[en] Seeds of Pelita I/1 rice variety were irradiated with 20, 30, 40 and 50 krad of gamma rays from a ⁶⁰Co source. Plants of M₃ lines were inoculated with bacterial leaf blight, Xanthomonas oryzae (Uzeda and Ishiyama) Downson, using clipping method. The coefficient of genetic variability of resistance against leaf blight disease increased with increasing dose. Highly significant difference in the genetic variance of resistance were found between the treated samples and the control. Dose of 20 krad gave good probability for selection of plants resistant against leaf blight disease. (author)

[en] The use of a complete thermoluminescens dosemeter in radiological diagnostic is presented. The techniques of preparation, grouping, annealing, calibration and characteristics of the dosemeter's reproducibility and fading are also given. It is also given the use of the TLD-100 in radioloaical diagnostic and the dose evaluation method. It has been obtained an accuracy of the grouping system of the TLD-100 to radiation in less than 4% and its reporroducibility in less than 6% at 95% confidence level. The speed of fading is 1% per month. (author)

[en] The experiment of mating efficiency of normal and gamma irradiated male population of Medan (M), Jakarta (J) and Kupang (K) was calculated when they were mated to their respective normal females or to females of different populations. The criterium used was the degree of failure in the egg-hatch. As males, irradiated M, when mated to normal females of M, K, and J, showed comparable results in their LD₅₀ and LD₁₀₀ values, which indicated that there were no differences in the responses of M, K, and J normal females to irradiated M males. Matings between irradiated males of K and J and their respective normal females compared to that between irradiated M males and K and J females (KK vs MK, JJ vs MJ) revealed, viewed from their respective LD₅₀ and LD₁₀₀ values, that M and J males were inferior to K males. Complete failure of egg-hatch was achieved at radiation doses between 9 and 10 krad, while 50 percent egg-hatch took place at doses of 5 krad and slightly below. (author)

[en] The resistance was assessed uased on the feeding activities of the insect on 15-day old seedling of six test varietes namely TN 1, Asahan, Brantas, Citarum, Serayu and Mudgo. A level of 175 μCi per seedling appeared to give sufficiently high absorption of radiophosphorus by the brown planthoppers. The level of radioactivity in the brown planthopper fed for 24 hours on labelled rice plants appeared to be correlated with the susceptibility of the rice plant to brown planthopper. The radioactivity in the honeydew of those hoppers was less correlated with the rice susceptibility. The promising resistance screening method using P-32 tracer is thus more reliable when the radioactivity is detected in the insect rather than in the honeydew. (author)

[en] An experiment has been done with several irradiation methods to determine the sensitivity of bacteria against gamma rays. For this purpose the bacteria were irradiated with ⁶⁰Co gamma radiation with doses of 0, 0.1, 0.2 and 0.3 kGy from a multipurpose panoramic batch irradiator (PANBIT), and then grown on the surface of TGY agar. The results indicated that irradiation with oxygen but without ice gave the best lethal effect. Irradiation showed a significant effect on the ability of bacteria to multiply, and the sensitivity of the bacteria depended on its respective generation time. (author)

[en] Isolation of thiobacillus ferrooxidans (T. ferrooxidans) and thiobacillus thiooxidans (T. thiooxidans) from West Kalimantan and North Sumatera U ore specimens have been carried out. T. thiooxidans have the ability to oxidize sulfur to sulfate, and T. ferrooxidans oxidizes ferro iron to ferric iron. Silverman medium (9 K medium) was used as growth medium for T. ferrooxidans. Starkey medium was used as growth medium for T. thiooxidans. For fungi contamination test the medium of malt extract agar was used. Meat pepton was used for the heterotrophic microorganisms contamination test. Results of the experiment showed that isolates of T. ferrooxidans have been obtained from 3 West Kalimantan U ore specimens from 2 North Sumatera U ore specimens. T. thiooxidans have been isolated from 2 West Kalimantan U ore specimens, but none has been isolated from North Sumatera U ore specimens. T. ferrooxidans isolated from West Kalimantan and North Sumatera have been tested in different growth conditions to determine the rate of growth. (author)

[en] Most of active rock samples from Lampung are granites and pegmatite granites. Result of petrographic studies are given, followed by a discussion stressed on their compositions related to their radioactivities. (author)

[en] A significat correlation (r=0.8774) was found between fertility and mating competitiveness of crocidolomia binotalis zell. The lower fertility of insects, the less their mating competitiveness became. (author)

[en] Linear absorption coefficient of materials for penetrating light depend on its energy. γ-ray which is emitted by radioactive materials, the linear absorption coefficient for penetrating material can be found from its table. In the case of x-ray, it cannot be decided easily, because x-ray is not monoenergitic. In this investigation radiographic method is applied to determine the practical value of the linear absorption coefficient for an x-ray instrument, by using film detector. Type of this film is Structurix Industrex-C, which is manufactured by KODAK. The results showed that the values of practical linear absorption coefficient depend on the voltage difference of its anode and cathode, i.e. the smaller of the voltage difference, the bigger is the value of the practical linear absorption coefficient. The connection between the voltage difference (KV) and the value of the practical linear absorption coefficient (μ) of an x-ray instrument for certain materials, represent the characteristics of the x-ray instrument. (author)

[en] An experiment on the study of nitrogen fertilizer application to IR-32 rice variety was carried out on the organic soil of the tidal swamp at the Test Farm P4S-ITB Delta Upang, South Sumatra. ¹⁵N labelled urea was used as nitrogen source with a dose rate of 100 kg N/ha applied as a single dose, two-split and four-split doses. It was observed that in general nitrogen fertilizer could increase the yield of rough grain up to 20% over that of the control. However, these yield increases were statistically not significant. The highest yield of about 4.82 tons per hectare was derived from a treatment of two-split doses of (25+75) kg N/ha, which was applied at transplanting and the midpoint in between 21 days after transplanting and the initial primordium respectively. The efficiency of nitrogen fertilizer utilization by IR-32 rice variety was in the range of 18-35 percent, which with the highest efficiency indicated by a four-split doses of (25+25+25+25) kg N/ha, while the lowest one obtained from a single dose application at transplanting. It seems that the highest efficiency does not correspond to the highest yield of rough grain. (author)