and pH of the growing medium, plant height, number of leaf, number of adventitious root, leaf area, shoot dry weight, root dry weight, shoot root ratio, percentage of aerenchyma, root diameter, cortical thickness, root stele and vessels diameter, leaf thickness, palisade thickness, spongious thickness, leaf vessels diameter, chlorophyll content, root ethylene, lactate, and ethanol content. Data were analyzed using Anova and Duncan’s Multiple Range Test with at α = 5 %. The results showed that the treatment of waterlogging and Bradyrhizobium sp. application decreased Eh and increased the pH of the A. hypogaea growing medium but those treatments only reduced pH of J. repens growing medium. Waterlogging decreased plant height, shoot dry weight, shoot root ratio, cortical thickness, root stele diameter, root vessel diameter and increased number of adventitious root and root dry weight of A. hypogaea while waterlogging increased plant height, leaf number, adventitious root number, shoot dry weight, root dry weight, shoot root ratio, leaf thickness, palisade thickness, spongious thickness, and decreased root diameter and cortical thickness of J. repens. Bradyrhizobium sp. increased plant height, adventitious root number, shoot root ratio, leaf thickness and leaf vessel thickness of A. hypogaea and decreased plant height, leaf number, adventitious root number, shoot dry weight, root dry weight and increased root diameter, root vessel diameter, leaf thickness, palisade thickness, and spongious thickness of J. repens. Physiological adaptations such as chlorophyll, root ethanol, and lactate content showed no difference in A. hypogaea and J. repens otherwise waterlogging treatment increased and Bradyrhizobium sp. decreased the formation of ethylene.

Kata Kunci : waterlogging, Arachis hypogaea, Jussiaea repens, Bradyrhizobium sp.