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: Morphological and physiological study for drought tolerance in rice (Oryza sativa L.) line
Abstrak: Rice (Oryza sativa L.) is one important source of food, since rice is the staple food of the majority of the people in Indonesia. Increased demand for rice due to the rapid population growth was not met by the slower increase of rice production in Indonesia. Increasing rice production every years, can not compensate for the basic needs population in Indonesia. In addition, an increase in atmospheric temperature is expected to greatly affect of climate global world. Such as the possibility of increasing the frequency and level of drought, this situation can affects the growth and decline in rice production. Drought is a major constrain to increase rice production and it is more prominent with the atmospheric temperature and climate change. Selection for drought tolerant lines and understanding the tolerance mechanism were needed to develop drought tolerant rice variety. A research was conducted in the green house of Cikabayan, University Farm, IPB, during May to September 2010, aimed to study the morphological and physiological aspects related to drought tolerance in rice and to identify drought tolerant lines. A split-Plot Design in a randomized complete block design was applied to a pot experiment with two factor treatments of drought stresses as the main plots and rice lines as the suplots. The drought stress treatment were no drought P1 where the standing water was maintained at 2.5 cm depth and with drought stress P2 where irrigation to 2.5 cm water depth was applied when the soil water potential reaching ≤ - 32 kPa. The line treatments including 100 rice lines obtained from the Indonesian Center for Rice Research (ICRR). Ten rice seeds were sowed on the pots filled with soil media up to 4 cm below the top pot surface. Three healthy and uniform seedlings were maintained in each pots by discarding the others at 3 weeks after sowing. Fertilizers; Urea, TSP, and KCL, were applied rating (2.5 g/pot, respectively). Analysis for prolin and relative water content (RWC) in leaf were done in Molecular marker and Spectrophotometry UV-VIS laboratory, IPB. Analysis chlorophyll content and stomatal density in Micro technique laboratory, IPB. The results of this study indicated that in drought stress treatment, drought tolerant lines exhibit morphological characteristics of broader leaves, more tillers, shorter canopies, and heavier dry canopy weights; and physiological characteristics of higher relative water content (RWC) of leaves as well as higher content of prolin and chlorophyll b. Eighteen drought tolerant lines were identified based on less dry weight reduction by the drought treatment among which B11599D-TB-2-24, B11629C-MR-1-2-1, B11598C-TB-4-1-1 were the most tolerant.
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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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