This study was conducted to evaluatethe nitrogen use efficiency and 13C isotope discrimination of rice mutant lines viz.NMR151 and NMR152. Both cultivars are developed under rice radiation mutagenesis programme for adaptability to aerobic conditions. In the present study, NMR151 and NMR152 were grown under conditions of varying water potentials and nitrogen levels in a shade house. The rice mutant lines were planted on sandy loam soil. Three watering regimes and three nitrogen levels in a completely randomized design with three replications were carried out. The rice mutants were grown for 110 days under three water potentials, (i) Field capacity from 0 to 40 DAS and saturated from 41 to 110 DAS [ST], (ii) Field capacity from 0 to 110 DAS [FC], and (iii) Field capacity from 0 to 40 DAS and 70% of field capacity from 41 to 110 DAS [SS]. Direct 15N isotopic tracer method was used in this study, whereby the 15N labelled urea fertilizer 5.20% atom excess (a.e) was utilized as a tracer for nitroge nuse efficiency study (NUE)by the test crops. 15Nisotope presence in the samples was determined using emission spectrometry and percentage of total nitrogen was determined by the Kjeldahl method. 15N a.e values of the samples were used in the determination of the efficiency of N used by the mutant varieties. The 13C isotope discrimination (Δ13C) technique was used as a tool to identify drought resistance rice species with improves water use efficiency (WUE). WUE is the ratio of the biomass produced by the water consumed. For 13C discrimination analysis, a sample of rice leaf was analyzed for 13C content by using Isotope Ratio Mass Spectrometer (IRMS).The parameter, viz. plant height, number of tillers, grain yield, 1000 grain weight, NUE, Δ13Cand WUE were recorded. Results from this study showed nitrogen rates imparted significant effects on plant height, number of tillers, grain yield, 1000 grain weight and WUE, while water potentials had significant effects on plant height, grain yield, 1000 grain weight, NUE, Δ13Cand WUE. Δ13C has a low but significantly negative relationship with WUE. Rice mutants NMR151 and NMR152 were found to be not significantly different except for their NUE.
Nowadays, in extreme changing environments, development of submergence tolerance variety is necessary for ensuring
crop production stability where, it is known that Malaysian commercial rice varieties such as MR219, MR220 and MR263
were severely susceptible to submergence. First step towards the development of submergence tolerance variety starts
with the breeding program by crossing MR263 and Swarna-Sub1. Marker-assisted selection (MAS) was carried out through
the utilization of simple sequence repeats (SSR) markers, considering its reliability as pre-selection tools to conduct this
research. F1
generations plants were confirmed by tightly linked markers. In case of background study, out of 180 SSR
markers, 38 were found polymorphic between two parents. Association of molecular markers and submergence tolerance
were determined using Chi-square test. MR263 × Swarna-Sub1 F2 lines were tested for Sub1 gene conformation using
the markers RM8300 and RM219. These markers showed a good fit to the expected marker segregation ratio (1:2:1) in
a Mendelian single gene model (DF=1.0, p≤0.05). Eleven homozygous lines with Sub1 gene out of 256 were selected
for future development of submergence tolerant varieties. Eleven lines were selected based on phenotypic study and
agronomic performance.
Kenaf (Hibiscus cannabinus L.) is one of the world’s most economically important fiber crops particularly in Asia-Pacific region. Mutation induction is a method to increase genetic divergence associated with selection, recombination, or a combination of these approaches in plant breeding. One of preliminary procedures for an execellent mutation breeding program is the radiosensitivity study to determine the optimal doses for irradiation. A total of 10 different doses of acute gamma rays (0, 100, 200, 400, 800, 1000, 1200, 1500, 1700 and 2000 Gy) from ceasium-137 source were applied to the seeds of V 36 kenaf variety. The irradiated seeds including the control were planted in trough for 30 days. The gamma irradiation effects on several parameters such as seedling survival percentages, plant height, root length, shoot fresh weight, root frest weight, shoot dry weight and root dry weight were analysed. From the radiosensitivity curve, the LD50 and LD25 values were estimated at 810 and 310 Gy, respectively. Two doses (200 Gy and 300 Gy) based on LD25 were chosen for evaluating the effects of gamma irradiation on morphological traits in M1 generation. Irradiated and non-irradiated seeds were planted in the field at Beseri, Perlis. About 10 phenotypic traits of irradiated plants were observed and evaluated against the controls. Cluster analysis on M1 progenies showed that the mutation could be classified into eight genotypic groups. The first two components from principal component analysis explained about 77.99% of variation. Number of seeds per pod, weight of seeds per plant and dry stem biomass play an important role in explaining the variation since they showed positive correlated values for the first component analysis. Morphological changes such as flower shape, flower colour, and leaf shape were also observed in M1 generation. The findings of this study are important in determining the effectiveness of these doses in generating mutations on kenaf plant and subsequent breeding program to develop new kenaf varieties with enhanced quality traits.
An archeological study, conducted by the Archaeological Global Research Centre, Universiti Sains Malaysia shows the evidence of shock metamorphisms (suevite breccia) and crater morphology at Bukit Bunuh in Lenggong area of north Perak, Malaysia. A regional gravity survey focusing at Bukit Bunuh and its surrounding area was conducted to justify the occurrence and to determine the diameter and subsurface geological structure of the Bukit Bunuh impact crater. The gravity survey, using a Scintrex CG5 gravity meter, comprises 476 gravity stations with a 500 m spacing covering an area of approximately 160 km2. The elevation of the gravity stations were obtained by using a pair of Wellace and Tiernan altimeters. The gravity data were corrected for drift, free air, bouguer, latitude and terrain in order to produce a corrected gravity data of the study area. The data were processed and analysed using Oasis Montaj (Geosoft software) to produce bouguer, residual, Total Horizontal Derivative (THD) residual, regional and Total Horizontal Derivative (THD) regional anomaly maps for qualitative and quantitative interpretations. The bouguer gravity map shows relatively low negative anomaly with nearly circular shaped contour around the Bukit Bunuh area. This anomaly was interpreted as the remnant of meteorite impact structure with rounded shaped crater in the study area. The bouguer anomaly map shows that the Bukit Bunuh impact crater has a diameter of approximately 2.5 km. The impact structure was successfully modeled as a complex impact crater with maximum depth of about 300 m. The bouguer anomaly map also showed the possible occurences of at least two more impact craters located in the northeast and southeast areas of the Bukit Bunuh crater and these structures need further investigation for confirmation.
The research on radiation induced mutation has been conducted as one of the promising method of plant breeding in Malaysia since 1980s. Nuclear Malaysia is leading research institute inMalaysia conducting plant mutationbreeding research. Gamma Greenhousefacility located in Nuclear Malaysiais one of the irradiation facilitiesto serve as a chronic irradiation facility for inducing mutation in various organisms including plants, fungi and microbes.Chronic irradiation refers to the exposure of materials at a lower dose rate over a long period of time. Previous studies have shown that this type of irradiation can minimize radiation damages to living materials and produces a wider mutation spectrum, therefore is very useful for trait improvements in irradiated organisms. Experiments on induce mutation using Gamma Greenhouse facility for crop improvement program have been conducted since its first operation in 2009. Various plant species including ornamental and herbal plants, food crops and industrial crops have been irradiated to improve their traits such as higher yield and biomass, pest and disease tolerance, higher bioactive compounds, longer bloom time and many others. Most of these crop improvement programs were done through collaborations with other agencies in Malaysia such as universities, research institutes and government departments. A number of publications on crop improvement using Gamma Greenhouse have been published inlocal and international journals as well as seminar presentations at national and international levels. The outputs from induced mutation via chronic radiation using Gamma Greenhouse could be of great interest for plant breeders dealing with improvement and development of new cultivars. This paper discusses the activities and achievement in plant breeding and improvement using Gamma Greenhouse Facility in Malaysia.
Blast caused by the fungus Magnaporthe oryzae is a significant disease threat to rice across the world and is especially prevalent in Malaysia. An elite, early-maturing, high-yielding Malaysian rice variety, MR263, is susceptible to blast and was used as the recurrent parent in this study. To improve MR263 disease resistance, the Pongsu Seribu 1 rice variety was used as donor of the blast resistance Pi-7(t), Pi-d(t)1 and Pir2-3(t) genes and qLN2 quantitative trait locus (QTL). The objective was to introgress these blast resistance genes into the background of MR263 using marker-assisted backcrossing with both foreground and background selection.