Dengan ini saya menyatakan bahwa disertasi Pengembangan Padi Gogo Indica Toleran Kekeringan melalui Transformasi Genetik Gen Regulator HD-Zip
Oshox6 dan Seleksi Populasi Padi yang Mengandung Marka Genetik QTL 12.1
adalah karya saya dengan arahan dari komisi pembimbing dan belum diajukan dalam bentuk apapun kepada perguruan tinggi manapun. Sumber informasi yang berasal atau dikutip dari karya yang diterbitkan dari penulis lain telah disebutkan dalam teks dan dicantumkan dalam Daftar Pustaka di bagian akhir disertasi ini.
Bogor, Januari 2011
Enung Sri Mulyaningsih
DAFTAR PUSTAKA
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HASIL DAN PEMBAHASAN Seleksi Genotipe pada MK-2008
Selama percobaan MK 2008 berlangsung tidak terjadi hujan sehingga air tersedia hanya berasal dari penyiraman. Dari percobaan MK 2008 dipilih sebanyak 21 genotipe sebagai kandidat toleran kekeringan yang diseleksi berdasarkan beberapa karakter terkait produksi (Tabel 1). Dari 21 genotipe terpilih, 13 genotipe yang memiliki marka qtl 12.1 dan 8 genotipe tidak mengandung marka (identifikasi keberadaan marka telah dilakukan sebelumnya, Bernier et al. 2007). Nilai analisis keragaman dan uji lanjut untuk karakter pengamatan (Mk 2008) disajikan pada Tabel 2, 3 dan 4.
Tabel 2. Rangkuman analisis keragaman perlakuan genotipe, taraf cekaman lingkungan dan interaksinya pada karakter jumlah anakan produktif, bobot gabah per plot dan jumlah gabah bernas per malai genotipe terpilih, Muneng, MK 2008.
Karakter Pengamatan Genotipe Taraf cekaman lingkungan
Interaksi (G x L) Anakan produktif 5,75** 74,68** 0,87tn Bobot gabah/plot (gr) 7,06** 261,24** 1,06 tn Jumlah gabah bernas/malai 8,41** 169,49** 1,28tn
Keterangan : (**) berbeda sangat nyata (tn) tidak berbeda nyata, uji F pada taraf 5%
Berdasarkan Tabel 2, faktor interaksi antara lingkungan dengan genotipe tidak berbeda nyata untuk ketiga karakter. Artinya semua genotipe akan memberikan respon sama terhadap perlakuan yang diberikan. Masing-masing faktor (lingkungan dan genotipe) dianalisis secara tunggal. Faktor lingkungan dan genotipe secara tunggal berbeda nyata terhadap ketiga karakter.
Hasil uji lanjut faktor lingkungan menunjukkan bahwa karakter anakan produktif antara lingkungan normal dan cekaman sedang tidak berbeda nyata. Jumlah anakan produktif rendah pada cekaman kekeringan berat. Meskipun demikian, karakter jumlah anakan produktif sulit dijadikan karakter seleksi karena perlakuan cekaman diberikan ketika jumlah anakan maksimum, menjelang fase generatif. Bobot gabah per plot pada lingkunga normal tidak berbeda nyata dengan bobot gabah per plot pada cekaman kekeringan sedang. Bobot gabah per
plot rendah pada cekaman kekeringan berat. Karakter bobot gabah per plot dapat dijadikan karakter seleksi pada faktor lingkungan. Jumlah gabah bernas per malai tidak berbeda nyata antara cekaman kekeringan berat dan lingkungan normal. Karakter gabah bernas pada dasarnya sangat dipengaruhi oleh taraf cekaman kekeringan ketika tanaman dalam fase generatif. Lingkungan kekeringan dapat menyebabkan gagalnya proses penyerbukan sehingga meningkatkan kehampaan. Jumlah gabah bernas pada kondisi cekaman berat adalah yang paling rendah dengan rerata 80 gabah bernas/ malai. Tidak adanya perbedaan yang nyata pada kondisi lingkungan yang berbeda menunjukkan bahwa lingkungan tersebut tidak mempengaruhi karaker seleksi yang diamati.
Berdasarkan percobaan MK-I, seleksi galur potensial toleran cukup berdasarkan data lingkungan normal dan berat. Hal ini disebabkan karena tidak ada perbedaan nyata antara kasil pengamatan karakter pada lingkungan normal dengan cekaman sedang.
Tabel 3. Hasil uji lanjut faktor lingkungan terhadap karakter anakan produktif, bobot gabah per plot dan jumlah gabah bernas/ malai genotipe terpilih, Muneng, MK 2008. Penyiraman Anakan produktif Jumlah gabah bernas/malai Bobot gabah/plot (gram) N 13 a 88 b 115 a CS 13 a 101 a 122 a CB 11 b 80 b 73 b
Keterangan : N = tanpa cekaman (normal), CS = cekaman sedang, CB = cekaman berat. Angka sekolom diikuti huruf yang sama tidak berbeda nyata, uji Tukey pada taraf 5%