EFFECTS OF SELECTIVE HERBICIDE, ATRAZINE ON THE RHIZOBIUM POPULATION AND NODULATION OF GROUNDNUT (ARACHIS HYPOGEAE)

Atrazine is a selective herbicide used to control weeds in farm operations. The effect of different concentrations of atrazine on Rhizobium population and nodulation in groundnut (Arachis hypogeae) was investigated using Yeast Extract Mannitol Agar (YEMA). The test crop was planted for 90 days after the soil was treated with the various concentration of atrazine. The following parameters; Rhizobium count, nodule count, plant height and germination percentage were observed. The total Rhizobium count obtained at 0% atrazine treatment has 3.0 x 108, 0.1% has 2.9 x 108, 0.5% has 2.5 x 108, 1% has 2.0 x 108, and 3% has 1.4 x 108 all in cfu/ml while the number of root nodules formed was also counted after uproot which was; 0% atrazine treated has 50 nodules, 0.1% has 50 nodules, 0.5% has 30 nodules, 1% has 23 nodules and 3% has 19 nodules. The study revealed that the higher the atrazine concentration the lower the population of Rhizobium, the numbers of root nodules increased with decrease in atrazine concentration and Plant height, root length and germination percentage was also affected adversely by increased in atrazine concentrations.

VIABILITAS RHIZOBIUM DALAM FORMULA BAHAN PEMBAWA DAN CARA INOKULASI DALAM TEKNIK PRODUKSI MASSAL PUPUK HAYATI

ABSTRAKTanaman kedelai dapat memfiksasi nitrogen dengan bantuan bakteri bintil akar yaitu bakteri Rhizobium sp. Pemanfaatan Rhizobium sp sebagai inokulan pupuk hayati sangat mendukungpeningkatan produktivitas kedelai. Inokulasi biji kedelai dengan Rhizobium spdapat membantu penyediaan N tanah untuk kedelai. Formula pupuk hayati yang terdiri atas 6 konsorsia isolat Rhizobium sp telah diuji di beberapa lokasi pada tanah masam menunjukkan hasil yang positif, sehingga untuk pengembangannya perlu dilakukan “produksi massal”. Penelitian teknik produksi massal dilakukan di “Pilot Plant Produksi Pupuk Hayati” Balai Penelitian Tanah di Bogor. Penelitian disusun dengan rancangan acak lengkap, perlakuan terdiri atas kombinasi antara cara inokulasi dan pengemasan dengan formula bahan pembawa. Perlakuan terdiri atas delapan kombinasi perlakuan diulang tiga kali. Pertumbuhan sp sebelum diinokulasi ke dalam bahan pembawa diamati. Hasil penelitian menunjukkan bahwa isolat Rhizobium sp yang digunakan mempunyai fase pertumbuhan berkisar antara 4–48 jam. Populasi Rhizobium dalamformula pupuk hayati yang diinokulasi ke dalam bahan pembawa Biochar+Gambut mampu mempertahankan populasi Rhizobium tertinggi hingga masa simpan 6 bulan dibandingkan perlakuan lainnya. Populasi Rhizobium pada perlakuan tersebut sebanyak8,13 log CFU.g -1 . Sedangkan populasi inokulan Rhizobium sp dalam pupuk hayati yang diinokulasikan menggunakan mesin injektor dengan bahan pembawa Biochar sebanyak 7,66 log CFU.g -1 .ABSTRACTSoybean plants can fix nitrogen with the help of root nodules bacteria, namely Rhizobium sp. The use of Rhizobium sp as an inoculant of biofertilizers supports to increase the productivity of soybean. Inoculation Rhizobium sp of soybean seeds helps to provide soil N for soybeans. Biofertilizer formula consist of six consortia of Rhizobium sp had been tested in more locations on acid soils showed positive results, so for it’s development for biofertilizer it is necessary to do "mass production", was conducted at the "Biofertilizer Production Plant Pilot" of Indonesian Soil Research Institute. The study was arranged in a completely randomized design, the treatment consist of ways of packaging methods and the carrier formula. The treatment consisted of eight combinations repeated three times. Rhizobium sp growth before inoculation into the carrier was observed. Rhizobium population in the formula of biofertilizer which is inoculated into the Biochar+Peat carrier and then packaged by packaging machine is able to maintain the highest Rhizobium population up to a shelf life of 6 months compared to other treatments,. Rhizobium sp population in this treatment was 8.13 logCFU.g -1 . While the population of Rhizobium sp inoculants in biofertilizers inoculated using an injector with Biochar carrier as much as 7.66 log CFU.g -1.

Peran Eksopolisakarida Azotobacter dan Bahan Organik untuk Meningkatkan Nodulasi dan Biomassa Kedelai pada Dua Ordo Tanah

Exopolysaccharide (EPS) produced by nitrogen-fixing bacteria Azotobacter protect nitrogenase from oxygen. In legume,EPS plays a role in the immobilization of rhizobia to the roots. The objective of this experiment was to study the effect of EPSAzotobacter and organic matter on increasing number of nodules and biomass of soybeans grown in Inceptisols and Ultisols;as well as nitrogen-fixing bacteria population in soybean rhizosphere. The experiment was set up in a completely randomizedblock design with five replications to test combined treatments of two doses of crude EPS and organic matter. Nodule number,shoot dry weight and nitrogen uptake, as well as Azotobacter and Rhizobium population in soybean grown in Inceptisolsfollowing crude EPS and compost application, were higher than those grown in Ultisols. The application of EPS and compostIn Ultisols did not affect the number of nodule and other traits, but in Inceptisols, adding 6.25 g of compost and 20 mL of EPSto each plant increased the number of nodules and shoot weight at 42 days after planting. However, the highest N uptake wasdemonstrated by soybean received 10 mL and 20 mL EPS along with 12.5 g compost.

Influence of fly ash seed pelleting on root rhizosphere populations of black gram and green gram

Investigations were carried out to study the influence of flyash seed pelleting on microbial populations of bacteria, fungi, actinomycetes, and rhizobium in black gram and green gram. The experimental results revealed that seed pelleting with fly ash seed pelleting @ 250 g with rice gruel as adhesive increased rhizobium population in black gram and fungi and actinomyctes population in green gram by 10 to 15 %. Increased microbial activity will enrich soil microflora and in turn will be helpful in increasing the crop yield.

Pertumbuhan Mucuna bracteata DC. pada Berbagai Waktu Inokulasi dan Dosis Inokulan

ABSTRACT<br /><br />Mucuna bracteata DC. is a legume cover crop to prevent erosion and to suppress weed growth. M. bracteata can fix N2 from the air with the help of Rhizobium. M. bracteata get benefit from the symbiosis in the form of increased nodule weight, shoot dry weight, and leaf nitrogen content when the Rhizobium population in the soil is optimal. Application of inoculant is one method to increase the Rhizobium population in the soil. This study aimed to analyze the effects of inoculation times and inoculant rates on M. bracteata growth. The research was conducted in Boyolali, Central Jawa, from February to August 2014. The inoculant contained Bradyrhizobium japonicum and Aeromonas punctata. This experiment was arranged in a randomized block design with two factors and three replications. The first factor was two inoculation times, i.e at the nursery when the seedlings were 2 weeks old and in the field when the seedlings reached 5 weeks old. The second factor was 5 inoculant rates (0, 2, 4, 6, and 8 g per plant). The results showed that inoculation on 5-week-old seedlings was the best result compared to the 2-week-old seedlings. The recommended inoculant rate for Mucuna bracteata was 6.43 g per plant. <br /><br />Keywords: legume cover crop, nitrogenase activity, nodule, nutrient content, runner

Genetic Diversity and Dynamics of Sinorhizobium meliloti Populations Nodulating Different Alfalfa Cultivars in Italian Soils

ABSTRACT We analyzed the genetic diversity of 531 Sinorhizobium meliloti strains isolated from nodules of Medicago sativa cultivars in two different Italian soils during 4 years of plant growth. The isolates were analyzed for DNA polymorphism with the random amplified polymorphic DNA method. The populations showed a high level of genetic polymorphism distributed throughout all the isolates, with 440 different haplotypes. Analysis of molecular variance allowed us to relate the genetic structure of the symbiotic population to various factors, including soil type, alfalfa cultivar, individual plants within a cultivar, and time. Some of these factors significantly affected the genetic structure of the population, and their relative influence changed with time. At the beginning of the experiment, the soil of origin and, even more, the cultivar significantly influenced the distribution of genetic variability of S. meliloti. After 3 years, the rhizobium population was altered; it showed a genetic structure based mainly on differences among plants, while the effects of soil and cultivar were not significant.

EVALUATION OF THE RHIZOBIUM POPULATION OF PIGEONPEA AND COWPEA RHIZOSPHERE AFTER INOCULATION WITH SEVERAL RHIZOBIUM STRAINS

Pigeonpea [Cajanus cajan (L.) Millsp.] and cowpea [Vigna unguiculata (L.) Walp.] seeds were inoculated with broth cultures of Rhizobium strains 3278, 3458, and 3472 at a population of ≈9.5 × 10 g viable cells/ml. They were planted at three air temperature regimes: 20/10C, 30/20C, and 38/25C (day/night), which generated variable rhizosphere temperatures of 17/6C, 26/15C, and 33/20C, respectively. Seeds and/or seedling roots were sampled at 3, 7, 11, and 15 days after planting and Rhizobium survival was enumerated as viable cells on agar media. Only strain 3458 in association with pigeonpea genotype ICPL8304 had a higher population at day 15 than that at the earlier sample dates. The duration of the strains in the rhizosphere, rather than temperature, influenced population changes. No strain showed a consistent increase in cell numbers from inoculation to 15 days after planting. There was no clear pattern of population changes for any strain within or across temperatures, hence it was difficult to identify any strain as having superior growth habits over another.