Judul: Toleransi genotipe padi (Oryza sativa L.) terhadap cekaman rendaman sesaat dan rendaman stagnan
Abstrak: Flood is one of abiotic stress limiting rice production especially at rainfed area in wet season or at basin swampy area. The major constraint of rice cultivation in the flood-prone area is lack of tolerant varieties. The objectives of this research were to evaluate the tolerant level of several rice genotypes and reveal the mechanism of submergence tolerance in rice and to obtain rapid screening method. Green house experiment was conduct to screening rice genotypes under flash flooding condition. This experiment was conducted at Muara Experimental Station. The experimental design used was randomized complete design with three replication. There were four sub-experiment, grouping based on seedling age (10 days and 35 days) and duration of submergence (10 days and 14 days). Those sub-experiment in the green house correlated with experiment in the field. The Flash Flooding Experiment was conducted at Muara Experimental Farm of Indonesian Center of Rice Research, Bogor in wet season 2011/2012 and dry season 2012, while the Stagnant Flooding Experiment was conducted at Babakan Experimental Farm of Bogor Agricultural University in wet season 2011/2012. In both experiments, stress conditions were compared to optimum environment. Experimental design was randomized complete block design with three replications. For flash flooding stress, 35-day-old plants of 15 rice genotypes were submerged completely in water for 10 days. For stagnant flooding stress, 35-day-old of 22 rice genotypes plants were partially submerged in water (water depth 50-60 cm) until harvest. The result showed that B13138-7-MR-2-KA-1 genotype was tolerant to flash flooding stress. Rice genotypes tolerant to flash flooding stress (complete submergence) experienced reduced growth rate of plant height and maintained the carbohydrate content in rice stem remain unchange after stress period. Percentage of recovery after 10 days stress could be used as early selection indicator to flash flooding stress since it was easy to observed and had high correlation with grain yield. Stagnant flooding stress increased plant height, increased stem length, lengthen flowering and maturity date and increase the number of unfilled grain. Stem elongation ability didn’t correlate with grain yield under stagnant flooding stress condition (r=-0.29), but the number of filled grain has positive significant correlation to grain yield under both flooding stress condition. Genotype IPB107F-5-1-1 (5.47 t/ha) and IPB107-F-95-1-1 (4.61 t/ha) showed grain yield decrease less than 10% under stagnant flooding compared to flash flooding and optimum condition. None of the twelve genotypes has double tolerance under flash and stagnant flooding conditions, but B13138-7-MR-2-KA-2 had moderate grain yield under both flooding conditions, 3.61 t/ha and 3.72 t/ha respectively. This genotype can be developed as variety for longer flash flooding period (e.g. more than two weeks). Complete submergence at 10-day-old seedlings in green house could be developed as rapid screening method of rice tolerant to flash flooding stress.
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Judul: Seleksi padi hibrida terhadap kekeringan untuk pengembangan di lahan sawah tadah hujan
Abstrak: The objective of the research was to determine method and character for early selection of rice to drought and to obtain drought tolerant hybrid rice genotypes to be used further in rainfed lowland. Experiments were conducted from April 2011 until July 2012 at Seed Science and Technology Laboratory, IPB and BB Biogen greenhouse Cimanggu, Bogor, at Babakan Experiment Station, IPB, Bogor, and at irrigated lowland, Cikembar, Sukabumi, and rainfed lowland, Gantar, Indramayu. The study consisted of seven experiments. The results showed that: (1) Polyethylene glycol (PEG) 6000 could detect and differentiate the response of hybrid rice genotypes to drought stress in both germination and seedling stage. The use of 25% PEG 6000 in the seedling stage could detect early hybrid rice genotypes tolerant to drought and have a compatibility with grouping of genotypes tolerant to drought based on yield criteria in the field. Variables of root dry weight, shoot dry weight and leaf dryness score were to detect hybrid rice genotypes tolerant to drought at seedling stage. (2) Genotypes BI485A/BP12, BI485A/BP15 and BI559A/BP15 under drought stress conditions decreased root length less (17.6 - 26.9 percent) than the IR64, the sensitive check variety (33.6 percent). Their grain weight, harvest index and grain yield (2.82, 2.58 and 2.72 ton ha-1) were higher than other genotypes. Moreover they were earlier to harvest, shorter in grain filling period and had sensitivity index to drought ≤ 0.50. Hybrid genotype tolerant to drought i.e BI599/BP15 under drought stress conditions had less stomatal density, maintained higher leaf relative water content, and contained non-structural carbohydrates in stem, sheath and leaf less than other genotypes. Genotypes BI485A/BP12, BI485A/BP15 and BI559A/BP15 were tolerant to drought and potentially could be developed for rainfed lowland; (3) The yield of these genotypes under irrigated lowland were not significantly different from those of Ciherang and Hipa 7 (i.e. 5.63, 6.87 and 6.30 ton grain ha-1, respectively). BI599A/BP15 genotypes under severe drought at rainfed lowland yielded 0.90 ton grain ha-1, whereas Hipa 7 and Limboto reached 0.34 and 0.29 ton grain ha-1, respectively.
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Judul: Pelabelan Super Vertex Magic
Abstrak: Super vertex magic labeling is labeling on graph with is a set of edges mapped into and is a set of vertices mapped into . It has a vertex magic labeling in which and represents the size and order of the graph respectively. This manuscript proves that paths, cyclics, and disjoint union of cyclics have a super vertex magic labeling. There are four theorems to be discussed. The first theorem proves that path is super vertex magic if and only if is odd and . The second theorem proves that cyclic is super vertex magic if and only if is odd. The third theorem proves that bijection function from an edge set onto of graph can be extended to a super vertex magic labeling if and only if the set amount of edge label that incidents with a vertex in the graph, consists of sequential integers as many as vertices in the graph. The fourth theorem proves that disjoint union of the cyclics consists of cyclics with each cyclic has vertices is super vertex magic if and only if and are odd.
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