Judul: Allelopathic Potential of Asystasia gangetica (L.) T.  Anderson from Various Populations on the Growth and Production of Sweet Corn (Zea mays L.)
Abstrak: Asystasia gangetica L. (T.) Anderson merupakan gulma invasif pada lahan perkebunan yang menghasilkan senyawa alelopati. Pengaruh senyawa alelopati A. gangetica terhadap pertumbuhan dan produksi tanaman kelapa sawit menghasilkan masih belum banyak dilaporkan. Penelitian bertujuan mempelajari potensi senyawa alelopati gulma A. gangetica dari berbagai populasi terhadap pertumbuhan dan produksi tanaman uji jagung manis. Penelitian dilakukan pada Maret hingga September 2022 di Agribusiness and Technology Park IPB. Penelitian menggunakan Rancangan Kelompok Lengkap Teracak (RKLT) dengan enam perlakuan dan empat ulangan. Perlakuan yang diuji yaitu populasi gulma A. gangetica 0, 1, 2, 4, 8, dan 16 individu per pot. Satuan percobaan berupa pot berukuran 25 cm – 19 cm (diameter – tinggi) dengan isi media 3 kg. Biji gulma diperoleh dari Kebun Percobaan Leuwikopo IPB. Biji A. gangetica ditanam di pot dan pada umur dua bulan setelah tanam dipotong setinggi 5 cm dari permukaan media. Benih jagung manis ditanam satu minggu setelah pemotongan gulma A. gangetica. Hasil penelitian menunjukkan bahwa perlakuan 16 populasi gulma A. gangetica menekan pertumbuhan jagung manis meliputi tinggi tanaman, panjang daun, lebar daun, jumlah daun, diameter batang, kehijauan warna daun, bobot per tongkol berkelobot dan tanpa kelobot, diameter tongkol, serta derajat kemanisan. Perlakuan populasi gulma A. gangetica tidak mempengaruhi indeks luas daun, panjang tongkol, bobot kering biomassa, bobot kering tajuk dan bobot kering akar saat panen. Populasi gulma A. gangetica yang semakin tinggi terbukti menghasilkan senyawa alelopati yang lebih banyak sehingga menekan pertumbuhan vegetatif dan hasil panen tanaman uji jagung manis.
Keyword: indole-3-carboxaldehyde, secondary metabolites, suppression, weeds

Judul: Allelopathic Potential of Asystasia gangetica (L.) T. Anderson at Various Populations in Suppressing the Growth and Production of Mustard Greens (Brassica juncea L.)
Abstrak: Asystasia gangetica (L.) T. Anderson direkomendasikan sebagai tumbuhan penutup tanah pada tanaman kelapa sawit menghasilkan, namun memiliki senyawa alelopati yang berpotensi menghambat pertumbuhan tanaman. Penelitian bertujuan mengetahui potensi alelopati gulma A. gangetica pada berbagai populasi terhadap pertumbuhan dan produksi caisim. Tanaman caisim digunakan sebagai tanaman uji. Penelitian dilakukan pada Maret hingga Juli 2022 di Agribusiness and Technology Park, IPB. Penelitian ini menggunakan rancangan acak kelompok (RAK) dengan 6 perlakuan dan 4 ulangan. Perlakuan yang diuji yaitu populasi A. gangetica 0, 1, 2, 4, 8, 16 individu per pot. Satuan percobaan berupa pot berukuran 20 cm – 13 cm (diameter – tinggi) dengan isi media tanam 2 kg. Biji A. gangetica ditanam di pot dan pada umur 2 bulan setelah tanaman dipotong setinggi 5 cm dari permukaan media. Caisim ditanam satu minggu setelah pemotongan gulma A. gangetica. Hasil penelitian menunjukkan bahwa perlakuan populasi 1 sampai 16 gulma A. gangetica per pot menekan pertumbuhan vegetatif tanaman caisim. Produksi segar, produksi kering, bobot basah akar, dan bobot kering akar pada perlakuan populasi 16 gulma A. gangetica berturut-turut berkurang sebesar 54,9%, 55,5%, 60,5% dan 54,2% terhadap kontrol. Perlakuan populasi gulma A. gangetica tidak mempengaruhi warna dan kandungan klorofil daun saat panen., Asystasia gangetica (L.) T. Anderson is recommended as a ground cover for mature oil palms, but has allelopathic compounds that have the potential to inhibit plant growth. The aim of the research was to study allelopathic potential of A. gangetica in various populations on the growth and production of mustard greens. Mustard greens was used as a test plant. The research was conducted from March to July 2022 at the Agribusiness and Technology Park, IPB. This study used a randomized complete block design (RCBD) with 6 treatments and 4 replications. The tested treatment i.e. A. gangetica 0, 1, 2, 4, 8, 16 individuals per pot. The experimental unit was a pot measured 20 cm – 13 cm (diameter – height) with 2 kg of media content. A. gangetica seeds were planted in pots and at the age of 2 months after the plants were cut to a height of 5 cm from the surface of the media. Mustard greens was planted one week after A. gangetica was cut. The results showed that the treatment of populations of 1 to 16 A. gangetica per pot suppressed the vegetative growth of mustard greens. Production fresh weight, production dry weight, root fresh weight, and root dry weight in the treatment population of 16 of A. gangetica reduced by 54.9%, 55.5%, 60.5% and 54.2% respectively, compared with control. The A. gangetica populations treatment did not affect the color and chlorophyll content of the leaves at harvest.
Keyword: competition, HPLC, indole-3-carboxaldehyde, secondary metabolites

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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