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Exploring the genetic aspects of germplasm using genotypic and phenotypic analysis is more reliable for the development of rice varieties that could lead to the attainment of food security. This is because genetic variations provide a space for recombinants, which is an important factor in new varietal development. This study was conducted to evaluate genetic variability and diversity among 32 coloured rice accessions using agro-morphological characteristics and simple sequence repeats (SSR) markers. Quantitative traits (morphological, grain quality and antioxidant properties) and 34 SSR molecular markers were used as tools for determining cultivar identities and genetic diversity. Most of the quantitative traits showed significant differences (p ≤ 0.01) among all rice accessions. Clustering analysis from quantitative traits categorised the accessions into four groups. Similarly, the 32 accessions were grouped into 4 cluster groups based on the analysis of 34 SSR markers. The accessions YTM15, Pulut Merah 3, Padi Randau, Ringan Bawang, DNJ128 and DV 107 can be potentially selected for development of new varieties for local cultivation. Finally, these accessions can be used as parents in further breeding programmes. [ABSTRACT FROM AUTHOR]

A large number of rice agronomic traits are complex, multi factorial and polygenic. As the mechanisms and genes determining grain size and yield are largely unknown, the identification of regulatory genes related to grain development remains a preeminent approach in rice genetic studies and breeding programs. Genes regulating cell proliferation and expansion in spikelet hulls and participating in endosperm development are the main controllers of rice kernel elongation and grain size. We review here and discuss recent findings on genes controlling rice grain size and the mechanisms, epialleles, epigenomic variation, and assessment of controlling genes using genome-editing tools relating to kernel elongation. [ABSTRACT FROM AUTHOR]

Global warming is the main cause of greenhouse gases (GHG) including carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). The Denitrification and Decomposition (DNDC) model is considered a good tool to validate and estimate these gases from various agricultural practices. The farmers of Kota Bharu, Kelantan, Peninsular Malaysia grow rice in soils which has clay loam soil texture with 5.59 soil pH and 0.0193 kg ha-1 initial soil organic carbon. The farmers grow two rice crops by applying 248 kg N ha-1 year-1. The model validation was found satisfactory and gave correct simulations while comparing with other international modeled studies. The yearly DNDC simulation for CO2 flux rate was 4392 kg C ha-1, 33.7 N2O kg ha-1 year-1 with -2 CH4 flux. The Global Warming Potential (GWP) for CO2 flux was 16105 kg CO2-eq ha-1 and N2O of 16403 kg CO2-eq ha-1; however, CH4 was found as sink (-66 kg CO2-eq ha-1). Bulk of all these gases had 32442 kg CO2-eq ha-1 net GWP. The DNDC simulations of field uncertainties by N rates (20% less than recommended, recommended and 20, 40 and 60% more than recommended) and SOC rates at 0.04, 0.03, 0.02 and 0.0193 kg C kg-1) were run through linear correlation. The unit increase in N as well as SOC rates correspondingly increased NH3 volatilization by 4.09, 3.76, 2.31 and 1.28 kg N ha-1 year-1, respectively, N2O flux by 10.06, 6.80, 6.51 and 1.16kg N ha-1, respectively, NO flux by 0.76, 3.25, 3.14 and 2.03 kg N ha-1 year-1 and N2 flux by 17.87, 18.21, 21.75 and 25.22 kg ha-1 year-1, respectively. In conclusion, the validation of agricultural data through DNDC model was perfect. The ongoing agricultural practices in the area have been found contributing small quantities of CO2 and N2O except CH4 which is serving as sink. In future, the increase in soil organic carbon as well as nitrogen rates probably may involve this area towards more GHG (CO2, N2O, CH4) emissions. [ABSTRACT FROM AUTHOR]

The experiment was conducted to assess the responses of salinity on the growth, nutrient accumulation and yield of rice genotypes. Five Malaysian genotypes (MR33, MR52, MR211, MR232 and MR219), two salt sensitive (BRRI dhan 29 and IR20) and one salt tolerant genotypes (Pokkali) were evaluated in four levels of salinity. Two factors complete randomized design (CRD) was used with four replications. Dry weight of root, shoot and yield significantly decreased with the increase of salinity levels, while MR232 and MR211 were less affected. Na+ ions accumulations increased in the root and shoot with the increase of salinity, while the lowest accumulation was in MR211. Na+/ K+ratio sharply increased in the root with increasing the salinity. Whereas, Ca++/Na+ and Mg++/Ca++ ratio showed decreasing trend with increasing salinity level. The maximum amount of nitrogen and phosphorous accumulation was observed in the shoot of MR211, while Na+ in BRRI dhan29, K+ in Pokkali. The highest accumulation of Na+ and K+ observed in the root of MR219. The maximum Ca++ and Mg++ were found in MR33 and MR211, respectively. Considering all, genotypes MR211 andMR232 were found to be relatively tolerant to salt than the other genotypes. [ABSTRACT FROM AUTHOR]

Rice production is a large industry and there are a lot of opportunities which can be obtained from it. Recently, the demand for specialty and high quality rice has increased remarkably, owing to the affluent and health-conscious consumers in Malaysia. The research on upland rice has been neglected because of its low yield, though it has many good characteristics, including good fragrance and long grains. Furthermore, it has the advantage of being cultivated on dry land without accumulation of water. Therefore, a large track of idle lands in Malaysia can be developed for this purpose. This study involves a documentation of upland rice in natural conditions. Basic information on the varieties of upland rice which produce high grain yields and quality (fragrance, colour) was collected from selected locations in Peninsular Malaysia, Sabah, and Sarawak. For this purpose, both soil and plant materials (at harvest) were collected. The soil and plant materials were analysed for their macro- and micro-nutrient contents. Standard agronomic characteristics, during growing period and at harvesting time, were also measured. The data were analysed using the SAS statistical software and the mean values were then compared using the Duncan's New Multiple Range Test (DMRT) at 0.05 level of significance. Seventeen upland rice fields were identified in several locations during the course of this survey. Thirty-five (35) varieties of upland rice seeds were successfully collected. In particular, upland rice and forest soil (as a control) were acidic, contain low nitrogen content and CEC value at 0 -20 and at 20-40 cm depth. Higher Fe content was also observed, with a major limitation for the growth of upland rice. Ageh, Kendinga, and Strao varieties were selected for further evaluation on nutrient requirements using an idle land soil, owing to its growth cycle, productivity, and seed availability. [ABSTRACT FROM AUTHOR]

Nitrogen and phosphorus efficiencies are the main constraints to food production in the sub-humid and humid tropic soils. A laboratory and glasshouse study was initiated to examine the differences in the root architecture of Malaysian upland rice landraces and relate them to efficiency of the nitrogen fertilizer uptake. Six upland rice landraces, obtained locally, were soaked in water and allowed to germinate using the cigar role method. The seedlings were fertilized with a complete nutrient solution daily and the roots which were allowed to develop after 14 days were measured using the WINRHIZO. The same landraces were planted in the glasshouse in polybags containing 25 kg soil in four replications. N-15 labelled urea was applied at 170 kg N/ha and N use efficiency was measured at harvest. Significant differences in root length, surface area, root volume, average root diameter, and number of forks, between the 6 landraces were studied. Nitrogen in the plant (derived from fertilizer applied) was found to range from 6.22-27.6%. Nevertheless, a poor correlation was obtained between the length of root and the dry matter yield and the total N uptake. Five of the landraces tested showed a good potential in taking up the fertilizer N applied. [ABSTRACT FROM AUTHOR]

Plant cells accumulate praline as an osmoprotectant to conserve osmotic stability and prevent damage. However, the accumulation of proline may not be associated with tolerance to salinity. This study considered the influences of NaCl and Na2SO4 compositions, at different concentrations, on seed germination and accumulation of proline in eleven rice genotypes. Rice seeds were grown in petri dishes in the laboratory and treated with distilled water as a control and NaCI and Na2SO4 (1:1 molar concentration ratio) at 2.5, 5.0, 7.5 and 10 dS m-1 electrical conductivity for 14 days. The mean germination time (MGT) was positively affected by the increase in the concentration of salt. Conversely, there was a negative relationship between germination index (GI) and salt concentration. Shirodi, Fajr, and Shafag can be classified into salt tolerant group, while Tarom-e-Hashemi was identified as salt susceptible, based on MGT and GI. Slight changes were recorded within dry weight and water content of seedlings at different salt levels. The maximum accumulation of proline was observed at 5 dS m-1 salt concentration. No relationship was established between the accumulation of proline and the growth parameters. [ABSTRACT FROM AUTHOR]