Judul: Morphological and genetic diversity and degree of competition of several Echinochloa crus-galli (L.) Beauv. accessions to rice.
Abstrak: Weed disturbance is an important issue in rice production in Indonesia. Echinochloa crus-galli (L.) Beauv. is the most dominant weed in rice leading to loss of production. The research aims to analyze the morphology and genetic diversity of weeds accession E. crus-galli from West Java and degree of competition of E. crus-galli to rice. Research was carried out by using several steps, i.e : (1) Preliminary experiments on growth and production of rice with E. crus-galli weed population levels originating from three locations, (2) Morphological and genetic evaluation, (3) Identification of potential weed allelophaty E. crus-galli accession, (4) Study effect of E. crus-galli accession on the growth and rice production (greenhouse experiments), (5) Effects of accession and population rate of E. crus-galli on the growth and rice production (field trial), (6) Estimation of degree competition of E. crus-galli by the replacement series method, (7) Study of physiology competition between rice with weeds. Results showed that E. crus-galli accession from West Java exhibited morphological and genetic diversity. Accession from different geographical locations showed differences in morphology. The diversity of morphology is presumably due to the phenotypic plasticity and adaptation ability of E. crus-galli accessions. Cluster analysis based on SSR molecular markers produced four sub-groups with similarity coefficient of 0.86, with most of the group clustered in geographic zones of western West Java and northen. This genetic diversity might be caused by the movement of genetic material through harvest or through irrigation, isolation distance, and the possibility of mutation. E. crus-galli accessions had the potential allelophaty based on inhibit of radicle and plumula growth of rice. Based on the potential allelophaty, the accessions clustered to six groups at 0.72 similarity coefficient. Each accession of E. crus-galli showed a potential difference in reducing the growth and yield of rice plants. This ability is probablt related to morphological characteristics and allelophatyic potential. Accession K6 from Karawang showed the highest ability to suppress the growth and production of rice plants. E. crus-galli weed had a higher degree of competition to rice plants when the weed population was higher than the population of rice plants. Based on the value of aggressiveness, E. crus-galli competed stronger than rice when the population of rice plants and weeds is equal or weed population was higher than that of rice population. Each rice variety had a different response to population levels of E. crus-galli. The competition between rice plants with a E. crus-galli inhibited the physiological process of rice plant.
Keyword: Oryza, Field crops

Judul: Studi kompetisi beberapa ekotipe gulma, Echinochloa crus-galli terhadap tanaman padi, Oryza sativa L.
Abstrak: Beras merupakan pangan utama di Indonesia, karena lebih dari setengah Jumlah penduduk Indonesia menjadikan beras sebagai makanan pokok. Kebutuhan beras terus meningkat seiring dengan peningkatan jumlah penduduk. Usaha untuk meningkatkan produksi beras dihadapkan pada berbagai kendala, salah satunya adalah gulma. E. crus-galli merupakan salah satu jenis gulma utama pada lahan sawah yang dapat menurunkan produksi padi. Penelitian bertujuan untuk mempelajari kompetisi beberapa ekotipe gulma E crusgalli dari beberapa sentra produksi padi terhadap pertumbuhan dan produksi padi. Penelitian dilakukan di Rumah Kaca Kebun Percobaan Cikabayan Dramaga Bogor, pada bulan Mei 2006 sampai dengan September 2006. Percobaan disusun dalam rancangan petak terbagi (split plot design) yang terdiri atas dua faktor. Ekotipe E. crus-galli sebagai petak utama terdiri dari tiga ekotipe, yaitu ekotipe Karawang, Cikampek, dan Sukabumi. Populasi E. crus-gall sebagai anak petak terdiri dari lima taraf, yaitu 0, 1, 2, 3, dan 4 gulma E. crus- galli per pot Pengamatan yang dilakukan meliputi tinggi tanaman padi, jumlah anakan, Jumlah daun, biomassa padi, jumlah anakan produktif, produksi gabah, bobot 100 butir gabah, indeks panen, panjang malai, kepadatan malai, panjang daun bendera, lebar daun bendera, luas daun bendera, dan kadar nitrogen daun bendera. Perlakuan ekotipe E. cras-galli mempengaruhi pertumbuhan tanaman padi. E crus-galli ekotipe Sukabumi menyebabkan tinggi tanaman padi yang lebih rendah dibandingkan ekotipe lainnya. Jumlah anakan dan kepadatan malai pada padi yang ditanam dengan E. crus-galli ekotipe Cikampek lebih rendah dibandingkan dengan padi yang ditanam dengan E. crus-galli ekotipe lain. E cris-galli ekotipe Cikampek memiliki daya kompetisi yang lebih besar dibandingkan dengan ekotipe lainnya dalam mempengaruhi produksi padi. Perlakuan populasi E crus-galli lebih besar pengaruhnya terhadap pertumbuhan dan produksi padi dibandingkan dengan perlakuan ekotipe E. crus- gall. Semakin tinggi populasi E. crus-galli pengaruh kompetisi terhadap tanaman padi semakin besar. Populasi E crus-galli sebanyak 4 per pot menurunkan produksi tanaman padi dalam bentuk bobot gabah kering sebesar 48% dan menurunkan bobot gabah isi sebesar 46.2%. Kompetisi gulma E. crus-galli tidak dipengaruhi oleh interaksi antara ekotipe E crus-galli dengan populasi, tetapi dipengaruhi oleh faktor tunggal ekotipe E. crus-galli dan populasi.
Keyword: 

Judul: Pembuatan Film Tipis Cu2ZnSnS4 sebagai Lapisan Penyerap Cahaya pada Sel Surya Menggunakan Metode Elektrodeposisi
Abstrak: Thin film of Cu2ZnSnS4 (CZTS) is an alternative semiconductor used as light absorber layer on solar cell. CZTS can replace silicon that commonly used as commercial semiconductor. The advantage of using CZTS as absorber layer is due to the abundance of its chemical composer on earth, and its high value of absorption coefficient. The absorber layer was made by using electrodeposition method on ITO glass substrates. The films were deposited at room temperature using potentiostatic mode with a potential of –1.05 V for 30, 45, and 60 minutes. After that, the films were annealed at two different temperatures, 180 ºC and 500 °C, for 45 minutes in N2/H2S atmosphere. Based on X-ray diffraction analysis, the polycrystalline thin film obtained fall into kesterite crystal phase. This type of crystal was obtained when the CZTS was annealed at 500 °C in H2S/N2 atmosphere. The value of optical band gap energy for the CZTS thin film was 2.2 eV with the film thickness about 1.228–6.366 μm. The sample of CZTS with electrodeposition time of 45 minutes and annealing temperature of 500 °C showed the best result and in conformity with absorber layers criteria for solar cells.
Keyword: semiconductor, ITO glass, CZTS thin film, electrodeposition