INDONESIAN JOURNAL OF AGRICULTURAL SCIENCE

43-53

Authors: Ika Roostika, Nurul Khumaida, Ika Mariska, and Gustaaf Adolf Wattimena

Smooth Cayenne is the largest pineapple type cultivated in Indonesia, but its vegetative planting materials for mass propagation are limited. Somatic embryogenesis is a potential method to be applied. The aim of this study was to investigate the somatic embryogenesis regeneration under the effect of picloram and light. Callus formation was induced by picloram (21, 41 and 62 mM) added with 9 mM thidiazuron. The calli were transferred onto MS or Bac medium enriched with N-organic compounds with or without addition of 21 mM picloram under dark or light condition. The compact calli were subcultured onto MS medium supplemented with 4.65 mM kinetin, while the friable calli were transferred onto BIG medium (modified MS + 1.1 mM benzyl adenine + 0.9 mM indole butyric acid + 0.09 mM giberelic acid) or B medium (MS + 0.018 mM benzyl adenine). The results showed that the events of somatic embryogenesis were started from cell polarization, asymmetrical division, proembryo formation as embryogenic tissues and friable embryogenic tissues, and embryo development. The best treatment for callus induction was 21 mM picloram. The addition of 21 mM picloram on N-organic enriched medium and the use of light condition proliferated embryogenic calli. The N-organic enriched Bac medium and light condition yielded the highest number of mature somatic embryos (17 embryos per explant in 2 months). The B medium was better than BIG medium to develop somatic embryos from friable embryogenic tissues. The somatic embryogenesis method presented is potential for pineapple mass propagation and artificial seed production.

68-79

Authors: Made Oka A. Manikmas

Farmers are rational in decision making process with respect to any introduced agricultural technology. Farmers may consider the economic sacrifices in term of additional cost and potential benefit or additional income before they accept and adopt the introduced technology. This study aimed to analyze farmer’s criteria and determine explanatory variables affecting farmer’s decision to accept or to adopt submergence tolerant (Sub-1) rice varieties at flash flood and flood prone affected rice area. The study was conducted in Indramayu District, West Java, and Kayu Agung District, South Sumatra. Contingent Valuation Method (CVM) that derived Willingness to Accept (WTA) approach was exercised to analyze explanatory variables that influence farmers’ willingness to accept introduced rice varieties. The results showed that the economic cost of flooding that damaged rice was about US$7.63 million in Kayu Agung and US$11.25 million in Indramayu in every wet season planting. Farmer’s criteria used in submergence tolerant varietal evaluation varied and location specific in nature. Most of explanatory variables used in the model were significantly influenced farmers’ WTA for submergence tolerant rice varieties such as: (1) availability of seed, (2) submergence tolerant for more than 14 days, (3) high yield, (4) proffer rice taste, (5) households’ income during normal year, (6) area planted during normal year, and (7) age of farm household head. The only indicator that did not significantly influence the farmers’ WTA for the Sub-1 rice varieties was farm household income during the flood year cropping.

86-95

Authors: Rita Harni, Supramana, and Supriadi

Pratylenchus brachyurus is an important parasitic nematode which significantly decreases quality and quantity of patchouli oil. One potential measure for controlling the nematode is by using endophytic bacteria. These bacteria also induce plant growth. This study aimed to evaluate the potential of endo-phytic bacteria to control P. brachyurus. The experiments were carried out in the Bacteriological Laboratory of the Plant Protection Department, Bogor Agricultural University, and the Laboratory and Greenhouse of the Indonesian Spice and Medicinal Crops Research Institute from April to December 2007. Endophytic bacteria were isolated from the roots of patchouli plants sampled from various locations in West Java. Antagonistic activity of the isolates were selected against P. brachyurus and their abilities to induce plant growth of patch-ouli plants. Isolates having ability to control P. brachyurus and promote plant growth were identified by molecular techniques using 16S rRNA universal primers. The results showed that a total of 257 isolates of endophytic bacteria were obtained from patchouli roots and their population density varied from 2.3 x 102 to 6.0 x 105 cfu g-1 fresh root. As many as 60 isolates (23.34%) were antagonistic against P. brachyurus causing 70-100% mortality of the namatode, 72 isolates (28.01%) stimu-lated plant growth, 32 isolates (12.47%) inhibited plant growth, and 93 isolates (36.18%) were neutral. Based on their antago-nistic and plant growth enhancer characters, five isolates of the bacteria, namely Achromobacter xylosoxidans TT2, Alcaligenes faecalis NJ16, Pseudomonas putida EH11, Bacillus cereus MSK, and Bacillus subtilis NJ57 suppressed 74.0-81.6% nema-tode population and increased 46.97-86.79% plant growth. The study implies that the endophytic bacteria isolated from patchouly roots are good candidates for controlling P. brachyurus on patchouly plants.

1-11

Authors: A. Wihardjakaa, S. Djalal Tandjungb, B. Hendro Sunarmintoc, and Eko Sugiharto

Incorporation of rice straw into soil is a common practice to improve soil productivity and increase inorganic fertilizer availability. However, this practice could contribute to methane (CH4) emission; one of the greenhouse gases that causes global warming. Nitrification inhibitors such as neem cake and carbofuran may reduce methane emission following application of rice straw. The study aimed to evaluate the application of rice straw and nitrification inhibitor to methane emission in rainfed lowland rice system. A factorial randomized block design was used with three replications. The first factor was rice straw incorporation (5 t ha-1 fresh straw, 5 t ha-1 composted straw), and the second factor was nitrification inhibitor application (20 kg ha-1 neem cake, 20 kg ha-1 carbofuran). The experiment was conducted at rainfed lowland in Pati, Central Java, during 2009/2010 wet season. Ciherang variety was planted as direct seeded rice with spacing of 20 cm x 20 cm in each plot of 4 m x 5 m. The rice straw was treated together with soil tillage, whereas nitrification inhibitor was applied together with urea application. Parameters observed were methane flux, plant height, plant biomass, grain yield, organic C content, and bacterial population in soil. The methane flux and soil organic C were measured at 25, 45, 60, 75, and 95 days after emergence. The results showed that composted rice straw incorporation significantly emitted methane lower (73.2 ± 6.6 kg CH4 ha-1 season-1) compared to the fresh rice straw (93.5 ± 4.0 CH4 ha-1 season-1). Application of nitrification inhibitors neem cake and carbofuran reduced methane emission as much as 20.7 and 15.4 kg CH4 ha-1 season-1, respectively. Under direct seeded rice system, methane flux level correlated with plant biomass as shown by linear regression of Y = 0.0015 X + 0.0575 (R2 = 0.2305, n = 27). This means that higher plant biomass produced more methane flux. The study indicates that application of nitrification inhibitors such as neem cake is prospective in decreasing methane emission from direct seeded rice cropping.

18-26

Authors: W. Setiawati, N. Gunaeni, T.S. Uhan, and A. Hasyim

Bemisia tabaci (Genn.) (Homoptera: Aleyrodidae) is one of the most serious pests on tomato. It is mainly controlled by chemical means, requiring some 25 sprays during the average growing season. The extensive and repeated use of insecticides has disrupted the natural balance between this pest and its natural enemies. In this study, Menochilus sexmaculatus F. was evaluated as a possible biological control agent of B. tabaci and its effect on gemini virus infestation. The study was conducted at the experimental station of the Indonesian Vegetables Research Institute (IVeGRI) in Lembang, West Java (1,250 m above sea level) from August to December 2008. The experimental plots consisted of 0.35 ha of tomato (± 100 m2 per plot) and spatially separated with four rows of maize (a minimum of 1 m) interplot distance to prevent cross-contamination among plots. The experiment was arranged in completely randomized block design with eight treatments and four replications. M. sexmaculatus were released at 24 days after planting. The treatments were designed according dosages and schedules at three released populations (i.e. 10 predators per plot, 20 predators per plot, and 10 predators per plot at vegetative stage followed by 20 predators per plot at generative stage); two places of release (center and edge of the plot); and two schedules of release (weekly and biweekly). Efficacy of the predator was measured in terms of the density of B. tabaci, both before and after release of the predator and its effect on gemini virus infestation. The result indicated the potential use of M. sexmaculatus to control B. tabaci and its effect on gemini virus infestation on tomato. Reductions in B. tabaci populations and subsequent tomato yields were significant. B. tabaci population in plots receiving 10 predators showed 73.62% and 75.75% reductions by the end of experiment. The incidence and intensity of gemini virus were consistently and significantly lowest and tomato yield gain was observed when 10 predators were released at weekly intervals. It is suggested that release of M. sexmaculatus against B. tabaci on tomato may be offered as an alternative solution to increase implementation of biologically-based B. tabaci management.

35-42

Authors: Dewa Ketut Sadra Swastika

Drying is a critical activity in rice postharvest handling. Any delay in drying will result in quality and quantity losses. Farmers and traders prefer to sell wet grain rather than dried grain of unhulled rice due to less attractive incentive for them to do drying. The study was conducted in Subang District, West Java, during March-June 2011 using survey method to analyze the financial feasibility of rice dryers. The respondents interviewed were 15 rice millers who have either sun-drying floor or mechanical dryer, or both. The main collected data were the investment cost, operational cost, maintenance cost, and the revenue of the dryers. The data were analyzed by using shortterm and long-term financial analyses to assess the profitability and feasibility of some drying technologies. The results showed that there were at least three drying technologies in the study area, namely sun-drying floor, flatbed dryer using gas fuel (gas dryer), and flatbed dryer using rice husk fuel (husk dryer). Under the mean capacity, the short-run MBCR of technological change from sun dryer to gas dryer was 1.29, while from sun dryer to husk dryer was 1.45. The long-run analysis showed that the IRRs were 44.44% for sun dryer, 233.47% for gas dryer, and 260.49% for husk dryer. These results showed that among the three drying technologies, husk dryer is the most profitable, most feasible, and most prospective to be adopted. Therefore, this type of dryer should be intensively promoted to the farmers’ group associations, rice traders, and rice millers. The government support in terms of rice dryers for farmers’ group associations should be focused on husk dryer.