Judul: Studi untuk Mempertahankan Keragaman Genetik Tanaman Jagung Melalui Pembentukan Core Collection
Abstrak: The research and development in maize are immense, leading to hundreds of maize-improved varieties being released in Indonesia. In order to ensure the sustained availability of broad genetic diversity, the conservation of genetic resources is carried out through ex-situ conservation in the form of seed genebanks. The Agricultural Genebank under the Ministry of Agriculture is the largest genebank in Indonesia and conserves 12,000 accessions covering 40 plant species. However, the cross-pollinated genetic system of maize makes maize genetic resources in the genebank prone to experience inbreeding depression and needs specific treatment to maintain the genetic integrity of the accession. Thus, maize germplasm’s regeneration cost in the genebank is higher than self-pollinated species. The dissertation aimed to develop a maize core collection as one of the solutions to overcome the challenge of maize germplasm management in the genebank and assess how the core collection could preserve the existing genetic diversity in the whole set of maize collections. The study consists of 4 main stages of research activities: 1) getting to know, 2) constructing, 3) assessing, and 4) validating. The first research was to identify the structure of the whole set maize collection in the genebank and analyze its genetic diversity status. The result showed that a moderate to high genetic diversity based on kernel characters and passport data was identified. Two kernel characters, i.e. kernel type and color, were demonstrated as key characters that successfully differentiated all accessions into 10 clusters. The data of kernel characters for all accessions in the maize collection of the genebank was then used in the next research stage. The second research evaluated and identified which methods are appropriate for developing maize core collection. Five methods have been evaluated and based on the homogeneity of the frequency distribution of collection structure, the value of genetic diversity, and the value of summary statistics of core properties, Core Hunter 3 was determined as the appropriate method to select 150 accessions accounting of 11.7% of the whole set maize collection in the genebank. Core Hunter 3 demonstrated better diversity core properties, such as a low mean difference (MD) value, high variance difference (VD) and variable rate (VR) values, a coincidence rate (CR) value of >80%, and the highest coverage value. Moreover, it showed a homogeneity of the mean value of almost all kernel characters and a significantly higher variance value indicating an increased diversity compared to the whole set maize collection. The third research was conducted to assess the dynamics in maize core collection development in terms of entries and characters number used in the core construction process. Four core collections were developed from different datasets, i.e. 1 whole set (1,279 accessions) and 3 combination subset collection (560 accessions). The results showed that 7 accessions were conformally selected by the three cores which were developed from subset collection, representing the most diverse accessions of the whole set maize collection. It also observed that the entries number had more influence in maize core collection development compared to the characters number. The last research was conducted to ensure the prior developed maize core
Keyword: conservation, Core Hunter 3, genebank, genetic resources

Judul: Identification of Morpho-Agronomic Characteristics of 48 Inbred Lines of Maize (Zea mays L.)
Abstrak: Pengembangan jagung sangat prospektif karena nilai multigunanya. Pemuliaan jagung merakit varietas hibrida merupakan upaya penting. Keragaman genetik dalam populasi jagung diperlukan untuk menyeleksi calon tetua hibrida. Penelitian ini bertujuan mempelajari keragaman karakter morfologi dan agronomi serta mengidentifikasi galur jagung yang potensial sebagai tetua hibrida. Penelitian dilakukan di Kebun Percobaan Leuwikopo, Dramaga, Bogor, pada September 2023 hingga Januari 2024 menggunakan rancangan kelompok lengkap teracak augmented. Varietas pembanding meliputi BISI-18, JHG02, P21, P27, NK Perkasa, dan NK Sumo dengan enam ulangan, serta 48 genotipe yang diuji. Hasil penelitian menunjukkan genotipe jagung berpengaruh nyata pada hampir semua karakter kecuali anthesis silking interval. Perbedaan nilai tengah ditemukan pada sebagian besar karakter agronomi dan komponen hasil. Keragaman morfologi juga terlihat pada intensitas antosianin pada malai, rambut, dan akar penyangga, serta mengombaknya tepi helaian daun. Seleksi dapat dilakukan pada hampir seluruh karakter kuantitatif karena memiliki nilai heritabilitas arti luas yang tergolong tinggi. Terdapat tiga klaster utama berdasarkan fenotipe. Genotipe dalam klaster 1 seperti L15, NEI, M8, M9, L41s, P13, dan L42 berpotensi dikembangkan sebagai tetua hibrida. Korelasi kuat antara karakter agronomi dan komponen hasil belum ditemukan, korelasi didapati pada beberapa karakter seperti umur berbunga jantan dan betina, tinggi tanaman dan tinggi tongkol serta antar karakter lainnya., The development of corn commodities is promising due to its multifunctional value. Corn breeding to develop hybrid varieties is an important effort. Genetic diversity in corn populations is needed as a source for hybrid breeding. This study aimed to elucidate genetic diversity based on morphological and agronomic characteristics of 48 inbred lines and identify potential lines. The research was conducted from September 2023 to January 2024 at Leuwikopo Experimental Station, Dramaga, Bogor, West Java. The experiment used an augmented randomized complete block design with six replications for the checks. Forty-eight inbred lines were evaluated along with six check varieties BISI-18, JHG02, P21, P27, NK Perkasa, and NK Sumo. The results showed that genotypes significantly influenced all observed traits except the anthesis silking interval. Differences in mean values were found in most agronomic traits and yield components. Morphological diversity was also observed in the intensity of anthocyanin on the tassels, silks, and brace roots, as well as the leaf edge pattern. Selection can be performed on almost all quantitative traits due to their high broad-sense heritability values. There are three main clusters based on phenotype. Genotypes in cluster 1 such as L15, NEI, M8, M9, L41s, P13, and L42 tended to be potential as hybrids’ parents due to their good per-se morpho-agronomic traits. There is no strong correlation between agronomic traits and yield, but correlations were observed among some traits such as male and female flowering time, plant height and ear height, as well as among other traits.
Keyword: karakterisasi, keragaman genetik, heatmap, characterization, genetic variation

Judul: Bifurkasi lokal pada titik tetap non-hiperbolik
Abstrak: Bifurkasi menggambarkan perubahan pada struktur orbit di sekitar titik tetap. Titik tetap dibagi menjadi dua yaitu titik tetap hiperbolik dan titik tetap non-hiperbolik. Titik tetap non-hiperbolik terjadi jika ada nilai eigen dengan bagian real sama dengan nol. Kestabilan dari titik tetap dapat diketahui dari nilai eigen yang diperoleh dari pelinearan medan vektor. Pada bifurkasi satu-dimensi ditemukan kasus-kasus untuk bifurkasi saddle-node, bifurkasi transcritical dan bifurkasi pitchfork. Bifurkasi saddle-node terjadi jika satu sisi dari nilai parameter tidak terdapat titik tetap dan pada sisi lain terdapat dua titik tetap, dimana yang satu stabil dan yang lainnya tak-stabil. Bifurkasi transcritical terjadi jika terdapat pertukaran kestabilan, yaitu dari titik tetap stabil menjadi titik tetap tak-stabil dan sebaliknya. Sedangkan bifurkasi pitchfork dibagi menjadi dua, yaitu: bifurkasi pitchfork supercritical dan bifurkasi pitchfork subcritical. Bifurkasi pitchfork supercritical terjadi jika satu titik tetap stabil berubah menjadi dua titik tetap stabil dan satu titik tetap tak-stabil, dan bifurkasi pitchfork subcritical terjadi jika satu titik tetap stabil dan dua titik tetap tak-stabil berubah menjadi satu titik tetap tak-stabil. Bifurkasi Hopf (bifurkasi dua-dimensi) terjadi jika terdapat orbit periodik pada struktur orbitnya yang berupa lingkaran dengan jari-jari konstan. Ada atau tidaknya orbit periodik dapat diketahui setelah sistem ditransformasikan ke dalam koordinat polar. Orbit periodik ini dapat bersifat stabil maupun tak-stabil. Model periklanan (advertising) Feichtinger merupakan salah satu contoh penerapan bifurkasi Hopf Model ini menghasilkan satu titik tetap dan orbit periodik yang bersifat stabil.
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