Judul: Potensi Kitosan dan Agens Antagonis dalam Pengendalian Penyakit Karat (Phakopsora pachyrhizi Syd.) Kedelai
Abstrak: Penyakit karat (Phakopsora pachyrhizi Syd.) merupakan penyakit utama pada tanaman kedelai yang mampu menurunkan produksi hingga 90%. Kemampuan penyebaran inokulum yang cepat, adanya inang alternatif, dan potensi yang tinggi untuk melakukan perubahan yang mengatur virulensi P.pachyrhizi mengondisikan penyakit ini sulit dikendalikan. Studi ini bertujuan untuk mengevaluasi potensi kitosan, Trichoderma harzianum, Bacillus subtilis, dan kombinasi kitosan dengan Streptomyces sp. pada dua galur kedelai. Percobaan dilakukan menggunakan rancangan faktorial acak lengkap (4x2) dengan 3 ulangan. Peubah yang diamati adalah perkembangan tanaman, kejadian penyakit, dan keparahan penyakit karat. Hasil penelitian menunjukkan bahwa perlakuan T.harzianum, B.subtilis, dan kitosan kombinasi kitosan dengan Streptomyces sp. efektif memiliki keparahan penyakit penyakit yang lebih rendah daripada kontrol pada kedua galur kedelai. Perlakuan T.harzianum merupakan taktik pengendalian yang paling efektif dan efisien menghambat penyakit karat dan meningkatkan pertumbuhan vegetatif tanaman tanpa menimbulkan fitotoksik.
Keyword: B.subtilis, chitosan, rust disease, Streptomyces sp., T.harzianum.

Judul: Potensi Kitosan dan Agens Antagonis dalam Pengendalian Penyakit Karat (Phakopsora pachyrhizi Syd.) Kedelai
Abstrak: The soybean rust disease (Phakopsora pachyrhizi Syd.) is the most important disease of soybean and may cause 90% yield loss. The ability to spread rapidly, present of alternative hosts, and the rapid changes of P.pachyrhizi virulence are the causal of the difficulty to control the disease. This study is to evaluate potential uses of chitosan, Trichoderma harzianum, Bacillus subtilis, and chitosan-Streptomyces sp. combination to control the rust disease in two soybean lines. The experiments were conducted using a complete randomized factorial design (4x2) with three replications. Plant developments, disease incidence and severity of rust infection were observed. The studies have shown that all treatments have significantly suppressed soybean rust disease incidence and severity in both soybean lines compared to that of control. The use of T.harzianum has found the most effective and efficient in suppressing disease severity and in increasing plant vegetative growth with no phytotoxic effect.
Keyword: T.harzianum., Streptomyces sp, rust disease, chitosan, B.subtilis

Judul: Penggunaan Teorema Homeomorphy 2-Manifold dan Teorema Euler Poincare pada Torus 𝑇�� dan Simplicial Complex 𝐾��
Abstrak: Two dimensional topological spaces are said to be homeomorphic if they have the same topological invariant, where one of topological invariant used is an Euler characteristic. Homeomorphy 2-Manifold’s Theorem and Euler Poincare’s Theorem are used to distinguish two topological spaces. Homeomorphy 2-Manifold’s Theorem uses Euler characteristic to identify two dimensional topological spaces. Euler Poincare’s Theorem is an alternative way to find Euler characteristic with Betti number, which is topological invariant as well. The objective of this paper is to investigate the homeomorphism of torus 𝑇����� and simplicial complex 𝐾�����. Topological space torus and simplicial complex 𝐾����� have the same Euler characteristic, which is two. Based on Homeomorphy 2-Manifold’s Theorem topological space torus 𝑇����� and simplicial complex 𝐾����� is homeomorphic.
Keyword: simplicial, torus, Euler, homeomorphism, topology