Nitrogenase Activity and IAA Production of Indigenous Diazotroph and Its Effect on Rice Seedling Growth

The diazotroph bacteria as ecofriendly biofer-tilizers play an important role in improving the N status and availability of paddy soil. Laboratory experiment to study nitrogenase activity and IAA production of diazotroph from rice rhizosphere and to assess its effect on the growth of rice seedling has been conducted from September to October 2014 in Agronomy and Horticulture Laboratory Faculty of Agriculture Jenderal Soedirman University, Purwokerto. The experiment was arranged as a completely randomized design and consisted of seven treatments and provided with 4 replications. The treatments were the isolates of indegenous diazotroph (T1 = A11003, T2 = A230041, T3 = A24001, T4 = A230022, T5 = A230021, T6 = A230042 and T7 = without inoculation). The nitrogenase activity measured by acetylene reduction assay method and IAA production was measured by HPLC method. Plant height, leaf greeness, leaf area, total dry weight and total root length were determined on 21 days after sowing. The experimental results showed that the isolat A230021 was identified as Rhizobium sp. LM-5 and have the highest nitrogenase activity at 0.07 µM C2H4 ml-1 h-1 and IAA production reached 19.01 ppm. Inoculation with strains of diazotroph enhanced chlorophyl content, total root length, and biomass production

Adaptation Behavior of Mango Farmers to Climate Change

The continuing climate change phenomenon causes disruption to agricultural sector including seasonal fruits such as mangoes. To anticipate the negative effects of climate change, the farmers adapt themselves in order to maintain their mango farming. The dynamics of mango farmers related to the adaptation of agribusiness strategy due to climate change occur at the level of production/cultivation and marketing. The objectives of this study are to: (1) Identify the factors that influence the behavior of mango farmers' adaptation as an effort to minimize the risks due to climate change; (2) Describe the adaptation behavior of mango farmers based on interactions among the factors that influence the adaptation by using causal loop diagrams. The results showed that the adaptation behavior of mango farmers was constructed on 37 variables from 8 categories, namely, climate change, production, marketing, income, financing, productivity, information adoption, and innovation. Adaptation behavior of mango farmers to climate change arises not only as the farmers' effort to maintain the mango farming they run but also to maintain their lives. The use of growth regulator and pesticides are shortcuts taken by farmers to increase production without realizing the side effects that can arise and accumulate in the long term. The income variable is the leverage point of the behavior pattern that is reflected in the causal loop diagram. Small changes in income will cause major changes in the overall system described

Pengaruh Mutagen Etil Metan Sulfonat Terhadap Regenerasi Tunas Pada Dua Genotip Manggis Asal Purwakarta Dan Pandeglang

Tanaman manggis termasuk tanaman apomik. Pemuliaan mutasi dapat meningkatkan keragaman genetik pada tanaman manggis. Penelitian bertujuan mengetahui pengaruh pembentukan tunas dua genotip manggis akibat perlakuan beberapa konsentrasi etil metan sulfonat (EMS) yang berbeda. Percobaan dilakukan di Laboratorium Kultur Jaringan Pemuliaan Tanaman, Fakultas Pertanian, Universitas Padjadjaran sejak bulan September 2012 – Februari 2013. Eksplan manggis yang digunakan adalah biji manggis asal Purwakarta (A) dan Pandeglang (B). Percobaan ditata dalam rancangan acak lengkap (RAL). Konsentrasi EMS terdiri atas 0; 0,05; 0,1; 0,15; dan 0,2% digunakan sebagai perlakuan. Hasil penelitian menunjukkan bahwa regenerasi tunas pada eksplan dua genotip asal Purwakarta dan Pandeglang memiliki respons yang berbeda akibat perlakuan mutagen EMS. Pada perlakuan a3 (genotip asal Purwakarta pada EMS 0,1%) menghasilkan waktu muncul tunas lebih cepat dan jumlah tunas per eksplan paling tinggi, sedangkan perlakuan b4(genotip asal Pandeglang pada perlakuan EMS 0,15%) memiliki nilai paling tinggi pada karakter tinggi tunas. Perlakuan a5(genotip asal Purwakarta pada EMS 0,2 %) merupakan perlakuan paling baik pada karakter jumlah pasang dau

PENINGKATAN KUALITAS HASIL UBI TIGA VARIETAS KENTANG MELALUI APLIKASI PAKLOBUTRAZOL DI DUA DATARAN MEDIUM

AbstractResearch aimed to know increase of quality of tuber yield due to packlobutrazol aplication in two medium altitude, was conducted in experimental station of Faculty of agriculture, Unpad, Jatinangor (760 asl) and Farmer land, Pasir Leungit (320 dpl), started from March until October 2011. Experiment was arranged in a randomized block design factorial pattern with two factors and replicated three times. First factor was cultivars namely 'GM08', 'Margahayu', and 'Atlantik', whereas second factors was four levels of packlobutrazol namely pure water, 30 mg, 60mg, and 90mg. Such experiments was conducted in two location with same design. Variables observed were starch content, dry matter content, specific gravity, and reducing sugar content.Results showed that there were interaction effect between cultivars and location on dry matter content, specific gravity, and reducing sugar content. Significant interaction effect between cultivars and packlobutazol was shown on specific gravity. Aplication of 60 mg packlobutrazol had given best quality of tuber yield of processing potato.Keywords: medium altitude, potato, tuber quality, packlobutrazol, processin