Simpulan
Berdasarkan rangkaian kegiatan percobaan, hasil dan pembahasan, disimpulkan beberapa hal sebagai berikut :
1. Seleksi in vitro berulang (repeat in vitro selection) pada media selektif PEG 15% meningkatkan frekuens i ES yang insensitif dan menghasilkan planlet R0
yang toleran terhadap media selektif yang mengandung PEG 15%.
2. Populasi tanaman R0 yang diregenerasikan dari ES hasil seleksi satu dan dua siklus (seleksi berulang) pada media selektif PEG 15% serta seleksi ganda (pada media PEG 15% dan kemudian pada media filtrat kultur 30%) dan zuriat R1-nya menghasilkan karakter varian kualitatif jumlah anak daun, fusi pangkal anak daun, daun variegata, dan jantan steril yang dikendalikan secara genetik, serta varian cabang majemuk, tunas majemuk, dan batang menjalar, dan daun bergelombang dikendalikan secara epigenetik. Tipe varian kualitatif pada generasi R0 dan R1 lebih banyak dijumpai pada tanaman hasil seleksi in vitro berulang. Karakter bobot polong kering dan jumlah polong bernas juga merupakan karakter varian kuantitatif diantara populasi tanaman
3. Tanaman hasil seleksi ES dua siklus (seleksi berulang) pada PEG 15% cv. Singa dan Kelinci menghasilkan pertumbuhan vegetatif yang lebih baik dengan hasil polong yang lebih tinggi terhadap cekaman kekeringan. Tanaman ini juga mempunyai tingkat toleransi yang lebih baik terhadap cekaman kekeringan dengan menghasilkan rata-rata bobot polong kering 11.75 g/polibeg untuk cv. Singa dan 10.96 g/polibeg untuk cv. Kelinci. Seleksi ES dua siklus (seleksi berulang) cv. Kelinci pada media selektif PEG 15% menghasilkan jumlah individu galur kacang tanah toleran lebih banyak (30%). 4. Seleksi berulang selama dua siklus dalam media selektif dengan filtrat kultur
30% menghasilkan ES yang insensitif terhadap cekaman media filtrat kultur S.
rolfsii. Setek pucuk planlet R0 yang diregenerasikan dari ES hasil seleksi
5. Tanaman hasil seleksi in vitro berulang dalam media selektif filtrat kultur S.
rolfsii 30% dan seleksi ganda (dalam media selektif yang mengandung filtrat
kultur dan polietilena glikol 15%) dapat menginduksi variasi somaklonal. Tanaman hasil seleksi in vitro berulang pada media filtrat kultur menghasilkan macam varian kualitatif lebih banyak. Macam varian kualitatif yang diwariskan secara genetik, yaitu karakter abnormalitas jumlah anak daun (pentafoliat, heksafoliat, heptafoliat, oktafoliat), jantan steril total, dan daun variegata, sedangkan varian epigenetik adalah daun bergelombang, cabang dan tunas majemuk, serta batang menjalar. Tanaman yang dihasilkan dari seleksi ES satu, dua siklus dan seleksi ga nda menghasilkan bobot polong kering melebihi atau lebih rendah dari tanaman standar, dan merupakan karakter varian.
6. Tanaman hasil seleksi ES dua siklus pada filtrat kultur menghasilkan polong lebih berat dengan penurunan hasil polong lebih rendah akibat infeksi S.
rolfsii. Tanaman ini juga lebih tahan terhadap serangan S. rolfsii dan
menghasilkan jumlah galur agak tahan dan tahan lebih banyak. Tanaman ini menghasilkan rata-rata bobot polong kering 11.75 g/polibeg untuk cv. Singa dan 11.67 g/polibeg untuk cv. Kelinci.
7. Seleksi ganda (double in vitro selection) masing- masing satu siklus pada media selektif PEG 15% dan kemudian diseleksi kembali pada media filtrat kultur S.
rolfsii 30% atau seleksi ganda pada media selektif filtrat kultur dan kemudian
diseleksi pada media PEG meningkatkan frekuensi ES yang insensitif dan planlet R0-nya yang toleran dan tahan terhadap dua media selektif yang mengandung PEG 15% dan filtrat kultur S. rolfsii 30% serta menghasilkan tanaman somaklon yang toleran terhadap cekaman kekeringan dan resisten terhadap infeksi S. rolfsii.
8. Seleksi in vitro berulang (repeat in vitro selection) pada media selektif PEG atau pada media filtrat kultur S. rolfsii 30% cukup efektif untuk mendapatkan tanaman kacang tanah yang toleran terhadap cekaman kekeringan atau resisten terhadap infeksi cendawan S. rolfsii. Seleksi in vitro ganda (in vitro double
selection) pada media selektif yang mengandung PEG dan kemudian pada
dilanjutkan pada media PEG, cukup efektif untuk mendapatkan tanaman kacang tanah yang sekaligus toleran terhadap cekaman kekeringan dan resisten terhadap infeksi cendawan S. rolfsii.
Saran
Pengujian pada generasi lanjut R3, R4, dan R5 perlu dilakukan untuk mendapatkan karakter toleran kekeringan, tahan penyakit busuk batang S. rolfsii, dan karakter ganda (toleran kekeringan dan resisten penyakit) yang lebih stabil.
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