Ketahanan Galur Isogenik IRBBN dan Galur Harapan Padi terhadap Patotipe Xanthomonas Oryzae Pv. Oryzae Dominan pada Tanaman Padi di Indonesia

Galur isogenik IRBB introduksi dari International Rice Research Institute (IRRI) telah diketahui gen ketahanannya dan dapat digunakan sebagai sumber ketahanan terhadap patotipe Xanthomonas oryzae pv. oryzae (Xoo) dominan di Indonesia. Kegiatan penelitian ini bertujuan untuk mengevaluasi ketahanan galur isogenik dan galur harapan terhadap patotipe Xoo dominan di Indonesia, yaitu patotipe III, IV, dan VIII. Penelitian dilaksanakan di Kebun Percobaan Sukamandi, Subang, Jawa Barat pada musim kemarau (MK) 2012 dan musim hujan (MH) 2012/2013. Penelitian dilakukan dengan Rancangan Faktorial Acak Kelompok dengan tiga ulangan. Faktor pertama adalah tiga patotipe Xoo, yaitu patotipe III, IV, dan VIII, sedangkan faktor kedua yaitu materi yang diuji sebanyak 20 galur IRBB, 6 galur harapan padi, dan 6 varietas pembanding, yaitu Conde, Lusi, Logawa, Java 14, Angke, dan Inpari 1. Hasil penelitian menunjukkan bahwa galur isogenik IRBB 21, IRBB 50, dan IRBB 52 bereaksi tahan terhadap Xoo patotipe III, IV, dan VIII pada MK 2012. Pada MH 2012/2013 diperoleh lima galur isogenik IRBB 52, IRBB 53, IRBB 54, IRBB 56, dan IRBB 57 bereaksi tahan terhadap Xoo patotipe III, IV, dan VIII. Galur isogenik IRBB 52 konsisten tahan terhadap Xoo patotipe III, IV, dan VIII pada dua musim tanam. Oleh karena itu, galur tersebut dapat direkomendasikan untuk dijadikan tetua tahan untuk perakitan varietas tahan HDB

Perkembangan dan Tantangan Perakitan Varietas Tahan dalam Pengendalian Wereng Coklat di Indonesia

Varietas tahan merupakan komponen utama dalam pengendalian wereng coklat pada tanaman padi. Namun, varietas tahan yang ditanam secara luas dan terus-menerus dapat patah ketahanannya karena wereng coklat mampu beradaptasi dengan membentuk biotipe baru. Saat ini lebih dari 70 gen ketahanan terhadap wereng, baik gen utama maupun quantitative trait loci (QTLs), telah diidentifikasi dan beberapa gen telah digunakan dalam perakitan varietas unggul padi. Keanekaragaman sumber gen ketahanan pada varietas dapat menjadi alternatif pergiliran tanaman dalam upaya meredam serangan wereng coklat. Tantangan perakitan varietas tahan ke depan ialah produktivitas tinggi dan toleran terhadap cekaman abiotik. Perakitan varietas tahan dengan ketahanan lestari (durable resistance) menggunakan marker-assisted selection (MAS) dengan menggabungkan lebih dari dua gen ketahanan (gen utama maupun QTLs) diharapkan dapat menghambat pembentukan biotipe baru wereng coklat. Gen-gen ketahanan pada beberapa varietas diferensial seperti Rathu Heenati (Bph3 dan Bph17) dan PTB33 (bph2 dan Bph3) masih mempunyai ketahanan yang baik terhadap populasi wereng coklat dari daerah endemis dan dapat dijadikan donor dalam perakitan varietas tahan. Deteksi gen ketahanan pada varietas unggul padi yang akan dilepas sangat penting untuk menentukan rekomendasi daerah/lokasi tanam dan pergiliran varietas. Selain itu, manajemen ketahanan varietas juga penting agar varietas tahan yang dilepas dapat bertahan lama di lapangan

Low Association of Bph17 Allele in Landraces and Improved Varieties of Rice Resistant to Brown Planthopper

Resistance traits to brown planthopper on rice varieties are controlled by dominant and recessive genes called Bph/bph. Bph17 is one of dominant genes that control rice resistance to brown planthopper. Marker of Bph17 allele can be used as a tool of marker assisted selection (MAS) in breeding activity. Association of Bph17 allele and resistance to brown planthopper in Indonesian landraces and new-improved varieties of rice is not clearly known. The study aimed to determine the association of Bph17 allele in landraces and new-improved varieties of rice resistant to brown planthopper. Twenty-one rice genotypes were used in the study, consisting of 13 landraces, 5 improved varieties, 3 popular varieties and a check variety Rathu Heenati. Two simple sequence repeat markers linked to Bph17 allele were used, i.e. RM8213 and RM5953. The results showed that association of Bph17 allele in landraces and new-improved varieties of rice resistant to brown planthopper resistance was very low (r = -0.019 and -0.023, respectively). The presence of Bph17 allele did not constantly express resistance to brown planthopper. The study suggests that Bph17 allele cannot be used as a tool of MAS for evaluating resistance of landraces and new-improved varieties of rice to brown planthopper. Further research is needed to obtain a specific gene marker that can be used as a tool of MAS and applicable for Indonesian differential rice varieties

Similarity of 26 New Released Rice Varieties and Rice Parental Hybrids Based on 36 SSR Markers

More than 200 rice varieties had been released in Indonesia, but the genetic variability among those released varieties was suspected to be relatively low. Molecular markers, especially SSR could be used as a tool to disect the distinctness among rice genotypes, albeit phenotipically similar varieties. The technique could also be used to prove the authenticity of a variety. This research was aimed to obtain DNA fingerprinting data of new released rice varieties and hybrid parental lines using SSR markers. A total of 26 rice genotypes consisted of three upland, ten irrigated, five swampy rice varieties, along with eight hybrid parental lines were used in this experiments. The DNA was extracted from young leaf samples using CTAB modified method and was amplified with 36 SSR markers linked to important rice traits which spread accross the 12 rice chromosomes. The experiment was conducted in Plant Breeding Laboratory of Indonesian Center for Rice Research (ICRR) during 2012. The results showed that PIC value of the genotypes were mostly at medium level of the genetic diversity with the average value of 0.4451. The phylogenetic analysis showed that at the genetic distance of 10%, the genotypes were separated into 9 groups, i.e. Inpago 6, Inpara 5, and BH33d each stood alone while (Inpara 1, Inpara 2 , and Inpara 3); (Inpari 18 and Inpari 19, Inpago 4, Inpago 5, and Inpara 4); (Inpari 11, Inpari 12, Inpari 13, Inpari 14, Inpari 15, Inpari 16, Inpari 17, and Inpari 20); (GMJ6B, B6, and IR79156B); (PK21, BH95E, Bio9, and R14) each belong to one group. The grouping of the genotypes in this study seemed to follow the adaptation type to agro ecosystems. The hybrid parental lines tended to stay in different group from the inbred varieties. The application of these 36 SSR markers was able to distinguish among 26 genotypes rather distinctly.The use of more markers should give more powerful data to distinguish among genotypes

Initial Study of the Response of Ultra Early Maturing Rice Genotypes to Drought Stress Conditions in Vegetative and Generative Phase

Global climate change has caused the spread of drought prone areas. Drought stress for rice mostly happen in upland, rainfed, and limited irrigation lowland areas. Development of varieties suitable for those areas would significantly increase rice yield. Early maturing genotypes are useful to anticipate predictable early or terminal drought by escape mechanism. Nevertheless, unpredictable drought happening during early, mid season and final planting season results in the need of genuinely droughttolerant genotypes. Combining early maturing and drought tolerant seems to be highly powerful to anticipate drought. This research was aimed to study the response of 23 early maturing rice genotypes consisting of 3 released varieties, 10 local varieties, and 10 introduced lines. The genotypes were exposed to vegetative (watered until 7 days after transplanting and rewater when the susceptible check was drying) and generative phase (watered until 28 days after transplanting and rewatered only if susceptible check was drying), drought stress conditions, and also optimum condition. The experiment was conducted in ICRR Experimental Station in Sukamandi during Dry Season (DS) of 2009. The genotypes were treated with three watering conditions mentioned above without replication to initially see the descriptive statistics of some agronomic traits of the genotypes under the mentioned conditions. The results showed that based on yield, Drought Sensitifity Index (DSS), Relative Values (RV), and agronomic performance, OM 1490 had been identified as tolerant to vegetative and generative drought stresses. It yielded 28.17 g/plant, 24.11 g/plant, and 24.72 g/plant at optimum, vegetative, and generative drought condition, respectively. OM 1490 had been released as Inpari 13 in 2010 and it had beed utilized for further breeding effort resulting new promising lines

Keragaan Galur-galur Green Super Rice pada Kondisi Sawah Tadah Hujan Saat Musim Kemarau di Kabupaten Pati

Green Super Rice (GSR) adalah tanaman padi yang dirancang untuk memiliki daya hasil tinggi, toleran terhadap cekaman biotik dan abiotik, serta efisien pemupukan dan air. GSR diharapkan memiliki daya adaptasi dan hasil yang baik pada kondisi sawah tadah hujan. Evaluasi galur-galur padi GSR pada lahan tadah hujan telah dilakukan di Kecamatan Jakenan, Kabupaten Pati, Provinsi Jawa Tengah pada MK 2014. Penelitian menggunakan Rancangan Acak Kelompok 2 ulangan dengan perlakuan 30 galur padi GSR dan empat varietas pembanding. Galur-galur GSR yang dievaluasi merupakan galur hasil seleksi di Indramayu pada musim sebelumnya. Varietas pembanding yang digunakan adalah Inpari 13, Inpari 10, Inpari 23, dan Situ Bagendit. Bibit umur 21 hari setelah sebar dari setiap galur dan varietas pembanding ditanam 1–3 bibit per lubang pada plot berukuran 2 m x 5 m dengan jarak tanam 20 cm x 20 cm. Pengairan bergantung pada turunnya hujan dan pompa air dari embung penampung air hujan. Hasil penelitian menunjukkan bahwa galur yang diuji memiliki perbedaan nyata dan sangat berbeda nyata pada karakter agronomi yang diamati. Galur GSR yang beradaptasi relatif baik di sawah tadah hujan Kabupaten Pati pada musim kemarau adalah HHZ2–SKI-2–7–0Kr-JK-IND (4,09 t/ha) yang memiliki hasil nyata lebih tinggi daripada cek terbaik Situ Bagendit (3,04 t/ha), dan HHZ4–SKI-5–4–0Kr-JK-IND (3,91 t/ha) serta Zhonghua1–SKI-1–IND (3,85 t/ha) yang memiliki hasil nyata lebih tinggi daripada cek terbaik kedua, yaitu Inpari 13 (2,88 t/ha). Galur-galur GSR tersebut prospektif untuk diuji lebih lanjut karena memiliki daya hasil yang tinggi dan memiliki karakteristik agronomis sesuai dengan preferensi petani di Indonesia. Faktor keunggulan daya hasil galur-galur GSR yang teridentifikasi dalam percobaan ini diduga didukung oleh karakter jumlah gabah isi/malai, jumlah anakan, dan umur yang relatif genjah. Galur-galur GSR yang diuji memiliki kemiripan relatif tinggi (50%)