Judul: Pengujian resistansi beberapa padi lokal terhadap wereng coklat, nilaparvata lugens stal
Abstrak: Twenty local rice varieties were identified showing moderate resistance reactions (Scale 3-6) during their seedling stage to colonies of biotype-1, biotype-2 and mixture of both biotypes of Brown Planthopper (BPH) in the laboratory. The varieties were further tested during their flowering stage of development to the BPH biotypes. The aim of the experiment is to determine weather rice plants showing moderate resistance in their seedling stage are also moderately resistant when they reach flowering stage or vice verca. This is important, since experience showed that the BPH caused hopperburn in any growth stage of susceptible varieties. Varieties having moderate resistance reactions in any stage of their development would reduce the threat of BPH for cousing hopperburn. None of the varieties tested showed moderate resistance reactions in both stages of their development to the biotypes of BPH. Paya Siam 8560 was found to be moderately resistant (Scale 4.66) in its seedling stage to biotype-1, biotype-2 and mixture of both biotypes of BPH, but as the plant becomes older they become susceptible. On the other hand, Paya Rumbiah 8558 was susceptible during its seedling stage, but showed moderate resistance reactions when they reach flowering stage. Crossing of both Paya Siam 8560 and Paya Rumbiah 8558 may be nescessary to obtain plants which would be moderately resistant in both seedling as well as flowering stage of the plant. Many more local germ plasms need to be tested for moderate reactions to the BPH biotypes in both their growth stages which would reduce the chance for hopperburn by BPH.
Keyword: Tanaman inang, Hama tanaman, Varietas padi, Wereng coklat

Judul: SURVEY OF DISTRIBUTION OF BROWN PLANTHOPPER POPULATION IN RICE CROPS IN SUBANG REGENCY WEST JAVA
Abstrak: Padi (Oryza sativa L.) merupakan komoditas penting sebagai sumber pangan pokok di Indonesia. Budidaya tanaman padi seringkali mengalami kegagalan akibat serangan hama wereng batang cokelat (WBC) Nilaparvata lugens Stål. Penelitian ini bertujuan mengetahui persebaran populasi WBC di Kabupaten Subang, kerapatan populasinya, dan tingkat kerusakan tanaman padi di tiga lokasi ketinggian tempat yang berbeda. Penelitian ini dilakukan dengan menelusuri keberadaan serangan WBC di lahan persawahan di areal kabupaten Subang dan memetakan persebarannya, menentukan lahan perlakuan terinfestasi di tiga lokasi ketinggian tempat berbeda, mengamati tingkat kerusakan tanaman pada umur 4 MST dan kerapatan populasi WBC. Data penunjang diperoleh melalui wawancara terhadap petani tentang teknik budidaya padi setempat kaitannya dengan pengendalian WBC di lahannya. Luas serangan dan intensitas kerusakan tanaman tertinggi 91,5% dan 41%, dengan jumlah populasi WBC tertinggi 1.8 ekor/rumpun ditemukan di lahan padi dataran rendah pada ketinggian 27-38 m dpl, sebaliknya kerusakan paling rendah sebesar 22% dan 4.3% dengan jumlah populasi 0.35 ekor/rumpun ditemukan di dataran tinggi pada 516-526 m dpl. Penggunaan varietas padi Ciherang dan Inpari 31 tidak berpengaruh terhadap jumlah populasi WBC. Lokasi penanaman padi di dataran rendah dengan curah hujan dan suhu lingkungan yang tinggi berkontribusi dalam peningkatan populasi WBC, Rice (Oryza sativa L.) is an important commodity as the staple food in Indonesia. Rice cultivation often fails due to attacks by the brown planthopper (BPH) Nilaparvata lugens Stål. This study aims to determine the distribution of BPH population in Subang Regency, the population density, and the level of damage to rice crops at three different altitude locations. This research was conducted by tracing the presence of BPH infestation in paddy fields in the Subang district area and mapping their distribution, determining the infested treatment areas at three different altitude locations, observing the level of plant damage at 4 WAP and the population density of BPH. Supporting data was obtained through interviews with farmers regarding local rice cultivation techniques in relation to BPH control in their fields. The highest attack area and intensity of crop damage were 91.5% and 41%, with the highest number of BPH populations of 1.8 individuals/hills found in lowland rice fields at an altitude of 27-38 masl, whereas the lowest damage was 22% and 4.3% with the lowest populations of 0.35 individuals/hills found in the highlands at 516-526 masl. Ciherang and Inpari 31 rice varieties had no effect on the number of WBC populations. The location of rice cultivation in the lowlands with high rainfall and ambient temperature contributed to the increase in the BPH population.
Keyword: Intensitas, Ketinggian tempat, Luas serangan, Varietas padi, Altitude, Attack area, Intensity, Rice varieties

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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