Judul: The Attack of the Brown Planthopper in Purwabakti Village and its Relation to Cultivation Techniques by Farmer
Abstrak: The population's outbreak of the brown planthopper occurred for the first time in Purwabakti Village, Bogor Regency during the 2020/2021 rice planting season. The factors related to this phenomenon has not been reported yet. Field research which included observing the level of plot damage, interviewing rice cultivation techniques by farmers, and exploring the diversity of endophytic fungi on rice stems was carried out with the aim of analyzing cultivation techniques related to the level of plot damage and knowing the diversity of endophytic fungi on rice stems. Observation of the level of damage to plots was carried out by estimating the percentage of damage to plots based on the appearance of visual symptoms of damaged plots due to planthopper attack. Information on rice cultivation practices was collected by interview technique. Isolation of endophytic fungi was carried out on samples of rice stems in damaged and undamaged plots. Data analysis was done by descriptive method through cross tabulation approach. The relation between cultivation techniques and the level of plot damage was analyzed by Chi-square test with a significance level of 5%. Based on the results of the study, the cultivation technique factors that were significantly related to the level of plot damage due to WBC attack in Purwabakti Village were rice variety, dose of N fertilizer, use of K fertilizer, and burning of straws. The level of moderate, severe, and puso damage was mostly found in the plots planted with IR Kebo rice varieties, plots that were given high doses of N fertilizer, plots that were not given K fertilizer, and plots where straw was burned. The diversity of endophytic fungi on rice stalks is low. The results of the isolation of endophytic fungi found three isolates that were suspected to have mutualistic potential for plants, namely HN 1, HN 2, and PN 2.
Keyword: brown planhopper, population’s outbreak, rice, endophytic fungi, rice

Judul: Population Dynamics of Brown Planthopper, Nilaparvata lugens Stål. and their Natural Enemies in Rice plants at Tamansari and Ciampea Subdistricts, Bogor Regency
Abstrak: Wereng batang coklat (WBC) merupakan salah satu hama utama tanaman padi. Musuh alami dari golongan predator maupun cendawan memiliki peran penting dalam mengendalikan populasi WBC. Penelitian ini bertujuan untuk memperoleh informasi tambahan terkait dinamika populasi WBC serta musuh alaminya di Kecamatan Tamansari dan Ciampea. Penelitian dilakukan dari bulan Februari hingga Mei tahun 2021 di Desa Sukaresmi dan Desa Pasir Eurih (Kecamatan Tamansari) serta Desa Bojong Jengkol (Kecamatan Ciampea). Hasil penelitian menunjukan nimfa WBC sudah ditemukan pada padi berumur 4 minggu setelah tanam (MST). Puncak populasi WBC di Kecamatan Tamansari terjadi pada fase vegetatif padi, sedangkan di Kecamatan Ciampea populasi WBC masih banyak ditemukan pada fase generatif padi. Kepadatan populasi WBC tertinggi terjadi pada padi berumur 9 MST di Desa Bojong Jengkol. Keanekaragam musuh alami di ketiga desa menurut perhitungan uji dari Shannon-Wiener berada di tingkat sedang. Terdapat 9 macam jenis musuh alami yang ditemukan dari ketiga desa. Tiga jenis predator yang paling banyak ditemui antara lain: Lycosa pseudoannulata, Cyrtorhinus lividipennis dan Paederus fuscipes. Selain itu ditemukan juga dua jenis cendawan antara lain: Hirsutella citriformis dan Beauveria bassiana., Brown planthopper, N. lugens (BPH) is one of the main pests of rice plants. Natural enemies such as predators and entomopathogenic fungi have an important role in controlling the BPH population. This study aims to obtain information related to the population dynamics of BPH and its natural enemies in Tamansari and Ciampea Sub-districts. This research was conducted from February to May in Sukaresmi Village and Pasir Eurih Village (Tamansari District) and Bojong Jengkol Village (Ciampea District). The results showed that BPH nymphs were found in 4 weeks after planting (WAP). The peak population in Tamansari District was in the vegetative phase of rice, while in Ciampea District BPH populations were still mostly found in the generative phase of rice. The highest BPH population density occurred in the village of Bojong Jengkol at 9 WAP. The diversity of natural enemies according to Shannon-Wiener from the three villages is at a moderate level. There are 9 types of natural enemies found from the three villages. The three most common types of predators were: Lycosa pseudoannulata, Cyrtorhinus lividipennis and Paederus fuscipes. And also there are two types of fungi in the field: Hirsutella citriformis and Beauveria bassiana.
Keyword: BPH, population dynamics, natural enemies

Judul: Penentuan energi aktivasi ion untuk melewati membran teflon pada berbagai larutan elektrolit
Abstrak: Kaseno (1999) menyatakan bahwa dalam teknologi pemisahan, membran adalah bahan yang dapat memisahkan dua komponen dengan cara yang spesifik yaitu menahan atau melewatkan salah satu komponen lebih cepat dari komponen lainnya. Kemampuan pemisahan yang dimiliki oleh membran untuk melewatkan suatu senyawa kimia atau molekul diakibatkan oleh adanya perbedaan sifat fisika atau kimia antara membran dengan senyawa kimia.
Keyword: