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28 November 2018, Volume 25 Issue 6 Previous Issue    Next Issue
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SRG1, Encoding a Kinesin-4 Protein, Is an Important Factor for Determining Grain Shape in Rice Ran Qin, Akhter Delara, Chengcong Yang, Kumar Nath Ujjal, Eshag Jamal, Xiaoli Jin, Chunhai Shi 2018, 25(6): 297-307.  DOI: 10.1016/j.rsci.2018.06.008 Abstract ( )   HTML ( )   PDF (1889KB) ( )   Grain shape is one of the important agronomic traits, which is closely related to the yield of rice. A new rice mutant, named small and round grain (srg1), was isolated from an indica cultivar Zhenong 34 by ethyl methane sulfonate (EMS) mutagenesis. The microscopic analysis showed that the cell length of spikelet in srg1 was decreased compared with that in wild type (WT), which caused the grain length short. Meanwhile, the grains of srg1 were wider than those of WT because of the increased cell layers in spikelet in the lateral direction. Therefore, the inhibition of cell expansion and increased cell proliferation collectively led to the small and round grain. By map-based cloning, the gene SRG1 was located on the short arm of chromosome 9, which encodes a kinesin-4 protein, represented by the gene LOC_Os09g02650. A single nucleotide polymorphism, occurred in the 16th exon of SRG1, led to premature translation stop in mutant. The cell cycle-related genes were up-regulated in srg1, which conferred that SRG1 controlled grain width through the cell proliferation. Since the role of SRG1 in regulating grain shape was not clarified well before, it is valuable to explore the mechanism of grain development. This study could, hence, provide a morphogenesis and molecular basis for elucidating the function of SRG1, as well as a new germplasm resource for the further study of grain development.

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Revealing Genetic Relationship and Prospecting of Novel Donors Among Upland Rice Genotypes Using qDTY-Linked SSR Markers Mukherjee Mitadru, Padhy Barada, Srinivasan Bharathkumar, Mahadani Pradosh, Yasin Baksh Sk, Donde Ravindra, Nath Singh Onkar, Behera Lambodar, Swain Padmini, Kumar Dash Sushanta 2018, 25(6): 308-319.  DOI: 10.1016/j.rsci.2018.10.001 Abstract ( )   HTML ( )   PDF (1234KB) ( )   A total of 17 simple sequence repeat (SSR) markers linked to QTLs (qDTYs) governing grain yield under reproductive stage (RS) drought stress were used to assess the genetic relationship and prospecting new donors for qDTYs among 32 popular upland rice genotypes. These SSR markers generated a total of 36 alleles with an average allele count of 2.1 per locus. Polymorphic information content value of the markers ranged from 0.376 to 0.662 with an average value of 0.484. The expected heterozyogosity ranged from 0.381 to 0.632. STRUCTURE analysis divided the 32 genotypes into three sub-populations. Subsequent phenotyping revealed that all the tolerant genotypes were grouped into one sub-population, whereas the moderately tolerant and susceptible genotypes were grouped into separate sub-populations. Phylogenetic tree constructed by the unweighted neighbour-joining method also divided the genotypes into three clusters. The grouping pattern of genotypes into the clusters was similar to that into the STRUCTURE analysis, on the basis of drought tolerance level. The average value of genetic dissimilarity coefficient among the genotypes was observed to be 0.486. Furthermore, by combining genotyping data with phenotyping data, 16 new donors for 6 qDTYs were identified.

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Effects of Exogenous 5-Aminolevulinic Acid and 24-Epibrassinolide on Cd Accumulation in Rice from Cd-Contaminated Soil Feijuan Wang, Yiting Zhang, Qinxin Guo, Haifeng Tan, Jiahui Han, Haoran Lin, Hewen Wei, Guangwei Xu, Cheng Zhu 2018, 25(6): 320-329.  DOI: 10.1016/j.rsci.2018.10.002 Abstract ( )   HTML ( )   PDF (604KB) ( )   High grain-Cd-accumulating rice variety Yongyou 9 was planted in Cd-contaminated farmland in Taizhou City, Zhejiang Province, China to study the effects of 5-aminolevulinic acid (ALA) and 24-epibrassinolide (EBR) on Cd accumulation in brown rice. Results showed that the exogenous ALA and EBR had no significant effects on agronomic traits, soil pH and total Cd content in soil, but had some effects on the available Cd content in soil, and significantly influenced the Cd accumulation in the different parts of rice. Results also showed that 100 mg/L exogenous ALA significantly reduced the Cd accumulation in brown rice to blow the food safety standard (0.2 mg/kg), and also significantly reduced the Cd contents in the roots and culm of rice. However, 200 mg/L exogenous ALA treatment increased the Cd content in brown rice remarkably. In addition, 0.15 mg/L EBR treatment increased Cd accumulation in roots, culm, leaves and brown rice notably, whereas 0.30 mg/L exogenous EBR treatment reduced the Cd accumulation in brown rice properly, but it was not significant. Therefore, proper concentration of ALA can effectively reduce the Cd accumulation in brown rice, which can be used as an effective technical method for the safe production of rice in Cd polluted farmland.

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Factors Affecting Sensory Quality of Cooked japonica Rice Yanjie Xu, Yining Ying, Shuhong Ouyang, Xiaoliang Duan, Hui Sun, Shukun Jiang, Shichen Sun, Jinsong Bao 2018, 25(6): 330-339.  DOI: 10.1016/j.rsci.2018.10.003 Abstract ( )   HTML ( )   PDF (1386KB) ( )   The sensory quality of cooked rice is an important factor in determining its market price, as well as consumer acceptance and breeding efforts aimed at improvement of rice grain quality. In this study, the sensory quality and physicochemical properties of three japonica rice varieties harvested in two different growing locations (Xiangshui and Hangzhou of China) were compared to determine the most important factors affecting the sensory quality. All the three varieties had higher scores for overall sensory quality in Xiangshui than in Hangzhou, indicating that the growing location is a key factor in determining the sensory quality of cooked japonica rice. In addition to growing location, variety (genotype) also had an important effect. Longdao 18 scored the highest for overall sensory quality in the two locations, whereas Longdao 30 had the lowest score in Xiangshui, and both Longdao 20 and Longdao 30 had the lowest scores in Hangzhou. Many physicochemical properties, such as apparent amylose content, protein content, thermal properties and free amino acid contents, showed significant differences between the two locations. Correlation analysis showed that apparent amylose content and protein content had contrasting effects on all the sensory attributes. The overall sensory quality was negatively correlated with protein content (r = -0.89, P < 0.01) and positively correlated with gel hardness (r = 0.91, P < 0.01), indicating that the protein content and hardness are important physicochemical properties for predicting the sensory quality of japonica rice. These findings will provide guidance for selection from the diverse genotypes available to develop new varieties with the desired eating and cooking quality.

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Cover Crops as Affecting Soil Chemical and Physical Properties and Development of Upland Rice and Soybean Cultivated in Rotation Stephan Nascente Adriano, Fernando Stone Luis 2018, 25(6): 340-349.  DOI: 10.1016/j.rsci.2018.10.004 Abstract ( )   HTML ( )   PDF (1411KB) ( )   Cover crops can provide changes in soil chemical and physical properties, which could allow a sustainable development of soybean and upland rice rotation in Brazilian Cerrado. The objective of this study was to determine the effects of cover crops (cultivated in the offseason) in the soybean-upland rice rotation (cultivated in the summer season) on the soil chemical and physical properties, yield components and grain yield of the cash crops. The experimental design was a randomized block design in factorial scheme 4 × 2 with six replications. Treatments were composed by four cover crops: fallow, millet (Pennisetum glaucum) + Crotalaria ochroleuca, millet + pigeon pea (Cajanus cajans), and millet + pigeon pea + Urochola ruziziensis in the offseason with one or two cycles of cover crops, with rice (Oryza sativa) or soybean (Glycine max) in the summer season. Cover crops alone provided no changes in soil chemical properties. However, the rotation cover crops / cash crops / cover crops / cash crops reduced pH, Al and H + Al and increased Ca, Mg, K and Fe contents in the soil. The cover crops millet + pigeon pea and millet + pigeon pea + U. ruziziensis improved soil physical properties in relation to fallow, especially in the 0-0.10 m soil layer. In spite of the improvement of the soil physical properties after two years of rotation with cover crops and cash crops, the soil physical quality was still below the recommended level, showing values of macroporosity, S index and soil aeration capacity lower than 0.10 m3/m3, 0.035 and 0.34, respectively. Upland rice production was higher under mixtures of cover crops than under fallow, mainly because of soil physical changes done by these mixtures of cover crops. Soybean grain yield was similar under all cover crops tested, but was higher after the rotation cover crops / upland rice / cover crops than after only one cycle of cover crops.

Short Communications

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Choices of Varieties and Demand for Improved Rice Seed in Fogera District of Ethiopia H. Mesfin A., Zemedu L. 2018, 25(6): 350-356.  DOI: 10.1016/j.rsci.2018.10.005 Abstract ( )   HTML ( )   PDF (726KB) ( )   In this study, 151 households were randomly drawn from three randomly selected Kebele in probability proportional to size method. The demographic and socio-economic factors that determine the participation in improved varieties were household labor availability, education level of the household head, land holdings, distance to the nearest village market, proximity to the main market, and distance to access agricultural extension and access to the source of rice seeds. However, determinants of choice decision varied from cultivar to cultivar. The evidence of the study from the interdependence among the decision of adoption of improved rice varieties suggested that technology adoption will be accelerated by launching a progressively developing package and scheme of rice technology generation, and points to the importance of mobilising additional resources to augment households’ efforts at popularization and promotion of improved rice cultivars. The findings from Linearized Almost Ideal Demand Systems (LA/AIDS) model showed that compelling evidence for small proportion changes in own prices and cross price of improved rice varieties led to greater than unitary proportionate changes in their purchases. The results generally showed that farmers were very sensitive to changes in improved rice seed prices and incomes. The major implication of the findings was that any intervention to improve farmers’ seed purchases should take into account efforts to increase farmers’ purchasing power of agricultural inputs like improved seeds and fertilizers.

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Appraisal of Biofertilizers in Rice: To Supplement Inorganic Chemical Fertilizer Iqbal Khan Haider 2018, 25(6): 357-362.  DOI: 10.1016/j.rsci.2018.10.006 Abstract ( )   HTML ( )   PDF (677KB) ( )   A field experiment was carried out to evaluate the feasibility of inoculating rice seedlings with biofertilizers (Azospirillum and Trichoderma) in order to reduce the use of chemical inorganic nitrogen (N) fertilizer on rice variety BU Dhan 1. The plant performances were better when 25% less inorganic N was applied with Trichoderma and combined application of Trichoderma and Azospirillum. Plants contained the highest chlorophyll concentrations when they were treated with 75% N + Trichoderma. Considering the yield attributes, 75% N + Trichoderma and 75% N + Trichoderma + Azospirillum performed similar to the control. The grain yield of rice was similar to the recommended dose even with 25% less N application. Application of Trichoderma resulted higher yield, followed by combined application with Azospirillum. Results revealed the greater scope of applying biofertilizer (Trichoderma) to supplement chemical N fertilizer with optimum yield of rice.